|SOLIS-SOTO, LUISA - Ciudad University - Mexico|
|GARCIA, SANTOS - Ciudad University - Mexico|
|HEREDIA, NORMA - Ciudad University - Mexico|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2010
Publication Date: 2/20/2011
Citation: Solis-Soto, L., Garcia, S., Wesley, I.V., Heredia, N. 2011. A charcoal- and blood-free enrichment broth for isolation and PCR detection of Campylobacter jejuni and Campylobacter coli. Journal of Food Protection. 74(2):221-227.
Interpretive Summary: Campylobacter jejuni is the number one cause of bacterial foodborne illness worldwide and consumption of contaminated poultry is a major risk factor for human infection. The unique oxygen requirements make methods for laboratory identification of Campylobacter difficult. We developed a blood-free enrichment broth (M-BFEB) which can be incubated in an ordinary laboratory incubator, is comparable to other enrichments broths, supports the growth of Campylobacter even in the presence of competitors, and appears to be free of PCR inhibitors. Taken together, these attributes will be of special importance as USDA performance standards for Campylobacter are realized.
Technical Abstract: Campylobacter spp. is a Gram negative bacterium and is the major cause of foodborne gastroenteritis worldwide. The microaerophilic nature of Campylobacter and its requirement of ~5% O2 for growth have complicated its recovery from foods. This is achieved with the addition to the enrichment media of oxygen quenchers such as charcoal or blood, which could interfere with PCR for Campylobacter detection. In this study, a two-step simple aerobic method for Campylobacter detection is proposed. A modification of the Tran blood-free enrichment broth (BFEB) in which charcoal was excluded from the medium (M-BFEB) was compared with the original Tran formulation and other conventionally used enrichment broths. C. jejuni and C. coli were detected by PCR directly from the enrichment media. Varying concentrations of pure cultures of C. jejuni and C. coli combined with E. coli were inoculated into Preston, Bolton, BFEB and the modified BFEB (M-BFEB). In addition, of C. jejuni and C. coli were inoculated together onto retail purchased chicken skin and recovery was compared. Rates of recovery after 24-48h of enrichment at 42 deg C under aerobic incubation for BFEB and M-BFEB and microaerobic incubations for the Preston and Bolton broth were determined. Results indicated that the isolation rates for M-BFEB were similar to those obtained using BFEB. M-BFEB could be directly coupled to a PCR assay to detect Campylobacter, avoiding plating to Campy Cefex agar. Campylobacter was detected in the presence of up to 108 E. coli/ml. M-BFEB facilitated detection of both C. jejuni and C. coli artificially inoculated onto chicken skin samples. In summary, M-BFEB enrichment coupled with PCR screening is a rapid alternative for identification of C. coli and C. jejuni from poultry.