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 2 Phenotypic susceptibility and genotypic characterization of M. tuberculosis isolates with disputed rpoB mutations

Isolate	Culture	Clinical	Phenotypic resistance	Susceptibility	Mutations detected in^c			embB	pncA	Spoligotyping	Final resistance
no.	no.	specimen	to anti-TB drugs^b	to PZA^b	rpoB	katG315	inhA-RR	mutation	mutation	lineage	pattern
D1	5853/05	BAL^a	INH + SM	Not done	H526N	S315 T	None	None	None	Orphan	INH + SM + RIF
D2	13,242/10	Sputum	INH + EMB	Not done	D516Y	S315 T	None	M306 V	R2P^d	EAI5/EAI3	INH + EMB + RIF + PZA
D3	10,268/11	Pleural fluid	INH + SM	Resistant	H526N	S315 T	None	M306 V	H51P	Orphan	INH + SM + PZA + RIF + EMB
D4	13,341/16	Sputum	INH + SM + EMB	Susceptible	S531C	S315 T	None	M306 V	None	T1 Uganda	INH + SM + EMB + RIF

INH, isoniazid; SM, streptomycin; EMB, ethambutol; RIF, rifampicin, PZA, pyrazinamide
HSR-rpoB, 81-base pair hot-spot region of rpoB gene; katG315, katG codon 315; inhA-RR, upstream regulatory region of inhA gene
^aBAL, bronchoalveolar lavage
^bThe susceptibility to anti-TB drugs was determined by MGIT 960 system
^cMutations in rpoB, katG codon 315 and inhA-regulatory region were detected by GenoType MTBDRplus assay and/or PCR-sequencing of respective loci
^dRepresents a novel mutation not described previously

ISSN: 1471-2334