Molecular and phenotypic characterization of multi drug resistant Acinetobacter baumannii from clinical isolates and genotypic approaches

Background: Acinetobacter baumannii is a bacterium frequently associated with hospital-acquired infections. It is characterized by intrinsic and acquired antimicrobial resistance, which has recently become increasingly uncontrolled. Differences in the genetic sequence of nucleotides between sensitive and resistant species naturally occur as a result of deletion, insertion, or duplication of nucleotides. Methods: 20 multi-drug resistant (MDR) isolates of A. baumannii were collected from various clinical cases at Thi-qar Educational Hospital in Iraq. Molecular investigation of several antimicrobial resistance genes (Bap, OmpA, blaOXA-51, and blaPER-1) was performed. Whole genome sequencing was subsequently conducted on the isolated strains. Results: The study revealed that most of the studied antimicrobial resistance genes were present in 100% of the isolates, except for the CsuE gene, which showed variable presence across different clinical isolates. Whole genome sequencing results showed that only 16 of the 20 (80%) isolates were A. baumannii, while the remaining four isolates were identified as Klebsiella grimontii, Acinetobacter pittii, Enterobacter cloacae, and Salmonella enterica. The sequencing results also indicated that MDR isolates contain more nucleotides than sensitive isolates. Conclusion: The antibiotic susceptibility testing results of the isolates in this study differ from those of similar studies conducted in other Iraqi cities in the recent past.