Genetic diversity of colistin-resistant Acinetobacter baumannii isolates in patients of Shahid Rajaee Trauma Hospital in Shiraz

Acinetobacter baumannii is the clinically significant bacteria easily capable acquiring multi-resistance to antibiotics. This study aims to evaluate the pattern of         resistance, colistin resistance gene, and the study of genetic diversity of colistin-resistant strains isolated from Shahid Rajaee Hospital in Shiraz.Materials &

This descriptive cross-sectional study was conducted on A. baumannii strains isolated from patients admitted to the intensive care unit ICU of Shahid Rajaei Hospital in Shiraz. A. baumannii strains were identified and confirmed by Microgen kit and blaOXA-51 gene. Antibiotic susceptibility testing was then performed by disk diffusion method according to CLSI 2020 instructions. PCR method was used to study pmrA and pmrB genes and also genetic           diversity of A. baumannii strains was analyzed by SPSS software and NTSYS version2.10e.

Fifty strains of A. baumannii were isolated and identified. These strains had multi-resistance and showed high resistance to most antibiotics. The lowest rate of resistance was observed to colistin and tigecycline antibiotics. In the study of colistin-resistance genes,  colistin-susceptible and colistin-resistant strains of A. baumannii carried pmrA and pmrB genes, respectively. Colistin-resistant strains were placed next to colistin-sensitive strains in a node in the dendrogram.

The results of the present study revealed the frequency of multi-resistant  A. baumannii strains in the hospital. These strains belonged to a common clone and seem to be circulating in the hospital. Infection control programs are required to be implemented in hospital wards.