TABLE 2.
Evolution of antibiotic resistance in Salmonella serotypes (1985–1987 and 1995–1998)
| Serotype and period | No. of strains | No. (%) of resistant strainsa
|
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| AMP | AMC | CTX | CHL | TET | SXT | GEN | NAL | CIP | ||
| Enteritidis | ||||||||||
| 1985–1987 | 648 | 56 (9) | 3 (0.5) | 0 (0) | 1 (0.1) | 1 (0.1) | 0 (0) | 1 (0.1) | 1/435e (0.2) | 0 (0) |
| 1995–1998 | 382 | 79 (21) | 0 (0) | 0 (0) | 0 (0) | 21 (5) | 3 (0.8) | 6 (1.6) | 21 (5) | 1 (0.3) |
| Typhimurium | ||||||||||
| 1985–1987 | 79 | 4 (5) | 1 (1.3) | 0 (0) | 5 (6) | 1 (1.3) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| 1995–1998 | 275 | 233 (85) | 41 (15) | 0 (0) | 191 (69) | 244 (89) | 61 (22) | 16 (6) | 3 (1.1) | 0 (0) |
| Hadar | ||||||||||
| 1985–1987 | 7 | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| 1995–1998 | 44 | 24 (55) | 2 (4.5) | 0 (0) | 0 (0) | 42 (95) | 2 (4.5) | 0 (0) | 38 (86) | 0 (0) |
| Virchow | ||||||||||
| 1985–1987 | 90 | 8 (9) | 0 (0) | 0 (0) | 6 (7) | 0 (0) | 1 (1) | 6 (7) | 0 (0) | 0 (0) |
| 1995–1998 | 15 | 2 (13) | 0 (0) | 1b (7) | 0 (0) | 0 (0) | 1 (7) | 1 (7) | 7 (47) | 0 (0) |
| Brandenburg | ||||||||||
| 1985–1987 | 13 | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| 1995–1998 | 13 | 9 (69) | 0 (0) | 0 (0) | 10 (77) | 10 (77) | 10 (77) | 4 (31) | 8 (62) | 0 (0) |
| Other serotypes | ||||||||||
| 1985–1987c | 238 | 16 (7) | 1 (0.4) | 0 (0) | 6 (2.5) | 9 (4) | 4 (1.7) | 0 (0) | 0 (0) | 0 (0) |
| 1995–1998d | 103 | 23 (22) | 5 (5) | 0 (0) | 14 (14) | 31 (30) | 18 (17) | 0 (0) | 11 (11) | 1 (1) |
| Total (all serotypes) | ||||||||||
| 1985–1987 | 1,075 | 84 (8) | 5 (0.5) | 0 (0) | 18 (1.7) | 11 (1) | 5 (0.5) | 7 (0.7) | 1/684f (0.1) | 0 (0) |
| 1995–1998 | 832 | 370 (44) | 48 (6) | 1b (0.1) | 215 (26) | 348 (42) | 95 (11) | 27 (3) | 88 (11) | 2 (0.2) |
Abbreviations AMC, co-amoxiclav; AMP, ampicillin; CHL, chloramphenicol; CTX, cefotaxime; CIP, ciprofloxacin; GEN, gentamicin; NAL, nalidixic acid; TET, tetracycline; SXT, trimethoprim-sulfamethoxazole.
Extended-spectrum beta-lactamase-producing strain.
The number of strains of each serotype was as follows: Blockley, 35; Bredeney, 23; Infantis, 16; Heidelberg, 11; Ohio, 10; Panama, 9; Newport, 8; Goldcoast and London, 7 each; Anatum and Sofia, 4 each; Mikawasima, Montevideo, and Tilburg, 3 each; Saintpaul, Kapemba, and Livingstone, 2 each; Agona, Newbrunswik, Litchfield, Hindmarsh, Newington, Richmond, Goettingen, Muenchen, Derby, Give, and Tournai, 1 each; untypeable or not typed, 78.
The number of strains of each serotype was as follows: Infantis, 9; Muenchen, 6; Ohio, 5; Newport, Heidelberg, Grumpensis, and Derby, 4 each; Bredeney, Mbandaka, and Braenderup, 3 each; Saintpaul, Litchfield, Mikawasima, Richmond, Goldcoast, Give, Bradford, Albany, Oranienburg, Toulon, Washington, Rissen, and Rideau, 2 each; Blockley, London, Agona, Anatum, Kapemba, Goettingen, Tshiongwe, Indiana, Singapore, Nima, Havana, and Tambacounda, 1 each; untypeable or not typed, 20.
Only 435 of the 648 strains were tested for nalidixic acid.
Only 684 of the 1,075 strains were tested for nalidixic acid.