Adherence of slime-producing strains of Staphylococcus epidermidis to smooth surfaces

Abstract

Slime production is not a generally recognized feature of Staphylococcus epidermidis. In a recent outbreak of S. epidermidis intravascular catheterassociated sepsis, we noted that 63% of clinically implicated strains grew as a slimy film coating the culture tube walls when propagated in tryptic soy broth. Only 37% of randomly collected blood culture contaminants and skin isolates demonstrated a similar phenomenon (p < 0.05). Transmission electron micrographs of these coating bacteria showed them to be encased in an extracellular matrix that stained with alcian blue. Slime production was most evident in autoclaved media containing Casamino Acids and glucose supplementation (0.25% wt/vol). There were strain and media preparation variability of slime production in the presence of other carbohydrates. Some strains were not able to produce slime under any of the tested conditions. The production or nonproduction of slime did not influence growth rate. When grown in vitro, slime producers accumulated on the surface of intravascular catheters as macrocolonies, whereas non-slime, producers did not. Transmission and scanning electron micrographs showed slime producers to be encased in an adhesive layer on the catheter surface, whereas nonproducers were not encased. These results suggest that slime-mediated adherence may be a critical factor in the pathogenesis of S. epidermidis infections of medical devices.

Biomaterial-associated staphylococcal peritoneal infections in a neutropaenic mouse model

“…The strongly slime producing strain RP12 and moderately slime producing S. epidermidis 3380 adhered at the highest numbers ( Fig. 2A,B) although it should be noted that the strains were grown under conditions which do not promote slime production [25]. Hence, it is unlikely that the adhesion is mediated by the extracellular slime.…”

“…S. epidermidis 3380, S haemolyticus E2498, S. lugdunensis 2342, and S. schleiferi 667-88 were isolated from clinical infections [7,23,24]. S. epidermidis RP12, a slimeproducing strain, was kindly supplied by Dr. G. Christensen (Columbia, MO, USA) [25]. Strains were grown in Brain-Heart Infusion Broth (BHIB, Difco, Detroit, MI, USA) or on agar (Lab M, Salford, UK) with 4% horse erythrocytes for 18 h at 37°C unless otherway stated.…”

“…The tube adherence test was used to characterize strains as slime-producers or non-slime producers in a semi-quantitative way: strong, moderate, weak or negative producers [25]. Slime production was also assessed by light microscopy of smears of bacteria stained with 1% safranin (Sigma Chemical Co., St. Louis, MO, USA).…”

Pathogenesis of catheter-related infections: lessons for new designs

“…During the course of polymer colonization, S. epidermidis and other staphylococci produce large amounts of extracellular slime in which cells are embedded and covered. This slimy substance protects bacteria against host defense mechanisms and antimicrobial agents [10]. Many other biological activities have been attributed to slime [11].…”

“…Many other biological activities have been attributed to slime [11]. Slime is an extensive and diffuse polyanionic matrix that surrounds the cells [10]. The composition of slime is controversial.…”