Background: The effectiveness of linezolid, vancomycin, ciprofloxacin and gentamicin for treating experimental Staphylococcus aureus catheter-related infection by the antibiotic-lock technique was assessed. Methods: Two methicillin-susceptible (MSSA) ATCC strains and two methicillin-resistant (MRSA) clinical strains were used. New Zealand white rabbits were surgically implanted with a silicone intravenous catheter. Infection was induced by filling and locking the catheter with 0.3 mL of broth culture containing S. aureus, with turbidity equivalent to that of a 0.5 McFarland standard. Eighteen hours later the antibiotic-lock technique was started and continued for 24 h. Treatment groups were: control without treatment; 2000 mg/L linezolid; 2000 mg/L vancomycin; 2000 mg/L ciprofloxacin; and 40000 mg/L gentamicin. Results: Linezolid and vancomycin showed equivalent activity, achieving significant reductions in log10 cfu recovered from catheter tips in one MSSA strain (>1.12) and one MRSA strain (>0.77) as compared with controls (P<0.05). Ciprofloxacin achieved significant log10 cfu reductions in MSSA strains relative to controls (>2.51, P<0.01). In one MSSA strain, ciprofloxacin showed a larger reduction in log10 cfu than linezolid or van- comycin (P<0.01). Gentamicin was the only antibiotic achieving negative catheter tip cultures (up to 87.5% in MSSA and up to 40% in MRSA, P<0.01), and showed the greatest log10 cfu reduction compared with controls (>4.25 in MSSA and >2.93 in MRSA, P<0.05) and significant differences relative to the remaining treatment groups (P<0.05 in both MSSA and MRSA). Conclusions: Gentamicin showed the highest activity against both MSSA and MRSA biofilms. © The Author 2010. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.
|Journal||Journal of Antimicrobial Chemotherapy|
|Publication status||Published - 18 Jan 2010|