Comparative activity of glycopeptide antibiotics against coagulase-negative staphylococci embedded in fibrin clots.
The susceptibilities of 16 strains of coagulase-negative staphylococci to vancomycin and teicoplanin were determined by three microdilution methods run in parallel; (i) a reference method in which the medium was Iso-Sensitest broth, (ii) a method in which the organisms were suspended in plasma and (iii) one in which the bacteria were incorporated into a fibrin clot. In comparison with the reference method there was a less than two-fold change in the geometric mean MICs of both antibiotics in plasma, while in clot the increase was 12-fold for vancomycin and 28-fold for teicoplanin. MBCs showed a similar trend although the increase was greater for teicoplanin. These results suggest that protein binding may have a much greater impact on antimicrobial activity when the mobility of the protein is reduced within a clot.
Cunningham
R
R
Department of Medical Microbiology, Royal Liverpool University Hospital, UK.
Cheesbrough
J
J
D001777:Blood Coagulation; D003030:Coagulase / Q000032:analysis; D005337:Fibrin; D006801:Humans; D008826:Microbial Sensitivity Tests; D013210:Staphylococcus / Q000187:drug effects* / Q000201:enzymology; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000201:enzymology; D017334:Teicoplanin / Q000494:pharmacology*; D014640:Vancomycin / Q000494:pharmacology*
D003030:Coagulase; D017334:Teicoplanin; D014640:Vancomycin; D005337:Fibrin