Effects of subinhibitory concentrations of clindamycin on the morphological, biochemical and genetic characteristics of Bacteroides fragilis

Authors


  • Editor: Mario Avila-Campos

Correspondence: Mario J. Avila-Campos, Anaerobe Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900, São Paulo, SP, Brazil. Tel.: +55 11 3091 7344; fax: +55 11 3091 7354; e-mail: mariojac@usp.br

Abstract

The effects of subinhibitory concentrations of clindamycin on the morphological, biochemical and genetic characteristics of species of the Bacteroides fragilis group isolated from children with diarrhea were determined. The minimal inhibitory and subinhibitory concentrations for clindamycin were determined. Minimal inhibitory concentration values ranging from 0.25 to 512 μg mL−1 were observed. Cultures grown with clindamycin were used to determine the macroscopic morphological characteristics, cellular viability, ultrastructural characteristics and DNA integrity. Clindamycin did not alter colonial morphology, but after 6 h elongated cells were observed. Also, extracellular vesicles and electron-lucent areas inside the cytoplasm were observed. Bacteria treated with clindamycin also showed fragmentation of DNA as determined by electrophoresis. The alterations produced by clindamycin might be indicative of a possible modification of the structures involved in bacterial pathogenesis.

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