Laboratory Diagnosis of Enterobacteriaceae Flashcards
identify
- BAP: shiny, opaque, smooth, nonhemolytic
- MAC: NLF/LF
Plesiomonas shigelloides
identify
produces flat colonies with jagged edges on MAC
Shigella sonnei
identify
TSI contains 10 parts (?) : 10 parts (?) : 1 part (?) and (?)
- lactose
- sucrose
- glucose
- peptone
identify
This test is used to determine the ability of an organism to utilize sodium citrate as its only carbon source and inorganic ammonium salts as its only nitrogen source
citrate utilization
identify
- MAC: NLF
- HE: colorless
- XLD: red or yellow
Hafnia alvei
identify
Christensen’s citrate medium incorporates phenol red (as the Ph indicator) and organic nitrogen.
At an alkaline pH, the indicator turns from yellow to (?)
citrate utilization
pink
identify
- Production of hydrogen sulfide (H2S)
- Salmonella spp. appear as brown to black precipitate
isolation of Salmonella spp. & Shigella spp.
Bismuth sulfite agar
identify
- H2S (TSI agar): (-)
- urease: (-)
- indole: (+/-)
- methyl red: (+)
- voges-proskauer: (-)
- citrate (simmons): (-)
- KCN: (-)
- phenylalanine deaminase: (-)
- mucate: (d)
- mannitol: (+/-)
Escherichieae
identify
- Shigella spp. appear colorless
- Salmonella spp. colorless with a black center
isolation of Salmonella spp. & Shigella spp.
Salmonella-Shigella agar (SS)
identify
used to differentiate sorbitolnegative E. coli O157:H7 from other strains of E. coli
MacConkeysorbitol agar (MAC-SOR)
identify
reagents
rapid spot indole test
- kovac’s reagent
- p-dimethylaminobenzaldehyde Bio Merieux (or equivalent)
identify
This test is helpful in initial differentiation of Proteus, Morganella, and Providencia organisms, which are positive
phenylalanine deaminase (PAD)
identify
may be red pigmented, especially if plate is left at 25°C on MAC
Serratia marcescens
identify
Bacteria that can grow on this medium turn the bromthymol blue indicator from green to (?)
citrate utilization
blue
identify
methyl red test positive:
(?) color at surface of the medium
MR-VP medium/MR-VP broth
red
identify
- H2S (TSI agar): (-)
- urease: (-/+)
- indole: (-)
- methyl red: (-)
- voges-proskauer: (+)
- citrate (simmons): (+)
- KCN: (+)
- phenylalanine deaminase: (-)
- mucate: (+/-)
- mannitol: (+)
Klebsielleae
identify
Rapid development of a (?) color on the filter paper, usually within 30 seconds, is indicative of a positive test result.
rapid spot indole test
bright pink-red
identify
(?) medium is an alternative test medium
citrate utilization
Christensen’s citrate
identify
- MAC: NLF
- HE: green, H2S production
- XLD: red with H2S
Salmonella spp.
identify
colonies on SBA are pinpoint at 24 hours but exhibit a rough, cauliflower appearance at 48 hours
Y. pestis
identify
- safety pin appearance
- bipolar appearnce
Yersinia spp
identify
- H2S (TSI agar): (-)
- urease: (+)
- indole: (+/-)
- methyl red: (+)
- voges-proskauer: (-)
- citrate (simmons): (-)
- KCN: (-)
- phenylalanine deaminase: (-)
- mucate: (none)
- mannitol: (+)
Yersiniae
identify
Simmons Citrate Agar contains (?)
ammonium dihydrogen phosphate
identify
methyl red test negative:
(?) color at surface of the medium
MR-VP medium/MR-VP broth
yellow