Biochemical Rxns
the product of ornithine decarboxylase is
putrescence
NLF
PPA neg
manitol pos
citrobacter
hafnia
salmonella
shigella
serratia
describe CIN agar, what its used for and its target organism
Cefsulodin, Irgasan, Novobiocin
mannitol fermentation by Y entercolitica produces red bulls eye on the media
EPEC (enterohemorrhagic e coli) infection can result in a condition called ___ and is treated by ___
HUS =hemolytic uremic syndrome
treatment: transfusion, hemodialysis
when serotyping salmonella, shigella, or e coli, why do you need to use a non-sugar containing media like BAP or LIA?
use of MAC, TSI can cause organisms to autoagglutinate
E coli
citrobacter (- c. freundii)
klebsiella oxytoca
how would you differentiate P mirabilis from vulgaris
indole and citrate
PM indole -, citrate +
PV indole +, citrate -
what's the difference between LIA and TSI
LIA only contains lactose and glucose
both contain thiosulfate for H2S production
therapeutic option for Yersinia
streptomycin #1
tetracycline
chloramphenicol
This org has the ability to use citrate as its only carbon source, lysine as a nitrogen source, and produces H2S, divided into 6 subspecies which can be identified by serotyping based in virulence properties
Salmonella enterica
Name the 3 PPA positive enterics
Proteus spp.
Providencia spp.
Morganella morganii
if an organism is a lactose fermenter what other biochemical test will be positive
ONPG
urea is hydrolyzed to from ammonia, CO2, H2O organisms that have a urease enzyme will complete this biochem reaction and turn the media from beige to bright pink.
urease positive orgs: citrobacter, kleb, proteus, providencia, Yersinia
describe the mechanism of an ESBL and what they are resistant to
B-lactamase producers that hydrolyze penicillins and cephalosporins
resistant to 3rd generation cephalosporins- ceftriaxone, ceftazidime, ceftizoxime
describe the 2 toxins produced by the ETEC form of ecoli
LT/ST
LT- heat labile enterotoxin
ST- heat stable enterotoxin
cause travelers diarrhea (mild watery no blood)
K/A TSI
plesiomonas
salmonella typhi
vibrio
shigella
Yersinia
aeromonas
what's the only oxidase negative enteric
plesiomonas
what makes SS agar selective and differential?
bile salts, citrate brilliant green inhibit GP
lactose is the sole carbohydrate, neutral red is the ph indicator, sodium thiosulfate is the H2S indicator.
H2S + organisms will produce black precipitate in the center of the colony
shigella appears colorless
salmonella is colorless with a black center
ecoli will ferment lactose and turn pink
infection associated with contaminated medial devices ie respirators
this organism has a capsule and is intrinsically resistant to AMP, 1st and 2nd gen cephalosporins,
its IMVIC is: --++
Enterobacter
why is it important to distinguish aeromonas from plesiomonas? how?
theyre both oxidase +
use string test or DNASE
aero DNase +
Ples DNase -
Salmonella typhi
Salmonella paratyphi
Salmonella typhimurium
name the PD positive organisms
Proteus
Morganella
Providencia
XLD agar is selective for salmonella and shigella isolation, which biochemical reactions can be seen in this media
sucrose and lactose fermentation, methyl red ph indicator
lysine to detect decarboxylation
sodium thiosulfate for H2S production
yellow colony= acid production, lysine decarbox -
colorless/red= non fermenters
yellow to red= xylose ferm, lysine decarbox +
black precipitate = H2S+
salmonella = red with black centers
shigella = red
ecoli = yellow
treatment for extraintestinal salmonella infection like typhoid fever
quinolones
3rd gen cephalosporins
what are the only gelatin positive enterics
Serratia
Proteus