Bacterial Upper Respiratory Infections Flashcards by Kathleen Carlos

Bordetella pertussis causes what?

whooping cough, caused by local effect of toxins

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Describe bordetella

Aerobic encapsulated gram negative coccobacilli

Single or in pairs

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There is waning immunity to bordetella pertussis. Who serves as a resevoir?

Adults

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Bordetella pertussis isolation media?

Bordet-gengou media is selective
Contains blood and starch (absorbs and neutralizes inhibitors of growth)
Penicillin is added to inhibit other respiratory flora

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How quickly does bordetella pertussis grow?

Takes 3-7 days for colonies to appear on Bordet-gengou media

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Is there an animal reservoir for bordetella pertussis?

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How is b. pertussis spread?

Person-person via airborne droplets

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Pathogenesis of b. pertussis?

Organism adheres to and then kills ciliated epithelial cells of upper respiratory tract, this prevents clearance of pulmonary secretions
Does not invade the blood stream

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Pertussis toxin action?

Binds to ciliated epithelial cells
Causes lymphocytosis and inhibits phagocyte function
2 subunit AB exotoxin: ADP ribosylating activity&raquo_space; increases cAMP > increases secretions

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What is filamentous hemagglutinin?

Adhesin that allows bacterium to bind to ciliated epithelial cells

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What are the three clinical stages of pertussis?

Catarrhal stage ~1 week
Paroxysmal stage ~1-6 weeks
Convalescence weeks to months

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Describe the catarrhal stage of pertussis

Presents like common cold, not very ill

Highly contagious - large number of organisms in respiratory organisms

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Paroxysmal stage of pertussis

Burst of rapid coughs without inspiration due to difficulty clearing thick mucus, may end with vomiting, cyanosis, exhaustion, convulsions
Whoop sound from inhaling through narrowed glottis

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What can happen to the eyes in pertussis?

Subconjunctival hemorrhages

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How do you diagnose pertussis

Nasopharyngeal aspirate (preferred) culture

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First line of defense against pertussis?

Antibody that prevents bacteria from binding to cilia of epithelium

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Pertussis vaccine

Acellular or subunit vaccine

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How much protection (%) does pertussis toxin monovaccine provide? Is it sufficient?

Not sufficient, only 70% protection

Which pertussis vaccine is used today, acellular or whole cell? Why?

Acellular

Reduced side effects

What is the DTaP vaccine? When is it given?

Diptheria, Tetanus, and acellular Pertussis toxoid

Three shots at 2, 4, 6 months

What is the Tdap vaccine?

It is a booster shot for adolescents and adults that contain less diptheria and acellular pertussis toxoid

Cyclic epidemic of pertussis spikes every how many years?

3-4 years

Describe corynebacterium?

Aerobic non-spore forming gram positive bacilli

Non-motile

Clinical manifestations of corynebacterium diphtheriae are due to what?

Toxin carried by a bacteriophage

Causes only localized disease

Gram stain of corynebacterium diphtheriae?

Gram positive Clubbed or irregularly shaped V or L shaped formations Beaded staining

Corynebacterium diphtheriae culture media?

Blood agar: small granular gray colonies with irregular edges Potassium tellurite agar (Tinsdale) black colonies - differential medium Loeffler's medium: corynebacterium grow faster than other respiratory pathogens - selective medium

C. Diphtheriae, human or animal resevoir?

Just human Normal flora of skin and mucous membranes Infections of respiratory tract

How does C. diphtheriae spread and does it invade tissues/blood?

Airborne droplets | Does not invade tissues or blood

Diphtheria toxin is encoded by what? Can it still be pathogenic without the toxin?

Diphtheria toxin is encoded by a bacteriophage | If it is not infected by the bacteriophage then it is not pathogenic

Diphtheria toxin - 2 subunit AB toxin - describe

Highly potent toxin with necrotizing effect Lethal at low dose A subunit inhibits host protein synthesis (inactivates elongation factor EF-2 by ADP-ribosylation, which leads to cell death)

Diphtheria toxin absorbed by mucous membranes causes what?

Epithelial necrosis which causes a gray pseudomembrane to form over tonsils and throat

Can diphtheria toxin affect anything other than tonsils/throat?

Yes it can cause heart and nerve damage

What does diphtheria do to the neck?

Causes bull neck - marked edema of neck and cervical lymphadenopathy

Does diphtheria toxin cause wounds?

Yes, forms a membrane of a non-healing wound or ulcer

What is the population at risk for infection with diphtheria?

Adults with decreased antitoxin titers

Resistance to disease caused by diphtheria depends on what?

Specific neutralizing antitoxin in bloodstream and tissues

Is there a vaccine for diphtheria?

Yes, formalin-inactivated C. diphtheria

Diphtheria vaccine is often combined with what?

DTaP | Diphtheria, Tetanus, acellular Pertussis

Adults need a diphtheria booster shot how often and when?

Every 10 years Also when they travel to developing countries Given with tetanus toxoid

A derivative of the diphtheria toxoid (CRM 197) is used in which other vaccines? Why?

Haemophilus influenzae type B, pneumococcal, meningococcal conjugate vaccines More immunogenic in children under 2

Which antibiotics for diphtheria toxin? How do they help?

Erythromycin or penicillin Inhibit growth of toxin-producing bacteria Stop toxin production Reduce shedding of organism

Do diphtheria patients have to be isolated?

Yes

Describe propionibacterium acne?

Normal skin flora, anaerobic Acne pathogenesis Occasionally contaminates blood Infections in patients with "hardware"

Which antibiotic is used for pertussis? What affect does it have during each stage?

Erythromycin Catarrhal stage: eliminates organism Paroxysmal stage: reduces severity and duration and lowers complication rate Limited benefit if given more than 3 weeks after paroxysmal cough