Back

In vitro activities of gatifloxacin, moxifloxacin and linezolid versus bloodstream isolates of methicillin-sensitive and methicillin-resistant Staphylococcus aureus at a Canadian tertiary-care centre

Abstract number: 1134_03_213

Karnauchow T., Binns M., Wobeser W., Suh K., Evans G.

Objectives:  

Staphylococcusaureusbacteraemia is a significant burden to patients and institutions in terms of morbidity and financial cost. Treatment of S. aureus bacteremias generally requires 2–4 weeks of IV antibiotics. Newer oral agents with anti-staphylococcal activity may offer alternative approaches to treatment and enhance patient quality of life by shortening the duration of IV therapy. As a first step toward investigating this possibility, we evaluated the in vitro activities of gatifloxacin, moxifloxacin and linezolid versus bloodstream isolates of methicillin-sensitive (MSSA) and methicillin-resistant S.aureus (MRSA) recovered from patients at Kingston General Hospital (KGH).

Methods:  

MICs for gatifloxacin, linezolid, moxifloxacin, ciprofloxacin, rifampin, cloxacillin, cefazolin, and vancomycin were determined against 200 randomly selected non-duplicate MSSA (05/01–05/03) and 50 consecutive non-duplicate MRSA (05/00–06/03) blood isolates.Agar dilution and MIC interpretations were performed in accordance with NCCLS guidelines (M7–A4; M100–S14).

Results:  

 MSSA MIC (n = 200)MRSA MIC (n = 50)
Range (mg/mL)MIC50MIC90Range (mg/mL)MIC50MIC90 
Cefazolin0.25–1.0<=0.5<=18.0–>256<=256>256
Ciprofloxacin0.25–>64<=0.5<=0.532–>64>64>64
Cloxacilin0.125–16<=0.25<=0.258.0–>128>128>128
Gatifloxacin0.0625–4.0<=0.0625<=0.1254<=4<=4
Linezolid2<=2<=22<=2<=2
Moxifloxacin0.025-2.0<=0.025<=0.06254<=4<=4
Rifampin0.0075–0.0175<=0.0075<=0.03750.0075–>128<=32<=32
Vancomycin0.5–1.0<=0.5<=11<=1<=1

Conclusions:  

Bloodstream isolates of MSSA from KGH demonstrate in vitro susceptibility to gatifloxacin, linezolid, and moxifloxacin*. MRSA isolates exhibit intermediate susceptibility to gatifloxacin and moxifloxacin* but are fully susceptible to linezolid. Linezolid may be an effective oral agent for treatment of MSSA and MRSA bacteraemia, but use of the newer fluoroquinolones may be limited to treatment of MSSA bacteraemia. Further studies are needed to clarify the role that these agents may play in the treatment of S. aureus bacteraemia.

*(low MICs for S. aureus ; no moxifloxacin interpretive criteria exist).

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
Back to top