Molecular characterization of multidrug-resistant Mycobacterium tuberculosis (MDR-TB) isolates identifies local transmission of infection in Kuwait, a country with a low incidence of TB and MDR-TB

Table 1 Phenotypic resistance by MGIT 960 system to anti-TB drugs among 93 multidrug-resistant M. tuberculosis isolates and number of susceptible and resistant isolates with mutations in target genes for each drug

Anti-tuberculosis	No. of isolates	No. of susceptible	No. of susceptible	No. of resistant	No. (%) of resistant
Drug	Tested	Isolates	Isolates with mutation^a	Isolates	Isolates with mutation^a
Rifampicin	93	0	0	93	93 (100)
Isoniazid	93	0	0	93	92 (98.9)
Pyrazinamide	47	11	0	36	30 (83.3)
Ethambutol	93	52	38^b	41	38 (92.7)
Streptomycin	93	34	0	59	49 (83.1)

^aResistance-conferring mutations were detected in rpoB for rifampicin, katG + inhA for isoniazid, pncA for pyrazinamide, embB for ethambutol, and rpsL + rrs for streptomycin
^bMycobacterium tuberculosis isolates with embB mutations usually confer low level of resistance to ethambutol which are often missed by the MGIT 960 system [23, 28]

ISSN: 2047-783X