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Published on: June 5, 2012
Mutant prevention concentration for ciprofloxacin and levofloxacin with Pseudomonas aeruginosa
Glen T Hansen1, Xilin Zhao, Karl Drlica
1Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Abstract:
The mutant prevention concentration (MPC) was determined by population analysis using six fluoroquinolone-susceptible isolates of Pseudomonas aeruginosa applied to fluoroquinolone-containing agar plates. The MPCs were 3 mg/L and 9.5 mg/L for ciprofloxacin and levofloxacin, respectively. At high concentrations of either compound, single-step gyrA resistance mutants were recovered. Using a modified method for estimating the MPC, 151 clinical isolates were surveyed. Modal MPCs were 2 mg/L and 8 mg/L, respectively, for ciprofloxacin and levofloxacin. Thus, ciprofloxacin is three to four times more active than levofloxacin against resistant mutant subpopulations. For individual isolates, the MPC correlated poorly with the minimum inhibitory concentration (r(2) = 0.41 and 0.39 for ciprofloxacin and levofloxacin, respectively).
Insights
Ciprofloxacin and levofloxacin mutant prevention concentrations (MPC) were determined for Pseudomonas aeruginosa. Ciprofloxacin demonstrated higher activity against resistant mutant subpopulations compared to levofloxacin.
Area of Science:
- Microbiology
- Pharmacology
- Antimicrobial Resistance
Background:
- Fluoroquinolones are critical antibiotics for treating Pseudomonas aeruginosa infections.
- Understanding the mutant prevention concentration (MPC) is crucial for optimizing antibiotic therapy and preventing resistance.
- Pseudomonas aeruginosa is an opportunistic pathogen known for developing antimicrobial resistance.
Purpose of the Study:
- To determine the mutant prevention concentration (MPC) of ciprofloxacin and levofloxacin against Pseudomonas aeruginosa.
- To compare the activity of ciprofloxacin and levofloxacin against resistant mutant subpopulations.
- To assess the correlation between MPC and minimum inhibitory concentration (MIC) for these fluoroquinolones.
Main Methods:
- Population analysis was used to determine MPCs for fluoroquinolone-susceptible Pseudomonas aeruginosa isolates.
- Agar-based methods were employed to identify resistant mutants at high drug concentrations.
- A modified MPC estimation method was used to survey 151 clinical isolates.
Main Results:
- The MPCs for ciprofloxacin and levofloxacin in susceptible isolates were 3 mg/L and 9.5 mg/L, respectively.
- Modal MPCs for clinical isolates were 2 mg/L for ciprofloxacin and 8 mg/L for levofloxacin.
- Ciprofloxacin showed 3-4 times greater activity than levofloxacin against resistant mutant subpopulations; MPC correlated poorly with MIC.
Conclusions:
- Ciprofloxacin is more effective than levofloxacin in preventing the emergence of resistance in Pseudomonas aeruginosa.
- The MPC is a valuable parameter for assessing the potential of fluoroquinolones to prevent resistance.
- Further research is needed to understand the clinical implications of MPC and MIC correlations.
