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Fluoroquinolone resistance in staphylococci: new challenges
C C Sanders1, W E Sanders, K S Thomson
1Department of Medical Microbiology, Crieghton University School of Medicine, Omaha, Nebraska 68178, USA.
Summary
Staphylococci exhibit limited susceptibility to fluoroquinolones, with resistance rapidly increasing. Prudent use and high-dose fluoroquinolones are recommended to combat rising resistance in Staphylococcus strains.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Staphylococci demonstrate limited susceptibility to newer fluoroquinolones.
- Fluoroquinolone resistance in staphylococci can arise from single mutations affecting target sites or permeability.
Purpose of the Study:
- To analyze the susceptibility patterns of staphylococci to fluoroquinolones.
- To investigate the prevalence and mechanisms of fluoroquinolone resistance in Staphylococcus species.
Main Methods:
- Minimum Inhibitory Concentration (MIC) determination for fluoroquinolone susceptibility testing.
- Analysis of clinical isolates of staphylococci to categorize resistance levels.
Main Results:
- Staphylococci susceptibility to fluoroquinolones is marginal, with MICs for susceptible strains ranging from 0.25 to 2.0 mg/l.
- Increased prevalence of fluoroquinolone-resistant staphylococci, particularly methicillin-resistant strains, has been observed.
- Clinical isolates fall into susceptible (MIC < 0.5 mg/l), moderately resistant (MIC 0.5 to 4 mg/l), and highly resistant (MIC > 4 mg/l) groups.
Conclusions:
- A single mutational event can lead to clinical resistance in staphylococci.
- Avoiding fluoroquinolone use when possible is advised to prevent further resistance.
- When fluoroquinolone use is necessary, dosages should achieve serum/tissue levels eight times the MIC of the infecting strain.