Abstract
BackgroundCarbapenems resistance in Enterobacter spp. has increased in the last decade, few studies, however, described the mechanisms of resistance in this bacterium. This study evaluated clonality and mechanisms of carbapenems resistance in clinical isolates of Enterobacter spp. identified in three hospitals in Brazil (Hospital A, B and C) over 7-year.MethodsAntibiotics sensitivity, pulsed-field gel electrophoresis (PFGE), PCR for carbapenemase and efflux pump genes were performed for all carbapenems-resistant isolates. Outer-membrane protein (OMP) was evaluated based on PFGE profile.ResultsA total of 130 isolates of Enterobacter spp were analyzed, 44/105 (41, 9%) E. aerogenes and 8/25 (32,0%) E. cloacae were resistant to carbapenems. All isolates were susceptible to fosfomycin, polymyxin B and tigecycline. KPC was present in 88.6% of E. aerogenes and in all E. cloacae resistant to carbapenems. The carbapenems-resistant E. aerogenes identified in hospital A belonged to six clones, however, a predominant clone was identified in this hospital over the study period. There is a predominant clone in Hospital B and Hospital C as well. The mechanisms of resistance to carbapenems differ among subtypes. Most of the isolates co-harbored blaKPC, blaTEM and /or blaCTX associated with decreased or lost of 35–36KDa and or 39 KDa OMP. The efflux pump AcrAB-TolC gene was only identified in carbapenems-resistant E. cloacae.ConclusionsThere was a predominant clone in each hospital suggesting that cross-transmission of carbapenems-resistant Enterobacter spp. was frequent. The isolates presented multiple mechanisms of resistance to carbapenems including OMP alteration.
Highlights
Carbapenems resistance in Enterobacter spp. has increased in the last decade, few studies, described the mechanisms of resistance in this bacterium
Studies have shown the presence of carbapenameses in association with Extended-spectrum β-lactamases (ESBL) in isolates of E. aerogenes and E. cloacae resistant to carbapenems [2, 3]
A total of 44/105 (41, 9%) E. aerogenes and 8/25 (32, 0%) E. cloacae were resistant to carbapenems
Summary
Carbapenems resistance in Enterobacter spp. has increased in the last decade, few studies, described the mechanisms of resistance in this bacterium. This study evaluated clonality and mechanisms of carbapenems resistance in clinical isolates of Enterobacter spp. identified in three hospitals in Brazil (Hospital A, B and C) over 7-year. Carbapenemase is the most frequent mechanism of carbapenems resistance reported in Enterobacter spp [2, 3]. Studies have shown the presence of carbapenameses (blaKPC, blaIMP, blaVIM and blaNDM) in association with ESBL (blaTEM, blaSHV and blaCTXM) in isolates of E. aerogenes and E. cloacae resistant to carbapenems [2, 3]. Few studies demonstrated the importance of OMPs and efflux pump on carbapenems resistance in Enterobacter spp [1, 2, 7]
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