Antibiotic resistance pattern of Acinetobacter baumannii from burns patients: increase in prevalence of blaOXA-24-like and blaOXA-58-like genes

Abstract

Background and Objectives: Notwithstanding the increased prevalence of Acinetobacter baumannii drug-resistant isolates,

treatment options are progressively limiting. This study aims to provide a recent report on antibiotic susceptibility in burn

wound isolates of A. baumannii, and the importance of OXA beta-lactamases in carbapenem resistance.

Materials and Methods: The susceptibility levels to different antimicrobial categories were determined among 84 A. baumannii

isolates from burn wound infection between 2016 and 2018. Multiplex PCR was used to detect OXA beta-lactamases

genes, including blaOXA-51, blaOXA-23, blaOXA-24 and blaOXA-58. ISAba-1 association with blaOXA-51, blaOXA-23 and blaOXA-58 was

detected by PCR mapping.

Results: All the isolates were determined as multidrug-resistant (MDR) and 69% as extensively drug-resistant (XDR).

Different carbapenems MIC ranges (MIC50 and MIC90) were observed among the isolates harboring blaOXA-like genes and

isolates with the OXA-24-like enzyme showed higher carbapenems MIC ranges. The prevalence of blaOXA-51-like, blaOXA-23-like,

blaOXA-24-like and blaOXA-58-like were 100%, 53.57%, 41.66% and 30.95%, respectively. ISAba-1 insertion sequence was found

to be upstream to blaOXA-23-like and blaOXA-58-like genes in 23 out of 45 (71.1%) blaOXA-23-like-positive and 4 out of 23 (15.3)

blaOXA-58-like-positive isolates, respectively.

Conclusion: Resistance to carbapenems as the last resort for treatment of A. baumannii infections is growing. This study,

for the first time in Iran, has observed the increased frequency of blaOXA-24-like and blaOXA-58-like genes and found an association

between ISAba-1 and blaOXA-58-like gene, which signifies the possible risk of increased diversity in OXA beta-lactamases and

growth in carbapenem resistance