Class 1 integrons in non-clonal multidrug-resistant Acinetobacter baumannii from Iran, description of the new bla IMP-55 allele in In1243

Abstract

Infections and outbreaks caused by multidrug-resistant Acinetobacter baumannii (MDR-AB) are prevalent and have been reported worldwide over the past 20 or more years. Class 1 integron in MDR-AB plays an important role in the spread of antibiotic resistance in clinical settings. This study has been conducted to evaluate the detection of metallo-b-lactamase, characterization of class 1 integron and determination of clonal relatedness among A. baumannii hospital isolates. Sixty-five clinical isolates of MDR-AB were recovered from two Iranian hospital's intensive care units from February to August 2013. Integrase (intI1) and bla IMP genes were detected in 70.8 % (n=46/65) and 9.23 % (n=6/65) of the isolates using PCR assay, respectively. No other metallo-b-lactamase genes (bla VIM , bla SIM and bla NDM ) were detected. PCR sequencing of integron gene cassette revealed the following arrays: bla OXA10 -aacA4-bla IMP-55 -cmlA5 (as a novel array was designated In1243), aacC1 and aadA1. Analysis of bla IMP gene revealed a new allele designated as bla . Gene transfer experiment by conjugation showed the 36 kb conjugative plasmid harbouring In1243. The clonal assessment by repetitive extragenic palindromic PCR demonstrated a high-degree relatedness among the strains, but strains harbouring In1243 displayed a different repetitive extragenic palindromic PCR profile. In this study, we found that a novel class 1 integron (In1243) that encoded a new bla IMP allele resided on a transferable plasmid in non-clonal strains of MDR-AB.

In Vitro Anti-Biofilm Activity of Curcumin Nanoparticles in Acinetobacter baumannii: A Culture-Based and Molecular Approach

“…The findings of the current study revealed that all isolates were susceptible to at least one antibiotic, but most isolates were resistant to most antibiotics. Similar to our data, Bassetti and Shakibaie studies showed that different isolates of A. baumannii were resistant to most antibiotics, and 70% of A. baumannii isolates were resistant to 3 or more antibiotics (9,21). According to various reports, the majority of A. baumannii isolated in Iran were resistant against the first-line drugs of Aminoglycosides, Ceftazidime, Fluoroquinolones, Imipenem, Meropenem (22,23).…”

Copy Number of an Integron-Encoded Antibiotic Resistance Locus Regulates a Virulence and Opacity Switch in Acinetobacter baumannii AB5075

“…A BLAST search with the first 300 nt of the aadB transcript yields hits to Ͼ100 A. baumannii genomes, with coverage ranging from 73% to 100%. Integrons encoding aminoglycoside modifying enzymes, including aadB, are also widely reported in the A. baumannii literature (45)(46)(47)(48)(49)(50). As the ϳ300-nt sRNA appears to be encoded mostly within the integron promoter region, it is possible that other integrons, even those not harboring aadB, still contain this transcript.…”

Multidrug-resistant Acinetobacter baumannii outbreaks: a global problem in healthcare settings

“…Transposons, such as Tn2006, Tn2007, and Tn2008, increase the spread of resistance genes and may present integrons, which were captured and express exogenous resistance genes 40,48,59 . Thus, integrons are composed of gene cassettes, and classes 1 and 2 are commonly found in A. baumannii clinical isolates [60][61][62] . As previously stated, insertion sequences act as strong promoters that increase the resistance levels of OXA carbapenemases in A. baumannii isolates 47,59,63 .…”