Detection of Blandm And Blaoxa-23 Genes in Acinetobacter Baumannii Isolated from Sputum Samples of Iraqi Patients

Abstract

Acinetobacter baumannii is a pivotal pathogenic bacterium causing hospital-acquired respiratory infections, particularly in critically ill patients, and its prevalence of multidrug-resistant strains has increased globally. Two of the most relevant carbapenemase genes from a clinical standpoint is blaOXA-23 and blaNDM which are highly involved in conferring resistance to carbapenems in A. baumannii. The aim of this study was to investigate the prevalence of the blaOXA-23 and blaNDM genes in A. baumannii isolates isolated from sputum samples obtained from Iraqi patients, and whether these genes were associated with patterns of resistance to specific antibiotics. This is a cross-sectional study performed in the Teaching Hospital in Al-Diwaniyah City, Iraq during March 2025 to August 2025. A total of 48 patients with a clinically suspected lower RTI were recruited. Sputum aspirates were obtained under aseptic conditions and processed by standard microbiological procedures. A. baumannii was identified by colony morphology, Gram staining and standard biochemical testing. The susceptibility testing for imipenem, meropenem, amikacin gentamicin ciprofloxacin ceftazidime and piperacillin–tazobactam (p-t) were performed by the Kirby–Bauer disk diffusion according to the CLSI. Molecular identification of blaOXA-23 and blaNDM genes was done by conventional polymerase chain reaction (PCR). High resistance rates were also noted for carbapenems, imipenem (87.5%) and meropenem (85.4%). Resistance was also high for ceftazidime (81.3%) and piperacillin/tazobactam (79.2%), which were much lower in case of aminoglycosides. Molecular investigation indicated that blaOXA-23 and blaNDM genes were observed in 83.3% and 37.5% of the isolates, respectively. The link between resistance to carbapenems and the simultaneous presence of blaOXA-23 and blaNDM genes was strongly significant. These observations show high rates of blaOXA-23 but still considerable rates of blaNDM enzymes among CRAB isolates in Al-Diwaniyah, and highlight the necessity for regular molecular surveillance, proper infection control measures and improved antimicrobial stewardship policies to prevent expansion of MDR A. baumannii strains.

Keywords:

blaOXA-23, blaNDM, Acinetobacter baumannii, pneumonia, Carbapenemase

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