Molecular detection and antibiotyping of multi-drug resistant Enterococcus faecium from healthy broiler chickens in Bangladesh

Abstract

Background: Enterococcus faecium is a ubiquitously distributed member of the intestinal microbiota of both humans and animals. Antibiotic resistant E. faecium are a major public health concern. Objectives: This study aimed to detect multi-drug resistant (MDR) E. faecium and their antibiotic resistance genes from broiler chickens in Bangladesh. Methods: A total of 100 faecal samples of healthy broilers were screened by conventional methods and polymerase chain reaction (PCR) to detect E. faecium and their resistance genes. Disk diffusion test was employed to determine antibiotic profiles. Results: By PCR, among 100 samples, 45% [95% confidence interval (CI): 35.62%–54.76%] were positive for E. faecium. Based on antibiogram, all the E. faecium isolates were found resistant to ampicillin, and frequently (93.33%–55.56%) resistant to ceftriaxone, cefotaxime, streptomycin, erythromycin, and imipenem; moderate to lower (26.67%–4.44%) resistance to tetracycline, ciprofloxacin, norfloxacin, chloramphenicol, gentamicin, and vancomycin. Interestingly, 80% (95% CI: 66.18%–89.10%) E. faecium isolates were MDR in nature. In addition, the indices of multiple antibiotic resistance (MAR) ranged from 0.08 to 0.83. By bivariate analysis, high positive significant correlations were observed between resistance profiles of erythromycin and imipenem, ciprofloxacin and norfloxacin, erythromycin and streptomycin, ceftriaxone and cefotaxime, tetracycline and chloramphenicol, and streptomycin and imipenem. Furthermore, the prevalence of resistance genes of E. faecium was 58.33% (tetA), 33.33% (tetB), 35.56% (blaTEM), 60% (CITM), 13.33% (aadA1), and 12% (SHV). Conclusions: To the best of our knowledge, this is the first study in Bangladesh to detect MDR and MAR E. faecium and their associated resistance genes. The detection of MDR and MAR E. faecium and their corresponding resistance genes from healthy broilers is of public health concern because of their potential to enter into the food chain.