EXAM 4

Bacterial Infection of skin: Acne

Propionibacterium acne

Opportunistic Pathogen - When immune system is weakend

Bacterial Infection of skin: Dermatitis “Hot Tub Rash”

Pseudomonas aeruginosa is naturally antibiotic resistant because it lives in the soil and is always exposed. True pathogen, hospital-associated. 

Found in soil 

Gram-negative rod (test)

Non-lactose fermenting on MacConkey agar (turns pale pink), 

Green pigment is found on general media 

Knowing that is microbe has oxidase +, oxidases enzymes/o2 to be used. Smells like a fruity, corn, nike ordor

Skin Bacteria: Staphylococus aureus

Apart of normal flora

Gram positive cocci
Majority cause of skin infection

How to identify Staphylococcus aureus (s. aureus)

Golden colonies 

Beta Hemolysis on blood agar plate 

Catalase + (turns more solid less liquid)

Coagulase + (Bubbles)

Staph aureus Virulence Factors

Has a capsule making it easy to invade into cells

Coagulation - allows bacteria to clot blood covering itself in a fibrin shield evading the immune response 

Protein A - Prevents antibodies from binding to IgG antibody, preventing phagocytosis

Releases toxemias: Exfoliative toxin + TSST-1 (toxic shock syndrome)

Strain of Staphylococcus Aureus: MRSA

MRSA: Methicillin-resistant Staphylococcus aureus, a strain that is resistant to many antibiotics, leading to more difficult treatment options for infections.

MRSA Strains: Hospital-Associated (HA-MRSA)

mecA gene present

Resistant to all antibiotics EXCEPT vancomycin

Treated with Vancomycin

MRSA Strains: Community-Associated (CA-MRSA)

mecA gene present

Resistant to methicillin, sensitive to many others

HAS PVL GENE

Staff Aureus toxemias that affect skin: What is toxemia?

A toxin enters bloodstream (-emia: in the blood prefix)

Bacteria is not present at the site of symptoms 

Bacteria are NOT in the blood, a TOXIN is

Staff Aureus toxemias that affect skin: Scalded Skin Syndrom (SSS)

Exfoliative toxin released causes this

Bacteria colonize in intestine, toxin enters the bloodstream, and skin peels off in sheets

More found in children under 2 

Staff Aureus toxemias that affect skin: Toxic Shock Syndrom (TSS)

TSST-1 caused this 

Toxin enters the bloodstream, and extreme fever, vomiting, and rash

More common in adults 

What is Group A Strep skin infection?

Defined by carbohydrates expressed on surface of bacteria 

Gram positive cocci 

Diagnosis of Group A Strep skin infection?

Catalase negative

Beta-hemolysis (transparent hemolysis on blood plate)

Group A typing 

Group A Strep (GAS) Virulence Factors skin infection?

Capsules

M protein - fuzzy layer of capsule that inhibits phagocytosis mimicing human molecules, creating self-reactive antibodies 

SPE A and SLO toxemias released 

Group A Strep (GAS) Necrotizing Fasciitis skin infection

Group A Strep cells are producing toxins that kill cells in said area. Group A Strep is more common to cause necrotizing fasciitis rather than staph. 

SPE A is a SUPER ANTIGEN - Toxin causes an OVER REACTION for immune response, leading to rapid tissue destruction 

Group A Strep (GAS): Toxic Shock Syndrome skin infection

Toxemia is associated with SPE A super antigen (staph = TSST-1)

Less common

Similar wound infection/menstral product infection

Treatment for Group A Strep skin infection

Antibiotic treatment is a MUST 

M proteins will attack our own cells, causing rheumatic fever 

Viral infections of the skin: Diseases/Microbes

1. Measles (Rubeola) - exanthems

2. Rubella (German Measles) - exanthems

3. Roseola - exanthems

4. Chickenpox/shingles (Varicella) - exanthems

5. Fifth disease - exanthems

6. Cold sores and skin herpes

7. Hand, foot, and mouth disease

8. Warts

What are exanthems?

Group of viral diseases that are characterized by a rash. The virus is actually causing a respiratory disease but we will be reacting from a rash

Vaccines must be live attenuated (weakened virus injected)

Viral infections of the skin: Measles (Rubeola) EXANTHEM

Caused by measles virus 

Macular ((colored and flat (versus papular which is colored and popped up)) rash, fever, cough

Koplik spots  - Red patches with white centers + diagnostic indicator 

Most contagious human virus 

Mnemonic: “Ruby has Koplik spots”

MMR Vaccine: Live attenuated because it is exanthem and covers measles, mumps, and rubella.

Severe outcomes of measles (Rubeola)

Pneumonia 

Immune amnseisa - kills immune cells to cause secondary infection 

Subacute sclerosing panencephalitis (SSPE) - virus replicates in brain after years of infection and is ALWAYS FATAL (brain goes hard)

Viral infections of the skin: Rubella (German Measles) EXANTHEM

Caused by rubella virus 

Macular rash, fever, respiratory symptoms

Congenital rubella syndrome: a serious condition resulting from maternal infection during pregnancy, leading to birth defects. Mother is infected in first trimester of pregnancy

Mnemonic: Bella is German and pregnant

Viral infections of the skin: Roseola EXANTHEM

Caused by human herpesvirus 

A common and mild disease, only lasting for a few days

Mnuemonic: Rosie is no big deal

Viral infections of the skin: Chickenpox (Varicella) + Shingles (Zoster) EXANTHEM

Cause by varicella-zoster virus (VSV), another herpesvirus via respiratory route 

Primary disease: Chickenpox (varicella), rash with vesicles

Virus goes latent in nerve cells, becoming shingles

Live-attenuated vaccine

Secondary Disease of Chickenpox + Shingles: Shingles

Virus is reactivated in the nerve 

Vesicles erupt in path of nerve 

Adults >50 

Shingles-specific, subunit vaccine

Viral infections of the skin: Fifth Disease EXANTHEM

Caused by parvovirus B19

“Slapped cheek” rash 

Viral infections of the skin: Cold sores and cutaneous herpes

Cold sores (sores near mouth) caused by HSV-1 (Herpes Simplex Virus)

Vesicular rash

Herpesviruses transmits via direct contact 

Virus goes latent in nerve ganglion on face 

Viral infections of the skin: Hand, Foot, and Mouth Disease (HFMD)

Caused by coxsackievirus 16

Vesicular rash spread via direct contact 

Respiratory + Enterovirus (infects gut)

Viral infections of the skin: Warts

Caused by Human Papillomavirus

Rough papules 

Transmits via direct contact 

Fungal Infections and skin

Fungal diseases are called “mycoses”

Fungal Infections and skin: Ringworm (Tinea)

Common fungal infection by dermatophytes because they love moisture

Fungal Infections and skin: Candidiasis

Caused by Candida albicans > Normal flora on our skin/Opportunistic infections 

Happens after antibiotic use and is common in immunocompromised individuals 

Parasitic infections and skin

Parasites: Leishmaniasis and Hookworm

Insects: Scabies and Lice

Parasitic infections and skin: Leishmaniasis (Parasite)

Caused by Leishmania species

Protozoan parasite, spread by sand fly (vector)

“Volcanic” ulcers form 

Parasitic infections and skin: Hookworm (Parasite)

Caused by helminths, it can be found in the South US

Hook enters skin after stepping barefoot on contaminated soil

Parasitic infections and skin: Scabies (Insect)

Caused by mites

Burrows under skin to lay eggs, causing an itchy maculopapular rash 

Parasitic infections and skin: Lice (Insect)

Head lice is caused by pediculus humanic capitis (cap = on head)

Common in children causing itchy scalp because of blood taken

Treated with insecticides

Diseases of the eyes

1. Conjunctivitis (Pink eye)

2. Ophthalmia Neonatorum 

3. Trachoma 

4. Keratitis

5. Ocular Hispoplasmosis  

Diseases of the eye: Conjunctivitis (-itis, infection of the conjunctiva)

Source can be viral or bacterial; viral is clear discharge, bacterial is purulent (includes yellow pus because of dead white cells) discharge

Very easy to spread

Diseases of the eye: Ophthalmia Neonatorum (newborn conjunctivitis)

Neisseria gonorrhoeae and Chlamydia trachomatis can be transferred from mother to baby (the mother had STIs and baby was given STIs during birth)

Treatment: Antibiotic eye drops/ointment

Diseases of the eye: Trachoma

Caused by chlamydia trachomatis

Causes chronic inflammation and scarring of the eyelid/conjunctiva, creating bumps on the cornea, leading to blindness due to damaged cornea/eyelid. Results in blindness

Treatment: Antibiotics because it is bacterial infection; lashes may grow inward

Bacteria of Trachoma: Chlamydia trachomatis 

Chlamydia trachomatis is an obligate intracellular bacterium: very small, cannot be seen under a microscope, gets inside of a cell, and replicates within the cell. Leads to lysis of the cell. 

Antibiotics need to inhibit the cell replication to block translation 

Diseases of the eye: Keratitis

Caused by: Herpes Simplex Virus 1 (HSV-1)

Virus infects cornea

Essentially reactivated herpes after being latent

Leads to blindness due to damage of the cornea, antiviral is used

Fungal infection of the eye: Ocular Histoplasmosis

Caused by a fungus in contaminated soil (from bat/bird droppings) 

Initially infects our lungs after inhalation, then passes to eyes

Plaques build up within our blood vessels within our retina, leading ot blindness

Treatment: No antifungals, only injections to halt the disease course of blood vessel buildup. Lasting blindness/eye damage may occur

Disease of the ears: Otitis externa (swimmer’s ear) (Otitis meaning ear infection, second word being location of ear infection)

Infection of the outer ear

Symptoms: Red, itchy ear canal with discharge 

Cause: Bacterial, fungal, or viral from 

1. Pseudomonas aeruginosa (found in hot tub rash)

2. Aspergillus sp.

Disease of the ears: Otitis Media

Infection of the middle ear and eustachian tubes (connected to respiratory system)

Symptoms: Pain, discharge, and pressure in ear

Caused by: Streptococcus pneumoniae or Haemophilus Influenzae (due to respiratory connection)

Disease of ear: Otitis Interna/Labyrinthitis

Infection of the inner ear

Caused: Viral infection

Symptoms: Vertigo, dizziness, vomiting

Disease of wounds: Burn Wounds

Bacteria: Pseudomonas Aeruginosa (gram-neg rod)

Disease of wounds: Surgical site infections (SSIs) 

Cause: Patient’s normal flora (staph a + escherichia coli) cause opportunistic infection after surgery 

Symptoms: Fever, pus, redness at surgery site 

Disease of wounds: Gas Gangrene

Cause: Clostridium perfringens (philanges), strict anaerobe creating gas bubbles within muscle tissue. Inhibiting blood flow to our muscle, resulting to tissue death 

Gangrene - tissue death due to lack of blood flow 

Can occur after childbirth or in diabetes 

Anatomy of the Cardiovascular system

• Closed sterile system

Function of the lymphatic system

• Permeable, carries white blood cells

• Supports the cardiovasular system and overlaps

Disease of the cardio/lymph systems

• If infections reac the cardio/lymph system, they are considered systemic

• Signs and symptoms are often non-specific (Non-specific means they do not clearly indicate a specific disease and may vary among patients.)

General diseases of the cardiovascular and lymphatic system

1. Bacteremia

2. Lymphangitis

3. Septicemia (sepsis)

4. Severe sepsis

5. Septic shock

6. Endocarditis

General diseases of the cardiovascular and lymphatic system: Bacteremia

• Presence of bacteria in the blood

• Any bacteria could cause disease given the right conditions

• Viremia, fungemia, and parasitemia

General diseases of the cardiovascular and lymphatic system: Lymphangitis

• Inflammation of lymph vessels

• Can occur after bacteremia

General diseases of the cardiovascular and lymphatic system: Septicemia

• Uncontrolled growth of microbes in the blood

• Sepsis is the body’s inflammatory response to septicemia

• Symptoms are present

  • Fever, chills, increased heart rate, shortness

General diseases of the cardiovascular and lymphatic system: Severe Sepsis

• Blood pressure drops (hypotension) following inflammatory response

• Must be treated with fluids

General diseases of the cardiovascular and lymphatic system: Septic Shock

• Severe sepsis but fluids no longer support the patient

• Organ failure, lower mortality rate

General diseases of the cardiovascular and lymphatic system: Endocarditis

• Infection causes inflammation of heart lining (endocardium)

• Abnormal heart architecture puts you at risk for

  • Rheumatic fever

• Symptoms include

  • Splinter

  • Hemorrhages under fingernails

  • Night sweats

  • Heart murmur

Diagnosis of sepsis and endocarditis

• Blood culture is necessary because few organisms are present

• Treatment must happen quickly because then it will become too broad for antibiotic treatment

Bacterial diseases: Causes of sepsis/endocarditis

1. Staphylococcus aureus

2. Staphylococcus epidermidis

3. Viridians streptococci

4. Enterococcus sp.

5. Streptococcus pyogenes

6. Streptococcus agalactiae

7. Endotoxic shock

   1. Gram-negative

   2. Gram-positive

Bacterial diseases that cause sepsis/endocarditis: Staphylococcus aureus

• Causes both sepsis and endocarditis

• Gram-positive cocci

Diagnosis of S. aureus

• Culture is beta-hemolytic on blood agar

• Catalase positive

• Coagulase positive

Bacterial diseases that cause sepsis/endocarditis: Staphylococcus epidermidis

• Causes sepsis

• Gram-positive cocci

• Causes biofilms

• May come from indwelling medical devices (medical devices inserted in the body)

Bacterial diseases that cause sepsis/endocarditis: Viridans Streptococci

• Causes endocarditis

• Gram-Positive cocci

• May come from dental procedures

• A group of streptococci that are normal flora in the mouth

Bacterial diseases that cause sepsis/endocarditis: Enterococcus sp.

• Causes both sepsis and endocarditis

• Gram-positive cocci

• Leading cause of endocarditis due to prosthetic heart valves

Bacterial diseases that cause sepsis/endocarditis: Streptococcus pyogenes (Group A Strep)

• Causes sepsis

• Gram-Positive cocci

Group A Strep sequelae (complications/diseases arising after untreated group a strep)

1. Rheumatic Fever

   1. Occurrece are pharyngitis (strep throat)

   2. The immune system makes antibodies to M protein

   3. Predisposes patient to endocarditis (Heart infection of inflammation of heart lining)

2. Lemierre’s Syndrome

   1. Occurs after pharyngitis

   2. An abscess may burst, and infection can cause clots in the jugular

   3. Can be fatal

Bacterial diseases that cause sepsis/endocarditis: Streptococcus agalactiae (Group B Strep)

• Sepsis of newborns

• Gram-positive cocci

• Passes through vaginal canal

Bacterial diseases that cause sepsis/endocarditis: Endotoxic shock

• Subtype of septic shock

• As bacteria die, a endotoxin is released and causes symptoms of fatigue, confusion, loss of apetite

• Endotoxins may be gram-negative or gram-positive bacteria characterized by a severe systemic inflammatory response that leads to organ dysfunction.

Gram-Negative Endotoxic Shock

• Endotoxin is in the LPS

• Antibiotics that lyse the bacterial cells will release more endotoxin

• Must use antibiotics carefully to avoid worsening the shock

Gram-Positive Endotoxic Shock

• Less common

• Endotoxin is lipoteichoic acid (LTA)

Bacterial Diseases: Zoonotic diseases

1. Plague

2. Brucellosis

3. Tularemia

4. Lyme Disease

5. Rocky Mountain Spotted Fever

Bacterial Diseases: Plague

• The bacteria is yersinia pestis

• Spread from rodents by fleas

• Can result in sepsis

Bacterial Diseases: Brucellosis

• The bacteria is Brucella sp.

• Can lead to sepsis

• Comes from unpasteurized dairy, handling infected animals, exposure to contaminated meat

• No person-to-person spread, only animal to person

Bacterial Diseases: Tularemia

• The bacteria is Francisella tularensis

• Spreads by vectors of infected animals and inhalation of aerosols

• Common in vets and landscapers

Bacterial Diseases: Lyme disease

• The bacteria is Borrelia Burgdorferi

• Vector: Deer ticks, because deer ticks feed on mice and bite deer

• Present across the U.S.

• Looks like a bullseye rash for diagnosis

Bacterial Diseases: Rocky Mountain Spotted Fever

• The bacteria is Rickettsia Rickettsii

• Vector: Wood ticks and dog ticks

• Rash on hands and feet

• Reservoir: mammals

Diseases of Cardio and Lymph: Viral Diseases

• Infectious Mononucleosis

  • Burkitt’s Lymphoma

• Hemorrhagic Fever

• Acute retrioviral syndrome and AIDS

Viral Diseases of Cardio and Lymph: Infectious mononucleosis (mono)

• Epstein-Barr Virus (Herpesvirus) EBV

• Seen in young adults/teens

• Diagnosis of mono

  • EBV infects B cells - look for atypical B cells in peripheral blood smear

• Monospot test is used

Viral Diseases of Cardio and Lymph: Infectious mononucleosis (mono) EBV → Burkitt Lymphoma

• Cancer of B cells, causing swelling in lymph nodes

Viral Diseases of Cardio and Lymph: Hemorrhagic Fever

• Bloody fever

• Causes damage to blood vessels and initiates leaks

• Caused by several viruses

  • Ebola virus

  • Yellow virus - vector is mosquitos

  • Dengue virus - vector is mosquitos

Changes to climate impact spread of vector-based diseases

Viral Diseases of Cardio and Lymph: Acute retroviral syndrome and AIDS

• Human immunodeficiency virus HIV

  • Retrovirus (RT)

• Primary disease: Acute retroviral syndrome

  • Virus infects CD4 T Cells

• A virus inserts itself into genome and become persistent

• Persistence becomes AIDS

  • Secondary disease: Acquired immunodeficiency syndrome AIDS

  • Lack of immune response leads to overwhelming infections, which leads to death

Prevention and treatment for AIDS

• Prevention

  • STD Screening

  • PrEP (pre-exposure prophylaxis)

• Treatment

  • Antiretroviral Therapy (ART)

  • If treated properly, no virus is present

Fungal Side Story of AIDS

ARC: AIDS-related complex

• Patients with AIDS suffer from infections that do not affect healthy people

• Most are fungal infections

  • Cryptococcus

  • Candidiasis

  • Pneumocystis

  • Histoplasmosis

Parasitic Diseases

1. Toxoplasmosis

2. Malaria

3. Trypanosomiasis

Parasitic Diseases: Toxoplasmosis

• Toxoplasma Gondii protozoa

• Comes from cat feces

• Dangerous for fetuses

Parasitic Diseases: Malaria

• Plasmodium sp. protozoa

• Vector: Mosquitoes

• Diagnosis

  • Parasites in peripheral blood smear

• Treatment

  • Anti-Malarial drugs

Parasitic Diseases: Trypanosomiasis

• Trypanosoma Cruzi protoza

• Vector: Tsetse fly

• Symptoms

  • Sleepiness

Anatomy of the Nervous System

• Central Nervous System (CNS)

  • Cerebral Spinal Fluid (CSF)

  • Should be sterile

• Meninges

  • Layers of lining around the spinal cord and brain

• Blood-Brain Barrier (BBB)

  • Helps prevent infection

  • Prevents uptake of drugs and antibiotics

• CNS is immunologically privileged meaning it reduced an immune response

Bacterial Diseases of the nervous system

• CNS

  • Meningitis

  • Neonatal meningitis

  • Toxemias

    • Tetanus

    • Botulism

• PNS

  • Hansen Disease (Leoprosy)

Bacterial Diseases of the nervous system: Meningitis

• Inflammation of the meninges

  • Bacterial is the most serious but can occur from many microbes

• Symptoms

  • Headache

  • Stiff or painful neck

• Brudzinski’s Sign:

  • Raising neck up will cause knees to flex.