In this study the effects of exposure to serum, lung and breakpoint concentrations on Streptococcus pneumoniae susceptibility to clarithromycin, azithromycin, amoxicillin/clavulanate, levofloxacin and moxifloxacin were evaluated. Development of resistance was determined by multi-step and single-step methodologies. In the first experimental set, minimum inhibitory concentrations (MICs) were determined after 10 passages on antibiotic-gradient plates and 10 passages on antibiotic-free plates. Acquisition of resistance was defined as an increase of (greater-than or equal to)4-fold from the starting MIC. In single-step studies, the rate of spontaneous mutations was calculated after a passage on antibiotic-containing agar plates. Azithromycin and levofloxacin gave the highest number of strains with MIC increased of at least 4 times the starting value, followed by moxifloxacin and by clarithromycin which only at the lowest concentration tested selected for resistance in 5 strains. Amoxicillin/ clavulanate never displayed (greater-than or equal to)4-fold MIC increase. Frequencies of mutation were lower for clarithromycin and moxifloxacin than for the comparators. At lung concentrations clarithromycin had limited potential to select for resistance. (copyright) E.S.I.F.T. srl - Firenze.
In vitro selection of resistance to clarithromycin in Streptococcus pneumoniae clinical isolates / L. Drago, D. Legnani, L. Nicola, E. De Vecchi, S. Ripa, M. Prenna. - In: JOURNAL OF CHEMOTHERAPY. - ISSN 1120-009X. - 17:2(2005), pp. 161-168.
|Titolo:||In vitro selection of resistance to clarithromycin in Streptococcus pneumoniae clinical isolates|
DRAGO, LORENZO (Primo)
LEGNANI, DELFINO (Secondo)
|Parole Chiave:||Streptococcus pneumoniae ; antibiotic resistance ; antibiotic sensitivity ; article ; bacterial strain ; bacterium isolate ; controlled study ; drug exposure ; in vitro selection ; lung ; minimum inhibitory concentration ; mutation rate ; nonhuman ; spontaneous mutation ; agar ; amoxicillin plus clavulanic acid ; azithromycin ; clarithromycin ; levofloxacin ; moxifloxacin|
|Settore Scientifico Disciplinare:||Settore MED/10 - Malattie dell'Apparato Respiratorio|
Settore MED/07 - Microbiologia e Microbiologia Clinica
|Data di pubblicazione:||2005|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1179/joc.2005.17.2.161|
|Appare nelle tipologie:||01 - Articolo su periodico|