Background: The
incidence of acquired resistance to antituberculous
drugs of
Mycobacterium tuberculosis in
Chile is approximately 23 percent.
Aim: To analyze the
mutations associated with
drug resistance in
drug resistant
strains of
Mycobacterium tuberculosis . Material and
Methods: In 28
drug resistant
Mycobacterium tuberculosis strains isolated in
Chile ,
genes leading to
drug resistance were studied.
DNA was amplifed by
polymerase chain reaction (
PCR ) and sequencing was carried out using the ABI PRISM big
dye terminator cycle sequencing ready reaction kit.
Results: In
rifampicin -resistant
strains , the
mutations in rpoβ
gene were in the
codons S531W/L (56 percent), D516Y (16 percent) and D516V (16 percent). The predominant
mutation in katG
gene was in the
codon S315L (73 percent) in
isoniazid -resistant
strains . The
mutation S95T was found in the 71 percent of ciprofoxacin resistant
strains . Only one
ethambutol resistant
strain had the M306I
mutation . Three unreported
mutations in katG were identifed.
Conclusions: Drug resistance associated
mutations of
Mycobacterium tuberculosis isolated in
Chile were
similar to those reported abroad.