Micro Haemophilus and Bordetella

Question 1

H. influenzae bacteriology

Answer 1

gram -, pleomorphic rod, nonmotie, non spore forming, needs media with X and V
-human restricted

Question 2

how is H. influenzae transmitted

Answer 2

respiratory droplets or direct contact

Question 3

which serotype of h. influenzae causes the most severe disease

Answer 3

capsule types especially type B (HiB) - causes meningitis, pneumonia, septic arthritis

Question 4

unencapsulated strains of h. influenzae

Answer 4

NTHi - causes local infections

Question 5

HiB pathogenesis

Answer 5

colonization facilitated by IgA protease in respiratory system -> invades bloodstream and causes invasive disease (meningitis from type B has high mortality)

Question 6

host defense against HiB

Answer 6

defense by complement and anti-capsule antibody

• vaccination against capsule
• maternal antibody in first 6 months

Question 7

NTHi pathogenesis

Answer 7

lacks capsule, but still has pili, attachment proteins, and IgA protease

Question 8

NTHi in cystic fibrosis patients

Answer 8

pneumonia with biofilm formation

Question 9

Hib on exam

Answer 9

meningitis, cellulitis, otitis media, sinusitis, epiglottitis, septic arthritis

Question 10

NTHi on exam

Answer 10

in neonates: associated with prematurity, premature rupture of membranes, low birth weight, maternal chorioamniotis - presents within 24 hours of birth

Question 11

H. influenzae lab

Answer 11

gram stain, culture on chocolate agar with both factors X and V (need growth only with factors)

Question 12

bordetella pertussis bacteriology

Answer 12

small encapsulated gram - rod, transmitted by respiratory droplets
-human restricted

Question 13

what does b. pertussis cause?

Answer 13

whooping cough

Question 14

b. pertussis pathogenesis

Answer 14

“filamentous hemagglutinin” - pilus attaches bacteria to epithelial cells lining respiratory tract where they cells release pertussis toxin and tracheal cytotoxin
-also produce mucopurulosanguineous exudate that compromises small airways

Question 15

pertussis toxin

Answer 15

A-B subunit ADP-ribosylator - secondary attachment factor that kills ciliated cells (also freezes them) and inhibits chemokine signal transduction (lmphocytosis)

Question 16

tracheal cytotoxin

Answer 16

pertussis toxin that also kills ciliated cells

Question 17

b. pertussis prognosis

Answer 17

good - symptoms are mostly toxigenic (no bacteremia) - problems really only from secondary bacteremia

Question 18

b. pertussis exam

Answer 18

• afebrile but dehydrated
• acute tracheobronchitis developing into severe paroxysmal cough
• history of no vaccination, prematurity, underlying disease, asthma, obesity, pregnant

Question 19

stages of symptoms in b. pertussis

Answer 19

• stage 1 (2 weeks): catarrhal,
• stage 2 (2 weeks): paroxysmal
• stage 3 (2 mo): convalescence

Question 20

catarrhal stage of b. pertussis

Answer 20

catarrhal: nonspecific upper respiratory symptoms: congestion, sneezing, rhinorrhea, contagious

Question 21

paroxysmal stage of b. pertussis

Answer 21

intense coughing with characteristic pattern: hacking cough, copious mucus, inspiratory whoop,

Question 22

convalescence stage of b. pertussis

Answer 22

fatigue and chronic cough

Question 23

b. pertussis lab

Answer 23

• bloodwork showed pronounce leukocytosis

- culture on regan-lowe or bordet-gengou agar (grows slow)

Question 24

b. pertussis treatment and prevention

Answer 24

macrolides only to stop spread - supportive care

prevention: acellular vaccine and need booster or killed vaccine also with booster