TABLE 2.

Antimicrobial drug susceptibilities and resistance mechanism of 8 XDR K. pneumoniae isolates in Singapore

Drug	MIC (mg/liter) for K. pneumoniae straina:
	1883 (SHV-11, TEM-1, CTXM-1, NDM-1)	3229 (SHV-1, TEM-1, CTXM-1, NDM-1)	7433 (SHV-11, TEM-1, CTXM-1, DHA, NDM-1	7522 (SHV-11, TEM-1, CTXM-1, NDM-1)	43320 (CTXM-1, NDM-1)	44591 (SHV-1, TEM-1, CTXM-1, CTXM-9, NDM-1)	21479 (OXA-181)	53879 (OXA-181, CTXM-15, CMY-4)
Amikacin	≥128	≥128	≥128	≥128	16	≥128	≥128	≥128
Gentamicin	≥256	≥256	≥256	≥256	≥256	≥256	≥256	≥256
Levofloxacin	≥64	≥64	≥64	≥64	≥64	≥64	≥64	≥64
Rifampin	≥64	≥64	≥64	≥64	≥64	≥64	≥64	≥64
Polymyxin B	2	2	2	4	2	1	4	1
Tigecycline	4	2	4	2	1	4	2	4
Cefepime	≥128	≥128	≥128	≥128	≥128	≥128	≥128	≥128
Meropenem	≥64	≥64	≥64	≥64	≥64	≥64	≥64	≥64
Doripenem	≥64	≥64	≥64	≥64	≥64	≥64	≥64	≥64
Imipenem	≥64	32	≥64	≥64	≥64	≥64	≥64	≥64
Aztreonam	≥128	≥128	≥128	≥128	≥128	≥128	≥128	≥128
Piperacillin-tazobactam	≥256/4	≥256/4	≥256/4	≥256/4	≥256/4	≥256/4	≥256/4	≥256/4
Ertapenem	≥32	≥32	≥32	≥32	≥32	≥32	≥32	≥32
Ampicillin-sulbactam	≥128/64	≥128/64	≥128/64	≥128/64	≥128/64	≥128/64	≥128/64	≥128/64
Ciprofloxacin	≥16	≥16	≥16	≥16	≥16	≥16	≥16	≥16
Ceftazidime	≥128	≥128	≥128	≥128	≥128	≥128	≥128	≥128
Sulfamethoxazole-trimethoprim	≥32	≥32	≥32	≥32	≥32	≥32	≥32	≥32

^aMICs were obtained using the broth microdilution method, according to CLSI guidelines. The resistance mechanisms are shown in parentheses after the strain designations.