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Activity of ciprofloxacin against methicillin-resistant Staphylococcus aureus
Abstract:
Ciprofloxacin, a carboxy quinolone antibiotic with a broad spectrum of activity, was tested against 54 strains of methicillin-resistant Staphylococcus aureus. The ciprofloxacin MICs for 50 and 90% of the isolates were 0.25 and 0.5 micrograms/ml, respectively, and its MBC for 90% of the isolates was 1.0 microgram/ml. Killing kinetic studies were conducted in vitro with ciprofloxacin and vancomycin individually and in combination. The results of these studies showed that ciprofloxacin at 2 micrograms/ml and vancomycin at 10 micrograms/ml decreased the number of organisms by approximately 1.5 log10 after 6 h. The combination of ciprofloxacin plus vancomycin did not alter the rate of killing over that achieved by ciprofloxacin alone. The in vitro killing of resistant staphylococci was rapid, and the potential use of ciprofloxacin for infections caused by methicillin-resistant S. aureus should be further explored.
Insights
Ciprofloxacin effectively inhibits methicillin-resistant Staphylococcus aureus (MRSA) in vitro. Further research is warranted to explore ciprofloxacin
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat due to its resistance to conventional antibiotics.
- Broad-spectrum antibiotics like ciprofloxacin are evaluated for their efficacy against resistant bacterial strains.
Purpose of the Study:
- To assess the in vitro activity of ciprofloxacin against clinical isolates of MRSA.
- To compare the bactericidal activity of ciprofloxacin and vancomycin, individually and in combination, against MRSA.
Main Methods:
- Determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for ciprofloxacin against 54 MRSA strains.
- In vitro killing kinetic studies using ciprofloxacin and vancomycin at specified concentrations.
Main Results:
- Ciprofloxacin demonstrated potent activity with MIC50 and MIC90 values of 0.25 and 0.5 µg/ml, respectively.
- The MBC90 for ciprofloxacin was 1.0 µg/ml.
- Ciprofloxacin alone and in combination with vancomycin showed similar rapid killing rates, reducing bacterial counts by approximately 1.5 log10 within 6 hours.
Conclusions:
- Ciprofloxacin exhibits significant in vitro bactericidal activity against MRSA.
- The combination of ciprofloxacin and vancomycin did not provide additive or synergistic killing effects compared to ciprofloxacin alone.
- Further investigation into the clinical utility of ciprofloxacin for treating MRSA infections is recommended.