Molecular and Biochemical Identification of Acinetobacter baumannii isolated from Different Clinical Sources in Kerbala and Najaf Governorates

University of Kerbala, Collage of science, kerbala, Iraq

Abstract

Acinetobacter baumannii has emerged as the best recognized and very important pathogen responsible for healthcare-associated infections as a result of its ability to survive under harsh environmental conditions. To investigate the prevalence of A.baumannii across various clinical sources and to evaluate selected virulence factors associated with this pathogen, a total of 150 clinical swabs were collected from burns, wounds, urine and sputum samples. These were cultured on blood agar and MacConkey agar, then incubated at 37°C for 24–48 hours. Bacterial isolates were identified based on colony morphology, cultural characteristics and standard biochemical tests, including catalase, oxidase and Simon’s citrate tests. Virulence factors, including hemolysis, protease production, and polysaccharide capsule formation, were also evaluated using qualitative methods. The results showed that out of 120 bacterial isolates, 30 (25%) were identified as A. baumannii, whereas the remaining 90 (75%) were belonging to other bacterial genera. The A. baumannii isolates were Gram-negative, non-motile and exhibited no hemolytic activity on blood agar. Biochemical testing confirmed that all the isolates were catalase and citrate positive. Confirmation of A. baumannii was performed using the VITEK 2 system and polymerase chain reaction (PCR) by targeting a specific gene namely blaOXA-51 (353 base pairs in size), The results confirmed that 30 (100% ) of the isolates were A. baumannii. The identified bacteria was also investigated for various virulence factors, the results revealed that all the isolates were incapable of producing hemolysin, whereas 25 (83.3%) of the tested becteria were positive for the protease qualitative test and all the isolates produced a polysaccharide capsule.