[Molecular characterization of resistance mechanisms to chloramphenicol in Shigella flexneri strains isolated from Chilean children with acute diarrhea].
BACKGROUND
Chloramphenicol is one of the therapeutic options for shigellosis, but resistance to this antimicrobial is increasing.


OBJECTIVE
To characterize molecular mechanisms conferring resistance to chloramphenicol (Cm) in Shigella flexneri strains isolated from Chilean children with acute diarrhea.


METHODS
Thirty one Shigella filexneri strains, including 22 with the Cm 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 chloramphenicol o-acetyl-transferase, by polymerase chain reaction and Southern blot analysis.


RESULTS
All Cm strains had a minimal inhibitory concentration over 64 micrograms/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 chloramphenicol in this group of Shigella flexneri strains was mediated by a chromosomally located cat gene.
Farfán
Mauricio
M
Programa de Microbiología, ICBM, Facultad de Medicina, Universidad de Chile, Unidad de Microbiología, Departamento Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile.
Flores
Oscar
O
Navarro
Niurka
N
Prado
Valeria
V
Mora
Guido
G
Toro
Cecilia
C
D000208:Acute Disease; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015139:Blotting, Southern; D002648:Child; D002701:Chloramphenicol / Q000494:pharmacology*; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D002702:Chloramphenicol Resistance / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000235:genetics; D003967:Diarrhea / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012763:Shigella flexneri / Q000187:drug effects* / Q000235:genetics
D000900:Anti-Bacterial Agents; D002701:Chloramphenicol; D015500:Chloramphenicol O-Acetyltransferase
Caracterización molecular de mecanismos de resistencia a cloranfenicol en cepas de Shigella flexneri aisladas en niños chilenos con diarrea aguda.