Genotyping and molecular characterization of clinical Acinetobacter baumannii isolates from a single hospital in Southwestern Iran

ABSTRACT

Acinetobacter baumannii

(A. baumannii) is a pathogen responsible for nosocomial infections among the hospitalized patients. The aim of this study was to investigate genotyping and molecular characterization and to examine the biofilm formation ability of A. baumannii isolates. In total, 70 A. baumannii isolates were collected from patients admitted to Imam Khomeini Hospital in Ahvaz, Southwestern Iran. Minimum inhibitory concentrations (MIC) test was performed using Vitek 2 system. The presence of genes encoding metallo-β-lactamases, oxacillinases, and integrase and the biofilm formation ability were then evaluated. Multiple locus variable-number tandem repeat (VNTR) analysis (MLVA) typing and multiplex PCR were performed to determine the genetic relationships. The bla_OXA-23-like gene had the highest prevalence. The frequency of genes encoding bla_SPM, bla_IMP, and bla_VIM among MDR A. baumannii isolates were 12 (17.1%), 18 (25.7%), and 22 (31.4%), respectively. Moreover, 46 isolates (75.4%) harbored class I integron and 10 isolates (16.39%) carried class II integron. The number of weak, moderate and strong biofilm-producing isolates were 3 (4.3%), 7 (10%), and 55 (78.5%), respectively. The results showed that 70 A. baumannii isolates were grouped into 12 distinct MLVA types with five clusters and four singleton genotypes. In addition, 25 (35.7%) isolates were assigned to international clone (IC) variants, 37 (52.8%) isolates belonged to group 1 (IC II), and 8  (11.4%) isolates belonged to group 2 (IC I). Our findings revealed that the population structure of the A. baumannii isolates was genetically diverse. More focus on genetic variation and antibiotic resistance of A. baumannii isolates are recommended.

KEYWORDS:

• Acinetobacter baumannii
• drug resistance
• integron
• metallo-β-lactamase
• MLVA

Acknowledgments

This study was a part of the Ph.D. thesis of Saeed Khoshnood. We would like to thank the Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, for their cooperation. Our appreciation goes to the Vice Chancellor for Research affairs, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran, and Tropical and Infectious Diseases Research Center of the University for their financial (Grant No. OG-9739) and executive support.

Disclosure statement

The authors declare that they have no conflict of interest in this study.