ENTEROBACTERIACEAE Flashcards
Most species are normal flora of GI Tract such
E. coli except
YSS - Yesernia, Salmonella, Shigella
Enterobacteriaceae are
Non – sporulating, facultative anaerobes (able
to survive with or without O2)
All are catalase (+) except
Shigella dysenteriae
Most are Cytochrome C oxidase negative
which separates enteric from oxidase positive
bacteria of genera
▪ Pseudomonas
▪ Aeromonas
▪ Vibrio
▪ Alcaligenes
▪ Achromobacter
▪ Flavibacterium
▪ Cardiobacterium
O antigen
Outer Membrane
H antigen
Flagella
K antigen
Capsule
Vi antigen
Capsule of Salmonella
German word meaning nonspreading
Ohne hauch
Among the E. coli, certain O antigens are
associated with specific virulent phenotype:
▪E. coli O 111 and E. coli O 125 are found
to cause infantile diarrhea
▪ E. coli O112 is often an invasive strain
that causes dysentery – like syndrome
HEAT STABLE and associated with lipopolysaccharide or endotoxin moiety of the cell wall
O – somatic antigen
From German word “Kapsel”
K – envelope or capsular antigen
A polysaccharide and Heat Stable
K – envelope or capsular antigen
K – envelope or capsular antigen is produced by?
KES - Klebsiella, E. coli, Salmonella
From German word meaning spreading
Hauch
Heat Labile & Protein in nature
H – Flagellar antigen
Enterobacteriaceae are further classified based on their
- Habitat
- Tribes
- Lactose fermentation
Coliforms in the Normal Flora – found In GI
TRACT
CHEEKS - Citrobacter, Hafnia, E. coli, Enterobacter, Klebsiella, Serratia
Non coliform in Normal Flora – Non-gramnegative bacilli found in GI Tract
MEPP - Morganella, Edwardsiella, Proteus, Providencia
True Enteric Pathogens – can cause disease in
GIT
YSS - Yersinia , Salmonella, Shigella
True Non – Enteric Pathogens
Yersinia Pestis - causes Bubonic
Plague
LACTOSE FERMENTERS, Appears pink (+) in MAC
CEEK - Citrobacter, Escherichia, Enterobacter, Klebsiella
NON – LACTOSE FERMENTERS
ShYPS - Shigella, Yersinia, Proteus, Salmonella
NON – LACTOSE FERMENTERS are further based on?
MOTILITY and H2S Production
Nonmotile, Non – H2s Producers
Shigella, Yersinia
Motile, H2s Producers
Proteus, Salmonella
is the degradation product of amino acid Tryptophan together with pyruvic acid and ammonia
Indole test
Indole is the degradation product of amino acid
Tryptophan together with pyruvic acid and
ammonia due to enzyme?
Tryptophanase
KOVAC’S reagent contain
PDAB - Paradimethylaminobenzaldehyde
Detects rapid indole producing organism
Spot Indole Test
Requiring overnight incubation which identifies weak indole producing organisms
Conventional Tube Method
Indole (+) organisms are
PEMPCK - P. vulgaris, E.coli, M. morganii, Providencia, C. koseri, K. oxytoca,
3 COMMONLY USED AGAR MEDIUM
- SULFIDE – INDOLE – MOTILITY (SIM MEDIUM)
- MOTILITY – INDOLE – UREASE (MIU) MEDIUM
- MOTILITY – INDOLE – ORNITHINE (MIO) MEDIUM
Methyl Red (+) organisms are:
- Echerichia coli
- Shigella species
- Salmonella species
- Citrobacter species
- Proteus species
- Yersinia species
Methyl Red (-) organisms are:
KESH -
1. Klebsiella pneumoniae
2. Enterobacter species
3. Serratia marcescens
4. Hafnia species
added as a catalyst or color intensifier to VP test
Alpha – naphthol
acetoin is oxidized to
diacetyl
Test should not be read after standing for over
1 hour because (-) VP cultures may produce a?
copper like color, potentially resulting in false (+) interpretation.
VP POSITIVE ORGANISMS
KESH
1. Klebsiella species
2. Enterobacter species
3. Serratia species
4. Hafnia species
sole carbon source
sodium citrate
sole nitrogen source.
ammonium salts
Product of indole test
Indole + Pyruvic acid + ammonia
pH indicator of sodium citrate
bromthymol blue
is an alternative test medium, which incorporates phenol red
Christensen’s medium
The alkaline carbonates and bicarbonates produced as by products of citrate catabolism raise the pH of the medium to?
to above 7.6, causing the bromothymol blue to change from the original green color to blue
Under alkaline conditions, pyruvate is metabolized to
acetate and formate.
At pH 7.0 and below, produced what?
lactate and acetoin
CITRATE NEGATIVE ORGANISMS
MESSSY (triple s)
Morganella, E. coli, Shigella, Salmonella typhi, Salmonella paratyphi A, Yersinia
CITRATE VARIABLE ORGANISMS
PVV - P. vulgaris, Vibrio cholerae, V. parahaemolyticus
Added to detect the production of hydrogen sulfide gas
Ferrous sulfate and Sodium thiosulfate
indicator of H2S formation
Iron (ferrous sulfate)
Acts as a source of nitrogen on TSI
peptone
A/A, Produces gas
EKE- E. coli, Klebsiella, Enterobacter
K/A, Produces gas, H2S positive
SPACE - Salmonella, Proteus, Arizona, Citrobacter, Edwardsiella
K/A
Shigella
K/K
Pseudomonas
can be determined by microscopic examination of bacteria or by observing growth in a semi solid medium
Motility
typically give diffuse, hazy growths that spread throughout the medium rendering it slightly opaque
Motile bacteria
Delayed positive organisms (E.g., Enterobacter) will no produce a positive reaction due to
high buffering capacity of this medium
Used for the presumptive evidence of the presence
of Helicobacter pylori in tissue biopsy material.
DIAGNOSTIC USE OF UREASE TEST
A positive urease test is considered presence of
Helicobacter pylori
UREASE POSITIVE
PUNCH : Proteus, Ureaplasma Nocardia, Cryptococcus, Helicobacter pylori
OXIDASE POSITIVE
PVNCH: Pseudomonas, Vibrio, Neisseria, Campylobacter, Helicobacter
