ObjectivesEscherichia coli is regarded as the most important etiological agent of urinary tract infections. Fluoroquinolones are routinely used in the treatment of these infections; however, in recent years, a growing rate of resistance to these drugs has been reported globally. The aims of this study were to detect plasmid-mediated qnrA, qnrB, and qnrS genes among the quinolone-nonsusceptible E. coli isolates and to investigate their clonal relatedness in Qazvin and Zanjan Provinces, Iran.MethodsA total of 200 clinical isolates of E. coli were collected from hospitalized patients. The bacterial isolates were identified through standard laboratory protocols and further confirmed using API 20E test strips. Antimicrobial susceptibility was determined by the standard disk diffusion method. Polymerase chain reaction (PCR) and sequencing were used for detecting qnrA, qnrB, and qnrS genes and the clonal relatedness of qnr-positive isolates was evaluated by enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) method.ResultsIn total, 136 (68%) isolates were nonsusceptible to quinolone compounds, among which 45 (33.1%) and 71 (52.2%) isolates showed high- and low-level quinolone resistance, respectively. Of the 136 isolates, four (2.9%) isolates were positive for the qnrS1 gene. The results from ERIC-PCR revealed that two (50%) cases of qnr-positive isolates were related genetically.ConclusionOur study results were indicative of the presence of low frequency of qnr genes among the clinical isolates of E. coli in Qazvin and Zanjan Provinces, which emphasizes the need for establishing tactful policies associated with infection-control measures in our hospital settings.

Carbapenems have been considered as last line antibiotics for treatment of multidrug-resistant (MDR) Acinetobacter baumannii but carbapenem resistant A. baumannii has been increased during the last decade in many parts of the world. OXA-type β-lactamase enzymes are the most common cause of carbapenem resistance in A. baumannii and presence of ISAba1 in upstream of these genes may increase the expression of these OXA genes. The aim of this study was to determine, for the first time, the antibiotic resistance pattern and prevalence of OXA type β-lactamases among nosocomial A. baumannii isolates from northwest of Iran. A total of 100 A. baumannii isolates were recovered from hospitalized patients in a university hospital in northwest of Iran. Sixty-two percent of isolates were resistant to imipenem. All isolates carried bla(OXA-51)-like gene. Among imipenem resistant isolates, 88.7% carried bla(OXA-23)-like, 1.6% carried bla(OXA-40)-like, and 3.2% had bla(OXA-58)-like resistance genes. Ninety percent of isolates contained ISAba1 element and in 74.2% of imipenem resistant isolates, ISAba1 was located in upstream of bla(OXA-23)-like. The results of this study demonstrated high prevalence of OXA-type carbapenemase among MDR A. bumanii in the Northwest of Iran.

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Integrons are associated with a variety of gene cassettes, which confer resistance to multiple classes of antibacterial drugs. In this study we tested the frequency of class 1 and 2 integrons among multidrug-resistant Acinetobacter baumannii (MDRAB) clinical isolates. One hundred clinical isolates of A. baumannii were screened for carriage of class 1 and 2 integrons by PCR method. Results showed that seventy four (92.5%) of 80 MDRAB carried class 1 integron. Integron-positive isolates were statistically more resistant to aminoglycoside, quinolone and beta-lactam compounds except for cefepime. This is the first report of class 1 integrons in MDRAB isolates in northwest Iran.

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