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The Effects of Magnesium, Calcium, EDTA, and pH on the In Vitro Adhesion of Staphylococcus epidermidis to Plastic
Author(s) -
Dunne Wm. Michael,
Burd Eileen M.
Publication year - 1992
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1992.tb02106.x
Subject(s) - adhesion , staphylococcus epidermidis , magnesium , calcium , divalent , in vitro , strain (injury) , chemistry , microbiology and biotechnology , biochemistry , biology , nuclear chemistry , bacteria , staphylococcus aureus , anatomy , organic chemistry , genetics
The effects of increasing concentrations of magnesium (Mg 2+ ), calcium (Ca 2+ ) or EDTA, and pH on the adhesion of five slime‐positive strains of Staphylococcus epidermidis (Se+) to plastic were examined using an in vitro microwell assay. The addition of Mg 2+ (as either MgSO 4 or MgCl 2 ) to the bacterial suspension in concentrations as low as 16 μ M significantly enhanced the adhesion of all test strains to plastic ( P <0.001). Similarly, the addition of Ca 2+ (as CaCl 2 ) in concentrations exceeding 128 μM produced a significant increase in the adhesion of all test strains, but not to the extent observed with Mg 2+ . In contrast, the adhesion of all test strains to plastic was significantly reduced in the presence of EDTA at concentrations greater than 8 mM. However, EDTA in concentrations as low as 0.25 mM caused a significant decrease in the adhesion of two strains of Se+. The effect of pH was variable, but at a pH of 5.0 and 6.0, the adhesion of all test strains was significantly reduced compared to control values at a pH of 7.0. Two strains showed a significant increase in adhesion at a pH of 8.0. We also compared the effects of these variables on the adherence of a slime‐negative phase variant derived from a slime‐positive parent strain. With the exception of pH, the adhesion of both strains in response to increasing divalent cations or EDTA was similar. These data indicate that, in addition to hydrophobic interactions, ligand‐specific binding, and slime production, pH and divalent cations, especially Mg 2+ , are important determinants of the adhesion of S. epidermidis to plastic surfaces in vitro . This has possible implications in the pathogenesis of biomedical implant infections caused by these organisms.