BASIMA MUHAMMED HAMZA AL.DUHAIMI

(1) Ameer.B.A(2)

Hala Hammadi,(3)

Abstract :

Background: Carbapenems, a class of beta-lactam antibiotics, are commonly used to treat multi-drug-resistant Acinetobacter baumannii isolates.

Objective: This study aimed to detecting Carbapenem-resistant gene and biofilm formation in Acinetobacter baumannii

Materials and Methods: From January – June 2024, 300 specimens were collected from Al-Hilla Teaching Hospital. These specimens were cultured on blood agar, MacConkey agar, and Hi-CHROM agar. Antibiotic susceptibility was assessed using the disc diffusion test and the minimum inhibitory concentration for Meropenem. Biofilm formation was evaluated using the tissue plate assay, and bla-OXA and metallo-beta-lactamase genes were identified via PCR. Results: Out of 300 isolates, 25 (8.3%) were studied. The isolates came from burns 75%, wounds 80%, blood 75%, and urine 70%. Susceptibility testing revealed 100% resistance to cefepime, ceftazidime, cefotaxime, ciprofloxacin, and levofloxacin; 70% to gentamicin; 60% to tobramycin; 84% to imipenem; 75% to polymyxin B; and 72% to meropenem. MIC assays confirmed meropenem resistance in all but seven isolates, with an MIC > 16 µg/ml according to CLSI 2024 guidelines. Biofilm formation tests indicated 60% of the isolates were strong biofilm formers and 40% were moderate. All CRAB isolates carried bla-OXA-51-like genes, 82.1% had bla-OXA-23-like, 68% had bla-VIM, fewer than 10% had bla-IMP, and no bla-NDM genes were detected.

Conclusion: Meropenem remains a critical option against multi-drug-resistant A. baumannii. Variations in biofilm formation correlate with infection severity. Oxacillinase genes are more prevalent than MBL genes.