title: Molecular epidemiology of heteroresistant vancomycin-intermediate Staphylococcus aureus in Brazil.
abstract: To determine the epidemiological and molecular characteristics of 12 Staphylococcus aureus isolates presenting heteroresistance to vancomycin in laboratories of two cities in Santa Catarina, southern Brazil. Epidemiological data, including the city of isolation, health institution, and date of isolation were considered, as well as the associated clinical specimen. For molecular characterization, we analyzed the staphylococcal cassette chromosome types, the erm gene presence, and the genomic diversity of isolates using pulsed-field gel electrophoresis. The 12 isolates of S. aureus were previously confirmed as heteroresistance to vancomycin using the population analysis profile-area under curve. Regarding genetic variability, two clones were detected: the main one (clone A) composed of four isolates and the clones B, with two isolates. For clone A, two isolates presented identical band patterns and were related to the same hospital, with an interval of 57 days between their isolation. The other isolates of this clone showed no epidemiological link between them because they were isolated in different hospitals and had no temporal relationship. The other clone showed no detectable epidemiological relationship. The heteroresistance to vancomycin recovered in Santa Catarina State from 2009 to 2012 had, in general, heterogeneous genomic patterns based on pulsed-field gel electrophoresis results, which is in accordance with the fact that these isolates had little or no epidemiological relationship among them. Due to the characteristic phenotypic instability and often prolonged vancomycin therapy for selection, clonal spread is not as common as for other resistance mechanisms disseminated through horizontal gene transfer.
authors: Laboratório de Cocos Gram Positivos, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil; Departamento de Ciências Farmacêuticas, Fundação Universidade Regional de Blumenau, Blumenau, SC, Brazil. Electronic address: alessandrocosilveira@gmail.com.
authors: Alessandro Conrado de Oliveira
authors: AC
authors: Silveira
authors: Laboratório de Cocos Gram Positivos, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil.
authors: Gabriela Rosa da
authors: GR
authors: Cunha
authors: Laboratório de Cocos Gram Positivos, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil.
authors: Juliana
authors: J
authors: Caierão
authors: Departamento de Ciências Farmacêuticas, Fundação Universidade Regional de Blumenau, Blumenau, SC, Brazil.
authors: Caio Mauricio Mendes de
authors: CM
authors: Cordova
authors: Laboratório de Cocos Gram Positivos, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil.
authors: Pedro Alves
authors: PA
authors: d'Azevedo
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D001938:Brazil / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D004269:DNA, Bacterial / Q000032:analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D060885:Multiplex Polymerase Chain Reaction; D010641:Phenotype; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D014640:Vancomycin
keywords: Antimicrobial resistance; MRSA; Small colony variants