Gram (-) Coccobacilli

Question 1

Bordetella pertussis micro, epi, clinical keys, prevention

Answer 1

• appears singly or in pairs and colonizes cilia of respiratory eptihelium
• whole cell vaccine reduced rate in U.S. in infants by 99%, neonates still susceptible
• infants: apnea, cyanosis
• children: paroxysmal cough, post-tussive vomiting, asymptomatic intervals
• adult: prolonged cough, scratchy throat
• prevention- acellular vaccination less systemic SEs, boosters needed Tdap vaccination of health workers

Question 2

Bordetella pertussis catarrhal stage

Answer 2

Catarrhal stage - First stage

• upper respiratory tract with increasing cough intensity over 10 days
• (FHA) filamentous hemagglutinin- forms filamentous structures on ciliated epithelial surface by binding to galactose residues
• (Ptx) pertussis toxin- (5 B subuntis and 1 A subunit) 6 subunits promote adhesion
• Pertactin- surface protein that participates in attachment
• Antibodies can be formed against all 3 to aid in protection

Question 3

Bordetella pertussis Paroxysmal stage

Answer 3

Second stage

• antimicrobials ineffective on duration of symptoms
• PTx (pertussis toxin) is primarily involved: B subunits bind to cell carbohydrate -> A subunit inserted into cytoplasm -> A inactivates AC inhibitor -> cAMP production -> cell fx disruption, reduction in chemotaxis and phagocytotic process -> lymphocytosis, hyperinsulinemia, histamine sensisitivity
• B. pertussis creates its own ACtoxin that reduces phagocytic activity
• Lethal toxin- inflammation and local necrosis adjacent to infection site
• Tracheal cytotixin- stops epithelial cilia from beating, release IL-1
• Endotoxin- whole cell vaccine side effects

Question 4

Bordetella pertussis Convalescent phase

Answer 4

Third phase

• resolution of cough episode
• recurrent paroxysmal cough “100 day cough”

Question 5

Haemophilus infuenzae Type B, micro, epi, prevention

Answer 5

• loves heme and X/V factors (grows on chocolate agar), polysaccharide capsule
• pre-vaccine most common cause of child meningitis, Hib vaccine widespread could significantly reduce worldwide morbidity, Hib ineffectiveness due to non-Hib strain or memory B cell deficiency
• prevention- Hib vaccine is highly effective, Hib conjugate with PRP protect younger infants

Question 6

Haemophilus infuenzae Type B pathogenesis and clinical manif.

Answer 6

• transmitted via airborn droplets
• infection begins in upper respiratory–nasopharyngitis–followed by sinusitis, otitis and maybe pneumonia; bacteremia/meningitis in sever cases
• encapsulated strains penetrate epithlium and survive complement/phagocytes in blood stream diractly invading capillaries
• nontypable (NTHI) are more responsable for respiratory infections
• **PRP (polyribosyl ribitol phosphate) capsule is most impt vf allowing it to evade immune system in absence of anti-capsular antibodies
• children susceptible due to minimal pre-formed bactericidal antibodies