TABLE 2.

Phenotypic and molecular characteristics of Nalr S. enterica serotype Typhi isolates in Vietnam from 1996 to 2004a

RegionYrNo. of isolatesAntimicrobial resistance patternMICs (mg/liter)Phage typePFGE combined type (XbaI-SpeI)RibotypegyrA mutation(s)
NalCip
South1996-199822ASCTeSulSxtNal (22)64 (1), 128 (4), 256 (15), 1,024 (2)0.125 (1), 0.25 (13), 0.5 (8)UT (13), UVS (6), Evar (2), E1 (1)X3a-S6a (8), X1a-S1a (4), X3a-S9 (1), X3b-S6b (2), X5c-S4 (1), X20-S27 (1), X21-S19a (1), X23-S22 (1), X11a-S5a (1), X11b-S5b (1), X14-S19b (1)3a (17), 341 (1), S007 (1), ND (3)Phe83 (16), Tyr83 (1), ND (5)
1999-200117ASCTeSulSxtNal (16), Nal (1)128 (3), 256 (3), 512 (1), 1,024 (1), >1,024 (9)0.25 (7), 0.5 (10)UVS (6), E1 (5), Evar (4), UT (2)X3a-S6a (4), X1a-S1a (3), X3b-S6b (3), X5a-S4 (1), X5a-S1b (1), X1a-S2 (1), X1b-S1b (1), X17-S17 (1), X18-S18 (1), X19-S1b (1)3a (11), S007 (1), 142 (1), ND (4)Phe83 (11), ND (6)
2002-200431Nal (18), ASCTeSulSxtNal (11), ASTeSulSxtNal (1), CTeTmpNal (1),256 (11), 512 (5), >1,024 (15)0.125 (1), 0.25 (5), 0.5 (25)UT (20), E1 (7), Evar (2), UVS (2),X1b-S1b (16), X1a-S1a (3), X8-S12 (4), X5b-S11 (2), X1b-S5b (1), X3a-S6a (1), X3b-S6b (1), X5c-S15 (1), X6-S1a (1), X9-S13 (1)3a (14), 73/34/8 (4), 177 (2), 23a (1), ND (10)Phe83 (22), ND (9)
Center1996-19980
1999-20015ASCTeSulSxtNal (4), ANal (1)256 (1), >1,024 (4)0.5 (5)UT (3), UVS (2)X3a-S6a (3), X3b-S6b (2)3a (4), ND (1)Phe83 (4), ND (1)
2002-20045ASCTeSulSxtNal (3), Nal (2)256 (1), >1,024 (4)0.25 (1), 0.5 (4)UVS (3), UT (2)X3b-S6b (2), X3b-S7 (1), X1a-S1a (1), X26-S14 (1)3a (4), ND (1)Phe83 (4), ND (1)
North1996-19988ASCTeSulSxtNal (8)1,024 (8)0.06 (1), 0.25 (4), 0.5 (3)E1 (4), Evar (4)X1a-S1a (3), X1b-S1b (1), X24-S24 (1), X5c-S4 (1), X11b-S16 (1), X16-S20 (1),3a (4), S007 (1), 350 (1), 351 (1), ND (1)Phe83 (4), Tyr83 (2), ND (2)
1999-20011ASCTeSulSxtNal1,024 (1)0.25 (1)E1 (1)X1a-S1a (1)3a (1)Phe83 (1)
2002-20042ASCTeSulSxtNal (1), Nal (1)128 (1), >1,024 (1)0.125 (1), 0.5 (1)E1 (2)X1a-S1a (1), X13-S1b (1)3a (2)Phe83 (1), Gly87 (1)
  • a Numbers in parentheses refer to the number of isolates. Abbreviations: UVS, untypeable Vi isolate; UT, not typeable (Vi negative); var, variant; A, amoxicillin; S, streptomycin; C, chloramphenicol; Te, tetracycline; Sul, sulfonamides; Tmp, trimethoprim; Sxt, sulfamethoxazole-trimethoprim; Nal, nalidixic acid; ND, not determined.