Micro 2 Flashcards
how to get food poisoning from S. aureus?
heat stable enterotoxin; NO FEVER
who’s more susceptible to SSS from S. aureus?
infants and children, acute onset of perioral erythema
how virulent is S. epidermitis compared to S. aureus?
less virulent and more indolent, does not ferment mannitol
does S. pneumoniae and viridans have lancefield ag?
nope
3 virulence factors in S. pneumoniae
polysacch capsule –> antiphag, igA protease, pneumolysin impairs mucociliary escalator
how to S. pneumoniae transmitted?
airborne and direct contact; mostly affects <2yo and >60yo; more in drier and colder months; viral infxns esp IAV inc S. pneumoniae shedding. nasopharyngeal carriage common –> lives in mucous layer, resists phag, attaches to epithelium
describe progression of S. pneumoniae
serotype dep, more likely in pts w/ COPD and IVDU
can S. pneumoniae cause bacteremia?
yes, common in pts w/ PNA but not w/ otitis media or sinusitis; endocarditis can occur secondary
how to dx S. pneumoniae?
urine pneumococcal ag rapid detection test, Quellung rxn for pneumococcal capsular serotyping
how to tx S. pneumoniae?
beta lactam and macrolide abx but resistance = increasing
what are the main virulence factors for Enterococcus?
adhere to tissues and form biofilms, high antimicrobial resistance to vancomycin
clinical dz of Enterococcus
UTI, peritonitis, wound infxns, bacteremia, endocarditis
how is B anthracis transmitted?
zoonotic, NOT person to person; spore enter body by skin contact, inhalation, ingestion of contaminate food, IV drug use
anthrax clinical pres
cutaneous by spore for vegetative form –> black eschar; GI by veg form –> nausea, bloody diarrhea, loss of appetite, fever, severe stomach pain; resp by spore form –> flu like sxs; bacteremia by any form –> fatal
how to dx B anthracis?
occupational and exposure hx (IVDU, farmer); can’t use sputum b/c airspace dz (broncho or alveolar PNA) = freq absent
how to tx B anthracis?
ab therapy w/ 2+ abx; 7-10d for cutaneous but other forms require 60d; monoclonal ab against protective ag in combo w/ abx; vaccine available and can be used w/ abx as postexposure prophylaxis
what dzs can B cereus cause?
gastroenteritis by 2 enterotoxins: heat stable (emetic) in unrefrigerated, contaminated, reheated rice; and heat liable (diarrheal) in contaminated meats and veggies. ocular infxns after penetrating eye w/ soil contaminated objects. device infxns, endocarditis in IVDU, PNA, bacteremia, meningitis
characteristics of B cereus?
opportunistic, environmental source like soil, common cx contaminant
what happened in 2001 for B anthracis?
bioterrorism in USPS envelopes
early vs late onset dz of neonatal listeriosis
acquired from placenta in utero –> granulomatous infantiseptica vs acquired at/soon after birth –> meningitis or meningoencephalitis w/ septicemia
pathogenesis of Listeria monocytogenes
enters into nonprof phagocyte –> internalized in a vacuole/phagosome –> secretes phospholipases and pore-forming toxin listeriolysin O –> released into cyto and uses actin polymerization to do actin rocket tail an jump to next cell –> enters another cell in double membraned vacuole
how to dx Listeria monocytogenes?
microscopy = nondiagnostic b/c bacterial titers = low –> selective media and cold enrichment (can grow in 4 degrees C) but tell lab you’re looking for Listeria monocytogenes and not confuse w/ Corynebacterium spp
how to tx Listeria monocytogenes?
combination therapy b/c bacteriostatic effects alone = not enough
morphology of Neisseria gonorrheae?
gram neg diplococci growing on chocolate agar, no capsule