Microbiological Hygiene Indicators and Campylobacter Enumeration by Four Different Plating Procedures in Naturally Contaminated Chicken Meat Samples

Introduction: The genus Campylobacter consists of significant thermophilic bacterial foodborne pathogens. The International Organization for Standardization (ISO) recommends the use of modified charcoal cefoperazone deoxycholate agar (mCCDA) for Campylobacter enumeration (ISO/TS 10272-2:2006), nevertheless alternative plating methods encompassing the use of chromogenic media have to be considered for easy reading and improved observation of presumptive Campylobacter colonies.

Purpose: The present work aims to determine the distributions for the hygiene indicator microorganisms most commonly found in poultry meat, as well as to describe the performance of four culture media used for Campylobacter enumeration in chicken meat.

Methods: Samples of naturally contaminated raw chicken meat with skin (n = 47, ca. 100 g per sample) were obtained from broilers, which were purchased from meat retailers within the metropolitan area of Athens, Greece. Sampling units (10 g) were analyzed for Campylobacter spp. (acc. to ISO 10272-2) and for aerobic plate count (APC), Enterobacteriaceae, and Escherichia coli enumeration. Analysis for Campylobacterenumeration involved two chromogenic media, besides the charcoal-based selective agars mCCDA and Karmali agar (KA), named, Campylobacter Selective Agar (CASA) and Brilliance CampyCount Agar (BCCA). Campylobacters on the latter media appear as dark “brick” red colonies.

Results: Plating for Campylobacter produced countable results (>0.92 log₁₀ CFU/g), at least in one medium, in all samples tested. Campylobacter spp. were enumerated onto mCCDA, KA, CASA and BCCA in 91.5% (43/47), 87.2% (41/47), 95.7% (45/47) and 93.6% (44/47) of total tested samples, respectively. Confirmed Campylobacter spp. counts (mean log₁₀ CFU/g ± SD) were 2.63 ± 0.76, 2.48 ± 0.82, 2.44 ± 0.86 and 2.65 ± 0.83 for mCCDA, KA, CASA and BCCA, respectively. The distributions (mean log₁₀ CFU/g ± SD) for the hygiene indicator organisms in chicken meat were 5.37 ± 0.92 (APC), 2.92 ± 0.87 (Enterobacteriaceae) and 2.16 ± 0.83 (E. coli).

Significance: The results demonstrate the microbiological hygiene condition of chicken meat and highlight the ability of the chromogenic media used in this study (CASA and BCCA) to perform equally (p>0.05) when compared to mCCDA medium, recommended by ISO. Therefore, CASA and BCCA can be considered as suitable alternatives for easy Campylobacter enumeration in chicken meat.