Enterobacteriaceae Flashcards
E.coli : LF/NLF, VP, CIT
- LF
- VP NEG
- CIT NEG
MACpp NLF
- PDA POS
- H2S POS
Proteus
MACpp: LF or pale LF or NLF
- VP NEG
- Citrate POS
Citrobacter species
this toxin is associated with bloody diarrhea
SHIGA
Usually NOT part of healthy human’s flora; found in water, soil, food
Serratia
What is prodigiosin
Red/pink/orange non-diffusible pigment found in Serratia
What is biochemically unique about Serratia (aside from pigment)
Produces 3 hydrolytic enzymes
- lipase
- gelatinase
- DNase
Serology (O/H/K) is used to confirm what?
- Biochemical ID of Salmonella, Shigella (polyvalent O for Salmonella)
- Pathogenic serotypes (monovalent for E. coli O:157)
How is Group D Shigella (S. sonnei) differentiated from the other 3 groups?
Delayed LF on MAC
Proteus, Providencia and Morganella are intrinsically resistant to tetracycline, _______ and colistin
NITROFURANTOIN
Category A abx
- Ampicillin
- 1st gen cefazolin
- Gentamicin
- Tobramycin
an acronym for those Enterobacteriaceae that are intrinsically resistant to certain B-lactam drugs (but not the 3rd generation cephalosporins)
SPICE
MACpp: domed LF
- VP POS
- Citrate POS
Klebsiella or Enterobacter
K1 antigen is the main virulence factor in ______
MNEC
abbr. - in this test, FeCl3 is added and a green complex forms in a positive test
PDA
if this is added to a truly negative nitrate test which is colourless after Nit A and B, a red colour will appear
ZINC
2 organisms that can cause complicated UTI in the elderly?
Proteus, Enterobacter
How is Group D Shigella (S. sonnei) differentiated from the other 3?
Delayed LF on MAC
Where are each of these antigens found on the cell: O, H, K
O - outer membrane
H - flagella
K - capsule
“currant jelly-like” sputum can result when colonization of this species of Klebsiella progresses to destructive disease in debilitated patients
PNEUMONIAE
There is no documented intrinsic resistance to the _________ in Proteus mirabilis
Beta-lactams
All Enterobacteriaceae except Plesiomonas are negative for this test
OXIDASE
Purpose of selenite enrichment broth?
Enhance growth of Salmonella and Shigella while inhibiting normal flora
2 words - when Salmonella Typhi sequesters here patients can “shed” the organism and can infect others while they themselves are asymptomatic
BILIARY TREE
Proteus is associated with alkaline encrusted cystitis, scarring and kidney stones because of hyper-production of this enzyme.
UREASE
What/which org(s) have intrinsic resistance against all of: tetra, nitro, colistin?
Proteus, Providencia, Morganella
Cronobacter sakazakii and Pantoea agglomerans were at one time included in this genus
ENTEROBACTER
Klebsiella pneumoniae is intrinsically resistant to this antibiotic as well as ticarcillin
AMPICILLIN
abbr. - organisms that lack permease but produce B-galactosidase will be NLF on MAC at 16-18 hrs., but POS in this test
ONPG
Intrinsic R in E. coli?
None
Most common E. coli serotype causing hemolytic uremic syndrome (hamburger disease)
STEC (EHEC)
Shiga-toxin producing E. coli (Enterohemorrhagic E. coli)
MACpp: LF or NLF
- VP NEG
- Citrate NEG
- Indole POS
E. coli
3 key biochemical features shared by this family
- ferment glucose
- oxidase NEG
- reduce nitrates to nitrites
this enrichment broth is used to inhibit normal enteric flora while promoting the growth of enteric pathogens within a short incubation period
SELENITE
this sugar replaces lactose in a “SMAC” plate; potential pathogens screen as colourless colonies from this stool media plate
SORBITOL
Unique among Enterbacteriaceae for oxidatively deaminating phylalanine (an alpha-amino acid) to pyruvic acid (i.e. PD positive; most Enter are PD neg)
Proteus
E. coli, Citrobacter koseri, Klebsiella oxytoca and Proteus vulgaris are positive in this test. Citrobacter freundii, Klebsiella pneumoniae and Proteus mirabilis are negative
INDOL
Salmonella Typhi has the __ antigen that is specific to it called the __ antigen
K antigen called Vi antigen
Serological testing should be done from ______ media
non-selective (BAP, MH)
What are the 3 PDA+ organisms?
Proteus, Providencia, Morganella
Organism that is the exception to all Enterobacteriaceae being oxidase NEG?
Pleiomonas shigelloides
Morphology of MOST Enterobacteriaceae on BAP?
NH lrg gr
Specimens that would be received for possible Yersinia?
Blood, sputum, lymph node aspirate
___________ are biochemially and antigenically related to Salmonella
Citrobacter
this enzyme causes the release of ammonia and CO2 which turns the phenol red indicator a hot pink colour
UREASE
Yersinia enterocolitica will appear as a pink “bull’s eye” colony an a CIN plate because it ferments this sugar
MANNITOL
MACpp NLF
- PDA POS
- H2S NEG
Providencia, Morganella
LF, H2S+
C. freundii
Very unique for it
Citrobacter: LF/NLF, VP, CIT
- LF
- VP NEG
- CIT POS
What to look for on YSA plate (CIN = Yersinia selective agar)?
Bull’s eye = mannitol fermented (MF)
What are the SPiCE organisms?
Serratia, Proteus, (indole+), Citrobacter, Enterobacter
this is the least serious and most common form of the plague caused by Yersinia pestis
BUBONIC
What is unique about Yersinia enterocolitica
Slow growing NLF that is motile at room temp, non-motile at 35C
abbr. - in this test, lactose and sucrose are present at 10x the concentration of glucose
TSI
What morphology to look for on SMAC?
NSF (non-sorbitol fermenter) => indicates E. coli O157
2 main differences between Enterbacter and Klebsiella?
Enterobacter are
- motile
- ornithine POS
Haloing gnb direct smear => potential org?
Klebsiella
BCIT classic E. coli morphology + biochemical
BAP: BH
MAC: LF dry/magenta
Spot indole (+)
Oxidase (-)
Causes mild gastroenteritis and is reportable from stools
Edwardsiella
2 non-zoonotic pathogens
- Shigella
- Salmonella Typhi
this sugar is fermented by most E. coli, Klebsiella and Enterobacter, variably by Citrobacter, but rarely or not at all by other Enterobacteriaceae studied at BCIT
LACTOSE
gnb are typically susceptible to this drug - Serratia, Proteus, Providencia and Morganella are exceptions
COLISTIN
enteric fever due to Salmonella Tyohii is termed ____ because it intially presents as blood culture POS but stool culture NEG then switches to stool culture POS but blood culture NEG
BIMODAL
Klebsiella: LF/NLF, VP, Orn
- LF
- VP POS
- Orn NEG
These 4 are commonly recovered in traumatic wound infections
- E. coli
- Proteus
and/or - Klebsiella
- Enterobacter
while E. coli has no known _____ resistance, acquired resistance is well documented, notably as ESBL producers
INTRINSIC
abbr. for the most serious form of illness associated with the EHEC, of which O157:H7 is the most common in this part of the world
HUS
abbr. - this term represents indole, motility, VP and citrate
IMVIC
this Citrobacter is H2S positive, indol negative
FREUNDII
MAC: NLF
- PD NEG
- DNase POS
Serratia
3 forms of plague caused by Yersinia pestis?
- bubonic
- septicemic
- pneumonic
abbr. - this signifies another group of E. coli that can cause bloody diarrhea due to cellular invasion
EIEC
Enterobacter: LF/NLF, VP, Orn
- LF
- VP POS
- Orn POS
antibiotics are generally not given to treat Salmonella gastroenteritis because it may promote ____ status in patients
CARRIER
NLF on MAC = separate by __ rxn
PD
O somatic = heat-______
H flagellar = heat-______
K capsular = heat-______
stable, labile, labile
the location of the heat-labile K antigen
CAPSULE
2 members of this family that are NEVER motile and why?
Klebsiella, Shigella
Lack flagella
this Shigella species causes the most severe disease
DYSENTERIAE
abbr. - Other than Proteus, Providencia and Morganella, other Enterobacteriaceae studied at BCIT would be negative in this tube test
PDA
Most common gnb causing neonatal meningitis?
MNEC
abbr. - a syndrome in which the endotoxin of gnb associated with Lipid A can lead to such intense clotting that factors are depleted resulting in septic shock with hemorrhage and possibly death
DIC (disseminated intravascular coagulation)
the heat-stable O antigen
SOMATIC
Easiest methods of differentiating Citrobacter freundii and Citrobacter koseri?
Indole and H2S rxns
VP+, CIT+, ORN+
Enterobacter
LF on MAC = separate by __ rxn
VP
4 species of Shigella?
A - S. dysenteriae
B - S. flexneri
C - S. boydii
D - S. sonnei
4 main LFs
- E. coli
- Klebsiella
- Enterobacter
- +/- Citrobacter
Delayed LF: _____ permease, _______ B-galactosidase
sluggish permease
HAS B-galactosidase
UPEC main virulence factor
Adhesion type 1
hyphenated - this scheme is used to serotype Salmonella using O and H1 and H2 antigens
KAUFFMANN-WHITE
Citrobacter most commonly causes which disease?
UTI (males >=65 years)
this test helps to differentiate LFs that are VP negative
CITRATE
Best biochemical test for distinguishing late LF from NLF
ONPG
Helps to distinguish some slow LF E.coli from Shigella
E.coli ONPG+
Shigella ONPG-
VP test detects which end product of glucose fermentation?
Acetoin
Gets converted to diacetyl (red/pink complex)
pH at which methyl red becomes positive
4.5
Urease production test - ammonia reacts to form what product?
Ammonium carbonate
Causes alkalinization which turns phenol red pink at pH 8.0
Why is a wet mount motility performed when MALDI identifies E. coli on the enterics bench?
Shigella is similar to E. coli and MALDI can misclassify it
Shigella must be ruled out as it is non-motile while E. coli is motile