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i. Adhesins: M protein, LTA, capsule
ii. Hyaluronidase
c. Transmission and epidemiology
i. Direct contact, through fomites and mechanical vectors
ii. Primarily preschool children
e. Prevention: good hygiene
f. Treatment: antibiotic that will target either causative organism
C. Cellulitis: fast spreading infection of the dermis and subcutaneous tissue
1. Signs and symptoms: Pain, tenderness, swelling and warmth; fever may occur
2. Causative organisms
a. Staphylococcus aureus
b. Streptococcus pyogenes
3. Immunocompromised and those with cardiac insufficiency are at high risk
4. Treatment is through oral or IV antibiotics
5. Surgical debridement in severe cases
D. Staphylococcal Scalded Skin Syndrome (SSSS)
1. Dermolytic condition caused by Staphylococcus aureus
2. Affects mostly newborns and babies
3. Systemic form of impetigo
4. Desquamation of the skin
5. Exfoliative toxin A and B
6. Must be distinguished from toxic epidermal necrolysis (TEN)
E. Gas gangrene
1. Most often caused by Clostridium perfringens (clostridial myonecrosis)
2. Signs and symptoms
a. Anaerobic cellulitis
i. Damaged necrotic muscle tissue or myonecrosis
ii. Toxins and gas
b. True myonecrosis
i. Toxins produced in large muscles and cause local necrosis
ii. Continued bacterial growth and tissue destruction
c. Pain, edema, bloody exudate, followed by fever, tachycardia, and blackened necrotic tissue filled with gas bubbles
3. Pathogenesis and virulence factors
a. Requires anaerobic environment from tissue damage
b. Alpha toxin: red blood celll rupture, edema, and tissue destruction
c. Collagenase, hyaluronidase, DNAse contribute to tissue destruction
4. Transmission and epidemiology: surgical incisions compound fractures, diabetic ulcers, septic abortion, puncture and
gunshot wounds, crushing injuries
5. Prevention and treatment
a. Cleaning and surgical repair of wounds
b. Broad spectrum antibiotics
c. Hyperbaric oxygen therapy
F. Vesicular or pustular rash diseases
1. Chickenpox
a. Signs and symptoms
i. Fever and skin lesions
ii. Macules and papules to itchy fluid-filled vesicles
iii. Centripetal lesions
iv. Secondary infections may result; treat with antibiotics
v. Infection during pregnancy may result in birth defects
2. Shingles: reactivation of latent virus in ganglia
a. Causative agent: Human Herpesvirus 3 (HHV-3), also called Varicella-Zoster virus (VSV
b. Pathogenesis and virulence factors
i. Enters respiratory tract, enters the bloodstream, disseminates to skin
ii. HHV-3 remains latent in ganglia, protected from the immune system
c. Transmission and epidemiology
i. Transmission by respiratory droplets and fluid of skin lesions
ii. Contracting the disease gives lifelong immunity
iii. Vaccination has dramatically reduced incidence
d. Prevention
i. Live, attenuated vaccine
ii. Zostavax for prevention of shingles in adults 60 years and older

e. Treatment: alleviation of discomfort
3. Smallpox
a. Signs and symptoms
i. Fever
ii. Rash in the mouth
iii. Macular, papular, vesicular, and pustular
b. Causative agent: variola virus, an orthopoxvirus
c. Pathogenesis and virulence factors
i. Invades nasopharyngeal mucosa and multiples in lymph nodes
ii. Lesion occurs at dermal level; scars remain
d. Transmission and epidemiology
i. Droplet transmission and fomites
ii. Eliminated worldwide but potential bioterrorism agent
e. Prevention
i. Vaccine; vaccines are no longer administered.
f. Treatment: none.
G. Hand, foot, and mouth disease
1. Most common in babies and children under age 5
2. Sore throat, fever, malaise, spots inside mouth, spots on palms and soles
3. Most frequently Coxsackie virus
4. Transmitted by secretions and direct contact.
5. Usually uncomplicated, no treatment, no vaccine
H. Maculopapular rash diseases
1. Measles (Rubeola)
a. Signs and symptoms
i. Koplik’s spots
ii. Maculopapular exanthem
iii. Subacute sclerosing panencephalitis (SSPE)
b. Causative agent: single-stranded enveloped RNA virus, Morbillivirus
c. Pathogenesis and virulence factors
i. Respiratory mucosa, travels to lymphatic system, causes viremia
ii. Induces formation of large syncytia (giant cells with many nuclei)
iii. Disables many aspects of the host immune response
d. Transmission and epidemiology
i. Transmitted through respiratory droplets
ii. No reservoir other than humans
f. Prevention
i. MMR vaccine (for measles, mumps, and rubella)
ii. Good vaccine coverage essential for herd immunity
g. Treatment: relieve symptoms
2. Rubella, German measles
a. Signs and symptoms
i. Postnatal: malaise, fever, sore throat, lymphadenopathy, rash of pink macules and papules first appear on
the face and moving down the trunk
ii. Congenital (prenatal) infection of the fetus: multiple permanent defects, including deafness, cardiac
abnormalities, retardation
b. Causative agent: Rubivirus, single-stranded RNA virus with loose envelope
c. Pathogenesis and virulence factors
i. Unremarkable in postnatal rubella
ii. Prenatal infection can stop mitosis and induce apoptosis
d. Transmission and epidemiology
i. Endemic worldwide
ii. Contact with respiratory sections and occasionally urine
iii. Close living conditions required for spread
f. Prevention: MMR vaccination
g. Treatment: for symptoms
3. Fifth Disease, Erythema infectiosum
a. Characteristic “slapped-cheek” appearance
b. The causative agent is parvovirus B19
c. Very contagious; can cause stillbirth in pregnant women
d. Transmitted through respiratory droplets or direct contact
4. Roseola

a. Maculopapular rash
b. HHV-6
c. No vaccine, no treatment recommended
I. Wart-like eruptions
1. Viruses cause all warts
2. Warts (papillomas)
a. Benign, squamous epithelial growths
b. Human Papilloma Virus (HPV)
i. Common (seed) warts HPV-2, -4, -27, -29
ii. Plantar warts HPV-1
c. Spread by direction contact, autoinoculation
d. Harmless, resolve over time
e. Non-prescription salicylic acid or cryosurgery for removal
J. Large pustular skin lesions
1. Cutaneous anthrax
a. Bacillus anthracis endospores entering through small cuts or abrasions
b. Eschar formation
c. Penicillin and ciproflaxin treatment
K. Ringworm (Cutaneous Mycoses)
1. Fungal dermatophytes cause mycoses that are confined to the nonliving epidermal tissues, hair and nails
a. Ringworm of the scalp (Tinea Capitis)
b. Ringworm of the beard (Tinea Barbae)
c. Ringworm of the body (Tinea Corporis)
d. Ringworm of the groin (Tinea Cruris)
e. Ringworm of the foot (Tinea Pedis)
f. Ringworm of the hand (Tinea Manuum)
g. Ringworm of the nail (Tinea Unguium)
2. Causative agents
a. There are about 39 species in the genera Trichophyton, Microsporum, and Epidermophyton;
3. Pathogenesis and virulence factors
a. Digest keratin
b. Spores may remain for years on fomites
4. Transmission and epidemiology: direct and indirect contact with infected animals; soil
5. Prevention and treatment
a. Avoid contact
b. Treatment with topical antifungal
L. Superficial mycosis: Outer epidermis; innocuous infection; cosmetic effect. (Tinea versicolor)
The Surface of the Eye and Its Defenses
A. Conjunctiva; secretes and oil- and mucus-containing fluid that protects the eye
B. Cornea; 5-6 layers of epithelial cells that can regenerate quickly following damage
C. The flushing action of tears, containing lysozyme and lactoferrin, is a major protective feature
D. Immune privilege
Normal Biota of the Eye: Generally Sparse
Eye Diseases Caused By Microorganisms
A. Conjunctivitis: Infection of the conjunctiva; pinkeye
1. Signs and symptoms
a. Most bacterial infections produce a milky discharge
b. Viral infections produce a clear exudate
2. Causative agents and their transmission
a. Neonatal eye infection—Neisseria gonorrhoeae or Chlamydia trachomatis
b. Bacterial conjunctivitis in other ages is usually caused by Staphylococcus aureus, Streptococcus pneumoniae,
occasionally by Haemophilus influenzae, and Moraxella species
c. Viral conjunctivitis: usually caused by adenoviruses
d. Both bacterial and viral conjunctivitis is highly contagious
3. Prevention and treatment
a. Good hygiene
b. Antibiotic treatment
B. Trachoma: Chronic infection of the eye with Chlamydia trachomatis
1. Preventable form of blindness
2. Transmitted by contaminated fingers, fomites, fleas, hot dry climate
3. Mild discharge, inflammation, pannus

4. Early treatment is effective and prevents complications
C. Keratitis
1. Keratitis is a more serious eye infection than conjunctivitis
2. Herpes simplex virus type 1 HSV-1 and HSV-2
3. Gritty feeling, conjunctivitis, sharp pain, sensitivity to light
4. Recent cases involving contact lens wearers; hygiene is critical; Acanthaemoba
Chapter 20: Infectious Diseases Affecting the Nervous System
The Nervous System and Its Defenses
A. The nervous system has two parts:
1. Central nervous system (the brain and spinal cord)
2. Peripheral nervous system (spinal and cranial nerves and ganglia)
B. Brain and spinal cord are enclosed within a tough casing, the meninges
1. Dura mater, arachnoid mater, and pia mater
2. Common site of infection
C. Subarachnoid space is filled with cerebrospinal fluid (CSF)
1. Provides nutrients to CNS
2. Liquid cushion for brain, spinal cord
D. Blood-brain barrier: Prevents most microorganisms from penetrating into CNS
Normal Biota of the Nervous System
A. No normal biota
B. Gut-brain axis
Nervous System Diseases Caused by Microorganisms
A. Meningitis
1. Inflammation of the meninges
a. Caused by bacteria, respiratory viruses, fung
b. Lumbar puncture is performed to obtain CSF when meningitis is suspected
2. Signs and symptoms
a. Photophobia, headache, painful or stiff neck, and fever
b. Increased number of white blood cells in the CSF
3. Neisseria meningitidis: gram-negative diplococcus
a. Pathogenesis and virulence factors
i. Portal of entry is the upper respiratory tract
ii. Petechiae on trunk and appendages
iii. Meningococcemia can become a fulminant disease with a high mortality rate
iv. Bacterial virulence factors
A. Protease that destroys IgA
B. Capsule that is antiphagocytic
b. Transmission and epidemiology
i. Transmitted through close contact with secretions or droplets
ii. Pili promote adherence to mucosal membranes
iii. 330% of adults are carriers
iv. Highest risk groups are young adults (1524 years)
d. Prevention and treatment
i. Immunization begins at 11 years (Menveo or Menactra); later booster
ii. When disease occurs, penicillin G is effective when administered as soon as
possible after presumptive diagnosis
4. Streptococcus pneumoniae (the pneumococcus)
a. Most likely in patients with underlying susceptibility
b. Gram-positive flattened coccus with an antiphagocytic polysaccharide capsule
c. Produces alpha hemolysin and hydrogen peroxide
d. Two vaccines
i. Prevnar (7 serotypes; childhood)
ii. Pneumovax (23 serotypes; adults)
5. Haemophilus influenzae
a. Gram-negative pleomorphic rod
b. Acute bacterial meningitis in humans
c. Hib vaccine has virtually eliminated the disease in the United States
6. Listeria monocytogenes
a. Gram-positive coccobacilli
b. Listeriosis

i. Affects the brain and meninges
ii. Septicemia
iii. Contaminated dairy products, poultry, and meat
iv. Grows at refrigeration temperatures (cold enrichment)
v. Rapid diagnostic kits now available for testing food products
vi. Start antibiotic therapy as soon as listeriosis is suspected
7. Cryptococcus neoformans, a fungus that causes a chronic form of meningitis
a. Transmission and epidemiology
i. Bird droppings
ii. AIDS patients are susceptible
b. Pathogenesis and virulence factors
i. Transported from respiratory system to blood to nervous system
ii. Tumor-like masses in the meninges and brain
d. Prevention and treatment
i. No prevention
ii. Treatment with fluconazole and amphotericin B for weeks-months
8. Coccidioides immitis
a. Fungal infection that causes "Valley Fever" in the United States southwest
i. Hyphae at 25ºC
ii. Spherule at 37ºC
b. Coccidioidomycosis of the meninges
c. Pathogenesis and virulence factors
i. Systemic fungal infection of high virulence
ii. Begins as pulmonary infection and quickly disseminates
d. Transmission and epidemiology
i. Found in semiarid, relatively hot climate
ii. Outbreaks usually associated with farming, archeological digs, construction, and mining
iii. Southwestern US, Mexico, and parts of Central and South America
f. Prevention and treatment
i. Most patients do not require treatment
ii. Disseminated disease requires oral fluconazole.
iii. Procedures to avoid aerosolizing soil are helpful
9. Viruses
a. Aseptic meningitis: no bacteria or fungi found in the CSF; milder
b. Often found in children
c. Enteroviruses cause 90% of cases
d. Herpesviruses such as herpes simplex type 2, HHV-6 and HHV-7, HHV-3 (Varicella-zoster virus), and
cytomegalovirus (CMV)
e. Arboviruses, arenaviruses, adenoviruses, and HIV infection
B. Neonatal and infant meningitis
1. Transmitted by the mother during passage through birth canal
2. Streptococcus agalactiae
a. Group B streptococci (All pregnant mothers are screened for this at the 2nd trimester).
b. Most frequent cause of neonatal meningitis
3. Escherichia coli K1 strain; most victims are premature; many die or suffer brain damage
4. Cronobacter sakazakii
a. Found in contaminated powdered infant formula
b. Rare, but with a high fatality rate
C. Acute encephalitis: Viral infection
1. Arboviruses: transmitted by fleas and ticks
a. Pathogenesis and virulence factors
i. Arthropod bite releases virus into bloodstream; replicate in lymphoid tissue,
viremia establishes brain infection
ii. Symptoms: coma, convulsions, paralysis, tremor, loss of coordination,
memory deficit, changes in speech & personality, heart disorders
c. Prevention and treatment
i. No satisfactory treatment; supportive measures for symptoms
ii. Mosquito abatement
iii. No vaccines available
d. Arboviral encephalitis
i. West Nile Encephalitis
ii. La Crosse Virus

iii. Jamestown Canyon Virus
iv. Powassan Virus
v. Eastern Equine Encephalitis
2. Herpes simplex virus
a. Type 1 and 2
b. Causes encephalitis in newborns born to HSV-positive mothers
4. Other Virus-Associated Encephalitides
a. Measles and other childhood rash diseases – postinfectious encelphalities (PIE)
b. Rabies (see later discussion)
D. Subacute encephalitis
1. Toxoplasma gondii: protozoan, causes toxoplasmosis
a. Signs and symptoms
i. Asymptomatic or mild symptoms in most
ii. In immunocompromised patients, becomes chronic or subacute
b. Pathogenesis and virulence factors: obligate intracellular parasite
c. Transmission and epidemiology
i. Pregnant women
ii. Feline contact
e. Prevention and treatment
i. Pyrimethamine and leucovorin and sulfadiazine
ii. Hygiene
2. Measles virus
a. Subacute sclerosing panencephalitis (SSPE)
b. Can appear after an initial measles episode
3. Prions: Proteinaceous infectious particles
a. Transmissible spongiform encephalopathies (TSEs)
i. Creutzfeldt-Jakob disease (CJD) in humans
ii. Scrapie in sheep and goats
iii. Bovine spongiform encephalopathy (BSE)
b. Signs and symptoms: altered behavior, dementia, memory loss, impaired senses, delirium and premature senility
c. Causative agent
i. PrPSC protein becomes catalytic to convert PrPC proteins
ii. Can be infectious in a new host
d. Pathogenesis and virulence factors
i Spongiform lesions in the brain
ii. Stimulates no immune response
iii. Resistant to chemicals, radiation, and heat.
e. Transmission and epidemiology
i. Contact with infected brain tissue or CSF
ii. Ingestion of contaminated tissue
iii. Aerosol may be a mode of transmission
iv. Can be transmitted via contaminated surgical instruments
g. Prevention and/or treatment
i. Avoid infected tissues, tainted meats
ii. No treatment; fatal
E. Rabies: Zoonotic disease characterized by fatal encephalitis
1. Signs and symptoms
a. Hydrophobia, agitation, disorientation, seizures, twitching, spasms in neck
b. Coma phase (death from respiratory or cardiac arrest)
2. Causative agent: Rabies virus, Family Rhabdoviridae, genus Lyssavirus
3. Pathogenesis and virulence factors
a. Animal saliva enter a puncture
b. Virus enters nerve endings and advance toward the spinal cord, brain
c. Virus multiplies in many other tissues, ultimately salivary glands
4. Transmission and epidemiology
a. The primary reservoirs of the virus are wild mammals
b. Can be transmitted through donated organs
6. Prevention and treatment
a. Wild animal bites are assumed to transmit and treatment is begun
b. Effective postexposure vaccine regimen is available
c. Vaccine used for mass immunization of wild animals
F. Poliomyelitis: Acute enterovirus infection of the spinal cord; infantile paralysis.

1. Signs and symptoms
a. Neurotropic virus: mild nonspecific symptoms, then muscle pain and spasm, meningeal
inflammation and vague hypersensitivity
b. Bulbar poliomyelitis: flaccid paralysis over a few hours to several days
2. Causative agent: Poliovirus, an enterovirus in the family Picornaviridae
3. Pathogenesis and virulence factors
a. Viruses adsorb to receptors of mucosal cells in the oropharynx and intestine
b. Large numbers of viruses are shed into the throat and feces
4. Transmission and epidemiology
a. Humans are the only known reservoir
b. Transmitted through food, water, hands, and mechanical vectors
c. Eradicated from Western hemisphere; still occasional outbreaks
6. Prevention and treatment
a. Alleviating pain; respiratory failure may require artificial ventilation
b. Inactivated Salk poliovirus vaccine (IPV)
c. Attenuated oral Sabin poliovirus vaccine (OPV)
G. Tetanus (lockjaw); caused by Clostridium tetani
1. Signs and symptoms
a. C. tetani releases tetanospasmin neurotoxin
b. Toxin blocks inhibition of muscle contractions
c. Muscles contract uncontrollably, resulting in spastic paralysis
2. Pathogenesis and virulence factors
a. Strict anaerobe that requires necrotic tissue that is poorly supplied with blood
b. Tetanospasmin toxin released as bacteria grow
3. Transmission and epidemiology
a. Endospores enter the body through accidental puncture wounds, burns, frostbite, crushed body parts
b. Incidence low in North America
c. Neonatal tetanus from unhygienic practices during childbirth
4. Prevention and treatment
a. Effective vaccine (tetanus toxoid)
b. Antitoxin therapy with human tetanus immune globulin (TIG)
H. Botulism: an intoxication caused by eating poorly preserved foods
1. Signs and symptoms
a. Food-borne botulism (in children and adults) resulting in flaccid paralysis
b. Botox used to treat cross-eyes and uncontrollable blinking; cosmetic
c. May help with headaches, including migraines
2. Causative agent: Clostridium botulinum
3. Pathogenesis and virulence factors: Botulinum is a powerful exotoxin
4. Transmission and epidemiology of food-borne botulism in children and adults
a. Often in home-processed foods
b. Not visible as contamination in the food
5. Transmission and epidemiology of infant botulism
a. May be associated with honey consumption
b. Floppy baby syndrome
6. Transmission and epidemiology of wound botulism: IV drug abusers
8. Prevention and treatment: Antitoxin therapy
I. African sleeping sickness
1. Signs and symptoms: intermittent fever, enlarged spleen, swollen lymph nodes, joint pain, uncontrolled sleepiness
during the day; sleeplessness at night
2. Causative agent: Trypanosoma brucei, a flagellated protozoan
3. Transmission and epidemiology
a. Tsetse fly
b. Sub-Saharan Africa
4. Pathogenesis and virulence factors: host IgM promotes antigenic shift
6. Prevention and treatment
a. Control of tsetse flies
b. Suramin and pentamidine
Chapter 21 -- Infectious Diseases Affecting the Cardiovascular and Lymphatic Systems
The Cardiovascular and Lymphatic Systems and Their Defenses
A. The cardiovascular system

1. Heart: Pericardium, epicardium, myocardium, endocardium
2. Blood vessels: Arteries, veins, capillaries
B. The lymphatic system
1. Lymph vessels, lymph nodes, spleen
C. Defenses of the cardiovascular and lymphatic systems
1. Systemic infections
2. Leukocytes
a. Lymphocytes
b. Phagocytes
3. Medical conditions involving the blood:
a. Sepsis and septic shock
b. Bacteremia
c. Viremia
d. Fungemia
Normal Biota of the Cardiovascular and Lymphatic Systems
A. The cardiovascular and lymphatic systems are “closed” systems with no normal biota
Cardiovascular and Lymphatic System Diseases Caused by Microorganisms
A. Endocarditis: Inflammation of the endocardium
1. Signs and symptoms
a. Fever, anemia, abnormal heartbeat, shortness of breath
b. Symptoms in subacute endocarditis are less pronounced than in acute form
2. Culture and diagnosis
a. Index of suspicion, considering medical history
b. Blood cultures
3. Acute endocarditis: overwhelming bloodstream challenge with bacteria
a. Causative agents
i. Staphylococcus aureus
ii. Streptococcus pyogenes
iii. Streptococcus pneumoniae
iv. Neisseria gonorrhoeae
b. Transmission and epidemiology
i. Parenteral route: intravenous or subcutaneous drug users
c. Prevention and treatment
i. Avoid introduction of bacteria during surgical procedures or injections
ii. Untreated it is fatal
iii. Nafcillin or oxacillin; vancomycin and gentamycin
4. Subacute Endocarditis: due to damage to heart valves or congenital malformation
a. Causative agents: Streptococcus sanguis, S. oralis, and S. mutans from the oral cavity
b. Transmission and epidemiology
i. Minor disruption in mucous membranes
ii. Average age is mid-50s
iii. Males more likely than females
c. Prevention and treatment
i. Prophylactic antibiotic therapy before surgical and dental procedures
ii. Treatment same as for the acute form
B. Sepsis: Organisms are actively multiplying in the blood
1. Signs and symptoms: fever, low blood pressure, altered mental state, shaking chills
2. Causative agents
a. Majority caused by bacteria, often polymicrobial
b. Approximately 10% caused by fungi
3. Pathogenesis and virulence factors: endotoxic shock from the release of endotoxin from bacterial cell wall
4. Transmission and epidemiology
a. Parenteral introduction via IV lines or surgery
b. serious UTIs or from organ abscesses
6. Prevention and treatment
a. Broad-spectrum antibiotic
b. New nucleic acid tests offer rapid information on agent and drug susceptibility
C. Plague
1. Signs and symptoms
a. Pneumonic plague: respiratory disease
b. Bubonic plague: lymph node infection
c. Septicemic plague: consequence of the other two forms involving sepsis

2. Causative agent: Yersinia pestis
3. Pathogenesis and virulence factors
a. Capsule formation
b. Plasminogen activation, leading to clotting; microbe can resist phagocytosis
4. Transmission and epidemiology
a. Fleas
b. Animal Reservoirs
i. Endemic reservoirs: harbor the organism but do not develop disease
ii. Amplifying hosts: acquires disease from endemic reservoirs and spread it to other mammals
before dying
c. Endemic in many areas of the world; in southwestern US
6. Prevention and treatment
a. Quarantine and rodent control
b. No vaccine available
b. Antibiotics: streptomycin or genatmycin
D. Tularemia, rabbit fever
1. Signs and symptoms
a. headache, backache, fever, chills, malaise, weakness
b. other symptoms related to portal of entry
2. Causative agent: Francisella tularensis.
3. Transmission and epidemiology
a. Vast animal reservoirs in northern Europe, Asia, North America
b. Rabbits, rodents, skunks, beavers, foxes, opossums, some domestic animals
c. Tick bites most common; also biting flies, mites, mosquitoes
d. Contact with animals, animal products, water, and dust (aerosolized form)
4. Prevention and treatment
a. Antibiotics: gentamycin or streptomycin
b. No vaccine
E. Lyme Disease
1. Signs and symptoms
a. Erythema migrans: Bull’s eye rash
b. Other types of lesions: flat and scaly, pustular, like ringworm
c. Early symptoms: fever, headache, stiff neck, dizziness
d. Later symptoms: facial palsy, crippling polyarthritis
2. Causative agent: Borrelia burgdorferi, a spirochete
3. Pathogenesis and virulence factors
a. Immune evasion by switching surface antigens
b. multiple proteins for attachment to host cells
4. Transmission and epidemiology
a. Tick bites
i. Ixodes scapularis ticks
ii. Ixodes pacificus ticks
b. Correlated with high deer populations
c. Increasing in incidence, largely in New England and mid-Atlantic states
d. Highest risk group include hikers and people living in new communities near
woodlands and forests
6. Prevention and treatment
a. Protective clothing
b. Insect repellant with DEET
c. No vaccine
d. Early prolonged treatment with doxycycline and amoxicillin
F. Infectious Mononucleosis: Known as the “kissing disease” or "mono"
1. Signs and symptoms
a. Sore throat, high fever, cervical lymphadenopathy, fatigue
b. Gray-white exudate in the throat, skin rash, enlarged spleen and live
c. Sudden leukocytosis
2. Epstein-Barr virus (EBV): herpesvirus
a. Pathogenesis and virulence factors: latency
b. Transmission and epidemiology
i. Extremely common worldwide
ii. Direct oral contact and contamination with saliva
c. Culture and diagnosis

i. Differential blood count shows excess lymphocytes
ii. Monospot test
d. Prevention and treatment: symptomatic relief
G. Anthrax
1. Signs and symptoms
a. Skin (cutaneous anthrax)
b. Lungs (pulmonary anthrax)
c. Gastrointestinal tract (ingestion of contaminated foods)
d. Central nervous system (anthrax meningitis)
2. Causative agent: Bacillus anthracis, a gram-positive endospore forming rod
3. Pathogenesis and virulence factors: Tripartite exotoxin
a. Edema factor: increases cellular cAMP levels leading to edema
b. Protective antigen: helps edema factor get to its target site
c. Lethal factor: triggers inflammation and initiation of shock
4. Transmission and epidemiology
a. Animal reservoir
b. Endospore-former in soil
c. Bioterrorism agent
6. Prevention and treatment
a. Vaccine available for livestock in endemic areas
b. Human vaccine for those with occupational contact or the military
c. Ciproflaxin, doxycycline
H. Hemorrhagic Fever Diseases
1. Extreme fevers, some of which cause internal hemorrhaging
2. RNA enveloped viruses, classified as biosafety level 4 pathogens
3. Dengue fever, "breakbone fever"
a. RNA flavivirus
b. Transmitted by Aedes mosquitoes
c. Endemic to Southeast Asia, India; epidemics in South and Central America
d. Global warming has increased the distribution of Aedes
4. Chikungunya
a. Alphavirus
b. Transmitted by Aedes albopictus
c. Symptoms similar to dengue fever plus sever joint pain
d. Endemic to Africa; recent spread to the Western Hemisphere
5. Ebola and Marburg
a. Filoviruses (family Filoviridae)
b. Massive hemorrhaging; patients bleed from orifices even mucous membranes
c. Bats may be a natural reservoir
d. Direct contact with an infected person or the person's fluids will transmit virus.
6. Lassa fever
a. Arenavirus found in West Africa
b. Reservoir is the multimammate rat; transmission through aerosolization of rat
droppings, urine, hair, eating food contaminated by rat excretion.
c. Ribavirin treatment in early stages
I. Nonhemorrhagic Fever Diseases
1. Brucellosis: Malta fever, undulant fever, or Bang’s disease
a. Signs and symptoms: fluctuating pattern of fever
b. Causative agent: species in the genus Brucella
c. Pathogenesis and virulence factors
i. Enters through damaged skin or mucous membranes
ii. Transported by blood to organs
iii. Fever fluctuations due to bacterial LPS
d. Transmission and epidemiology
i. Occupational hazard in slaughterhouses, livestock handling
ii. Common disease in herds of bison and elk; transmitted to cattle herds
e. Culture and diagnosis
i. Patient history
ii. Serological test of blood
iii. Blood culture
f. Prevention and treatment
i. Human vaccine not available

ii. Doxycycline, gentamycin, rifampin
2. Q fever
a. Coxiella burnetii, intracellular parasite
b. Harbored by ticks and other arthropods
c. Airborne spread from infected domestic animals (urine, feces, milk)
d. Occupational hazard for farm workers, meat cutters, consumers of raw milk
e. Mild cases resolve spontaneously; more severe cases resolve with doxycycline
3. Cat scratch disease
a. Bartonella henselae
b. Pathogen present in over 40% of cats
c. Cluster of papules at inoculation site, swelling lymph nodes
d. Most cases resolve in a few weeks
e. Azithromycin, erythromycin, rifampin.
f. Prevention by antiseptic cleansing of cat bite/scratch
4. Trench fever
a. Bartonella quintana
b. Lice
c. Reemerging in poverty-stricken areas of large cities. "Urban trench fever"
d. Highly variable symptoms
e. Doxycycline, erythromycin
5. Ehrlichiosis
a. Ehrlichia, a small intracellular bacterium, strict parasite
b. Ticks (Ixodes)
c. Acute fever, headache, muscle pain, rigors.
d. Rapid diagnosis through PCR and indirect fluorescent antibody tests
e. Critical to differentiate from Borrelia
f. Doxycycline
6. Anaplasmosis
a. Similar to Ehrlichia: same clinical manifestations, same treatment
b. Differ in geographic distribution, species of ticks
7. Babesiosis
a. Protozoan that infects red blood cells
b. Symptoms similar to Ehrlichia and Anaplasma
c. Diagnosed by blood smear
d. Atovaquone + azithromyin or clindamycin + quinine
8. Rocky Mountain spotted fever
a. Tick-borne
b. Rickettsia rickettsii
c. Distinctive spotted rash appearing on the wrist, forearms, then spreading
d. Fluorescent antibody staining from tissue biopsy or PCR assay.
J. Malaria
1. Signs and symptoms
a. Fever and chills in cycles due to rupture of blood cells
b. Complication: cerebral malaria
2. Causative agent
a. Plasmodium species: P. malariae, P. vivax, P. falciparum, and P. ovale
b. Two distinct phases
i. The asexual phase, in the human
ii. Sexual phase, in the mosquito
3. Pathogenesis and virulence factors
a. Damage to RBCs results in anemia
b. Liver and spleen enlargement
c. Cytoadherence of RBC to blood vessels
d. Surface protein GPI may be responsible for fever
e. Antigenic variation
4. Transmission and epidemiology
a. Female Anopheles mosquito
b. Shared hypodermic needles, blood transfusions
c. Endemic in equatorial regions
d. Placental damage, leading to high mortality among fetuses and neonates
6. Prevention
a. Mosquito control

b. Vaccine development
7. Treatment
a. Artemisinin in combination with other drugs
b. Chloroquine, if the local strain is not resistant
K. HIV Infection and AIDS
1. Signs and symptoms
a. Distinct dynamics of viral load
b. T-cell numbers
c. AIDS-defining illnesses
d. Initial symptoms: fatigue, diarrhea, weight loss, opportunistic infections
e. Wasting of body mass, protracted fever, sore throat
f. Neurological complications: social withdrawal, memory loss, sensory loss
2. Causative agent: Human Immunodeficiency Virus (HIV)
a. Retrovirus in the genus Lentivirus
b. Contains reverse transcriptase
c. HIV-1 and HIV-2: different evolutionary paths
3. Pathogenesis and virulence factors
a. Grows and is shed from dendritic cells without killing them
b. Amplified by macrophages
c. Binds to helper T-cell receptors
d. Latent period
e. Leukopenia: loss of essential T4 memory clones and stem cells
f. Secondary effects: opportunistic infections and malignancies
4. Transmission
a. Sexual intercourse
b. Blood or blood products
c. Before or during birth, through breast milk
5. Epidemiology
a. Notifiable disease
b. Increasing transmission through intravenous drug users
c. Treatment of HIV-infected mothers decreased rate of transmission
6. Culture and diagnosis
a. HIV infection means a positive test for exposure to HIV
b. AIDS diagnosis
i. CD4 helper T-cell count of fewer than 200 cells/microliter of blood
ii. CD4 cells account for fewer than 14% of all lymphocytes
iii. One or more AIDS-defining illnesses
c. OraQuick – mouth swab to detect antibodies in 2040 minutes
7. Prevention
a. Safe sex
b. Drug addicts should clean syringes, not share
c. PrEP: pre-exposure prophylaxis for people at high risk of infection (Truvada)
d. Vaccines in clinical trials
8. Treatment
a. No cure (FDA is looking at some possible new research)
b. Antiviral drugs
i. Reverse transcriptase inhibitors
ii. Protease inhibitors
iii. Integrase inhibitors
Chapter 22 -- Infectious Diseases Affecting the Respiratory System
The Respiratory Tract and Its Defenses
A. The most common place for infectious agents to gain access to the body
B. The upper respiratory tract
1. Mouth, nose, nasal cavity, and the sinuses above it
2. Throat or pharynx
3. The epiglottis and larynx
C. The lower respiratory tract
1. Trachea
2. Bronchi and bronchioles in the lungs

3. Alveoli
D. Defenses
1. Nasal hair
2. Ciliated epithelium of the trachea and bronchi
3. Mucus
4. Coughing, sneezing, swallowing
5. Macrophages in lungs
6. Lymphoid tissue (tonsils) in throat
7. Secretory IgA in mucus
Normal Biota of the Respiratory Tract
A. Some bacteria capable of causing serious disease are frequently present in the upper respiratory tract as “normal” biota:
Streptococcus pyogenes, Haemophilus influenzae, Streptococcus pneumonia, Neisseria meningitidis, and Staphylococcus
aureus.
B. The lung microbiome is altered in patients with lung disorders.
C. Normal biota is important for microbial antagonism.
Upper Respiratory Tract Diseases Caused by Microorganisms
A. The common cold
1. Signs and symptoms: sneezing, scratchy throat, running nose
2. Causative agents: over 200 kinds of viruses, notably
a. Rhinoviruses
b. Coronaviruses and adenoviruses
3. Pathogenesis and virulence factors
a. Penetrate mucus and attach to host cells
b. Symptoms are due to the immune system reaction to infection
4. Transmission and epidemiology
a. Droplet contact, fomites
b. Everyone gets colds, frequently
5. Prevention
a. No vaccine because of the wide variety of viruses
b. Best prevention is to stop transmission between hosts
6. Treatment: antihistamines, decongestants to address symptoms
B. Sinusitis
1. Signs and symptoms: nasal congestion, facial pressure and swelling
2. Causative agents
a. Viruses, same as for the common cold
b. Bacteria, often the normal microbiota
i. Predisposition from underlying infection
ii. Fluid build-up provides a rich environment
iii. Not communicable
iv. Recommendation to wait it out rather than treat
c. Fungi (rare)
C. Acute otitis media (ear infection): mixed biofilm infection
1. Signs and symptoms
a. Fullness or pain in the ear and loss of hearing
b. Irritability, fussiness, difficulty in sleeping, eating, hearing
2. Causative agents: many viruses and bacteria, notably
a. Streptococcus pneumoniae
b. Haemophilus influenzae
3. Transmission and epidemiology
a. Occurs as sequelae after upper respiratory tract infection
b. Not communicable
c. Children are particularly susceptible
4. Prevention: vaccine PCV13
5. Treatment
a. “Watchful waiting” for 72 hours
b. Tubes in ears
D. Pharyngitis
1. Signs and symptoms: throat inflammation, reddened mucosa, swollen tonsils
2. Causative agents
a. Cold viruses
b. Streptococcus pyogenes: gram-positive coccus in chains, nonmotile, forms
capsule and slime layers, facultative anaerobe, catalase negative

3. Pathogenesis due to autoimmunity
a. Scarlet fever – sandpaper-like rash and high fever
b. Rheumatic fever – affects heart valves and arthritis in multiple joints
c. Glomerulonephritis – antigen-antibody complexes deposited in kidney
4. Virulence factors
a. M protein
b. Lipoteichoic acid (LTA)
c. Cell wall polysaccharides
d. Hyaluronic acid capsule
e. Extracellular toxins
i. Streptolysins O and S
ii. Erythrogenic toxin (scarlet fever)
iii. Superantigens
5. Transmission and epidemiology
a. Transmission via respiratory droplets or direct contact
b. Immunity is serotype-specific, so a person can have multiple infections
7. Prevention
a. Vaccine not available
b. Good hand washing
8. Treatment: penicillin
E. Diphtheria
1. Signs, symptoms, and causative organism
a. Corynebacterium diphtheriae, exotoxin
b. sore throat, appetite loss, low-grace fever, pseudomembrane on tonsils
2. Prevention and treatment: DTaP Vaccine
Diseases Caused by Microorganisms Affecting the Upper and Lower Respiratory Tracts
A. Whooping cough
1. Signs and symptoms
a. Catarrhal stage: cold symptoms
b. Paroxysmal stage: severe, uncontrollable coughing
c. Convalescent phase: secondary infections may occur
2. Causative agent: Bordetella pertussis
3. Pathogenesis and virulence factors
a. Filamentous hemagglutinin (FHA) for attachment to epithelial cells
b. Pertussis toxin, an exotoxin, copious mucus production
c. Tracheal cytotoxin, an exotoxin, destroys ciliated cells
d. B. pertussis endotoxin, leads to cytokine production
4. Transmission and epidemiology
a. Respiratory droplets
b. Most serious in infants
c. Outbreaks occur; vaccine does not provide lifelong immunity
d. B. pertussis is evolving and the vaccine may not be the best
6. Prevention and treatment
a. DTaP vaccine
b. Antibiotics: azithromycin
B. Respiratory syncytial virus infection
1. Respiratory syncytial virus (RSV) infects the respiratory tract and produces giant multinucleated cells (syncytia)
2. Most prevalent in newborn age group
3. Causes colds in older children and adults
4. Severe disease in children 6 months of age or younger
5. Symptoms include fever, rhinitis, pharyngitis, otitis, croup (coughing, wheezing, difficulty in breathing)
6. Highly contagious, spread through droplet contact and fomites
7. Diagnosis by indirect fluorescent staining, ELISA, DNA probes
8. No vaccine available
C. Influenza
1. Signs and symptoms
a. Headache, chills, dry cough, body aches, fever, stuffy nose, sore throat
b. Susceptible to secondary infection
c. Serious complications may occur in patients with emphysema,
cardiopulmonary disease, the very young, elderly, and pregnant

2. Causative agent
a. Orthomyxoviridae family of viruses
b. Influenza A, B, or C
i. Neuraminidase
ii. Hemagglutinin
c. Antigenic drift: constant mutation of the surface glycoproteins
d. Antigenic shift: swapping genomic portions among strains
e. Influenza viruses also infect birds and pigs
3. Pathogenesis and virulence factors
a. Influenza virus binds to ciliated cells of the respiratory mucosa
b. Infection causes rapid shedding of cells
c. Cytokine "storm" causes severe inflammation and irritation
4. Transmission and epidemiology
a. Inhalation of virus-laden aerosols
b. Transmission is facilitated by crowding and poor ventilation
c. Highly contagious; infects all age groups
6. Prevention
a. Annual vaccination
b. Each year the vaccine composition changes based on likely flu variants
7. Treatment: Tamiflu; must be taken early in infection
Lower Respiratory Tract Diseases Caused by Microorganisms
A. Tuberculosis
1. Signs and symptoms
a. Primary tuberculosis; mild fever or asymptomatic; tubercles form and calcify
b. Secondary (reactivation) tuberculosis: violent bloody cough, fever, anorexia,
weight loss, extreme fatigue, night sweats, chest pain
c. Extrapulmonary tuberculosis in immunocompromised patients and children
2. Causative agents
a. Mycobacterium tuberculosis; acid-fast rod; mycolic acids in cell wall
b. Mycobacterium avium complex (MAC) in AIDS patients
c. Mycobacterium bovis (bovine TB) (rare)
3. Pathogenesis and virulence factors
a. Mycolic acids in cell wall form a waxy surface
b. Stimulates a strong immune response
4. Transmission and epidemiology
a. Fine droplets of respiratory mucus suspended in air
b. Factors contributing to susceptibility include:
i. Inadequate nutrition
ii. Lung damage
iii. Poor access to medical care
iv. Debilitation of the immune system
6. Prevention
a. Limit exposure to infectious airborne particles
b. BCG attenuated vaccine used in other countries
7. Treatment
a. Latent TB: isoniazid, rifampin, and rifapentine
b. Active TB: isoniazid, rifampin, ethambutol, and pyrazinamide
c. Both regimes require months of treatment
B. Multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis (MDR-TB and XDR-TB)
1. Multidrug-resistant tuberculosis (MDR-TB)
a. Resistant to isoniazid and rifampin; requires 1824 months with 46 drugs
b. Results from noncompliance in treatment
c. Patients may be incarcerated for treatment
2. Extensively Drug-resistant tuberculosis (XDR-TB)
a. Resistant to isoniazid and rifampin and two other drugs
b. Few treatment options; mortality rate 70% by the time of diagnosis
C. Pneumonia
1. Introduction
a. Anatomical diagnosis
b. bacterial or viral (viral is milder)

2. Signs and symptoms
a. Starts with upper respiratory tract symptoms (congestion, headache, fever)
b. Lung symptoms (chest pain, fever, cough, discolored sputum) follow
3. Causative agents of community acquired pneumonia
a. Streptococcus pneumonia
i. Normal biota in upper respiratory tract of 550% of healthy people
ii. Factors favoring development of disease include:
A. Old age
B. Season (winter)
C. Underlying disease (viral respiratory disease, diabetes, chronic abuse of alcohol or
narcotics)
iii. Lobar pneumonia
iv. Consolidation
v. Prevent with pneumococcal polysaccharide vaccine
vi. Treat with antibiotics: broad-spectrum cephalosporins
b. Mycoplasma pneumonia
i. Lack a cell wall
ii. Atypical pneumonia transmitted by aerosol droplets (“walking pneumonia”)
iii. Diagnosis by ruling out other bacteria or viral agents
c. Legionella pneumophila
i. Gram-negative bacterium with a range of shapes
ii. Causes pneumonia with a fatality rate of 330%
iii. Found in aqueous habitats
iv. Opportunistic disease in elderly people
v. Not transmitted person to person
d. Histoplasma capsulatum
i. Pathogenesis and virulence factors
A. Array of manifestations
B. Mild symptoms: aches, pain, cough
C. Severe symptoms: fever, night sweats, weight loss
ii. Transmission and epidemiology
A. Endemic worldwide except Australia, prevalent in Ohio
B. Associated with soil supplemented by bird and bat droppings
C. Transmitted from environment to people, not person to person
iv. Prevention and treatment
A. Avoidance of fungus is the only prevent
B. Amphotericin for 12 weeks, itraconazole for several weeks
C. Surgery may be needed to remove lung masses
e. Pneumocystis jirovecii
i. Symptoms, pathogenesis, and virulence factors
A. Found in immunocompromised patients
B. Cough, fever, shallow respiration, cyanosis
ii. Transmission and epidemiology
A. Inhalation of spores is common, may be normal biota
B. Before AIDS, infections were rare
iv. Prevention and treatment
A. Trimethoprim/sulfamethoxazole
B. Antifungals are ineffective
4. Healthcare-associated pneumonia: associated with mechanical ventilation
a. Causative agents: S. aureus, gram-negative bacteria, polymicrobial
b. Prevention and treatment
i. Elevate patients' heads
ii. Care of ventilation and respiratory therapy equipment
iii. Antibiotic therapy as soon as it is suspected
Chapter 23 -- Infectious Diseases Affecting the Gastrointestinal Tract
The Gastrointestinal Tract and Its Defenses
A. A long tube extending from mouth to anus
B. Composed of eight main sections: the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and
anus
C. Four accessory organs: the salivary glands, liver, gallbladder, and pancreas

D. Often called the digestive tract or the enteric tract
E. Defenses include:
1. Mucus
2. Secretory IgA
3. Peristalsis
4. Saliva contains lysozyme and lactoferrin
5. Stomach fluid is highly acidic
6. Bile is antimicrobial
7. Gut-associated lymphoid tissue (GALT)
8. Commensals in system provide antagonism towards pathogens
Normal Biota of the Gastrointestinal Tract
A. Bacteria live on the teeth as well as the soft structures in the mouth
B. Pharynx has a variety of microorganisms
C. Stomach and esophagus are sparsely populated
D. The normal biota in the gut provides not only protection, but also aid in digestion
1. Anaerobes outnumber aerobes in gut
E. Accessory organs (salivary glands, gallbladder, liver, and pancreas) are free of microorganisms
Gastrointestinal Tract Diseases Caused by Microorganisms (Nonhelminthic)
A. Tooth and gum infections
B. Dental caries (tooth decay)
1. Causative agents
a. Streptococcus mutans
b. Streptococcus sobrinus
c. Scardovia wiggsiae
2. Pathogenesis and virulence factors
a. Produce sticky polymers of glucose
b. Contribute to plaque biofilm
c. Streptococci ferment the carbohydrates, producing acid
d. Acid comes in contact with enamel of tooth, dissolving it
e. Nursing bottle caries
3. Transmission and epidemiology
a. Transmission to infants from caregivers
b. Worldwide distribution
c. Incidence varies with carbohydrate consumption, hygiene practices, genetic factors.
5. Prevention and treatment
a. Dietary restriction of sucrose
b. Regular brushing and flossing to remove plaque
c. Removal of the tooth and surface restoration
C. Periodontal disease
1. Periodontitis
a. Signs and symptoms
i. Gingivitis
ii. Periodontitis
b. Causative agent: polymicrobial biofilm
c. Pathogenesis and virulence factors
i. Calculus and plaque accumulating in gingival sulcus causes abrasions in gingival membrane
ii. Chronic trauma leads to pronounced inflammatory reaction
d. Transmission and epidemiology
i. Transmission from close oral contact
ii. Extremely common in all populations
e. Culture and diagnosis: by visual examination
f. Prevention and treatment
i. Regular brushing and flossing
ii. Dental hygiene
2. Necrotizing ulcerative gingivitis and periodontitis
a. Necrotizing ulcerative gingivitis (NUG)
b. Necrotizing ulcerative periodontitis (NUP)
c. Synergistic infections involving three pathogens:
i. Treponema vincentii
ii. Prevotella intermedia
iii. Fusobacterium species

D. Mumps
1. Signs and symptoms
a. fever, nasal discharge, muscle pain, malaise
b. swelling of parotid glands
c. Complications in mumps: orchitis and epididynitis
2. Causative agent: Paramyxovirus
3. Pathogenesis and virulence factors
a. HN spikes in infected cells results in syncytium formation
4. Transmission and epidemiology of mumps virus
a. Transmission through salivary and respiratory secretions
b. Infection occurs worldwide, with increases in late winter and early spring
6. Prevention and treatment
a. MMR vaccine
b. Most cases resolve without treatment
E. Gastritis and gastric ulcers
1. Signs and symptoms
a. Gastritis: sharp or burning pain emanating from the abdomen
b. Gastric or duodenal ulcers (peptic ulcers) can be accompanied by bloody stools, vomiting, or both
2. Causative agent: Helicobacter pylori
3. Pathogenesis and virulence factors
a. Cell receptor is the same molecule that confers blood type O
a. Urease produced by H. pylori can neutralize stomach acid
4. Transmission and epidemiology
a. Probable transmission is oral-oral or fecal-oral route.
b. H. pylori colonizes about half of the world's population
6. Prevention and treatment
a. No vaccine and no obvious way to avoid colonization
b. Antibiotics (tetracycline and metronidazole)
c. Acid suppressors for symptom relief
F. Acute diarrhea (with or without vomiting)
1. Salmonella: HKO antigens; motile; glucose fermentation; produce H2S
a. Signs and symptoms
i. Typhoid fever – Salmonella enterica serotype Typhi
ii. Salmonellosis – other variants of S. enterica
b. Pathogenesis and virulence factors
i. Pathogenicity islands of genes
ii. Responsible for entry, adhesion, or invasion into the host
c. Transmission and epidemiology
i. High ID50
ii. Usually traced to milk or eggs
d. Prevention and treatment
i. Prevention: avoid contact
ii. Vaccine for poultry
iii. Fluid and electrolyte replacement in salmonellosis
iv. Antibiotics (trimethoprim and sulfamethoxazole)
2. Shigella: gram-negative rods, nonmotile, non-endospore-forming, urease negative
a. Signs and symptoms
i. frequent watery stools, fever, intense abdominal pain
ii. Dysentery (blood-containing diarrhea)
b. Pathogenesis and virulence factors
i. Enterotoxin damages intestinal mucosa and villi
ii. Heat-labile exotoxin called shiga toxin that damages the intestine
c. Transmission and epidemiology
i. Oral route
ii. Person-to-person contact, low ID50
d. Prevention and treatment
i. Prevention: good hygiene
ii. Antibiotic treatment with ciprofloxacin
3. Shiga-Toxin-Producing E. coli (STEC)
a. Signs and symptoms
i. Mild gastroenteritis with fever
ii. Hemolytic uremic syndrome (HUS)

b. Pathogenesis and virulence factors
i. Produces shiga toxin
ii. Effacement in the gut – lesion formed by the bacteria that results in the bloody diarrhea
c. Transmission and epidemiology
i. Transmission by ingestion of contaminated beef, esp ground beef
ii. Farm products that contact cattle feces may be contaminated: lettuce, vegetables, apples
e. Prevention and treatment
i. Prevention: do not consume raw or rare hamburger; wash vegs well
ii. Antibiotics are contraindicated
iii. Supportive therapy
4. Other E. coli
a. Enterotoxigenic E. coli (Traveler’s diarrhea)
i. Adults: self-limiting; treat with fluid replacement
ii. Infants: can be life threatening; treat with fluid replacement
b. Enteroinvasive E. coli
i. Blood and mucus found in stood; significant fever
ii. Contaminated food and water
iii. Treat with fluid replacement
c. Enteropathogenic E. coli
i. Profuse water diarrhea
ii. Treat with fluid replacement
d. Enteroaggregative E. coli: chronic diarrhea in young children & AIDS patients
e. Diffusely adjerent E. coli: urinary tract infections in addition to acute diarrhea
5. Campylobacter
a. Campylobacteriosis: symptoms may last 2 weeks
b. Most common bacterial cause of diarrhea in the United States
i. Campylobacter jejuni
A. Curved gram-negative rods, microaerophiles
B. Transmitted through contaminated beverages and food
C. Resistant to heating
ii. Guillain-Barré syndrome
A. Acute paralysis
B. Follows Campylobacter infection
6. Clostridium difficile
a. Pseudomembranous colitis (antibiotic-associated colitis)
b. Two enterotoxins
c. Metronidazole or vancomycin
d. Fecal transplant
7. Vibrio cholerae: comma-shaped rods, fermentative, unique HO antigens
a. Signs and symptoms
i. Rice-water stools
ii. Muscle cramps, severe thirst, flaccid skin, sunken eyes, coma
b. Pathogenesis and virulence factors: enterotoxin called cholera toxin (CT)
c. Transmission and epidemiology
i. Transmission from environmental water
e. Prevention and treatment
i. Proper sewage treatment and water purification
ii. Key to therapy is replacement of water and electrolytes
8. Non-cholera Vibrio species
a. V. vulnificus and V. parahaemolyticus
b. Associated with eating contaminated shellfish
9. Cryptosporidium
a. Intestinal water-borne protozoan
b. Gastroenteritis
c. Often associated with swimming pools, as chlorination is not completely effective
d. No treatment available
10. Rotavirus
a. 1 million cases per year in the United States
b. Fecal-oral route
c. Babies 624 months are at greatest risk of death
d. Vaccine RotaTeq
11. Norovirus

a. Fecal-oral route
b. Often associated with cruise ships
c. Treatment focuses on rehydration
G. Acute diarrhea with vomiting caused by exotoxins (food poisoning)
1. Staphylococcus aureus exotoxin
a. Associated with eating food that have been contaminated by handling and then left unrefrigerated for a
few hours
b. Heating the food after toxin production may not prevent disease
2. Bacillus cereus exotoxin
a. Two exotoxins, one of which causes a diarrheal-type disease, the other of which causes an emetic
(vomiting) disease
b. Most frequently linked to fried rice cooked and then kept warm for long periods of time
3. Clostridium perfringens exotoxin
a. Endospores not killed if food is not cooked thoroughly
b. Toxin initiates acute abdominal pain, diarrhea, and nausea
H. Chronic diarrhea
1. Enteroaggregative E. coli (EAEC)
a. Adheres to cells as aggregates, not single cells
b. Transmission through contaminated food or water
c. Common in people who are malnourished
2. Cyclospora
a. Emerging freshwater protozoan pathogen
b. Fecal-oral transmission
c. Diagnosis by microscopy of stool
d. Trimethoprim and sulfamethoxazole
3. Giardia flagellated protozoan
a. Signs and symptoms
i. Diarrhea of long duration, abdominal pain, and flatulence
b. Pathogenesis and virulence factors
c. Transmission and epidemiology of giardiasis
i. Isolated from intestines of beavers, cattle, coyotes, cats, and human carriers
ii. Cysts are long-lived in the environment
e. Prevention and treatment
i. Water treatment
ii. Therapy is tinidazole or mitazoxanide
4. Entamoeba histolytica
a. Signs and symptoms
i. Dysentery, abdominal pain, fever, diarrhea, and weight loss
ii. Extraintestinal infection occurs in the liver or lung.
b. Pathogenesis and virulence factors
c. Transmission and epidemiology of amoebiasis
i. Cysts continuously shed by chronic carriers
ii. Common in fresh water sources
e. Prevention and treatment
i. Prevent through purification of water
ii. Metronidazole or chloroquine
I. Hepatitis: Necrosis of hepatocytes and a mononuclear response causing jaundice
1. Hepatitis A virus: nonenveloped, single-stranded RNA enterovirus
a. Signs and symptoms
i. Often subclinical or vaguely flulike
ii. More overt cases include jaundice and swollen liver
iii. Darkened urine
iv. Virus is not oncogenic (does not result in cancer)
b. Pathogenesis and virulence factors
c. Transmission and epidemiology
i. Fecal-oral route
ii. Associated with deficient personal hygiene and inadequate public health measures
e. Prevention and treatment: an inactivated viral vaccine (Havrix)
2. Hepatitis B virus: enveloped DNA virus in the family Hepadnaviridae
a. Signs and symptoms
i. Similar to symptoms in Hepatitis A infection with additional symptoms including fever, chills,
malaise, anorexia, diarrhea, rash

ii. Some cases develop cirrhosis
iii. Malignancy: HBV is associated with hepatocellular carcinoma
iv. May be coinfected with hepatitis D virus, the delta agent
b. Pathogenesis and virulence factors
i. Enters through a break in the skin
ii. Multiplies in the liver
c. Transmission and epidemiology
i. Blood (needlesticks, drug addicts, tattooing, piercing)
ii. Sex (bodily fluids)
iii. Donated organs
e. Prevention and treatment
i. Recombinant HBV vaccine
ii. Passive immunization with HB immune globulin in exposed individuals
iii. Chemotherapy in chronic infections to manage disease; no cure
3. Hepatitis C virus: RNA virus in Flaviviridae family
a. Signs and symptoms
i. More likely to become chronic than hepatitis B disease
ii. Liver cancer due to HCV is a more common cause in the United States than HBV
b. Pathogenesis and virulence factors
c. Transmission and epidemiology
i. Blood contact
ii. Vertical transmission
iii. Transmission through other body fluids is less common
d. Prevention and treatment
i. No vaccine
ii. Treatment is sofosbuvir and simeprevir
Chapter 24 -- Infectious Diseases Affecting the Genitourinary System
The Genitourinary Tract and Its Defenses
A. Urinary tract
1. Kidneys, ureters, bladder, urethra
2. Defenses include:
a. Flushing action of urine
b. Shedding of epithelial cells lining the urinary tract (desquamation)
c. Acidity of urine
d. Lysozyme and lactoferrin in urine
e. Secretory IgA
B. Male reproductive system
1. Produces, maintains, and transports sperm cells
2. Testes, epididymis, vas deferens, prostate gland, scrotum (testes), penis
3. Defenses include flushing action of urine
C. Female reproductive system produces eggs in a 28-day cycle
1. Uterus, fallopian tubes, ovaries, vagina
2. Defenses include:
a. Mucus
b. Acidic pH in vagina
c. Secretory IgA
Normal Biota of the Genitourinary Tract
A. Outer region of the urethra harbors some normal biota
1. Nonhemolytic streptococci, staphylococci, corynebacteria, and some lactobacilli
2. Prevotella, Veillonella, Gardnerella
B. Normal biota of the male genital tract
1. Same as that of the urinary tract above
2. Shifts with onset of sexual activity
C. Normal biota of the female genital tract
1. Vagina has normal biota
2. Cervix and above has no normal biota
3. Before puberty and after menopause, pH of vagina is close to neutral
a. Normal biota similar to that of the urethra
4. After onset of puberty, release of glycogen induced by estrogen leads to an acidic pH in the vagina:
a. Lactobacillus species

b. Also Candida albicans (fungus) in low numbers
Urinary Tract Diseases Caused by Microorganisms
A. Urinary tract infections (UTIs)
1. Locations: bladder (cystitis); kidneys (pyelonephritis); urethra (urethritis)
2. Signs and symptoms
a. Dysuria
b. Hematuria
c. Fever and nausea
d. Back pain
e. Septicemia can occur if pyelonephritis is inadequately treated
3. Causative agents
a. Distinguish between UTIs that occur in versus outside of health care setting
b. E. coli, Staphylococcus saprophyticus and Proteus mirabilis
4. Transmission and epidemiology
a. Nosocomial infections
b. Transmission is from one organ system to another
5. Treatment: Sulfa drugs
B. Leptospirosis
1. Signs and symptoms
a. Leptospiremic phase
b. Immune phase
i. Weil’s syndrome
2. Causative agent: Leptospira interrogans
3. Pathogenesis and virulence factors
a. Genome encodes adhesins and invasion proteins
b. Target is kidney tissue
4. Transmission and epidemiology
a. Zoonosis, found in rodents, skunks, raccoons
b. Also found in cattle, dogs, horses, and pigs
c. Infection through contact of skin abrasions with animal urine
5. Prevention
a. Wear protective footwear
b. Avoid wading in natural water sources frequented by livestock
6. Treatment: amoxicillin or doxycycline
C. Urinary Schistosomiasis: Helminth lodged in blood vessels of the bladder
1. Signs and symptoms
a. Itch at invasion site
b. Fever
c. Chills
d. Diarrhea
e. Cough
2. Causative agent: Schistosoma haematobium
3. Pathogenesis and virulence factors
a. Invades intact skin
b. Eggs in bladder induce a granulomatous response
c. Bladder may fill with granuloma and scar tissue
4. Transmission and epidemiology
a. Helminths pass from liver and enter the bladder
b. Snail vector not found in the United States; cases are all imported
6. Prevention and treatment
a. Avoid exposure to untreated sewage
b. Praziquantel
Reproductive Tract Diseases Caused by Microorganisms
A. Vaginitis: inflammation of the vagina
1. Signs and symptoms
a. Vaginal itch
b. Burning
c. Discharge (sometimes)

2. Causative agents
a. Candida albicans; dimorphic fungus that is normal biota
i. Pathogenesis and virulence factors
A. Colony debris contributes to white vaginal discharge
ii. Transmission and epidemiology
A. Opportunitistic
B. Sexual partners can transmit and should be treated
iii. Prevention and treatment
A. No vaccine available
B. Topical and oral azole drugs
b. Trichomonas vaginalis; protozoa with 4 anterior flagella and undulating membrane
i. Pathogenesis and virulence factors
A. Often asymptomatic
B. Women have vaginitis symptoms
ii. Transmission and epidemiology: STI
iii. Prevention and treatment
A. No vaccine
B. Metronidazole
B. Vaginosis: disruption of vaginal microbiota; mixed infection
1. Pathogenesis and virulence factors
a. Can lead to pelvic inflammatory disease, infertility, ectopic pregnancy
b. Babies born to mothers with vaginosis have low birth weight
2. Transmission and epidemiology
a. Common in sexually active women
b. Exact etiology unknown
4. Prevention and treatment
a. No known prevention exists
b. Asymptomatic cases are not treated
c. Oral or topical metronidazole or clindamycin
C. Prostatitis:
1. Acute: caused by bacterial infection
2. Chronic: often bacterial, may be mixed species biofilm
3. Symptoms include pain in the pelvic area, lower back, or genital area; frequent urge to urinate; blood in the urine;
and/or painful ejaculation
4. Treatment: ciprofloxacin or levofloxacin
D. Discharge diseases with major manifestation in the genitourinary tract
1. Gonorrhea
a. Signs and symptoms in the male
i. Urethritis
ii. Painful urination
iii. Yellowish discharge
b. Signs and symptoms in the female
i. Urethritis
ii. Bloody vaginal discharge
iii. Painful urination
iv. Salpingitis
v. Pelvic inflammatory disease (PID)
c. Causative agent: Neisseria gonorrhoeae
d. Pathogenesis and virulence factors
i. Attachment through fimbriae
ii. Host cell invasion
iii. IgA protease to cleave IgA molecules on mucosa
e. Transmission and epidemiology
i. Sexually transmitted infection (STI)
ii. Approximately 10% of males and 50% of females experience no symptoms
f. Prevention
i. No vaccine available
ii. Condom use is effective to avoid transmission
g. Treatment
i. Gonococcal Isolate Surveillance Project (GISP)
ii. Widespread resistance is moving around the world
iii. CDC now recommends ceftriaxone + azithromycin or doxycycline

2. Chlamydia
a. Signs and symptoms
i. Nongonococcal urethritis (NGU), cervicitis, PID
ii. Lymphogranuloma venereum
iii. Many cases asymptomatic
b. Causative agent
i. Chlamydia trachomatis
ii. Two-stage life cycle: elementary body/reticulate body
c. Pathogenesis and virulence factors
i. Obligate intracellular pathogen escapes host immune system
ii. Cytokine release provokes inflammation leading to tissue damage
d. Transmission and epidemiology
i. Disease incidence is very high
ii. Transmitted both sexually and vertically
f. Prevention
i. No vaccine available
ii. Condom use is effective to avoid transmission
g. Treatment: azithromycin or doxycycline
E. Genital ulcer diseases
1. Syphilis
a. Signs and symptoms
i. Primary syphilis
A. Hard chancre at the site of entry
B. Spirochete present in lesions and blood
ii. Secondary syphilis
A. Fever, headache, sore throat
B. Lymphadenopathy, rash all over including palms and soles
C. Hair loss
D. Spirochete present in blood
iii. Latency and tertiary syphilis
A. Can last for decades
B. Gummas may develop in liver, skin, bone, cartilage
iv. Congenital syphilis: mild birth defects to spontaneous miscarriage
b. Causative agent: Treponema pallidum, a spirochete
c. Pathogenesis and virulence factors
i. Binds to epithelium with hooked tip
ii. Enters bloodstream and any tissue can be infected
iii. Organ damage results from granulomas around sites of infection
d. Transmission and epidemiology
i. Humans are sole natural hosts
ii. Bacterium is very sensitive to heat, drying, soap, disinfectants
iii. Can be transmitted both sexually and vertically
f. Prevention
i. Detection and treatment of sexual contacts of syphilitic patients
ii. Barrier protection
g. Treatment: penicillin G
2. Chancroid
a. Haemophilus ducreyi—pleomorphic gram-negative rod
b. Transmitted through sexual contact
c. Associated with sex workers and poor hygiene
d. No vaccine exists
e. Azithromycin and ceftriaxone
3. Genital herpes
a. Signs and symptoms
i. Genital herpes
A. Fluid-filled vesicles on the genitalia, perineum, thigh
B. Malaise, anorexia, fever, swelling and tenderness in groin
C. Recurrence may occur but be less severe
ii. Herpes of the newborn: often fatal
b. Causative agent
i. Herpes simplex viruses (HSV)
ii. HSV-1 and HSV-2 are DNA viruses

c. Pathogenesis and virulence factors
i. Often latent in the ganglion of the lumbosacral spinal nerve trunk
d. Transmission and epidemiology
i. Transmission through direct exposure to secretions
f. Prevention
i. Vaccines in clinical trials
ii. Condoms only effective if they cover the lesion
g. Treatment
i. Acyclovir
F. Wart diseases
1. Human papilloma virus
a. Signs and symptoms
i. Genital warts
ii. Condyloma acuminata
iii. MalignaBIOL-241 – Principles of Microbiology
John-Paul Vermitsky, Ph.D.
Chapter 19 -- Infectious Diseases Affecting the Skin and Eyes
The Skin and Its Defenses: Constantly Exposed to the Environment; a Vulnerable Site for Infection
A. Integument: Skin, hair, nails, sweat, skin, and oil glands
B. The skin is organized in layers
1. The epidermis
a. The stratum corneum (epithelial cells) contains the protein keratin that protects the
cells from damage, abrasion, and water penetration
b. Three or more layers of epithelial cells lie below the stratum corneum
c. Lowest layer is stratum basale (basal layer), which is attached to the underlying dermis
2. The dermis is composed of connective tissue instead of epithelium
a. Fibroblast cells and collagen
b. Mast cells and macrophages
c. Nerves, blood vessels, lymphatic vessels
d. Hair follicles
e. Sebaceous glands
C. Defenses of the skin
1. Keratinized surface
2. Low pH of sebum
3. High salt in sweat
4. Lysozyme in sweat
5. Antimicrobial peptides
Normal Biota of the Skin: data from the Human Microbiome Project
A. Dense microbial populations in moist areas, skin folds, hair follicles, and glandular ducts
B. Hundreds of species distributed over many areas
C. Distribution variable in different regions
D. Large differences among individuals
E. An individual's own skin microbiota is stable over time
Skin Diseases Caused by Microorganisms
A. MRSA
1. General.
a. Staphylococcus aureus: gram-positive coccus, nonmotile, highly virulent, present as
normal microbiota; withstands exposure to heat, pH, high salt, desiccation
b. Usually resistant to several antibiotics
2. Signs and symptoms: raised, red, tender, localized lesions, often with pus, hot to touch
3. Transmission and epidemiology
a. Common contaminant of all kinds of surfaces
b. Persons with infections should keep them covered
4. Pathogenesis and virulence factors
a. Coagulase
b. Hyaluronidase: digests intercellular glue that binds connective tissue
c. Staphylokinase: digests blood clots
d. DNase
e. Lipases: help colonize oily skin surfaces
5. Prevention and treatment
a. Prevention requires good hygiene
b. Treatment: draining pus; more than one antibiotic
B. Impetigo: highly contagious superficial bacterial infection, predominant among children
1. Causative organisms
a. Staphylococcus aureus
b. Streptococcus pyogenes
2. Signs and symptoms: itchy, peeling skin, crusty and flaky scabs, honey-colored crusts
3. Impetigo caused by Staphylococcus aureus
a. Pathogenesis and virulence factors
i. Exfoliative toxins A and B: attacks protein that binds cells in skin
ii. Coagulase
4. Impetigo caused by Streptococcus pyogenes
a. Streptococcus pyogenes: Lancefield group A and ß-hemolytic on blood agar
b. Pathogenesis and virulence factors