TABLE 1.
Pneumococcal isolates collected as part of national sentinel surveillance for invasive pneumococcal disease, 1978 to 2001
| Years | No. of hospitals that reported cases | No. of cases reported | No. of isolates tested for susceptibility to penicillin | % of isolates nonsusceptible to penicillin (% of isolates resistant to penicillin)a | % of isolates with very-high-level resistance to penicillinb |
|---|---|---|---|---|---|
| 1978-1979 | 40 | 1,059 | 592 | 1 (0) | 0 |
| 1980-1984 | 49 | 3,765 | 3,041 | 4 (0) | 0 |
| 1985-1989 | 52 | 4,566 | 2,162 | 3 (0) | 0 |
| 1990-1994 | 38 | 4,003 | 1,372 | 11 (2) | 0 |
| 1995-1999 | 34 | 2,822 | 608 | 18 (7) | 0 |
| 2000-2001 | 9 | 418 | 87 | 8 (1) | 0 |
| Total | 103 | 16,633 | 7,862 | 6 (1) | 0 |
a
Nonsusceptibility to penicillin was defined as intermediate susceptibility or resistance according to NCCLS 2003 breakpoints (23); for strains resistant to penicillin the MIC was ≥2 μg/ml.
b
Very-high-level penicillin resistance was defined as a minimum inhibitory concentration of ≥8 μg/ml.