Unit 4 - Enterics Flashcards
What shape are Enterobacteriaceae
GNR
Straight Rods
What orgs are straight rods
Enterobacteriaceae (enterics)
Non-fermentative GNR
What orgs are curved rods
Vibrio and relatives
What orgs are bacilli to coccobacilli, fastidious
Haemophilus
What orgs are unusual, fastidious rods
The Ella sisters
(eg. pasteurella)
Where are enterics found?
Everywhere
“Ubiquitous”
Where is Enterobacteriaceae found as normal flora?
Bowel of humans and animals
Oxidase result of Enterics family
Negative
What sugar do all enterics ferment?
Glucose
What do all enterics reduce?
NitrATES to nitrITES
What plates do all enterics grow on?
Non-enriched media
What kind of oxygen environment do enterics require?
Facultative anaerobes
(can grow with or without oxygen)
Do enterics form spores?
No,
non-spore formers
What enterics are OPPORTUNISTIC
“run of the mill” E. coli
Klebsiella
Enterobacter
Serratia
Proteus
Where are opportunistic enterics found?
Normal flora of the bowel (large intestine)
Where are opportunistic enterics capable of escaping to to cause disease
Blood
Surgical wounds
Urinary Tract
Which enterics are strict pathogens
Salmonella
Shigella
Yersinia
Some strains of E. coli (O157:H7)
Enterics virulence factors
Adherence
Colonizing ability
Toxins
Invasiveness
Antigenic structure of Enterics
O Ag
H Ag
K Ag
O antigens
Cell wall antiens
Somatic antigens
Heat stabile
H antigens
Flagella antigens
Only in motile species
Heat labile
K antigens
Polysaccharide capsule
Heat labile
Only in some species (ex. S. typhi)
What medias are used to ISOLATE
TSA with SBA - Non-selective, enriched, differential
MAC - Selective & Differential
EMB - Selective & Differential
What tube medias are used to IDENTIFY
XXXXXX FIX XXXXXX
(Biochemical)
TSI
LIA
Urea
Citrate
(Enzyme production detection)
How do enteric colonies appear on SBA?
Large, dirty, gray
Not distinct
Maybe slimy
SOMETIMES hemolytic
How do you assess an enteric based on hemolysis?
You don’t
Not critical for ID
How is MAC Selective and differential?
Selective for GNR
Differential for lactose or non-lactose fermentation
how are EMB Selective and differential?
XXXX CONFIRM ANS XXXX
Selective for GNR
Differential for Lactose fermentation or H2S production
Is E. coli normal flora?
Yes, in bowel
How does E. coli look like on the plate
Dirty gray colony
Beta Hemolytic
Pink - MAC
Metallic Green - EMB
What organism is characteristic based on its metallic green sheen on EMB?
E. coli
What organism is characteristic for possible B hemolysis
E. coli
What organism is a slow lactose fermenter?
E. coli
Is E. coli a lactose fermenter?
No, not always