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Abstract Background Productions of metallo-β-lactamases enzymes are the most common mechanism of antibiotic resistance to all beta-lactam classes (except monobactams) in Acinetobacter baumannii. MBLs are usually associated with gene cassettes of integrons and spread easily among bacteria. The current study was performed to detect the genes encoding MBLs and integron structures in A. baumannii isolates from burn patients. Methods This study was performed on 106 non-duplicate A. baumannii isolates from burn patients referred to Shahid Motahari Hospital in Tehran. Antibiotic susceptibility of A. baumannii isolates was performed using disk diffusion and broth microdilution method in accordance with the CLSI guidelines. The presence of class 1 integron and associated gene cassettes as well as MBLs-encoding genes including bla VIM, and bla IMP were investigated using PCR and sequencing techniques. Results In this cross-sectional study all (100%) of the A. baumannii isolates examined were multidrug resistant. All isolates were sensitive to colistin and simultaneously all were resistant to imipenem. PCR assays showed the presence of bla VIM and bla IMP genes in 102 (96.2%) and 62 (58.5%) isolates of A. baumannii respectively. In addition, 62 (58.5%) of the A. baumannii isolates carried integron class 1, of which 49 (79.0%) were identified with at least one gene cassette. Three types of integron class 1 gene cassettes were identified including: arr2, cmlA5, qacE1 (2300 bp); arr-2, ereC, aadA1, cmlA7, qacE1 (4800 bp); and aac(3)-Ic, cmlA5 (2250 bp). Conclusion A high prevalence of MBLs genes, especially bla VIM, was identified in the studied MDR A. baumannii isolates. In addition, most of the strains carried class 1 integrons. Furthermore, the gene cassettes arrays of integrons including cmlA5 and cmlA7 were detected, for the first time, in A. baumannii strains in Iran.

Background: Productions of metallo-β-lactamases enzymes are the most common mechanism of antibiotic resistance to all beta-lactam classes (except monobactams) in Acinetobacter baumannii. MBLs are usually associated with gene cassettes of integrons and spread easily among bacteria. The current study was performed to detect the genes encoding MBLs and integron structures in A. baumannii isolates from burn patients.Methods: This study was performed on 106 non-duplicate A. baumannii isolates from burn patients referred to Shahid Motahari Hospital in Tehran. Antibiotic susceptibility of A. baumannii isolates was performed using disk diffusion and broth microdilution method in accordance with the CLSI guidelines. The presence of class 1 integron and associated gene cassettes as well as MBLs-encoding genes including blaVIM, and blaIMP were investigated using PCR and sequencing techniques.Results: In this cross-sectional study all (100%) of the A. baumannii isolates examined were multidrug resistant. All isolates were sensitive to colistin and simultaneously all were resistant to imipenem. PCR assays showed the presence of blaVIM and blaIMP genes in 102 (96.2%) and 62 (58.5%) isolates of A. baumannii respectively. In addition, 62 (58.5%) of the A. baumannii isolates carried integron class 1, of which 49 (79.0%) were identified with at least one gene cassette. Three types of integron class 1 gene cassettes were identified including: arr2, cmlA5, qacE1 (2300 bp); arr-2, ereC, aadA1, cmlA7, qacE1 (4800 bp); and aac(3)-Ic, cmlA5 (2250 bp).Conclusion: A high prevalence of MBLs genes, especially blaVIM, was identified in the studied MDR A. baumannii isolates. In addition, most of the strains carried class 1 integrons. Furthermore, the gene cassettes arrays of integrons including cmlA5 and cmlA7 were detected, for the first time, in A. baumannii strains in Iran. [ABSTRACT FROM AUTHOR]

Background Multidrug-resistant Pseudomonas aeruginosa is a serious challenge for antimicrobial therapy of nosocomial infections, as it possesses several mechanisms of antimicrobial resistance. In Central Greece, a sudden increase of infections caused by carbapenem-resistant P. aeruginosa was observed during 2011, indicating the need for further analysis. Methods Five-hundred and sixty-eight P. aeruginosa isolates were collected consecutively during an 8-month period in 2011 from inpatients treated in three hospitals in the Thessaly region (1,000,000 habitants) of Greece. Carbapenem-resistant P. aeruginosa (n = 284) were characterized by antimicrobial susceptibility testing and β-lactamase content, and the genetic relatedness of carbapenemase-producing isolates was assessed by BOX-PCR, multilocus sequence typing, and eBURST analysis. Mapping of the class I integrons of Verona integronencoded metallo-β-lactamase (VIM)-carrying isolates was also performed, and clinical data of the VIM producers were reviewed. Results Eighty (14.1%) out of the 568 P. aeruginosa isolates recovered from clinical specimens were VIM producers. Multilocus sequence typing revealed high prevalence of the international clones ST111 and ST235 among blaVIM-2- and blaVIM-4-positive isolates, respectively. blaVIM-17 was identified in an isolate of a novel sequence type (ST1457). blaVIM gene cassettes were carried by five distinct class I integrons, including two novel ones. Conclusions Since the first report of VIM-producing P. aeruginosa in 2000, this microorganism still remains among the most prevalent multidrug resistant pathogens in Greece. The spread of VIM-producers belonging to the most common international clones (ST111 and ST235), the spread of integrons of divergent structures, and the emergence of novel integrons underscore their ongoing evolution. [ABSTRACT FROM AUTHOR]