What is the role of bacterial cultures in the diagnostic assessment of bacterial gastroenteritis?

Updated: Jul 17, 2018
  • Author: Jennifer Lynn Bonheur, MD; Chief Editor: BS Anand, MD  more...
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Answer

Identifying the causative agent underlying the gastroenteritis is important in the management of patients with severe or prolonged diarrhea, symptoms consistent with invasive disease, or a history that may predict a complicated disease course. [22] Moreover, stool culture findings are a means for public health officials to identify and track outbreaks of bacterial gastroenteritis.

Table 3, below, lists common bacteria and the optimal culture media for their growth.

Table 3. Common Bacteria and Optimum Culture Media (Open Table in a new window)

Organism

Detection Method

Microbiologic Characteristics

Aeromonas species

Blood agar

Oxidase-positive, flagellated GNB

Bacillus species

Blood agar

Facultatively aerobic, spore-forming GPR; beta hemolytic; reduces nitrates; ferments carbohydrates

Campylobacter species

Skirrow agar

Rapidly motile, curved GNR; Campylobacter jejuni 90% of infections, Campylobacter coli 5% of infections

C difficile

CCFE agar, EIA for toxin, LA for protein

Anaerobic, spore-forming GPR; toxin-mediated diarrhea; produces pseudomembranous colitis

C perfringens

None available

Anaerobic, spore-forming GPR; toxin-mediated diarrhea

E coli

MacConkey, EMB, or SM agar

Lactose-producing GNR

Listeria species

Blood agar

Flagellated GPB

Plesiomonas species

Blood agar

Oxidase-positive GNR

Salmonella species

Blood, MacConkey, EMB, XLD, or HE agar

Nonlactose, non–H2S-producing GNR

Shigella species

Blood, MacConkey, EMB, XLD, or HE agar

Nonlactose and H2S-producing GNR; verotoxin (neurotoxin)

Staphylococcus species

Blood agar

Heat-stable, preformed toxin-mediated GPC

Vibrio species

Blood or TCBS agar

Oxidase-positive, motile, curved GNB

Y enterocolitica

CIN agar

Nonlactose-producing, oval GNR

CCFE = cycloserine-cefoxitin-fructose-egg; CIN = cefsulodin-irgasan-novobiocin; EIA= enzyme immunoassay; EMB = e-methylene blue; GNB = gram-negative bacillus; GNR = gram-negative rod; GPB = gram-positive bacillus; GPC = gram-positive cocci; GPR = gram-positive rod; H2S = hydrogen sulfide; HE = Hektoen enteric; LA = latex agglutination; SM = Sorbitol-MacConkey; TCBS = thiosulfate-citrate-bile-sucrose; XLD = xylose-lysine-deoxycholate.


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