Volume 5, Number 6—December 1999
Dispatch
Changes in Antimicrobial Resistance among Salmonella enterica Serovar Typhimurium Isolates from Humans and Cattle in the Northwestern United States, 1982–1997
Margaret A. Davis
, Dale D. Hancock, Thomas E. Besser, Daniel H. Rice, John M. Gay, Clive Gay, Lynne Gearhart, and Ronald DiGiacomo
, Dale D. Hancock, Thomas E. Besser, Daniel H. Rice, John M. Gay, Clive Gay, Lynne Gearhart, and Ronald DiGiacomo
Table 1
Resistance to individual antibiotics among Salmonella Typhimurium isolates from cattle and humans
| A. From cattle | ||||
|---|---|---|---|---|
| Number (%) resistant by year |
||||
| 1982-1985a |
1986-1990 |
1991-1994 |
1995-1997 |
|
| Antimicrobial drug |
n = 49 |
n = 116 |
n = 90 |
n = 123 |
| Ampicillin | 39 (79.6) | 99 (85.3) | 72 (80.0) | 113 (91.9) |
| Chloramphenicola | 2 (4.1) | 2 (1.7) | 56 (62.2) | 90 (73.2) |
| Gentamicin | 1 (2.0) | 6 (5.2) | 14 (15.6) | 5 (4.1) |
| Kanamycina | NA | 103 (90.4) | 49 (54.4) | 50 (40.7) |
| Streptomycin | 43 (87.8) | 109 (94.0) | 78 (86.7) | 116 (94.3) |
| Tetracycline | 43 (87.8) | 101 (87.1) | 77 (85.6) | 115 (93.5) |
| Trimethoprim | NA | 1 (0.9) | 11 (12.2) | 6 (4.9) |
| Trimethoprim- | 7 (14.3) | 1 (0.9) | 11 (12.2) | 9 (7.3) |
| sulfamethoxazole | ||||
| Triple sulfa | 39 (79.6) | 108 (93.1) | 75 (83.3) | 117 (95.1) |
| B. From humans | ||||
| Number (%) resistant by year |
||||
| 1989 |
1994 |
1996 |
1997 |
|
| Antimicrobial drug |
n = 90 |
n = 189 |
n = 187 |
n = 249 |
| Ampicillina | 22 (24.4) | 107 (56.6) | 109 (58.3) | 164 (65.9) |
| Chloramphenicola | 3 (3.3) | 84 (44.4) | 92 (49.2) | 116 (46.6) |
| Gentamicin | 2 (2.2) | 5 (2.7) | 5 (2.7) | 2 (0.8) |
| Kanamycin | 25 (27.8) | 44 (23.3) | 34 (18.2) | 47 (18.9) |
| Streptomycina | 42 (46.7) | 112 (59.3) | 109 (58.3) | 174 (69.9) |
| Tetracyclinea | 36 (40.0) | 101 (53.4) | 109 (58.3) | 158 (63.5) |
| Trimethoprim | 0 | 7 (5.1) | 6 (3.1) | 5 (2.0) |
| Trimethoprim- | 0 | 6 (3.7) | 6 (3.2) | 5 (2.0) |
| sulfamethoxazole | ||||
| Triple sulfaa | 36 (40.0) | 123 (65.1) | 143 (76.5) | 231 (92.8) |
aChi-square test for trend, p value <0.001.
NA, data not available.
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