Molecular characterization of resistance mechanisms to chloramphenicol in Shigella flexneri strains isolated from Chilean children with acute diarrhea
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Date
2002
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Abstract
Background: Chloramphenicol is one of the therapeutic options for shigellosis, but resistance to this antimicrobial is increasing. Aim: To characterize molecular mechanisms conferring resistance to chlorampbenicol (Cm-R) in Shigella flexneri strains isolated from Chilean children with acute diarrhea. Material and methods: Thirty one Shigella filexneri strains, including 22 with the Cm-R phenotype were analyzed. Strains were tested for antimicrobial susceptibility by plate dilution and for the presence of an internal fragment of the cat gene encoding for chlorampbenicol o-acetyl-transferase, by polymerase chain reaction and Southern blot analysis. Results: All Cm-R strains had a minimal inhibitory concentration over 64 mug/ml and amplified the internal fragment of the cat gene. Southern blot analyses indicated that this gene was located in the bacterial chromosome. Conclusions: Resistance to chlorampbenicol in this group of Shigella flexneri strains was mediated by a chromosomally located cat gene.
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chloramphenical o-acetyl-transferase, chloramphenical resistance, genes, cat, Shigella flexneri