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. 2001 Aug;45(8):2348–2353. doi: 10.1128/AAC.45.8.2348-2353.2001

TABLE 3.

Antimicrobial susceptibilities, MIC50 and MIC90, gyrA sequence, production of toxins A and B (Tox A/B), and AP-PCR type (AP type) of 19 MXF-resistant C. difficile isolates, 4 in vitro-selected strains, and 3 ATCC strains (ATCC 17857 and ATCC 43255, C. difficile; ATCC 25285, Bacteroides fragilisa,b,e

Strain MIC (μg/ml)
GyrA aa/ntc Tox A/B AP type
Group I Group II Group III Group IV
NOR CIP GRX GAT GMX TVA CLX MXF MEO VAN
ATCC 17857 8 >32 16 2 2 2 0.5 2 0.125 1.5 T/ACT −/− NTd
ATCC 43255 8 >32 2 1 1 1 0.5 0.5 0.047 1 T/ACT +/+ NT 
ATCC 25285 4 >32 4 0.5 1 1 0.5 0.5 0.5 NT NT NT NT
1542 >64 >32 32 16 32 16 2 16 0.38 1 V/GTT +/+ 2
2897 >64 >32 32 >32 32 32 4 >32 0.125 0.75 I/ATT +/+ 2
2923 >64 >32 32 32 32 32 2 16 0.25 1 T/ACT +/+ 1
2518 >64 32 32 32 8 4 2 >32 0.125 1 T/ACT +/+ 3
1000 >64 >32 32 32 32 32 2 32 0.125 1 I/ATT +/+ 5A,B
1001 >64 >32 32 16 32 32 2 16 0.19 1 I/ATT +/+ 5A,B
1002 >64 >32 32 32 32 32 2 16 0.125 1 I/ATT +/+ 5A,B
1009 >64 >32 32 32 16 32 2 16 0.125 0.75 I/ATT +/+ 5A,B
1111/1 >64 >32 32 32 32 32 2 16 0.125 0.5 IATT +/+ 4
1111/2 >64 >32 32 32 32 32 2 16 1 1.5 IATT +/+ 4
E 213 >64 >32 32 32 16 16 2 16 0.125 0.75 T/ACT −/− 5A,B
E 214 >64 >32 >32 32 16 32 2 16 0.094 0.75 T/ACT −/− 6
E 239 >64 16 16 16 16 32 2 >32 0.094 0.25 IATT +/+ 7
E 287 >64 >32 >32 32 32 32 2 32 0.094 1 IATT +/+ 5A,B
E 496 >64 >32 32 32 32 32 2 16 0.5 0.75 IATT +/+ 5A,B
E 497 >64 >32 32 32 32 32 2 16 0.19 1 T/ACT +/+ 5A,B
E 498 >64 >32 32 32 16 32 2 16 0.5 1 IATT +/+ 6
E 510 >64 >32 16 32 16 32 2 16 0.125 0.75 IATT +/+ 5A,B
E 511 >64 >32 32 32 32 32 2 16 0.094 1 IATT +/+ 6
6MX4 >64 >32 >32 8 16 8 2 8 0.094 1.5 T/ACT +/+ NT
6MX8 >64 >32 >32 8 16 4 2 8 0.064 1.5 T/ACT +/+ NT
9MX16 >64 >32 32 8 8 4 2 4 0.023 1 T/ACT +/+ NT
9MX32 >64 >32 32 8 8 4 2 4 0.016 0.75 T/ACT +/+ NT
a

NOR, norfloxacin; GRX, grepafloxacin; GMX, gemifloxacin; and CLX, clinafloxacin. 

b

Groups I to IV are fluoroquinolone groups (22). 

c

aa, amino acid; nt, nucleotides. E. coli coordinates are given; boldface indicates mutations leading to amino acid substitution. 

d

NT, not tested. 

e

MIC50s for NOR, CIP, GRX, GAT, GMX, TVA, CLX, MXF, MEO, and VAN are >64, >32, 32, 32, 32, 32, 2, 16, 0.125, and 1 μg/ml, respectively. MIC90s for the same drugs are >64, >32, 32, 32, 32, 32, 2, >32, 0.5, and 1 μg/ml, respectively.