Table 3. MIC₅₀ and MIC₉₀ of S. Typhi (n = 77) and S. Paratyphi A (n = 25) isolates from Kolkata, 2009 to 2013.

Antimicrobial agents	MIC Range (µg/ml)		MIC50 (µg/ml)		MIC90 (µg/ml)		MIC (µg/ml) breakpoint for resistancec
	STa	SPAb	STa	SPAb	STa	SPAb
Ampicillin	0.094–≥256	1–3	0.5	1.5	≥256	3	≥32
Chloramphenicol	1.5–≥256	4–8	2	6	≥256	8	≥32
Co-trimoxazole	0.008–≥32	0.032–0.125	0.023	0.094	≥32	0.125	≥4
Tetracycline	1–16	1.5–4	1.5	3	3	4	≥16
Nalidixic acid	2–≥256	1.5–≥256	≥256	≥256	≥256	≥256	≥32
Ciprofloxacin	0.064–≥32	0.032–0.75	0.38	0.5	≥32	0.75	≥1
Ofloxacin	0.047–≥32	0.125–4	0.75	2	24	3	≥2
Levofloxacin	0.023–24	0.064–1	0.25	0.75	4	1	≥2
Ceftriaxone	0.032–0.19	0.064–0.19	0.064	0.125	0.125	0.19	≥4
Ceftazidime	0.064–0.38	0.19–0.75	0.19	0.38	0.38	0.5	≥16
Cefotaxime	0.023–0.125	0.125–0.25	0.064	0.19	0.094	0.19	≥4
Azithromycin	1.5–16	3–32	8	16	12	32	>16
Amoxicillin/clavulanic acid	0.25–≥256	0.75–3	0.5	1.5	32	1.5	≥32

^aST, S. Typhi.

^bSPA, S. Paratyphi A.

^cCLSI, 2013 guideline followed for all antimicrobials except azithromycin.