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Journal of Clinical Microbiology, December 1999, p. 3844-3850, Vol. 37, No. 12
Victorian Infectious Diseases Reference
Laboratory,
Received 24 May 1999/Returned for modification 30 June
1999/Accepted 20 August 1999
To develop a better understanding of the epidemiology and molecular
biology of rifampin-resistant Mycobacterium tuberculosis strains in Australia, 50 clinical isolates (33 rifampin-resistant and
17 rifampin-sensitive strains) cultured between 1990 and 1997 were
analyzed by a number of bacteriological and molecular techniques. Examination of the drug resistance profiles of the 33 rifampin-resistant isolates revealed that 91% were resistant to
rifampin in combination with resistance to isoniazid, 88% were
resistant to rifampin on first isolation, and 81% showed
cross-resistance with rifabutin. On the basis of the demographic data
provided for the patients infected with the rifampin-resistant strains,
90% of the patients were born overseas. Of these patients, 64%
developed clinical symptoms within 5 years of residence in Australia.
On a molecular level, analysis of the rpoB gene revealed
that 97% of the rifampin-resistant isolates had missense mutations
within a conserved region of the gene, and eight types of missense
mutations were detected. Of the 31 rifampin-resistant isolates that
were typed by restriction fragment length polymorphism (RFLP) analysis,
28 distinct patterns were obtained by RFLP analysis with
IS6110, and three clusters of genetically related isolates
were identified. All isolates within the clusters were from patients
who were born overseas and who had the same country of origin. The
results from this study provide an overview of the current situation of
rifampin resistance in Australia and can serve as a basis for continued monitoring of drug-resistant M. tuberculosis strains
isolated within the country.
0095-1137/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Bacteriological and Molecular Analysis of
Rifampin-Resistant Mycobacterium tuberculosis Strains
Isolated in Australia
*
Corresponding author. Mailing address: Victorian
Infectious Diseases Reference Laboratory, 10 Wreckyn St., North
Melbourne, 3051, Australia. Phone: 61-3-9342-2618. Fax: 61-3-9342-2665. E-mail: lilly.yuen{at}nwhcn.org.au.
Journal of Clinical Microbiology, December 1999, p. 3844-3850, Vol. 37, No. 12
0095-1137/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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