| Title | Minimum Inhibitory Concentration and Postantibiotic Effect of Amikacin for Equine Isolates of Methicillin-Resistant Staphylococcus aureus In Vitro. | | Author(s) | Caron JP, Bolin CA, Hauptman JG, Johnston KA | | Institution | Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI. | | Source | Vet Surg 2009 Jul; 38(5):664-669. | | Abstract | Objective- To report the minimum inhibitory concentration (MIC) of amikacin sulfate for equine clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and characterize the initial kill and duration of the postantibiotic effect (PAE) for selected strains. Study Design- Experimental study. Methods- Isolates of MRSA (n=35) had their amikacin MIC determined using the E-test agar diffusion method. Two isolates with MICs>256 mug/mL limit were further characterized using broth macrodilution. Six distinct isolates with amikacin MICs of 32, 48, 128 (2 isolates) and 500 (2 isolates) mug/mL had PAE determinations made over a range of amikacin concentrations from 31.25-1000 mug/mL using standard culture-based techniques. Results- Median MIC of the 35 isolates was 32 mug/mL (range 2 to >256 mug/mL). Mean PAE of selected MRSA strains had an overall mean (all amikacin doses) of 3.43 hours (range 0.10-9.57 hours). PAE for MRSA exposed to amikacin at 1000 mug/mL was 6.18 hours (range 3.30-9.57 hours), significantly longer than that for all other concentrations (P<.0001). There was no statistically significant effect of isolate MIC on PAE. Conclusions- Isolates had a wide range of MIC; however, growth of all 6 selected strains were inhibited within the range of concentrations tested, including 2 strains with MICs of 500 mug/mL. PAE duration was not influenced by the MIC of amikacin but was significantly longer with treatment at 1000 mug/mL than at lower concentrations. Clinical Relevance- Clinical isolates of MRSA are susceptible to amikacin at concentrations achieved by regional perfusion: however, the modest duration of PAE observed suggest that further laboratory and in vivo evaluation be conducted before recommending the technique for clinical use. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19573072 |
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