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ARS Home » Research » Publications at this Location » Publication #71378


item Harmon, Karen

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Campylobacter jejuni, Campylobacter coli, and Listeria monocytogenes are major human foodborne pathogens. We evaluated a multiplex PCR to distinguish C. jejuni from C. coli colonies present on modified charcoal-cefazolin-sodium deoxycholate agar (mCCDA) supplemented with 0.01% amphotericin B. Initial studies demonstrated that C. jejuni yielded two PCR products (450 bp and 160 bp); C. coli generated a single PCR product (450 bp). Livestock feces was streaked onto mCCDA agar plates. After incubation (48 h in 5% 02, 10% CO2, 85% N2), Campylobacter colonies were processed directly for PCR. Of 1,051 pig fecal samples examined, 69% were positive for C. coli and 3% were positive for C. jejuni. Of 510 cattle fecal samples processed on mCCDA, 37.5% were positive for C. jejuni and 2% were positive for C. coli. These results indicate that performing a multiplex PCR on colonies growing on selective agar provides an efficient method for screening large numbers of livestock for potential human foodborne pathogens. Next, we evaluated the ability of a multiplex PCR to distinguish L. monocytogenes from other Listeria species. Earlier studies indicated that L. monocytogenes yielded two PCR products (938 bp and 174 bp); other Listeria species generated a single PCR product (938 bp). Specificity of the multiplex PCR assay was tested on 96 field isolates of Listeria, which had been previously identified by biochemical methods and/or by their reactivity with a probe targeted to the listeriolysin O (LLO) gene of L. monocytogenes. The PCR assay correctly distinguished L. monocytogenes (n=79 isolates) from field isolates (n=14) of other Listeria species. These results indicate the reliability of PCR-based methods to identify major human foodborne pathogens.