Quick Review Cards for Medical Laboratory Science

Commonly Isolated

Enterobacteriaceae continued

Clinical Microbiology Review 184

KEY REACTIONS

ORGANISM PATHOGENICITY POSITIVE NEGATIVE OTHER

Serratia marcescens

Proteus vulgaris&

mirabilis

Morganella morganii

Providencia

Yersinia enterocolitica

UTI = urinary tract infection; RTI = respiratory tract infection; IMViC = indole, methyl red, Voges-Proskauer, citrate.

Some produce red pigment when

incubated at RT.

Swarming. Burned chocolate odor.

P. mirabilisis most common & indole

neg. P. vulgarisindole pos, A/A on

TSI because of sucrose fermentation.

P. rettgeriis urease pos.

GN coccobacilli. Bipolar staining. Op-

timal temperature 25°–30°C. Motile

at 25°C but not 35°C. CIN agar is

selective. Incubate 48 hr. Red “bull’s-

eye” colonies surrounded by colorless

halo. Y. pestiscauses plague.

Opportunistic pathogen.

Pneumonia & septicemia

in immunosuppressed

UTI, wound infections,

septicemia

Mainly nosocomial infec-

tions. UTI, wound infections.

UTI, diarrhea

Diarrhea

VP, citrate, motility

H 2 S, MR, PD, urease,

motility

Indole, MR, PD, urease

(weak), motility, ODC

Indole, MR, citrate,

PD, motility

MR, urease

Lactose, H 2 S, in-

dole, PD, urease

Lactose

Lactose, H 2 S, VP,

citrate

Lactose, H 2 S, VP

Lactose, H 2 S, VP,

citrate, PD