Module 10 Flashcards
What organisms are normal enteric flora?
Escherichia
Klebsiella
Enterobacter
Serratia
Citrobacter
Proteus
Morganella
Providencia
What organisms are intestinal pathogens?
Shigella
Salmonella
Yersinia
How does Escherichia grow on media?
BAP- grey, moist, usually gamma
MAC- LF, often with ppt
XLD, HE, SS- stunted LF
What are the ID results for Escherichia?
Glucose pos
Lactose pos
H2S neg
A/A, gas
Indole pos
VP neg
Cit neg
Urease neg
Deaminase neg
Mostly motile
Lysine pos
Sorbitol pos (negs are possible pathogens)
What is the rapid ID for E. coli?
BAP- grey moist
Spot indole pos
MAC- LF
Send for sensitivity
What is a MUG test and what is the result for E. coli?
Glucuronidase enzyme breaks down MUG reagent releasing fluorescent compound
E. coli pos
What is the clinical significance of E. coli?
Large portion of NF in intestine
UTIs
Found in upper respiratory specimens when there’s an alteration in NF or colonization due to antibiotics
What types of pathogenic E. Coli strains are there and what are their characteristics?
Enteropathic (EPEC)- microvilli destruction causes diarrhea, screen with antisera
Enterotoxigenic (ETEC)- traveller’s diarrhea, heat stable and/or heat labile enterotoxin, fimbriae or pili, hypersecretion of electrolytes and water
Enteroinvasive (EIEC)- dysentery-like, shigatoxin, mucosal cell destruction, non motile, lysine decarboxylase neg
Enterohemorrhagic (EHEC)- verotoxin, bloody diarrhea, acute renal failure in young children, fails to ferment sorbitol, 0157:H7 (hamburger disease)
What types of antigens do E. coli display?
O- cell wall (heat stable)
B, Vi, K- capsule (heat labile)
H- flagella
What is the susceptibility of E. coli?
Most sensitive to broad spectrum
Testing required
ESBLs
What are the common Klebsiella isolates?
Pneumoniae
Oxytoca
How does Klebsiella grow on media?
BAP- large, grey, mucoid
MAC- LF (pale), mucoid
Moderately selective and selective enrichment media- some growth
What are the ID results for Klebsiella?
Non motile
Glucose pos with gas
A/A, gas
Lactose pos
Sucrose pos
H2S neg
Indole neg for pnuemonia, pos for oxytoca
VP pos
Cit pos
Ornithine neg
Urease pos
Arabinose pos
What are the characteristics of Enterobacteriaceae?
Most found in GI tract
Gram neg rods
Non spore forming
Facultative anaerobes
Oxidase neg
Glucose fermenting
Nitrate reducing
Catalase pos
Growth on MAC
What is the clinical significance of Klebsiella?
Pneumoniae causes primary lobar pneumonia, lung infection, pleuritis, part of NF, nosocomial infections
What is the antimicrobial susceptibility of Klebsiella?
Lots of resistance
Treat with aminoglycosides, some cephalosporins
What are the common species of Enterobacter?
Aerogenes
Cloacae
How does Enterobacter grow on media?
BAP- large, grey, moist
MAC- LF, pale
Some growth on moderately selective and selective enrichment media
What are the ID results for Enterobacter?
Motile
Glucose pos with gas
A/A, gas
Lactose pos
Sucrose pos
H2S neg
Indole neg
VP pos
Cit pos
Ornithine pos
Lysine pos for aerogenes, neg for cloacae
Arabinose pos
What is the clinical significance of Enterobacter?
Cloacae is the most common isolate
NF in intestine
Contamination of IV fluids
Urinary, respiratory, cutaneous and wound infections
What is the treatment for Enterobacter infections?
Cefepime and gentamicin
What is the most common isolate of Serratia?
Marcescens
What is the growth of Serratia on media?
BAP- grey moist, may have pink orange centre
MAC- LLF
What are the ID results for Serratia?
Glucose pos with little has
A/A or K/A
Lactose pos (LLF)
Sucrose pos
H2S neg
ONPG pos
Deaminase neg
Indole neg
VP pos
Cit pos
Motile
Arabinose neg
How is Serratia differentiated from Shigella?
Pos motility
Sucrose fermentation
Citrate pos
How is Serratia differentiated from Klebsiella and Enterobacter?
Negative for arabinose
How is Serratia differentiated from PPM?
Deaminase neg
What is the clinical significance of Serratia?
Human pathogen
Nosocomial infections
Endotoxins- septic shock
How is Serratia treated?
Tends to be resistant
Aminoglycosides, antipseudomonal beta lactam antibiotics, fluoroquinolones and cefipime
