A novel cost-effective methodology for Campylobacter isolation from human stool and chicken sample matrix containing extended-spectrum β-lactamase-producing Escherichia coli.

Campylobacter jejuni and C. coli are major causes of bacterial gastroenteritis, but their isolation from samples contaminated with extended-spectrum β-lactamase (ESBL)-producing Escherichia coli remains challenging. This study evaluated the performance of modified charcoal cefoperazone deoxycholate agar (mCCDA) and Preston broth, supplemented with different concentrations of a commercially available pharmaceutical-grade tazobactam-piperacillin (TP) combination for the selective isolation of Campylobacter. After determining the optimum concentration of TP to inhibit the growth of ESBL-producing E. coli while the growth of Campylobacter remained unaffected, a field evaluation was conducted for the investigation of 120 chicken caecal and 120 stool samples from pediatric diarrhea patients to compare Campylobacter recovery and background flora contamination rates in real field situations. The results demonstrated that TP-mCCDA containing 4 mg/L tazobactam flanked by 32 mg/L piperacillin effectively inhibited ESBL-producing E. coli while allowing Campylobacter growth, but TP at 4/32 mg/L in Preston broth failed to inhibit the growth of seven of the 12 ESBL E. coli isolates tested, suggesting that a unique concentration combination of TP for both mCCDA and Preston broth could not be recommended for real field situations. Based on these initial findings for determining TP concentration, TP at 4/32 mg/L in mCCDA was used for selective isolation of Campylobacter from the cecal matrix and stool samples, whereas Preston broth was used without TP supplementation for pre-enrichment of Campylobacter from the stool samples before selective isolation on TP-mCCDA. The results revealed that TP-mCCDA yielded a significantly higher Campylobacter recovery rate (59.2%) from chicken caeca compared to standard mCCDA (20.0%), with substantially reduced background flora contamination (6.7% vs. 70.0%). In stool samples from pediatric patients with diarrhea following pre-enrichment in Preston broth, TP-mCCDA also outperformed mCCDA in both Campylobacter recovery rate (4.2% vs. 0%) and competing flora contamination (19.2% vs. 80.0%). Compared with other ESBL inhibitors, TP-mCCDA was found to be highly cost-effective, achieving a higher Campylobacter isolation rate while minimizing contamination by competing ESBL-producing microflora.