Application of molecular methods for detection and transmission analysis of Mycobacterium tuberculosis drug resistance in patients attending a reference hospital in Italy
A. Cingolani et al., Application of molecular methods for detection and transmission analysis of Mycobacterium tuberculosis drug resistance in patients attending a reference hospital in Italy, J INFEC DIS, 179(4), 1999, pp. 1025-1029
A molecular analysis of drug-resistant isolates of Mycobacterium tuberculos
is was done in a population with a high prevalence of human immunodeficienc
y virus infection. Seventy-one consecutive isolates were tested for genotyp
ic resistance to isoniazid, rifampicin, streptomycin, and ethambutol by pol
ymerase chain reaction-single strand conformation polymorphism analysis and
automated sequencing of target regions. Phenotypic and genotypic resistanc
e to isoniazid, rifampicin, streptomycin, and ethambutol were detected in 2
3.4%, 11.2%, 7%, and 5.6% of isolates and in 87%, 88%, 40%, and 100% of res
istant isolates, respectively. Specificity was 100% for all target regions.
When rpoB, katG, and ahpC mutation analysis were combined, 86% of resistan
t isolates to any drug were identified. No mutations in inhA were found in
isoniazid-resistant isolates. Molecular detection of drug resistance, parti
cularly for isoniazid and rifampicin, may represent a sensitive and very sp
ecific technique. The strategy of selecting rpoB, katG, and ahp C to quickl
y identify most resistant isolates, with a relevant saving of resources, is
warranted.