Specimen Collection, Transport, and Processing
There are no special requirements for the collection, transport, and processing of clinical specimens for the detection of Campylobacters; the two most common specimens submitted to the laboratory are feces (rectal swabs are also acceptable for culture) and blood. If a delay of more than 2 hours is anticipated, stool should be placed either in Cary-Blair transport medium or in campy thio, a thioglycollate broth base with 0.16% agar and vancomycin (10 mg/L), trimethoprim (5 mg/L), cephalothin (15 mg/L), polymyxin B (2500 U/L), and amphotericin B (2 mg/L). Cary-Blair transport medium
is also suitable for other enteric pathogens; specimens received in this transport medium should be processed immediately or stored at 4° C until processed.
Because of their characteristic microscopic morphology, that is, small, curved or seagull-winged, faintly staining, gram-negative rods (Figure 36-1), Campylobacter spp. can sometimes be detected by direct Gram stain examination of stool (Figure 36-2). Various molecular assays based on polymerase chain reaction (PCR) amplification may provide an alternative to culture methods for the detection of Campylobacter spp. directly in clinical specimens. The finding of Campylobacter DNA in stools from a large number of patients with diarrhea suggests that Campylobacter spp. other than C. jejuni and C. coli may account for a proportion of cases of acute gastroenteritis in which no etiologic agent is currently identified.15
Stool. To successfully isolate Campylobacter spp. from stool, selective media and optimum incubation conditions are critical; culture methods are biased toward the detection of C. jejuni and C. coli in feces. For optimum recovery, the inoculation of two selective agars is recommended.7 Because Campylobacter and Arcobacter spp. have different optimum temperatures, two sets of selective plates should be incubated, one at 42° C and one at 37° C. Table 36-2 describes the selec-
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