Research Note: A baseline survey of thermotolerant Campylobacter in retail chicken in southern Brazil.

Chicken is a leading source of thermotolerant Campylobacter, which triggers human foodborne enteritis. This study evaluated thermotolerant Campylobacter contamination of retail chicken in southern Brazil, using qualitative and quantitative analyses. Selective enrichment in Bolton broth for 24 and 48 h after plating onto modified charcoal-cefoperazone-deoxycholate (mCCD) agar and Preston agar was assessed. The combined results of the detection and enumeration methods revealed a frequency of 70% occurrence of thermotolerant Campylobacter in chicken samples. Campylobacter was enumerated in 60% of the samples, whereas 46% of the samples were positive in the qualitative analysis. Quantitative analysis showed average counts of 3.10 ± 0.15 log10 CFU/sample. Higher numbers of Campylobacter-positive samples were found using 24-h enrichment before plating onto Preston agar (46%) than onto mCCD agar (2%). The majority of isolated strains were identified as Campylobacter jejuni, and Campylobacter coli was also found but to a lesser extent. Subtyping revealed a clear distinction between strains isolated from different chicken sources. The enriched samples plated onto mCCD agar showed extensive spreading of nonproducing extended-spectrum ß-lactamases Proteus mirabilis that hampered the identification of Campylobacter colonies. P. mirabilis strains showed resistance to cefoperazone, trimethoprim, and polymyxin B present in broth and plate media used and were inhibited by rifampicin present in Preston agar. The results underline the effect of the spread of contaminant strains on Campylobacter cultures, which might be prevented using a recently revised International Organization for Standardization method for qualitative analysis of chicken.

Population Dynamics of Thermotolerant Campylobacter in Broilers Reared on Reused Litter.

A study using sentinel broiler chickens was performed to address Campylobacter persistence in litter that was reused for successive flocks. Cloacal swabs, litter, drag swabs, darkling beetles, feed, and drinking water were weekly sampled and analyzed by standard microbiological procedures. Thermotolerant Campylobacter isolated strains were confirmed by polymerase chain reaction and subtyped by pulsed-field gel electrophoresis analysis. Campylobacter was not detected in samples collected immediately after downtime between broiler flocks. However, Campylobacter-positive samples were first detected at 21 d. After Campylobacter was initially isolated from the cloacal swabs, reused litter, drag swabs, or darkling beetles, these samples remained Campylobacter positive in the following weeks until the end of the rearing period. Campylobacter-positive cloacal swabs obtained from sentinel broilers ranged from 97.3% to 100% at 42 d. All isolated strains were identified as Campylobacter jejuni. Among the subtypes identified, an indistinguishable C. jejuni strain was predominant in sentinel broilers and was also detected in the other environmental samples analyzed, suggesting a common and persistent contamination source within the flocks. Sentinel broilers may have contributed to amplify the Campylobacter level, maintaining flock and broiler house contamination until the end of the production cycle.