BIOFILM FORMATION OF STAPHYLOCOCCUS-AUREUS STRAINS ISOLATED FROM IMPETIGO AND FURUNCLE - ROLE OF FIBRINOGEN AND FIBRIN

The formation of membranous structure (thickness from the plastic tiss ue-culture coverslip (hematoxylin-eosin) > 1 mm; periodic acid-Schiff- positive) was more prominent with Staphylococcus aureus (S. aureus) st rains isolated from impetigo (coagulase types I . V origin) than with S. aureus strains isolated from furuncle (coagulase type IV origin) (P < 0.05) in the plastic tissue-culture coverslip in human plasma after 72 h. Attachment of S. aureus cells to a plastic tissue-culture cover slip was more marked in 0.3% fibrinogen/tryptic soy broth (TSB) than i n plasma (P < 0.05). The formation of the membranous structure was obs erved on the plastic tissue-culture coverslip with 0.3% fibrinogen/hum an serum but not with 0.3% fibrinogen + 5% glucose/TSB. Electron micro scopy revealed abundant fibrin around S. aureus cells at 4 h and Ruthe nium red-positive materials increased at 24 and 72 h in plasma, Staphy lococcus aureus cell attachment to the plastic tissue-culture coversli p in plasma decreased by addition of levofloxacin (LVFX) at 1/2 minimu m inhibitory concentration (MIC) and clarithromycin (CAM) at 1/4 MIC. Polysaccharide production of S. aureus cells on the plastic tissue-cul ture coverslip in plasma decreased with the addition of CAM at 1/4 MIC . Fibrinogen is closely related to initiation of infection but biofilm formation requires the conversion of fibrinogen to fibrin. Thus, atta chment of S. aureus cells to the plastic tissue-culture coverslip, con version of fibrinogen to fibrin by coagulase-prothrombin complex, and production of abundant glycocalyx by S. aureus cells are at least requ ired for the production of biofilm in staphylococcal skin infection. ( C) 1997 Elsevier Science Ireland Ltd.