Tehran University of Medical Sciences Journal of Arthropod-Borne Diseases 2322-1984 17 1 2023 07 30 1520 1520 EN Behroz Davari Department of Medical Entomology, Hamadan University of Medical Sciences, Hamadan, Iran Ali Ezat Hassanvand Department of Medical Entomology, Hamadan University of Medical Sciences, Hamadan, Iran Aref Salehzadeh Department of Medical Entomology, Hamadan University of Medical Sciences, Hamadan, Iran Mohammad Yousef Alikhani Infectious Disease Research Center, Hamadan University of Medical Science, Hamadan, Iran Seyed Mostafa Hosseini Infectious Disease Research Center, Hamadan University of Medical Science, Hamadan, Iran, Department of Microbiology, Hamadan University of Medical Sciences, Hamadan, Iran 2021 12 18 2023 06 11 Background: Cockroaches are one of the most important carriers of pathogenic microorganisms. Therefore, the pres­ence of cockroaches in public places, especially in hospitals, homes, and restaurants, is dangerous, and threatens the health of society, people, and the environment. The aim of this study was evaluation of bacterial contamination of cock­roaches and the sensitivity of these bacteria to various antibiotics, captured from Khorramabad City, Iran Methods: This descriptive cross-sectional study was performed on 150 cockroaches collected from hospital environ­ments, homes, and restaurants in Khorramabad. The outer surface of the cockroaches was washed with physiological sa­line. The suspension was centrifuged for 5 minutes at 2000rpm. Isolation and identification of bacteria was performed using phenotypic methods. Antibiotic susceptibility testing was performed by disk diffusion method according to Clini­cal and Laboratory Standard Institute (CLSI) guideline. Results: A total of 100 American cockroaches (66.66%), 28 B. germanica (18.66%) and 22 Blatta orientalis (14.66%) were identified. In total, 97.33% of the collected cockroaches were infected with bacteria. The most bacterial infection of the cockroaches was Escherichia coli, coagulase-negative Staphylococci and Bacillus respectively. The overall re­sults of the antibiogram test showed that the identified bacteria were resistant to cephalothin, ampicillin, cefotaxime, and kanamycin antibiotics, semi-sensitive to ciprofloxacin and sensitive to tetracycline, gentamicin, nitrofurantoin, Tri­methoprim/sulfamethoxazole, and Chloramphenicol. Conclusion: Infection of cockroaches with pathogenic bacterial agents in hospital, residential, and restaurant environ­ments, as well as the observation of bacterial resistance to some common antibiotics is worrying. https://jad.tums.ac.ir/index.php/jad/article/view/1520 https://jad.tums.ac.ir/index.php/jad/article/download/1520/617