Plasmid-Mediated Class 1 and 2 Integron Carriage in Drug-Resistant Nosocomial Isolates of Acinetobacter baumannii

Abstract

Background: Acinetobacter baumannii is an opportunistic multidrug-resistant pathogen associated with nosocomial infections in critically ill patients. Antibiotic resistance genes are often encoded by class 1 and 2 integrons and located on plasmids that can facilitate their horizontal transfer among bacteria. Objectives: The aim of this research was to study the correlation between plasmid carriage and presence of class 1 and 2 integrons in nosocomial isolates of A. baumannii. Methods: Fifty isolates collected between October 2014 and March 2015 from Imam Hussein hospital in Tehran were examined. Bacterial identification was carried out by biochemical identification as well as detection of the blaOXA-51 gene among the isolates. Susceptibility to 18 antibiotics was determined by disc diffusion method. Class 1 and 2 integrons were detected in total DNA extracts as well as in isolated plasmids using specific primers and PCR. Results: All isolates were extremely drug-resistant (XDR). Integron carriage was observed in 32 isolates (64%). Seventeen isolates (34%) carried plasmids with molecular sizes of > 20 kbp. Among them, six (35.4%) carried class 1, three (17.6%) harbored class 2, four (23.5%) had both integron classes, and four isolates (23.5%) carried no integrons. Of the plasmid negative isolates, 14 (42.4%) had no integron, 10 (30.3%) carried integron 2, five (15.2%) harbored integron 1 and interestingly, four (12.1%) carried both integron classes. Conclusions: No correlation was found between antibiotic resistance profiles and integron carriage. Class 1 integron was significantly associated with plasmid carriage showing its role in the dissemination of drug resistance in A. baumannii. No association was observed between class 2 integrons and plasmid carriage suggesting their chromosomal location.

Investigation of Class 1 Integrons With Antibiotic Resistance Genes in Multidrug-Resistant Acinetobacter Baumannii Strains and Determination of Plant Extract Effects on Multidrug-Resistant Isolates

“…The presence of CTX-M-1 and CTX-M-2 β-lactamases in 96 A. baumannii isolates from Turkey was investigated and no positive results were obtained for the isolates [19]. In the same study, the presence of OXA- [20].…”

Molecular Investigation of Resistance to Disinfectants in Acinetobacter Baumannii Isolates Collected From Qazvin Hospitals, Iran (2017)

“…About half of the class 1 integrons contain a gene resistant to quaternary ammonium compounds as a factor involved in resistance to disinfectants [7,8]. This study, while analyzing the antibiotic susceptibility pattern, investigates the frequency of qacE and qacEΔ1 genes as disinfectant resistance genes in A. baumannii isolates collected from hospitalized patients in different departments of hospitals in Qazvin, Iran.…”