| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
The purpose of this study was to investigate biofilm formation among gram-positive bacteria (methicillin-resistant Staphylococcus aureus [MRSA] and Enterococcus faecalis) isolated from patients with urinary tract infection (UTI) and to assess the relationship between biofilm-forming capacities and virulence determinants/clinical background. Over a 12-year period from 1990 through 2001 and from 1991 through 2002, a total of 109 MRSA and 352 E.faecalis isolates, respectively, were collected from patients (one isolate per patient) with UTI at the urology ward of Okayama University Hospital. The associated medical records of patients were retrospectively reviewed. The presence of 12 and 5 genes associated with virulence, adherence, aggregation, biofilm formation and antibiotic resistance in MRSA and E.faecalis isolates, respectively, was detected by using PCR assays. We used in vitro microtiter plate assay to quantify biofilm formation. Enhanced biofilm formation was confirmed in hla, hlb, and fnbA-positive MRSA isolates, both individually and in combination. The biofilm forming capacities of MRSA isolates from catheter-related cases were significantly greater than those from catheter-unrelated cases. The percentage of hla, hlb, and fnbA-positive isolates was higher among MRSA isolates from catheter-related cases than those from catheter-unrelated cases. On the other hand, E.faecalis isolates with both asa1 and/or esp genes formed biofilms at significantly higher rates than those with neither gene. The genes encoding asa1, cylA and aac(6')/aph(2") were transferable and appeared to have accumulated in E.faecalis isolates possessing asa1 and/or esp genes. These isolates were found from both catheter-related or -unrelated UTI. In conclusion : 1) MRSA colonization and infection of the urinary tract may be promoted by hla, hlb, and fnbA gene products. 2)E.faecalis isolates that have accumulated virulence genes are apt to form persistent biofilms in the urinary tract.
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