9th International Symposium on Antimicrobial Agents and Resistance (ISAAR), 2013, 02, 16-16

The investigation of biofilm formation and biofilm- forming related factors against methicillin-resistant Staphylococcus aureus bloodstream isolates

Jeong Ok Cha, Hwa Su Kim, Gyung Tae Chung, Yeong Seon Lee

Abstract

Background: The pathogenesis of S. aureus is attributed to the effects of many virulence determinants and biofilm formation in S. aureus appears due to multiple factors. In this study, we investigated the biofilm-forming ability and biofilm-forming related factors against MRSA bloodstream isolates.
Materials and methods: We collected 126 MRSA isolates from consecutive patients in ICU with bloodstream infection. The biofilm formation assay was performed by tissue culture plate assay and the biofilm-forming ability were divided into three categories in this study. All 126 strains were analyzed by PCR assay; nine staphyloccocal enterotoxin genes (sea to sej), three exfoliative toxin genes (eta, etb, etd), six adhesin genes (icaA, clfA, cna, atl, fnbA, fnbB), two surface-associated genes (cap5HK, cap8HK), and two staphylococcal regulators (sarA, arlRS) were investigated. We analyzed the gene expression level of adherent factors (hlyA, icaD), cell surface proteins (mapW, isdA), peptidoglycan hydrolase (atl, lytM), cellular process & transport (kdpA, vraF, lip, gntP) by RT-PCR. Additionally we evaluated the kdpA gene expression by daptomycin and tigecyline concentration.
Results: 86 out of 126 strains (68.3%) had biofilm-forming ability. No significant differences were found between adhesion genes, toxin genes, staphylococcal regulators and biofilm-forming ability (P >0.05). The fnbB in the biofilm forming isolates showed significantly more distribution than biofilm non-forming isolates (74.4% vs. 45.0%; P =0.001). In tranion level, the expression of only kdpA gene on biofilm-formers was higher than biofilm non-formers and tigecycline concentration didn’t make difference to the kdpA gene expression.
Conclusion : The fnbB gene showed high frequency in most of MRSA biofilm formers, and the kdpA gene showed relatively high expression in biofilm formers.

• 본 연구는 질병관리본부 연구개발과제(과제번호 2010-N44001-00) 연구비를 지원받아 수행되었습니다.
• This research was supported by a fund(code 2010-N44001-00) by Research of Korea Centers for Disease Control and Prevention.