In vitro development and analysis of Escherichia coli and Shigella boydii azithromycin-resistant mutants.
Microb Drug Resist
; 19(2): 88-93, 2013 Apr.
Article
en En
| MEDLINE
| ID: mdl-23176550
ABSTRACT
The aim of this study was to develop and analyze in vitro azithromycin (AZM)-resistant mutants of Escherichia coli and Shigella boydii. Three clinical isolates of E. coli and one S. boydii isolated from feces samples collected from children under 5 years of age with diarrhea in Lima, Peru were inoculated onto Mueller-Hinton plates containing increasing serial dilutions of AZM ranging from their specific minimal inhibitory concentration (2 or 4 mg/l) to 64 mg/l. From these plates, 16 AZM-resistant mutants were selected to determine the stability of the resistance and the presence of cross resistance with other antibiotics. The role of Phe-Arg-ß-Naphthylamide (PAßN)-inhibitible efflux pumps as well as the presence of mutations in the rplV, rplD, and rrlH (23S rRNA) genes and alterations in the outer membrane profiles were determined in these 16 mutants. The rate of mutation ranged from < 2.70×10(-10) to 2.17×10(-7) for E. coli and from < 9.58×10(-10) to 1.05×10(-8) for S. boydii. E. coli mutants showed an increase in the AZM-MIC up to sixfold with one strain achieving a MIC >256 mg/l. In contrast, S. boydii only presented increases of up to twofold in MIC levels. All the strains obtained, but one showed stable AZM resistance. In the presence of PAßN, the AZM MICs decreased to parental levels in Shigella mutants, while no MIC returned to parental levels among the E. coli mutants. No cross resistance to other classes of antibiotics was found. These results show the relevance of PAßN-inhibitible efflux pumps in the basal levels and development of AZM resistance. Further studies to characterize the remaining unidentified mechanisms of AZM resistance are needed.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Shigella boydii
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Azitromicina
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Farmacorresistencia Bacteriana
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Escherichia coli
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Antibacterianos
Límite:
Child, preschool
/
Humans
Idioma:
En
Revista:
Microb Drug Resist
Asunto de la revista:
MICROBIOLOGIA
/
TERAPIA POR MEDICAMENTOS
Año:
2013
Tipo del documento:
Article
País de afiliación:
España