P1-10 Modification of Charcoal-cefoperazone-deoxycholate Agar by Supplementation with a High Concentration of Polymyxin B for Detecting Campylobacter jejuni and Campylobacter coli in Chicken Carcass Rinse

Monday, July 23, 2012
Exhibit Hall (Rhode Island Convention Center)
Jin-Hyeok Yim, Konkuk University, Seoul, South Korea
Jung-Whan Chon, Konkuk University, Seoul, South Korea
Ji-Yeon Hyeon, Konkuk University, Seoul, South Korea
Jun-Ho Park, Konkuk University, Seoul, South Korea
Kwang-Young Song, Konkuk University, Seoul, South Korea
Hong-Seok Kim, Konkuk University, Seoul, South Korea
Dong-Hyeon Kim, Konkuk University, Seoul, South Korea
Soo-Kyung Lee, Konkuk University, Seoul, South Korea
Kun-Ho Seo, Konkuk University, Seoul, South Korea
Introduction:  Although culture with selective media is the standard method for detecting Campylobacter,it is difficult to isolate the bacteria from raw chicken with numerous background microflora. We improved modified charcoal cefoperazone deoxycholate agar (mCCDA) by adding polymyxin B to enhance selectivity of the media.

Purpose:  The aim of this study was to evaluate the effect of high concentration of polymyxin B on the detection ability and selectivity of mCCDA to isolate C. jejuni and C. colifrom chicken carcass rinse.

Methods:  Modified mCCDA (P-mCCDA) was made by adding 100,000 IU of polymyxin B to 1 liter of mCCDA. Chicken carcasses were rinsed with 400 ml of buffered peptone water. To ensure even distribution, the carcass rinse was mixed thoroughly by gently shaking the sample for 1 min. A 25 ml test portion from the 400 ml rinse was enriched with 25 ml of 2× blood-free Bolton enrichment broth in a 50-ml screw-cap conical tube. Less than 0.5 cm of headspace was left in the tubes and the lids were tightly capped. Each sample (50 ml) was enriched at 42°C for 48 h. A loopful of the enrichment broth was streaked onto mCCDA, Campy-Cefex agar, and P-mCCDA followed by incubation under microaerobic condition at 42°C for 48 h. Suspected colonies (maximum-10) were removed and sub-cultured onto 5% horse blood agar. Presumptive C. jejuni and C. coli colonies were confirmed with colony PCR. We compared the number of plates of C. jejuni/ C. coli and competing organisms in terms of isolation rate and selectivity, respectively.

Results:  The number of P-mCCDA (70 out of 80) plates positive for both C. jejuni and C. coli was significantly higher (P < 0.05) than those of positive mCCDA (51 out of 80) and Campy-Cefex (36 out of 80) plates. Furthermore, fewer (P < 0.05) P-mCCDA plates (31 out of 80) were contaminated than other media plates (mCCDA, 34 out of 80; Campy-Cefex, 79 out of 80), indicating the superior selectivity of P-mCCDA.

Significance:  Addition of high concentration of polymyxin B to conventional media could be a useful option to improve selectivity and isolation rate in chicken carcass rinse.