: Infectious diarrhoea result from a wide range of bacteria, viruses and parasites. This condition is also identified as gastroenteritis, is a well-known as one of most common bacterial pathogens causing gastroenteritis. This study aims to estimate the incidence and identifying both the phenotypic and genotypic characterization of causing gastroenteritis in children under the age of five in al-Ramadi Maternity and Children Teaching Hospital.: Stool samples were collected for 106 children suffering from gastroenteritis, Cultural and microscopical approaches were used for selection, its characteristic features were confirmed using the Vitek2 compact system, anti-microbial sensitivity test, and biofilm production test. furthermore, DNA extracted, purification and Polymerase chain reaction (PCR) were accomplished for genotypic confirmation. In the presented research, stool samples were collected for 106 children suffering from gastroenteritis, and 100 samples were identified as source for bacterial gastroenteritis. The bacterium under consideration () has a percentage of 30%. This isolate revealed resistance to Ceftazidime (80%), nalidixic acid (33%), amikacin (36%), Azithromycin (20%), vancomycin (10%), and Imipenem (6%). Likewise, four genes in isolate were studied via PCR and the results indicates htrA, iss, Mrka and rmpA were 15 (50%), 9 (30%), 6 (20%), 0 (0%) respectively. The results of biofilm production for exposed that 3 (10%) were strong, 10 (33%) moderate, 7 (24%) weak, and 10 (33%) non-producers. : The presented research displayed the bacterium under consideration () has a higher resistance rate to the commonly antibiotics used for bacterial gastroenteritis. In addition, (under consideration) with high resistance to antibiotics showed resistance genes in PCR, in addition to strong biofilm production.
