Investigation of Antimicrobial Resistance and Integron Profiles of Poultry Pathogenic Escherichia coli

Integrons are mobile DNA elements which play an important role in the acquisition and transmission of antimicrobial resistance genes. The rapid spread of multidrug resistant bacteria threaten public health giving also causes economic problems worldwide. The aim of this study was to evaluate the presence of integron in Avian Pathogenic Escherichia coli (APEC) isolated from internal organs in broiler chickens with respiratory system conditions and to determine the contribution of integrons to antimicrobial resistance in these microorganisms. For this purpose, a total of 112 (82.9%) E. coli isolates isolated from the internal organs of 135 colibacillosis suspected broiler chickens constituted the material of this study. Antibiotic resistance of the isolates was determined by the disk diffusion method. The identification of bacteria at species level and the presence of integron gene (class 1, 2, 3) were investigated by polymerase chain reactions (PCR). It was determined that 70.5%, 68.8%, and 58.9% of isolates were resistant to ampicillin, tetracycline, and trimethoprim sulfamethoxazole, respectively. While 14.3% (16/112) of all isolates in the study was sensitive to all antibiotics used, 85.7% (96/112) of the isolates were resistant to only one antibiotic. Moreover, multiple antibiotic resistance (MDR) was found in 64.3% (72/112). The integron was detected among 52.7% (46.4% of them class 1; 1.8% of class 2; 4.5% class 1 and class 2) of the isolates while in 47.3% were without the integron. In this study, no integron was detected in any of the antibiotic susceptible isolates. However, 61.4% (59/96) of isolates with antibiotic resistance; 33.3% (8/24) of the non-MDR isolates; 70.8% (51/72) of the MDR isolates were detected carrying the integron. All isolates with antibiotic resistance were not carrying integron. However, the presence of an integron was significantly higher in isolates resistant to trimethoprim sulfamethoxazole, ampicillin, tetracycline, gentamicin, florfenicol and to ciprofloxacin resistant isolates. In these cases, the presence of integron may have played an important role in the resistance of APEC isolates to antimicrobial drugs. This study is important in that it is the first study to show the presence of integrons in E. coli isolates originating from broilers in western Turkey. The availability of strains of E. coli that are multi-resistant to antibiotics in poultry farms may also pose a risk to the public health. Studies focusing on the structure of integrons involved in the transfer of resistance genes may provide not only a better understanding of the mechanisms of resistance, but also provide useful information for the development of policies regarding the use antimicrobials.