TABLE 2.
Longitudinal comparison of susceptibility of pneumococcal isolates from 1997-1998 (n = 3.352) and 1999 (n = 3.315)a
| Antimicrobial agent | Yr | % of isolates (% change)b
|
P valuec | MIC (μg/ml)
|
|||
|---|---|---|---|---|---|---|---|
| S (change) | I (change) | R (change) | Mode | 90%f | |||
| Penicillin | 1997-1998 | 65.4 | 21.9 | 12.7 | ≤0.03 | 2 | |
| 1999 | 64.4 (−1.0) | 19.2 (−2.7) | 16.4 (+3.7) | <0.001 | ≤0.06 | 2 | |
| Amoxicillin-clavulanate | 1997-1998 | 83.0 | 8.6 | 8.4 | ≤0.01 | 1 | |
| 1999 | 77.7 (−5.3) | 10 (+1.4) | 12.3 (+3.9) | <0.001 | ≤0.03 | 2 | |
| Cefuroxime | 1997-1998 | 73.6 | 3.4 | 23.0 | ≤0.12 | 4 | |
| 1999 | 69.4 (−4.2) | 1.9 (−1.5) | 28.7 (+5.7) | <0.001 | ≤0.25 | 8 | |
| Ceftriaxone | 1997-1998 | 85.8 | 10.6 | 3.6 | ≤0.01 | 1 | |
| 1999 | 82.4 (−3.4) | 14.1 (+3.5) | 3.5 (−0.1) | 0.809 | ≤0.03 | 1 | |
| Azithromycind | 1997-1998 | 78.0 | 2.9 | 19.1 | ≤0.03 | 4 | |
| 1999 | 74.6 (−3.4) | 3.9 (+1.0) | 21.5 (+2.4) | 0.014 | ≤0.06 | 8 | |
| SXT | 1997-1998 | 69.1 | 15.5 | 15.4 | 0.12 | 4 | |
| 1999 | 62.4 (−6.7) | 6.8 (−8.7) | 30.8 (+15.4) | <0.001 | 0.25 | >4 | |
| Levofloxacin | 1997-1998 | 99.9 | 0 | 0.1 | 0.5 | 1 | |
| 1999 | 99.5 (−0.4) | 0.1 (+0.1) | 0.4 (+0.3) | 0.017 | 0.5 | 1 | |
| Moxifloxacin | 1997-1998 | 99.9 | <0.1 | <0.1 | 0.12 | 0.25 | |
| 1999 | 99.6 (−0.3) | 0.4 (>+0.3) | <0.1 (−0.0)e | 0.670 | 0.12 | 0.12 | |
a
Only data from the 156 laboratories that participated in both studies and submitted a minimum of 10 isolates of pneumococci were included in the longitudinal analysis.
b
Values illustrate the percent change in the susceptible (S), intermediate (I), or resistant (R), population between 1997-1998 and 1999.
c
P values were calculated based on the number of isolates resistant to each antimicrobial in each study period.
d
Erythromycin was the macrolide tested in 1997-1998; azithromycin was tested in 1999.
e
Actual percent change, −0.03%.
f
90%, MIC90.