CH. 24-26

Pharyngitis

inflammation of the mucous membranes of the throat

Laryngitis

an infection of the larynx

Tonsillitis

inflamed tonsils

Sinusitis

an infection of a sinus

• sinus headache or internal pressure

Epiglottitis

Threatening infectious disease of the upper respiratory system

• rapidly developing disease

Causative Agent of Epiglottitis

Haemophilus influenzae type B

Prevention of Epiglottitis

Hib vaccine

• primarily for meningitis, but reduce for epiglottitis

Streptococcal Pharyngitis (Strep Throat)

Upper respiratory infection

Causative agent of Streptococcal Pharyngitis (Strep Throat)

Group A streptococci (GAS)

• gram positive, mostly consists of Streptococcus pyogenes

What is Pharyngitis?

local inflammation and fever

Group A Streptococci Pathogenicity

Enhanced by their resistance to phagocytosis

• Streptokinases: lyse fibrin clots

• Streptolysins: cytotoxic to tissue cells, red blood cells, and leukocytes

GAS is sensitive to penicillin

Scarlet Fever

• Produces an erythrogenic toxin

– Toxin produces pinkish red skin rash and high

fever

Causative agent of Scarlet Fever

Streptococcus pyogenes causes streptococcal pharyngitis

Symptoms of Scarlet Fever

Tongue is spotted

• Becomes red and enlarged

Diphtheria

Causative agent: Corynebacterium diphtheriae

• Gram positive, non-endopore rod

• frequently pleomorphic, club-shaped

• stains unevenly

Prevention of Diphtheria

DTaP Vaccine

• Protects against diphtheria, tetanus, and pertussis

• “D” represents the diphtheria toxoid, inactivated toxin

  • causes the body to produce antibodies against he diphtheria toxin

• Nonvirulent strains found in throats of symptomless carriers

C. diphtheriae Transmission (Diptheria)

• Via droplet transmission

• Tough grayish membrane forms at infection site

• Powerful toxin that circulates the bloodstream

  • interferes with protein synthesis

• Diphtheria is also expressed as cutaneous diphtheria

• Bacteria causes slow-healing ulcerations that are covered by a gray membrane

Diphtheria Vaccine Program

• Was the leading cause of death in children

• Children immunization program

Otitis Media

• Infection of the middle ear

• Formation of pus which builds up pressure against the eardrum

  • causing inflammation and pain

• Most frequently observed in early childhood

  • auditory tube is small and more horizontal than in adults

  • more easily blocked

Most common agents of Otitis Media

• S. pneumoniae

• non-encapsulated H. influenzae

• Moraxella catarrhalis

• S. pyogenes

30% cases no bacteria

viruses

What % of antibiotic prescriptions does acute otitis media account for?

25%

Common Cold

Over 200 different cold causing viruses

• Accumulate immunity against cold viruses

• Immunity based on ratio of IgA antibodies to single serotypes

  • a specific strain of a cold causing virus

Causative agent of Common Cold

30-50% rhinovirus and 10-15% coronavirus

Symptoms of Common Cold

• Sneezing

• Excessive nasal secretion

• Congestion

• Infection can spread from throat to sinus, lower respiratory system and middle ear

Transmission of Common Cold

Carried on airborne droplets of water vapor

• In dry air, droplets are smaller and remain airborne longer

Mostly transmitted via finger contact with nostrils and eyes

• Virus in mucus remains viable on surfaces for several hours

Enterovirus D68

In 2014 the United States experienced a nationwide outbreak

• associated with severe respiratory illness

• Children and teenagers are most susceptible

Symptoms of Enterovirus D68

Causes cold like symptoms

Treatments of Enterovirus D68

• cough suppressants

• antihistamines

Pertussis

Attaches to ciliated cells in trachea, destroys them

• Produces Tracheal cytotoxin damages ciliated cells

• Then, Pertussis toxin enters the bloodstream

  • systemic symptoms

Causative agent of Pertussis

Bordetella pertussis

• Small, obligate aerobes, gram -, coccobacillus with capsule

Stages of Pertussis

Initial stage: catarrhal stage

• Resembles a common cold

Second stage: paroxysmal stage

• Prolonged fits of coughing

• Mucus accumulates and ciliary action is inhibited

  • Coughing fits can occur several times a day for 1-6 weeks

Third stage: convalescence stage

• Can last for months

• Brain damage can result in infants

Tuberculosis

Co-infection with HIV increases susceptibility

Tuberculosis

Mycobacterium tuberculosis

• Slender rod and obligate aerobe

What group of people does Tuberculosis effect?

Elderly and malnourished

• Usually defeated by immune system

  • If defenses fail, host becomes aware

Acid-Fast Stain

Mycolic acids stained with carbolfuchsin dye

• stimulate inflammatory response

1. Can’t be decolorized with acid-alcohol

2. Cell walls contain a large amount of lipids

3. Lipids may contribute to environmental resistance

   • Resistant to chemical antimicrobials

   • Can survive for weeks in dried sputum

Pathogenesis of Tuberculosis

1. Tubercle bacilli reach lung alveoli, ingested by macrophage

   • infection is present, no symptoms

2. Tubercle bacilli multiply in macrophages, clump up

   • surrounding macrophages can’t destroy bacteria

   • release enzymes and cytokine that cause lung damaging inflammation

3. Disease symptoms appear after a few weeks

   • as macrophages die, release tubercle bacilli forming a caseous center in tubercle

   • Lesions become calcified called Ghon’s Complexes

4. Disease symptoms appear as a mature tubercle forms

   • Caseous center enlarges

   • Aerobic bacilli multiply outside the macrophages

5. If the body’s defense fails, tubercle breaks and releases m-o into airways of the lung

• Travels to the cardiovascular and lymphatic systems

Why does people w/ Tuberculosis respond with cell-mediated immunity?

Because the pathogen is mostly within macrophage

Tuberculin skin test

• Protein derivative of tb is injected cutaneously

If person has been infected with TB in the past, sensitized T cells react with these proteins

Positive result: Hardening and reddening around injection site

Treatment of Tuberculosis

Multiple-drug therapy treatment

• to minimize emergence of resistant strains

First line drugs: Isoniazid, Rifampin, Ethambutol, and Pyrazinamide

• can be susceptible to treatment

• resistance may develop because patients fail to follow ~ 130 doses of the drugs

Resistant Strains of Tuberculosis

Multi-drug resistant strains

• Resistant to the two most effective first-line drugs isoniazid and rifampin

• When drugs are resistant to second line drugs, called extensively drug-resistant

  • untreatable and are emerging globally

  • 30-90% infected individuals are also HIV positive

Prevention of Tuberculosis

Vaccine has live culture of M.bovis

• Widely used vaccine world wide

• Effective in young children

• Not effective in adolescents and adults

• HIV infected children often develop fatal infection from the vaccine

What are the 2 types of Bacterial Pneumonias?

Pneumococcal Pneumonia and Leigonellosis

Symptoms of Pneumococcal Pneumonia

• High fever, breathing difficulty

• blood vessels dilate

• alveoli fill with red blood cells, neutrophils, and fluid from surrounding tissues

• sputum is rust colored

Causative agent of Pneumococcal Pneumonia

S. pneumoniae

• gram-positive, ovoid bacteria, surrounded by a dense capsule

Legionellosis (Legionnaires disease)

Can grow in water of air-conditioning cooling towers

• whirlpool spas, humidifiers, showers, fountains

Causative agent of Legionellosis

Legionella pneuemophila can replicate in macrophages

• Aerobic gram negative rod

Viral Pneumonia

Can occur as a complication of influenza, measles or chickenpox

• Some enteric viruses have caused viral pneumonia

Causative agent of Viral Pneumonia

Coronaviruses

Epidemiology of SARS-associated coronavirus (SARS)

Emerged in Asia in 2003 and quickly spread

• since 2004, no new cases reported

Prevention: Isolation and quarantine have eliminated the virus

Causative agent: Related viruses are found in bats in the Eastern hemisphere

In 2012 Middle East Respiratory syndrome coronavirus (MERS-CoV) was reported in Saudi Arabia

• 2 cases reported in the United States 2014

COVID-19

In 2019, first reported in Wuhan, China and quickly spread

• Shortage of PPE and ventilators

Prevention: The U.S. is mostly following the “Safer at Home” quarantine

• Face masks are required in public settings

Symptoms of COVID-19

• highly infectious, primarily affects the lungs

• fever, coughing, shortness of breath

1.43 million confirmed cases, 85, 601 deaths as of 5-14-20

Respiratory Syncytial Virus

Most common cause of viral respiratory disease in infants

• Can cause life-threatening pneumonia in older adults, misdiagnosed as influenza

• Epidemics occur during winter and early spring

Symptoms of Respiratory Syncytial Virus

coughing and wheezing lasting more than a week

• 14,000 deaths a year

Influenza

Characterized by chills, fever, headache, and muscular aches

• Recovery occurs in a few days

• Cold-like symptoms appear as the fever wanes

  • 30,000-50,000 Americans die each year from the flu

Virus of Influenza

Protein coat, envelope and two types of spikes

1. Hemagglutinin (HA) spikes

   • Allow the virus to recognize and attach to the body cells before infecting them

   • Red blood cells will mix with the virus

2. Neuraminidase (NA) spikes

   • Stimulate formation of antibodies

   • Help virus separate from infected cells

Antigenic drift

A minor variation in the antigenic makeup of influenza viruses

Antigenic shifts

Mark changes great enough to evade immunity

• genetic recombination

• very common in areas where swine, birds, and humans live in close proximity

• breeding grounds for outbreaks of avian influenza

Epidemiology of Influenza

The very young and old are at higher risk of dying from influenza

• 2009, H1N1 virus circulating in pigs

  • Function as an incubating vessel

• Mutations occur in humans

  • Have a longer life span

  • Pigs and birds (help spread virus) have a short life span

Influenza Vaccines

No vaccine for long-term immunity

• Each new strain of circulating virus is identified around February of the same year

• Strains of the influenza virus are collected and analyzed

  • Decide on the composition of the vaccines for the next flu season

Two types of vaccines

• Injected: inactivated version

• Nasal-spray: live, attenuated virus

The 1918-1919 Pandemic

Worldwide 20 to 50 million people died

• Young adults then had the highest mortality rate

• Dying within a few hours

  • cytokine storm

  • infection usually restricted to upper respiratory system, but it also invaded the lungs

• Infected many organs in the body

Treatment of Influenza

Relenza and Tamiflu

• Slow replication

• Allows immune system to be more effective

• Shortens duration of symptoms

• Shortens mortality rate

Fungal Pulmonary Disease: Coccidioidomycosis

Wind carries spores to transmit the infection

• Incidence increasing in California and Arizona

Causative agent of Coccidioidomycosis

Coccidioides immitis

• Found in dry, alkaline soils of the American Southwest

• Frequently found in the San Joaquin Valley

Symptoms of Coccidioidomycosis

• Chest pain

• Fever

• Coughing

• Weight loss

Older residents

• Increased prevalence of HIV/AIDS

• Outbreaks occur after soil turnover (ex: fires, earthquakes, tillea)

Diagnosis of Coccidioidomycosis

Organism in the tissue forms thick celled walled spherule

• Filled with endospores, wind carries for dispersal

• Observe spherules in tissues or fluids

  • dangerous aerosoles

Diarrhea

Infection and intoxication of bacterial m-o

• High infant mortality in developing countries

Symptoms of Diarrhea

• Abdominal cramps, nausea and vomiting

  • Trying to rid the body of harmful material

Treatment for Diarrhea

Oral rehydration therapy

• Replacement of lost fluids and electrolytes

Staphylococcal Food Poisoning

Ingesting an enterotoxin produced by S. aureus

• Microbes can enter food and incubate in food

• S. aureus outgrows most competing bacteria

  • Toxin is heat stable

  • Survives 30 minutes of boiling

• Refrigeration during storage to prevent toxin formation

• No obvious spoilage when growing in food

Causative agent of Staphylococcal Food Poisoning

S. aureus

• outgrows most competing bacteria

Shigellosis (Bacillary Dysentery)

Severe form of diarrhea

• Spread only from person to person

Symptoms of Shigellosis (Bacillary Dysentery)

• Can cause as many as 20 bowel movements in one day

• Abdominal cramps and fever

Causative agent of Shigellosis (Bacillary Dysentery)

Bacteria which is facultative, anaerobic gram-negative rod

Treatment for Shigellosis (Bacillary Dysentery)

• Antibiotics for severe cases

• Oral rehydration therapy

Transmission of Salmonellosis (Salmonella Gastroenteritis)

Meat products susceptible to contamination

• First invade the intestinal mucosa and multiply

Causative agent of Salmonellosis (Salmonella Gastroenteritis)

Bacteria which is Gram-negative, facultative anaerobe, non-endospore forming bacillus

Symptoms of Salmonellosis (Salmonella Gastroenteritis)

• Moderate fever, nausea, abdominal pain

• Cramps, diarrhea

Typhoid Fever

Spread in feces of humans

Pathogenesis: Multiply within phagocytic cells, Spread to multiple organs

• Incubation period is 2 or 3 weeks

Symptoms of Typhoid Fever

• High fever

• Headache

• Diarrhea at second or third week

Causative agent of Typhoid Fever

Salmonella typhi (most virulent serotype)

Typhoid Carriers

1-3% of recovered patients become chronic carriers

• Harbor pathogen in the gallbladder

  • continue to shed the bacteria for a few months

Mary Mallon (Typhoid Mary)

• Cook in New York in the early twentieth century

• Responsible for several outbreaks of typhoid, 3 deaths

• State restrained her from working as a cook

Foreign travel can result in exposure to typhoid fever

Cholera

Grow in the small intestine

• Produce cholera toxin

Containment is key

Causative agent of Cholera

Bacteria: Vibrio cholerae ,Gram negative rod, single polar

flagellum

Symptoms of Cholera

12 to 20 liters of fluids (3 to 5 gallons) lost in one day

• Loss of fluids and electrolytes cause shock

• Blood lacking fluids becomes viscous

• Vital organs are unable to function properly

• Violent vomiting

Escherichia coli (Gastroenteritis)

Normally harmless, some strains are pathogenic

• Some toxin-secreting pathogenic strains can invade intestinal epithelial cells

• Cause E. coli gastroenteritis

Sites to cause infection: Urinary tract, bloodstream, central nervous system

What are the 4 different types of Diarrhea-causing pathovar groups?

1. Enteropathogenic E. coli (EPEC)

2. Enteroinvasive E. coli (EiEC)

3. Enterohemorrhagic E. coli (EHEC)

4. Enterotoxigenic E. coli (Traveler’s Diarrhea)

Enteropathogenic E. coli (EPEC)

Major cause of diarrhea in developing countries

• Potentially fatal in infants

• Bacteria attach to the intestinal wall

Enteroinvasive E. coli (EiEC)

• Uses M cells to gain access to the submucousa of the intestinal tract

• Results in inflammation, fever, and shigella-like dysentery

Enterohemorrhagic E. coli (EHEC)

• Produces a Shiga-like toxin

• Reservoirs are cattle and leafy vegetables

Symptoms of Enterohemorrhagic E. coli (EHEC)

In 6% of infected patients, inflammation of the colon

• Hemolytic uremic syndrome (Blood in the urine)

  • Leads to kidney failure

  • Some survivors may need kidney dialysis or transplants

Enterotoxigenic E. coli (Traveler’s Diarrhea)

Most common bacterial cause

• Caused by other gastrointestinal pathogens

• Usually the agent is never identified

• Best treatment is oral rehydration therapy

Campylobacter Gastroenteritis

Leading cause of foodborne illness in the US

• Adapt well to the intestinal environment of animals

  • Especially poultry

• Do not replicate in food

  • Almost all retail chicken is contaminated

  • 60% of cattle excrete the organism in feces and milk

Causative agent of Campylobacter Gastroenteritis

Campylobacter jejuni

• gram-negative, microaerophilic, spiral

Symptoms of Campylobacter Gastroenteritis

• Cramping

• diarrhea or dysentery

Pathogenesis of Clostridium difficile- associated diarrhea

• Exotoxin symptoms cause diarrhea

• Other microorganisms are eliminated, allowing for C. difficile to grow rapidly

Causative agent of Clostridium difficile- associated diarrhea

Clostridium difficile

• Gram-positive, endospore forming anaerobe

Transmission of Clostridium difficile- associated diarrhea

Healthcare-associated disease

• Day care centers

• Caregivers can acquire it from patients

  • Near-epidemic rate

Bacillus cereus Gastroenteritis

Common in soil and vegetation

• Cause of outbreaks of foodborne illness

• Heating food does not always kill the spore

• Competing microbes are eliminated in cooked food

Causative agent of Bacillus cereus Gastroenteritis

B. cereus

• Large, gram-positive, endospore-forming bacterium

• grows rapidly as food cools and produces toxins

Symptoms of Bacillus cereus Gastroenteritis

• Nausea

• Vomiting

• Diarrhea

Mumps

Transmitted in saliva and respiratory secretions