Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum biofilm eradication\nconcentration (MBEC) and kill kinetics were established for vancomycin, rifampicin, trimethoprim, gentamicin, and ciprofloxacin\nagainst the biofilm forming bacteria Staphylococcus epidermidis (ATCC 35984), Staphylococcus aureus (ATCC 29213), Methicillin\nResistant Staphylococcus aureus (MRSA) (ATCC 43300), Pseudomonas aeruginosa (PAO1), and Escherichia coli (NCTC 8196).\nMICs and MBCs were determined via broth microdilution in 96-well plates. MBECs were studied using the Calgary Biofilm\nDevice. Values obtained were used to investigate the kill kinetics of conventional antimicrobials against a range of planktonic\nand biofilm microorganisms over a period of 24 hours. Planktonic kill kinetics were determined at 4xMIC and biofilm kill kinetics\nat relative MBECs. Susceptibility of microorganisms varied depending on antibiotic selected and phenotypic form of bacteria.\nGram-positive planktonic isolates were extremely susceptible to vancomycin (highest MBC: 7.81mg L?1: methicillin sensitive and\nresistant S. aureus) but noMBEC value was obtained against all biofilmpathogens tested (up to 1000 mg L?1). Both gentamicin and\nciprofloxacin displayed the broadest spectrum of activity with MIC and MBCs in the mg L?1 range against all planktonic isolates\ntested and MBEC values obtained against all but S. epidermidis (ATCC 35984) and MRSA (ATCC 43300).
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