antibiotic resistance pattern of acinetobacter baumannii from burns patients: increase in prevalence of blaoxa-24-like and blaoxa-58-like genes

Background and objectives: notwithstanding the increased prevalence of acinetobacter baumannii drugresistant 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 betalactamases 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 betalactamases genes, including blaoxa51, blaoxa23, blaoxa24 and blaoxa58. isaba1 association with blaoxa51, blaoxa23 and blaoxa58 was detected by pcr mapping.results: all the isolates were determined as multidrugresistant (mdr) and 69% as extensively drugresistant (xdr). different carbapenems mic ranges (mic50 and mic90) were observed among the isolates harboring blaoxalike genes and isolates with the oxa24like enzyme showed higher carbapenems mic ranges. the prevalence of blaoxa51like, blaoxa23like, blaoxa24like and blaoxa58like were 100%, 53.57%, 41.66% and 30.95%, respectively. isaba1 insertion sequence was found to be upstream to blaoxa23like and blaoxa58like genes in 23 out of 45 (71.1%) blaoxa23likepositive and 4 out of 23 (15.3) blaoxa58likepositive 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 blaoxa24like and blaoxa58like genes and found an association between isaba1 and blaoxa58like gene, which signifies the possible risk of increased diversity in oxa betalactamases and growth in carbapenem resistance.