Nowadays, in the poultry industry, antibiotics are used to treat, prevent, and enhance poultry growth and production efficiency. Their irregular consumption has resulted in the spread of antibiotic-resistant bacteria in this industry. Antibiotic-resistant bacteria in contaminated waters can be transmitted into soil. The purpose of this study was to investigate the antibiotic resistance pattern of bacteria isolated from the water of chicken slaughterhouses around Hamadan (Iran) province. In this study, 20 water samples were collected from four slaughterhouses in Hamadan province (during spring and summer 2019). Initial isolation and identification of the bacteria were performed by pour plate culture and biochemical tests. The disc diffusion method was applied to investigate the resistance pattern. This study presents 109 screened isolates. Of these, 57.8% E.coli, 35.7% Salmonella spp., and 6.42% Klebsiella spp. were detected. Antibiograms of isolates showed that in E.coli, 23.09% were resistant to four types of the antibiotic tetracycline, amoxicillin, gentamicin, and chloramphenicol, 76.19% had only one type of antibiotic. Antibiotics for Salmonella spp. showed that 35.9% were resistant to tetracycline, gentamicin, and chloramphenicol, 64.10% to only one type of antibiotic. Also, in Klebsiella spp., 85.71% were sensitive to antibiotics, and only 14.28% were resistant to tetracycline. Conclusion: The results showed that the rate of multiple antibiotic resistance is relatively high, and contaminated water has a high potential for soil contamination. Therefore, resistant bacteria become more stable in the environment, and the health of the environment will be endangered. Therefore, it is necessary to study the antimicrobial resistance patterns of bacteria to study and maintain the health of the environment.
