<p>Association of the genes encoding Metallo-β-Lactamase with the presence of integrons among multidrug-resistant clinical isolates of <em>Acinetobacter baumannii</em></p>

Abstract

Background: Metallo-β-Lactamases (MBL) are usually encoded on the gene cassettes harboring integrons and disseminated easily among Acinetobacter baumannii isolates. This study was aimed to investigate the association of the genes encoding MBL with the presence of class 1 and 2 integrons among multidrug-resistant (MDR) A.baumannii isolates. Methodology: A total of 85 non-duplicated A.baumannii isolates were collected and evaluated for the amplification of bla OXA-51. The presence of genes encoding MBLs, including bla IMP , bla VIM , bla SIM , bla SPM , bla GIM , bla DIM and bla NDM , as well as intI 1 and intI 2 was evaluated by PCR. Also, the production of MBLs was screened phenotypically by the combination of EDTA and meropenem. Results: In this study, 77 out of 85 isolates were MDR. Also, 34 isolates had only intI 1 , 10 had only intI 2 and 15 had both intI 1 and intI 2 . The phenotypic detection of MBLs was found in 30 isolates, among which bla VIM was as the most common the gene encoding MBL followed by bla IMP , bla SPM and bla SIM . The gene cassettes analysis revealed that class 1 integron is often responsible for transferring the genes harboring MBLs. Conclusion: The production of MBLs among A. baumannii strains is one of the main mechanisms of resistance to carbapenems. Therefore, the development of inexpensive screening methods for the phenotypic detection of MBLs in clinical laboratories settings is essential. Also, our data revealed that the class 1 integron is often responsible for the dissemination of the MBL genes among A. baumannii isolates.

Molecular typing, biofilm production, and detection of carbapenemase genes in multidrug-resistant Acinetobacter baumannii isolated from different infection sites using ERIC-PCR in Hamadan, west of Iran

“…In Amin et al, study, 77 out of 85 MDR isolates were detected that only 2 isolates were resistant to Colistin which is inconsistent with a present study that all isolates were sensitive to Colistin. Also, blaVIM gene was the most common gene encoding MBL followed by blaIMP, blaSPM which is similar to our study [ 22 ]. In Ranjbar et al, a study in 2019, more than 93 % of A. baumannii samples were resistant to the studied antibiotics, but high sensitivity to Polymyxin (100 %) and Colistin (85.9 %) was observed, indicating the effect of this antibiotic on Acinetobacter [ 23 ].…”

Multidrug-Resistant Acinetobacter baumannii Genetic Characterization and Spread in Lithuania in 2014, 2016, and 2018

“…The most common MBL coding genes were bla VIM-1 (76.3% of all isolates) and bla IMP-1 (20.6%). These results are comparable to those of previous studies in Iran [ 33 ] and differ from the results observed in Poland, where A. baumannii strains harbouring bla VIM were very rare, detected only in two isolates [ 31 ] and no isolates had bla IMP .…”

Acinetobacter baumannii Antibiotic Resistance Mechanisms

“…Moreover, four types of MBLs have been described in A. baumannii, namely IMP, VIM, NDM, and SIM [34]. The detection of MBL-producing organisms with the help of phenotypic methods, such as double disc synergy test, MBL E-test, and combined disk test, has been challenging [35,36]; however, molecular methods and in particular next generation sequencing are going to shed some light on their detection [37][38][39]. Phenotypic methods are not sensitive enough and thus do not detect all MBL producing strains [36].…”