Evaluation of potassium clavulanate supplementation of Bolton broth for enrichment and detection of Campylobacter from chicken

Culture-based detection of Campylobacter can be affected by competing flora, temperature, incubation time, and presence of blood. The presence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in poultry has become one of the most common factors interfering with the detection of Campylobacter. In the present study, we evaluated potassium clavulanate (ESBL inhibitor) as a supplement in Bolton broth (C-Bolton broth) for enrichment and detection of Campylobacter. First, we determined growth kinetics of Campylobacter in the presence of different concentrations of ESBL E. coli in C-Bolton broth during enrichment. The effects of other factors such as incubation time, incubation temperature, and presence of blood on Campylobacter detection in C-Bolton broth were also investigated. The growth of Campylobacter co-cultured at a low concentration (2 and 4 log ₁₀ CFU/mL) of ESBL E. coli was similar to that of Campylobacter alone in C-Bolton broth, and Campylobacter co-cultured at a high concentration (6 and 8 log ₁₀ CFU/mL) of ESBL E. coli showed slower growth than the pure Campylobacter culture. The Campylobacter detection limit was 1 log ₁₀ CFU/mL when mixed with 2, 4, or 6 log ₁₀ CFU/mL of E. coli and 3 log ₁₀ CFU/mL when mixed with 8 log ₁₀ CFU/mL of E. coli after 48 h enrichment in the broth. Campylobacter detection from chicken feces and litter samples was not affected by incubation time, or presence of blood in the broth. A modified procedure of enrichment in C-Bolton broth at 37°C for 24 h without blood showed a significantly (P ≤ 0.05) higher detection rate and a lower false-negative rate than the ISO 10272-1:2006 method for Campylobacter detection from chicken feces and litter samples. In summary, the present study demonstrates the efficacy of Bolton broth supplemented with potassium clavulanate in the detection of Campylobacter mixed with ESBL E. coli, and an improved procedure to detect Campylobacter from chicken feces and litter samples.