Enteric Bacterial Infections Flashcards
what is the morphology of all foodborne enterobacteriaceae?
gram negative rods
how do enterobacteriaceae colonize the lumen of the intestine?
they cannot colonize the epithelium in the lumen
how do enterobacteriaceae gain access to the host?
they are sampled by M cells of Peyers patches to gain access to the serosa side of the intestine
how do enterobacteriacea avoid the immune system?
they use macrophages as trojan horses and infect the lymphatics
what are the diseases caused by Yersinia and salmonella using macrophages as trojan horses?
yersina- local false appendicitis
salmonella- systemic enteric fever or post sepsis focal disease
what are the differences in clinical presentation of noninvasive vs invasive/destructive enterobacteriaceae?
noninvasive- watery diarrhea
invasive- bloody diarrhea
which enterobacteria are noninvasive?
salmonella, enterotoxic e coli and yersinia
which enterobacteria are invasive/destructive?
shigella and enterohemorrhagic e coli
what are the common exposures of foodborne enterobacterial infections?
proteins
meat for e coli and meat or eggs for salmonella
what causes the most complications of enterobacterial infections?
dehydration and electrolyte loss
what life threatening complication may follow gut tissue necrosis?
bacteremia
how are virulence factors often carried in enterobacteria?
plasmids
what are the common virulence factors for foodborne enterobacteria?
fimbriae/pilli for attachment, T3SS for immune evasion and/or host cell invasion and toxins
what determines the disease caused by E coli?
the acquired virulence factors make it able to cause certain diseases
which is the only enterobacterial pathogen that is likely to ferment lactose?
e coli
pink on MacConckey agar which detects fermentation of lactose
who has the highest risk of developing a foodborne enterobacterial infection? who is at the highest risk for mortality?
children
neonates and elderly
which pathogens cause HUS? when does it occur?
shigella and enterohemorrhagic E coli
when shiga toxin (protein synthesis inhibitor) reaches the bloodstream
what is one postinfectious sequalae of shigella, salmonella and yersinia infection?
reactive arthritis/ reiter’s syndrome
what should be done before treatment of enterobacterial infection?
antimicrobial susceptibility testing
how is exposure to enterobacteriacae minimized?
sewage treatment, pasteurization, water chlorination, food processing and hand washing
what causes noninfectious bacterial- toxigenic food poisoning?
a patient eats a food containing preformed toxins secreted by non GI bacteria
which three pathogens cause toxigenic food poisoning? what happens to the bacteria when they are ingested?
staph aureus, B. cereus and C. botulinum
they do not survive ingestion but their toxins cause gastroenteritis