Table 3. Additional second-line susceptibility testing of recovered isolates.

Drug	MIC µg/ml (IQR)	Total, N = 28	Conversion <3 mo., N = 13	Conversion ≥3 mo., N = 15
		Resistant (%N)	Resistant (%N)	Resistant (%N)
Ofloxacin	0.5 (IQR 0.5–1.0)	3 (11)	1 (8)	2 (13)
Moxifloxacin	0.12 (IQR 0.06–0.25)	4 (14)	1 (8)	1 (7)
Amikacin	0.25 (IQR 0.25–0.5)	1 (4)	0	1 (7)
Kanamycin	1.2 (IQR 1.2–2.5)	3 (11)	1 (8)	2 (13)
Ethionamide	2.5 (IQR 1.2–5.0)	9 (32)	3 (23)	6 (40)
PAS	≤0.5 (IQR 0) (min ≤0.5-max 1.0)	0	0	0
Cycloserine*	8.0 (IQR 8.0–16.0)	n/a	n/a	n/a

Pyrazinamide susceptibility was not performed. PAS = para-aminosalicylic acid. Conversion =  time to sputum culture conversion to negative in months (mo). Resistance determined by minimum inhibitory concentration (MIC) analysis on MYCOTB Sensititre plates (TREK Diagnostics) with the following resistance breakpoints (ofloxacin 2.0 µg/ml; moxifloxacin 0.25 µg/ml; amikacin 1.0 µg/ml, kanamycin 5.0 µg/ml, ethionamide 5.0 µg/ml; PAS 2.0 µg/ml)[21;27].

^*Resistance correlation with MIC in liquid media is not well established for cycloserine. One subject with culture conversion ≥3 months was resistant to both ofloxacin and kanamycin, considered extensively drug-resistant (XDR-TB).