Ferreira Rosana Barreto Rocha, Nunes Ana Paula Ferreira, Kokis Valéria Miguelote, Krepsky Natascha, Fonseca Leila de Souza, Bastos Maria do Carmo de Freire, Giambiagi-deMarval Márcia, Santos Kátia Regina Netto dos
Institute of Microbiology, Federal University of Rio de Janeiro, Brazil.
Diagn Microbiol Infect Dis. 2002 Mar;42(3):205-12. doi: 10.1016/s0732-8893(01)00345-5.
Coagulase-negative Staphylococcus spp. (CNS) has been associated with primary bloodstream infections and implanted medical devices. Its importance is increasing due to the acquisition of resistance to oxacillin (Oxa) and, recently, resistance to mupirocin (Mup). Mupirocin, a topical antimicrobial, has been used in the prevention of staphylococci catheter colonization. Susceptibility to Oxa and Mup was analyzed by different testing methods in clinical CNS isolates. Among 112 CNS strains, 69 (61.6%) were Oxa(R) by the disk diffusion (DD) method and 72 (64.2%) grew on the oxacillin agar screen plate. S. epidermidis and S. haemolyticus presented high rates of oxacillin resistance, 75.4% and 96.1%, respectively. Twenty four (21.4%) strains were Mup(R) by the DD test and 21 of them (87.5%) were identified as S. epidermidis. The detection of the mecA and ileS-2 genes, determined by multiplex-PCR, showed that 72 (64.2%) CNS strains possessed the mecA gene, while 16 (14.3%) possessed the ileS-2 gene. Fifteen of these strains presented the two resistance genes simultaneously. The isolates containing the ileS-2 gene presented a minimum inhibitory concentration (MIC) >1024 microg/mL in the E-test, while low-level mupirocin resistance (MICs of 12-16 microg/mL) was observed in those strains without ileS-2. The resistances to high and low levels of mupirocin could not be distinguished when the DD test was used. The analysis of the Mup(R) S. epidermidis strains by Pulsed Field Gel Electrophoresis showed that 17 (80.9%) strains belonged to one of two patterns (A and B), which have been shown to be prevalent in hospitals in Rio de Janeiro. This report showed that the PCR method for detection of oxacillin and mupirocin resistance in CNS is necessary to determine accurate rates of these resistance, and will can help in the staphylococcal infections prevention and control policies in Brazil.
凝固酶阴性葡萄球菌（CNS）与原发性血流感染及植入式医疗器械有关。由于对苯唑西林（Oxa）耐药性的出现，以及最近对莫匹罗星（Mup）耐药性的出现，其重要性日益增加。莫匹罗星是一种外用抗菌药物，已被用于预防葡萄球菌导管定植。采用不同检测方法分析了临床CNS分离株对Oxa和Mup的敏感性。在112株CNS菌株中，采用纸片扩散法（DD）检测，69株（61.6%）对Oxa耐药，72株（64.2%）在苯唑西林琼脂筛选平板上生长。表皮葡萄球菌和溶血葡萄球菌对苯唑西林的耐药率较高，分别为75.4%和96.1%。采用DD试验，24株（21.4%）菌株对Mup耐药，其中21株（87.5%）为表皮葡萄球菌。通过多重PCR检测mecA和ileS-2基因，结果显示72株（64.2%）CNS菌株携带mecA基因，16株（14.3%）携带ileS-2基因。其中15株同时携带这两种耐药基因。携带ileS-2基因的分离株在E试验中的最低抑菌浓度（MIC）>1024μg/mL，而未携带ileS-2基因的菌株对莫匹罗星表现出低水平耐药（MIC为12 - 16μg/mL）。使用DD试验时，无法区分对高水平和低水平莫匹罗星的耐药性。通过脉冲场凝胶电泳分析对Mup耐药的表皮葡萄球菌菌株，结果显示17株（80.9%）菌株属于两种模式（A和B）之一，这两种模式在里约热内卢的医院中较为普遍。本报告表明，采用PCR方法检测CNS对苯唑西林和莫匹罗星的耐药性对于确定这些耐药性的准确发生率是必要的，这将有助于巴西制定葡萄球菌感染的预防和控制策略。
