Flashcards in Bacterial Upper Respiratory Infections Deck (44):
Aerobic encapsulated gram negative coccobacilli
Single or in pairs
Bordetella pertussis causes what?
whooping cough, caused by local effect of toxins
There is waning immunity to bordetella pertussis. Who serves as a resevoir?
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
How quickly does bordetella pertussis grow?
Takes 3-7 days for colonies to appear on Bordet-gengou media
Is there an animal reservoir for bordetella pertussis?
How is b. pertussis spread?
Person-person via airborne droplets
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
Pertussis toxin action?
Binds to ciliated epithelial cells
Causes lymphocytosis and inhibits phagocyte function
2 subunit AB exotoxin: ADP ribosylating activity >> increases cAMP > increases secretions
What is filamentous hemagglutinin?
Adhesin that allows bacterium to bind to ciliated epithelial cells
What are the three clinical stages of pertussis?
Catarrhal stage ~1 week
Paroxysmal stage ~1-6 weeks
Convalescence weeks to months
Describe the catarrhal stage of pertussis
Presents like common cold, not very ill
Highly contagious - large number of organisms in respiratory organisms
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
What can happen to the eyes in pertussis?
How do you diagnose pertussis
Nasopharyngeal aspirate (preferred) culture
First line of defense against pertussis?
Antibody that prevents bacteria from binding to cilia of epithelium
Acellular or subunit vaccine
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?
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?
Aerobic non-spore forming gram positive bacilli
Clinical manifestations of corynebacterium diphtheriae are due to what?
Toxin carried by a bacteriophage
Causes only localized disease
Gram stain of corynebacterium diphtheriae?
Clubbed or irregularly shaped
V or L shaped formations
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?
Normal flora of skin and mucous membranes
Infections of respiratory tract
How does C. diphtheriae spread and does it invade tissues/blood?
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?
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?
Describe propionibacterium acne?
Normal skin flora, anaerobic
Occasionally contaminates blood
Infections in patients with "hardware"