Molecular Study of Colistin Resistance Genes in Acinetobacter baumannii Isolated from Patients in the Intensive Care Unit (ICU)

Abstract

Backgrounds: Bacteria which form part of the genus Acinetobacter (Acinetobacter spp.) are widely distributed Gram-negative coccobacilli, which are found in nature and hospital wards and cause various nosocomial infections, including pneumonia, meningitis, endocarditis, skin and soft tissue infections, conjunctivitis, burn Wound infections, and bacteremia. These bacteria exhibit different resistance mechanisms. This study aimed to evaluate Acinetobacter baumannii strains' resistance against different antibiotics in the presence and absence of pmrA, pmrB, and pmrAB genes.
Methods: This descriptive-cross-sectional study was conducted on 100 isolates of Acinetobacter baumannii isolated from hospitalized patients in the intensive care unit (ICU) of Namazi, Ali Asghar, and Shahid Rajaei hospitals in Shiraz. Bacterial identification of the species was performed using standard biochemical tests, and Microgen kits with verified isolates. Antibiotic sensitivity was analyzed on 12 antibiotics according to the standard technique and CLSI criteria, and the pmrA, pmrB, and pmrAB genes were used to identify and multiply them.
Results: The isolates of Acinetobacter baumannii were resistant to most antibiotics and had less resistance to their latest treatment line, the antibiotic colistin. Most isolates were a carrier for pmrA, pmrB, and pmrAB genes.
Conclusions: This study has found that Acinetobacter baumannii resistance in Iran is increasing like in other parts of the world, indicating the necessity to adopt appropriate treatment strategies.