Abstract

Background: Acinetobacter baumannii has emerged as a critical pathogen with high morbidity and mortality in long-term hospitalized patients who stay in intensive care units. Carbapenemases and integrons are two critical DNA elements that contribute to the emergence of multidrug-resistant (MDR) A. baumannii. Objectives: The current study aimed at characterization and molecular detection of class 1, 2, and 3 integrons among carbapenemase-producing A. baumannii strains recovered from a clinical setting in Tehran, Iran. Methods: A total of 65 non-replicated clinical strains were considered in this study. Class 1, 2, and 3 carbapenemase genes and clonal relatedness of the isolates were investigated by PCR assay. Results: The prevalence of carbapenemases was as follows: blaOXA23 (92.31), blaVIM (69.23), and blaNDM (1.54). In addition, PCR sequencing confirmed the presence of gene cassette arrays consisting of aacA4-catB8-aadA1 (12/46, 26.09), aadB-aadA1 (26.09, 12/46), arr2-cm1A5 (30.43, 14/46), and dfrA1-aadA1 (7.39, 8/46) in class 1 integron and dfrA1-sat2 (52.94, 9/17), and sat2-aadA1 (47.06, 8/17) in class 2 integron. Sequence-based typing of both blaOXA-51-like and ampC revealed the following distribution of three different clone types among isolates: clonal complex (CC) 10 (46.15, 30/65), CC2 (40, 26/65), and CC3 (13.85, 9/65). Statistical analysis showed that the presence of the intI1, blaOXA23, blaVIM, or blaNDM genes can significantly increase the acquiring MDR phenotypes in A. baumannii isolates. Conclusions: High prevalence of carbapenemase-producing A. baumannii harboring integrons is alarming public health. It seems that class 1 integron can be served as a predictive biomarker for the presence of MDR phenotypes in the clinical setting. However, integrons do not carry carbapenemases in these strains. © 2021, Author(s).