ID Exam 2: Toxogenic bacteria, mycoplasma, legionella

Question 1

Atypical pneumonia presentation (usually)

Answer 1

Moderate sputum
No consolidation
Small increases in white counts
No alveolar exudate

Question 2

Eaton’s medium

Answer 2

Grows mycoplasma

Lots of abx - grows slow, need to suppress rest

Question 3

M. Pneumo pathogenesis

Answer 3

Airbone, person to person
Army barracks and dorms
Attaches and damages respiratory epithelium
(terminal cytoadherence organelle)
P1 adhesion protein (PCR target)
CARDS toxin (PCR target)

Question 4

M. pneumo replication

Answer 4

Duplicates terminal organelle first

Question 5

CARDS toxin

Answer 5

Similar to S1 subunit of pertussis toxin

ADP ribosylating - slows ciliary movement

Question 6

Cold agglutinin

Answer 6

IgM agglutinin in blood when cooled

Question 7

Dx

Answer 7

Culture
PCR
Serum (acute and convalescent)

Question 8

Treatment of m. pneumo

Answer 8

Macrolides
Respiratory FQs (not cipro)

Question 9

Legonella - sketchy

Answer 9

Soil and water pathogen
Intracellular pathogen
Massive macrophage/PMN infiltration
Urine antigen test (sheds LPS in urine)

Question 10

Legonella - intracellular mechs

Answer 10

Survival in specialized endosome
Creates legonella containing vacuole
Type 4 secretion system

Question 11

Legonella treatment

Answer 11

macrolides

respiratory FQs

Question 12

C. Diphtheriae and B. pertussis site of infection

Answer 12

Posterior pharynx/URT

Question 13

Corynebacterium diphtheriae: characteristic and toxin

Answer 13

Gram+ rod
ß-prophage encodes
Dip tox: ADP ribosylation (of EF2), regulated by available iron
Metachromatic granules

Question 14

Corynebacterium diphtheriae treatment

Answer 14

Passive immunity via anti-toxin to bind unbound
Toxin that is bound is irreversible
+/- abx (erythromycin)
Vaccine for close contacts

Question 15

Corynebaterium diphtheriae s/sx

Answer 15

Pseudomembranous pharyngitis
Lymphadenopathy -> Bull’s necks
Myocarditis, arrhythmia, heart block
Local nerve demyelination -> pharynx paralysis

Question 16

Corynebacterium diphtheriae: dx testing

Answer 16

Culture: see metachromatic granules, takes 5days (too long)
Black colonies on cystine-tellurite agar
Loeffler’s medium
Elek test for toxin

Question 17

Bordetella pertussis: characteristics, tox, and dx

Answer 17

Gram-, aerobic coccobacillus
Toxins: pertussis tox (rib Gi, vir gene), tracheal toxin, AC toxin
Lymphocytosis - can be confused with viral
Culture is gold standard but very slow - used to confirm outbreaks
Filamentous hemagglutin (FHA) - strong attachment (need saline wash to get sample for culture)

Question 18

Bordetella pertussis treatment

Answer 18

Acellular vaccine - not immune for life, but will decrease severity
Pregnant women receive in 3rd tri (even if already immunized) - infant get at 2 months
Macrolides
No antitoxin

Question 19

Bordetella pertussis:

3 stages of whooping cough

Answer 19

1. Catarrhal: inflammation with discharge, communicible, dry cough
2. Paroxysmal: 1-6 weeks, sudden recurrence and intensity, whoop
3. Convalescent: decreasing symptoms, but last for months (100 days)