TABLE 3.
Interval antimicrobial resistance profile of clinical L. monocytogenes isolatesa
| Antimicrobial agent | No. (%) of isolates susceptible or resistant during
|
|||||
|---|---|---|---|---|---|---|
| 1955-1966
|
1970-1979
|
1991-1997
|
||||
| Susceptible | Resistant | Susceptible | Resistant | Susceptible | Resistant | |
| Penicillin | 17 (94.4) | 1 (5.6) | 39 (97.5) | 1 (2.5) | 24 (100) | 0 |
| Ampicillin | 4 (100) | 0 | 29 (82.9) | 6 (17.1) | 24 (100) | 0 |
| Erythromycin | 17 (94.4) | 1 (5.6) | 41 (100) | 0 | 24 (100) | 0 |
| Tetracycline | 16 (88.9) | 2 (11.1) | 22 (100) | 0 | 24 (100) | 0 |
| Chloramphenicol | 14 (77.8) | 4 (22.2) | 9 (90) | 1 (10) | 22 (91.7) | 2 (8.3) |
a
During 1955 to 1979 a disc susceptibility test was used (11, 16), and during 1990 to 1997 a microdilution method was employed (13).