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Postantibiotic effects and postantibiotic sub-MIC effects of erythromycin, roxithromycin, tilmicosin, and tylosin on
1Division of Veterinary Pharmacology and Toxicology, Chungnam National University, 220 Kung-dong, Yusong-ku, Taejon, South Korea.
Abstract:
When intermittent dosing is used during treatment, the concentrations of antibiotics fluctuate and subinhibitory concentrations may occur between doses. Postantibiotic effects (PAEs) and postantibiotic subinhibitory effects (PA SMEs) on bacteria may provide additional, valuable information for the rational use of a drug in clinical practice. In this study tilmicosin was the most active antibiotic tested against P. multocida type D with MICs ranging from 4-16 mg/l. Roxithromycin and tilmicosin induced a statistically significantly longer PAE than did tylosin against P. multocida types A and D (P < 0.05). The duration of PAEs and PA SMEs were proportional to the concentrations of drugs used for exposure. The PA SMEs were substantially longer than PAEs on P. multocida. Tilmicosin had a longer PA SME compared with erythromycin, roxithromycin and tylosin for P. multocida. The computerized incubator used in the present study provided an efficient and convenient determination of PAE and PA SME, allowing frequent measurements of the bacterial growth.
Insights
Tilmicosin demonstrated significant postantibiotic effects (PAEs) and postantibiotic subinhibitory effects (PA SMEs) against P. multocida. These effects, longer with higher drug concentrations, offer insights for rational antibiotic use.
Area of Science:
- Veterinary Microbiology
- Pharmacology
- Antimicrobial Resistance
Background:
- Intermittent antibiotic dosing leads to fluctuating drug concentrations, potentially reaching subinhibitory levels between doses.
- Understanding postantibiotic effects (PAEs) and postantibiotic subinhibitory effects (PA SMEs) is crucial for optimizing antimicrobial therapy.
- These effects provide valuable data for the rational clinical application of antibiotics.
Purpose of the Study:
- To evaluate the postantibiotic effects (PAEs) and postantibiotic subinhibitory effects (PA SMEs) of specific antibiotics on *Pasteurella multocida*.
- To compare the efficacy of tilmicosin, roxithromycin, tylosin, and erythromycin in inducing PAEs and PA SMEs.
- To assess the influence of drug concentration on the duration of PAEs and PA SMEs.
Main Methods:
- Utilized a computerized incubator for efficient and frequent measurement of bacterial growth.
- Determined Minimum Inhibitory Concentrations (MICs) for antibiotics against *P. multocida*.
- Quantified the duration of PAEs and PA SMEs following exposure to different antibiotic concentrations.
Main Results:
- Tilmicosin exhibited the highest activity against *P. multocida* type D (MICs 4-16 mg/l).
- Tilmicosin and roxithromycin induced significantly longer PAEs than tylosin against *P. multocida* types A and D (P < 0.05).
- PAE and PA SME durations were dose-dependent, with PA SMEs being considerably longer than PAEs. Tilmicosin showed a longer PA SME than other tested antibiotics.
Conclusions:
- Tilmicosin is a potent antibiotic against *P. multocida*, demonstrating significant PAE and PA SME.
- The duration and magnitude of PAEs and PA SMEs are influenced by antibiotic concentration.
- PA SMEs are a critical consideration, potentially offering extended bacterial growth inhibition beyond traditional PAEs, informing rational antibiotic strategies.