García Ayerim, Martínez Carlos, Juárez Rosa Isela, Téllez René, Paredes Marco Antonio, Herrera María Del Rocío, Giono Silvia
Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México.
Biomedica. 2019 Sep 1;39(3):513-523. doi: 10.7705/biomedica.4131.
Introduction: Infections associated with health care caused by S. aureus and coagulase-negative Staphylococci multi-resistant to antibiotics cause a high epidemiological impact due to their high morbidity and mortality. Biofilm formation, which has been associated with antimicrobial resistance, can also occur. Objectives: To determine methicillin resistance and to quantify the biofilm production to establish if there is a relationship in clinical isolates of S. aureus and coagulase-negative Staphylococci. Material and methods: A total of 11 strains of S. aureus and 12 of coagulase-negative Staphylococci were studied. Methicillin resistance was determined with cefoxitin discs and the Clinical Laboratory Standards Institute (CSLI), 2018 reference values. Biofilm production was quantified by the crystal violet method. The mecA and icaADBC genes were identified by PCR. A bivariate analysis was performed with chi-square (c2) and Cramér’s V statistical tests, using SPSS™, version 20.0 software. Results: Nine S. aureus strains were methicillin-resistant and two were sensitive. Eight coagulase-negative Staphylococci strains were resistant and four were sensitive. The mecA genotype was found in eight of the nine S. aureus resistant strains and six of eight resistant coagulase-negative Staphylococci. All strains formed biofilms. Ten strains of S. aureus and 11 of coagulase-negative Staphylococci presented the icaADCB genotype. No association was found between methicillin-resistance and biofilm formation. Conclusions: Cefoxitin is enough to define the resistance phenotype and is associated with the mecA genotype. All strains formed biofilms and were related to the presence of the icaADCB operon. Biofilm formation and methicillin resistance were independent features in both groups of strains.
由对多种抗生素耐药的金黄色葡萄球菌和凝固酶阴性葡萄球菌引起的医疗保健相关感染，因其高发病率和死亡率而具有很高的流行病学影响。与抗菌药物耐药性相关的生物膜形成也可能发生。目的：确定耐甲氧西林情况并量化生物膜产生，以确定金黄色葡萄球菌和凝固酶阴性葡萄球菌的临床分离株之间是否存在关联。材料和方法：共研究了11株金黄色葡萄球菌和12株凝固酶阴性葡萄球菌。使用头孢西丁纸片和临床实验室标准协会（CSLI）2018年参考值确定耐甲氧西林情况。通过结晶紫法量化生物膜产生。通过PCR鉴定mecA和icaADBC基因。使用SPSS™20.0版软件，通过卡方（c2）和克莱默V统计检验进行双变量分析。结果：9株金黄色葡萄球菌菌株耐甲氧西林，2株敏感。8株凝固酶阴性葡萄球菌菌株耐药，4株敏感。在9株耐甲氧西林的金黄色葡萄球菌菌株中的8株以及8株耐药的凝固酶阴性葡萄球菌中的6株中发现了mecA基因型。所有菌株均形成生物膜。10株金黄色葡萄球菌和11株凝固酶阴性葡萄球菌呈现icaADCB基因型。未发现耐甲氧西林与生物膜形成之间存在关联。结论：头孢西丁足以定义耐药表型，且与mecA基因型相关。所有菌株均形成生物膜，且与icaADCB操纵子的存在有关。生物膜形成和耐甲氧西林是两组菌株的独立特征。
