URT bacteria

Question 0

Corynebacterium diphtheria

Answer 0

URT bac
-Gr+ club shaped (coryneform) to pleomorphic rod
-not normal microbiota (where endemic, up to 5% carriers in oropharynx and skin)
-aerobe to fac anaerobe
-cat +
-metachromatic granules (stored polyphosphates)
-clumps resemble chinese characters or palisades
Diagnostic
-blood agar
-loeffler medium (enhance metachromatic granule formation and proteolysis)
-tinsdale agar (turns from gray to black)
Virulence
-diphtheria toxin
-A-B exotoxin
-encoded by lysogenic B-phage
-ADP-ribosylates elongation factor 2
Disease
-causes respiratory diphtheria
-transmitted through respiratory droplets and skin contact
-pseudomembrane=bacteria+WBC+RBC+dead cell debris+fibrin
-“bull neck”
Treatment
-antitoxin (immediately!)+erythromycin or penicillin+airway support

Question 1

Streptococcus pyogenes

Answer 1

URT bac
-Gr+ coccus, *chains
-normal microbiota, oropharynx
-facultative anaerobe
-*catalase-
-*B-hemolytic
-susceptible to penicillin G
-*sensitive to bacitracin (A disk)
Disease
-transmitted through respiratory droplets, skin contact, fomites
-causes GAS pharyngitis
Diagnosis
-*centor criteria
-*rapid antigen detection tests (RADT)
-*throat culture
Virulence
-*hyaluronic acid capsule
-*SpyCEP cell envelope proteinase
-*C5a peptidase
-*M/F protein
-*streptolysin S & O
-*streptokinase
-*hyaluronidase
-*DNases A-D
-SpeB=exotoxin B (superantigen)

Question 2

Neisseria gonarrhoeae

Answer 2

URT bac
-Gr- diplococcus (kidney bean shaped)
-obligate human pathogen
-fragile/sensitive to drying, sunlight, heat, etc)
-aerobe to fac anaerobe
-oxidase+
-catalase+
-*oxidizes glucose
Disease
-causes gonococcal pharyngitis
-transmitted though oral sex
Diagnostic
-*chocolate or thayer-martin agar
Virulence
-*opa
-*pili (twitching motility)
-*IgA1 protease
-*LOS
-*outer membrane blebbing