导管相关血流感染金黄色葡萄球菌耐药性及其生物膜形成机制

Drug resistance and biofilm formation mechanisms of Staphylococcus aureus causing catheter-related and bloodstream infection

目的探究临床分离导管相关血流感染金黄色葡萄球菌(SA)菌株的耐药性、生物膜形成能力和生物膜相关基因之间的关系。方法收集临床分离血液及导管标本42株SA,其中导管13株、非导管29株;采用结晶紫染色法分析生物膜形成能力;聚合酶链反应(PCR)检测多糖编码基因和毒力基因。结果42株SA中耐甲氧西林SA(MRSA)16株、甲氧西林敏感SA(MSSA)26株且导管组MSSA比例更高;强产膜株5株、弱产膜株20株、不产膜株17株,且导管组产膜率高于非导管组;icaA、icaD、icaBC、agr、sarA的表达率分别为69%、42.9%、4.8%、42.9%、85.7%且在导管组的表达高于非导管组;而毒力基因tsst、sea、pvl、hlg只在非导管组表达;毒力基因clf B、fnbA、fnbB、hla、hlb、hlg-2和黏附素基因在导管组的表达高于非导管组,肠毒素基因和中毒性休克综合征毒素基因反之。结论同属菌株在导管与非导管、耐药性、产膜能力方面均有相似性。导管内植物容易导致生物膜形成扩散,相关基因随之高表达。生物膜在导管相关菌株中形成能力较强,且产膜菌株耐药率高。多糖编码基因和黏附素基因可能正向调控生物膜形成,与导管呈正相关;肠毒素基因和中毒性休克综合征毒素基因为负调控因素。

OBJECTIVE To explore the relationship between the drug resistance,biofilm-forming ability and bio-film-associated genes in clinical isolates of Staphylococcus aureus causing catheter-related and bloodstream infec-tion.METHODS A total of 42 strains of S.aureus were isolated from clinical blood specimens and catheter speci-mens,including 13 catheter strains and 29 non-catheter strains.The biofilm forming ability was analyzed by crys-tal violet staining method,the polysaccharide encoding genes and virulence genes were detected by means of poly-merase chain reaction(PCR).RESULTS Among the 42 strains of S.aureus,there were 16 strains of methicillin-resistant S.aureus(MRSA)and 26 strains of methicillin-sensitive S.aureus(MSSA);the percentage of MSSA strains was higher in the catheter group.There were 5 strains of strong film-producing isolates,20 strains of weak film-producing isolates and 17 strains of no-film-producing isolates,and the biofilm-producing rate of the catheter group was higher than that of the non-catheter group.The expression rates of ica A,icaD,icaBC,agr and sarA were 69%,42.9%,4.8%,42.9%and 85.7%,respectively;the expression rates of the catheter group were high-er than those of the non-catheter group.The virulence genes tsst,sea,pvl and hlg were only expressed in the non-catheter group.The expression rates of virulence genes clfB,fnbA,fnbB,hla,hlb and hlg-2 as well as ad-hesin genes were higher in the catheter group than in the non-catheter group,while the expression rates of entero-toxin genes and toxic shock syndrome virulence genes were higher in the non-catheter group than in the catheter group.CONCLUSION There is similarity in the catheter and non-catheter,drug resistance and biofilm-producing a-bility among the strains of same genus.The implants inside the catheter is more likely to result in the diffusion of biofilm forming,and the related genes are highly expressed.The biofilms show strong forming ability in the cathe-ter-related strains,and the drug resistance rates of the biofilm-producing strains are high.The polysaccharide en-coding genes and adhesin genes may positively regulate the formation of the biofilms and are positively associated with the catheters.The enterotoxin genes and toxic shock syndrome virulence genes are the negative regulation factors.