The effects of adherence to silicone surfaces on antibiotic susceptibility in Staphylococcus aureus.
Sensitivity of Staphylococcus aureus to the antibiotics tetracycline, benzylpenicillin and vancomycin was found to decrease by 2-10 fold when cells were grown adherent to silicone catheter surfaces. Sensitivity to rifampicin and fusidic acid was not significantly altered in adherent cells. Susceptibility further decreased with increased adherence time prior to antibiotic challenge. The resistance observed was not genotypic, or due to the presence of a specialized subpopulation of bacteria, as it disappeared when the bacteria were removed from the catheter, subcultured and retested. Also, adherent bacteria were found to grow more slowly than bacteria growing planktonically. It is concluded that the decrease in antibiotic susceptibility of adherent bacteria is a function of the physiological status of the individual cells rather than a function of biofilm formation or slime production. The decrease in growth rate of the adherent bacteria is a result of the adherence process rather than a result of nutrient depletion. The decrease in growth rate is implicated, but is not the sole factor, in the decreased antibiotic susceptibility of adherent bacteria.
Williams
Ian
I
Microbiology Group, School of Pure and Applied Biology, University of Wales College of Cardiff, PO Box 915, Cardiff CF1 3TL, UK.
Venables
W Alfred
WA
Microbiology Group, School of Pure and Applied Biology, University of Wales College of Cardiff, PO Box 915, Cardiff CF1 3TL, UK.
Lloyd
David
D
Microbiology Group, School of Pure and Applied Biology, University of Wales College of Cardiff, PO Box 915, Cardiff CF1 3TL, UK.
Paul
Frank
F
SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, 3rd Avenue, Harlow, CM19 5AW, UK.
Critchley
Ian
I
SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, 3rd Avenue, Harlow, CM19 5AW, UK.
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000502:physiology*; D004352:Drug Resistance, Microbial / Q000502:physiology*; D008826:Microbial Sensitivity Tests; D010400:Penicillin G / Q000494:pharmacology; D010406:Penicillins / Q000494:pharmacology; D012828:Silicones; D013211:Staphylococcus aureus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013752:Tetracycline / Q000494:pharmacology; D014640:Vancomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D010406:Penicillins; D012828:Silicones; D014640:Vancomycin; D013752:Tetracycline; D010400:Penicillin G