Background: Antibiotic resistance Genies causes many problems in hospitals. Dissemination of these agents to the environment is a great concern worldwide. The aim of this study was to investigate the concentration of antibiotic resistant bacteria (ARB) and presence of antibiotic resistance genes(ARGs) in hospital wastewaters.

Methods: in present work, 33 sample from raw hospital wastewater were taken from three hospitals. Heterotrophic plate counts (HPC) method was used to assess the concentration of ARB in hospital wastewater samples. Six conventional antibiotics were selected. Presence of six resistance genes regarding to the selected antibiotics were surveyed in wastewater samples and isolated ARB by PCR method.

Results: Average concentration of ARB in raw hospital wastewater was 3.81 ×10⁷ CFU/100mL. Frequency pattern of ARB in raw hospital wastewater was as follows: ceftazidim(CAZ)> tetracycline(TE)> sulfomethoxazol (STX)> chloramphenicol (CHL)> erythromycin (ER)> and gentamicin(GM), respectively. ARGs in raw wastewater samples were detected more than isolated bacteria. ARGs frequency pattern in wastewater samples were as follows: sul1>cmlA1>ermB>tetW>aac3-1>ctx-m-32.

Conclusion: The results of this study revealed that there are high concentration of ARB and ARGs in hospital wastewaters. Therefore, hospital wastewaters could play an important role in dissemination of ARB and ARGs into the natural environment and therefore, may pose serious public health risks.