Emergência de enterococcus sp. resistentes à vancomicina na cidade do Natal-RN

Abstract

Vancomycin-resistant enterococci (VRE) clonal spread and outbreaks cause major problems in health institutions around the world. In Brazil, several available studies describe VRE outbreaks or clonal dissemination scenarios mostly involving Enterococcus faecalis and Enterococcus faecium. We aimed to characterize, at molecular level, the VRE recovered from patient in different hospitals of Natal. Sixtytwo VRE isolates from surveillance culture and others clinical specimens were collected from 51 patients of 7 hospitals, for two years (2015-2016). Identification at the species level by specific primers sodA and ddl was performed by Polymerase Chain Reation (PCR). Susceptibility to antibiotics were assessed by disk-difusion, MIC test strip (vancomycin) and agar dilution (teicoplanin) (EUCAST, 2018; CLSI, 2018). Search of vancomycin resistance (vanA/vanB) and putative virulence (cylA/asa1/gelE/esp) genes was performed by PCR. Clonal relationship was evaluated by Pulse-filed Gel Electrophoresis (PFGE), and representative strains from main PFGE types also by Multilocus Sequence Typing (MLST). Sixty-one isolates were identified as Enterococcus faecalis and only one as Enterococcus faecium. Resistance to vancomycin, teicoplanin ciprofloxacin, tetracycline and erythromycin were observed in all isolates, and 98,4% were to teicoplanin. Vancomycin and teicoplanin MICs were 16 to ≥ 256 µg/ml and 4 to 64µg/L, respectively. In addition, 88,7% (n=55) and 40,3% (n=25) isolates were also resistant to gentamicin or streptomycin, respectively. None was resistant to linezolid or chloramphenicol. Just the E. faecium was ampicillin resistant. Operon vanA was observed in all isolates. Occurrence of E. faecalis virulence factors included gelE (98,4%; n=60), asa1 (100%; n=61), cylA (16,4%; n=10) and esp (9,8%; n=6). Two PFGE types were identified; type A (50,8%; n=31) and type B (49,18%; n=30). The MLSTs of the representative isolates were typed as ST525 and ST6. Both clones were co-circulating during the period of the study. This study highlights a high rate of patient colonization with vancomycin-resistant E. faecalis with vanA and a silent spread of two clones previously associated with human infections in Brazil (ST525) or worldwide (ST6). Although their transmission routes of this ERV in Natal remain to clarify, the interhospital spread during a long period of time highlight the need of preventions measures to contain a potential ERV infection epidemic scenario.