Silveira Alessandro Conrado de Oliveira, Cunha Gabriela Rosa da, Caierão Juliana, Cordova Caio Mauricio Mendes de, d'Azevedo Pedro Alves
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.
Laboratório de Cocos Gram Positivos, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil.
Braz J Infect Dis. 2015 Sep-Oct;19(5):466-72. doi: 10.1016/j.bjid.2015.06.013. Epub 2015 Aug 21.
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.
为确定巴西南部圣卡塔琳娜州两个城市实验室中12株对万古霉素呈现异质性耐药的金黄色葡萄球菌分离株的流行病学和分子特征。研究考虑了流行病学数据，包括分离城市、医疗机构和分离日期，以及相关临床标本。为进行分子特征分析，我们使用脉冲场凝胶电泳分析了葡萄球菌盒式染色体类型、erm基因的存在情况以及分离株的基因组多样性。这12株金黄色葡萄球菌分离株先前已通过群体分析谱-曲线下面积法确认为对万古霉素异质性耐药。关于基因变异性，检测到两个克隆：主要克隆（克隆A）由4株分离株组成，克隆B由2株分离株组成。对于克隆A，有2株分离株呈现相同的条带模式，且来自同一家医院，其分离间隔为57天。该克隆的其他分离株之间未显示出流行病学关联，因为它们是在不同医院分离的，且没有时间上的关系。另一个克隆未显示出可检测到的流行病学关系。根据脉冲场凝胶电泳结果，2009年至2012年在圣卡塔琳娜州分离出的对万古霉素异质性耐药菌株总体上具有异质性基因组模式，这与这些分离株之间几乎没有或没有流行病学关系这一事实相符。由于其表型不稳定的特性以及万古霉素治疗选择通常需要较长时间，克隆传播不像通过水平基因转移传播的其他耐药机制那样常见。
