Occurrence of disputed rpoB mutations among Mycobacterium tuberculosis isolates phenotypically susceptible to rifampicin in a country with a low incidence of multidrug-resistant tuberculosis

Table 1 Phenotypic resistance by MGIT 960 system to anti-TB drugs and genotypic screening of mutations in HSR-rpoB, katG315 and inhA-RR among 242 clinical M. tuberculosis isolates

Phenotypic resistance to anti-TB drug	No. of isolates tested	Number of isolates detected by gMTBDR⁺ with a mutation in
Phenotypic resistance to anti-TB drug	No. of isolates tested	HSR-rpoB	katG315 (S315 T)	inhA-RR
None	64	0	0	0
SM	15	0	0	0
INH	51	0	15	21^a
INH + SM	75	2	58	11^b
INH + EMB	26	1	10	2^b
INH + SM + EMB	11	1	6	0

gMTBDR⁺, GenoType MTBDRplus assay; HSR-rpoB, 81-base pair hot-spot region of rpoB gene; katG315 (S315 T), S315 T mutation at katG codon 315; inhA-RR, upstream regulatory region of inhA gene
SM streptomycin, INH isoniazid, EMB ethambutol
^a20 isolates contained − 15 C/T and 1 isolate contained − 8 T/A mutation
^bAll isolates contained − 15 C/T mutation

ISSN: 1471-2334