Table 2.

Additional drug resistance of M. tuberculosis isolates from children with lab-confirmed MDR TB in the United States, 1993–2014 (N=82)

Drug category	Tested	Resistant
	N	n	%
Other first-line drugs	82	66	81
Ethambutol	81	47	58
Pyrazinamide	70	36	51
Streptomycin	80	56	70
Second-line drugs	73	24	33
Any second-line injectable	68	10	15
Any fluoroquinolone	57	5	9
Extensive drug resistancea	54	3	6
Other second-line drugsb	70	15	21

MDR TB = multidrug-resistant tuberculosis; M. tuberculosis resistant to isoniazid and rifampicin

^aResistance to a fluoroquinolone and ≥ 1 second-line injectable

^bcycloserine, ethionamide, p-aminosalicylic acid