Killing of Streptococcus pneumoniae by azithromycin, clarithromycin, erythromycin, telithromycin and gemifloxacin using drug minimum inhibitory concentrations and mutant prevention concentrations.

Autor: Blondeau JM; Department of Clinical Microbiology, Royal University Hospital and Saskatoon Health Region, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Departments of Pathology and Ophthalmology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Electronic address: joseph.blondeau@saskatoonhealthregion.ca., Shebelski SD; Department of Clinical Microbiology, Royal University Hospital and Saskatoon Health Region, University of Saskatchewan, Saskatoon, Saskatchewan, Canada., Hesje CK; Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Jazyk: angličtina
Zdroj: International journal of antimicrobial agents [Int J Antimicrob Agents] 2015 Jun; Vol. 45 (6), pp. 594-9. Date of Electronic Publication: 2015 Feb 16.
DOI: 10.1016/j.ijantimicag.2014.12.034
Abstrakt: Streptococcus pneumoniae continues to be a significant respiratory pathogen, and increasing antimicrobial resistance compromises the use of β-lactam and macrolide antibiotics. Bacterial eradication impacts clinical outcome, and bacterial loads at the site of infection may fluctuate. Killing of two macrolide- and quinolone-susceptible clinical S. pneumoniae isolates by azithromycin, clarithromycin, erythromycin, telithromycin and gemifloxacin against varying bacterial densities was determined using the measured minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC). For kill experiments, 10(6)-10(9) CFU/mL were exposed to the drug and were sampled at 0, 0.5, 1, 2, 3, 4, 6, 12 and 24 h following drug exposure. The log(10) reduction and percent reduction (kill) of viable cells was recorded. MICs and MPCs (mg/L) for azithromycin, clarithromycin, erythromycin, telithromycin and gemifloxacin were 0.063-0.125/0.5-1, 0.031-0.063/0.25-0.5, 0.063/0.25-0.5, 0.008/0.016 and 0.031/0.25, respectively. Killing 10(6)-10(9) CFU/mL of bacteria by the drug MIC yielded incomplete killing, however log10 reductions occurred by 12 h and 24 h for all drugs. Exposure of 10(6)-10(9) CFU/mL to MPC drug concentrations resulted in the following log(10) reduction by 6h of drug exposure: azithromycin, 1.3-3.9; clarithromycin, 1.9-5.8; erythromycin, 0.8-4.7; telithromycin, 0.3-1.7; and gemifloxacin, 1.8-4.2. Bacterial loads at the site of infection may range from 10(6) to 10(9), and kill experiments utilising a higher bacterial inoculum provided a more accurate measure of antibiotic performance in high biomass situations. Killing was slower with telithromycin. Kill was greater and fastest with MPC versus MIC drug concentrations.
(Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.)
Databáze: MEDLINE
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