Exam 2 - Enterobacteriaceae Flashcards
Which pathogen is the most common cause of nosocomial infections:
E. coli
Describe the colony appearance of Entero on SBAP and CAP:
large, gray, smooth colonies
Entero are all oxidase ____::
negative
Most entero are catalase____, the exception is _____ ______:
most are catalase+
Shigella dysenteriae is catalase-
List the 11 opportunistic EB pathogens:
Hint: CCEEEEHKMPS
Citrobacter Cronobacter Edwardsiella Enterobacter Escherichia coli Ewingella Hafnia Klebsiella Morganella Proteus Serratia
List the 3 EB intestinal pathogens:
Salmonella
Shigella
Yersinia
List the 5 EB that ferment lactose:
Hint: CEEEK
Citrobacter E. coli Enterobacter aerogenes Enterobacter cloacae Klebsiella pneumoniae
List the 5 EB that do NOT ferment lactose:
Hint: PSSSY
Proteus Salmonella Shigella Serratia marcescens Yersinia enterolitica
Which Shigella species does contain beta-galactosidase but not permease, and is therefor a LATE fermenter:
Shigella sonnei
List the two enzymes required to ferment lactose and what they do:
1) permease (allows lactose to penetrate bacterial cell wall)
2) Beta-galactosidase (hydrolyzes lactose to glucose + galactose)
These are defined as non-pathogenic strains of microorganisms, commonly used as bacterial indicators of food/water sanitation:
coliforms
Citrobacter, Enterobacter, Escherichia, Klebsiella, Serratia
T/F
Coliforms are rod shaped, Gram-, non-spore forming bacteria which can ferment lactose with production of acid and gas:
True
T/F
An example of horizontal transmission of disease would be nosocomial infections:
True.
person to person
What type of infection is caused when normal flora get into normally sterile body sites:
Endogenous
Is food poisoning from Salmonella or Shigella considered endogenous infections:
No.
S and S are not normal flora.
95% of all EB isolated are which 3 species:
1) E. coli
2) Klebsiella pneumoniae
3) Proteus mirabilis
(>99% of all isolates belong to 23 species)
List the 3 EB that are non- motile:
Hint: KSY
- Klebsiella
- Shigella
- Yersinia
EB all grow well on ___ and ____:
SBAP
CAP
T/F
Enterics from sterile body sites are not significant.
False. They are highly significant.
MacConkey agar is selective for ______ and differential for _____:
Selective for Gram- rods (inhibits Gram+)
Differential for lactose fermentation
What are the two additives in MacConkey besides lactose:
Bile salts
Crystal violet
If you see H2S concentrated between slant/butt, think this:
Salmonella typhae
What differentiates both Proteus species:
P. mirabilis: Indole-
P. vulgaris: Indole+
What is used to differentiate E. coli O157:H7 from other E. coli species:
O157:H7 does not ferment sorbitol (which would create clear colonies) on MacConkey w/ Sorbitol media)