Table 2.
Antimicrobial susceptibility of 128 S. pneumoniae isolates from middle ear fluids and trends in antibiotic nonsusceptibility divided in two periods depending on year of strain isolation
|
Antibiotics |
MICs (μg/mL) |
Overall% susceptibility n = 128 |
NS rates in 1994–2005 n = 49 |
NS rates in 2006-2011n = 79 |
|||
|---|---|---|---|---|---|---|---|
| MIC50/90 | MIC range | S | I | R | % | % | |
| Penicillin |
0.12/4.0 |
0.01 - 8.0 |
31.2 |
40.6 |
28.1 |
73.5 |
65.8 |
| Amoxicillin |
0.12/4.0 |
0.01 - 8.0 |
89.1 |
6.2 |
4.7 |
8.2 |
12.7 |
| Cefuroxime sodium |
≤0.5/8.0 |
≤0.5- ≥ 16.0 |
63.3 |
5.5 |
31.2 |
28.6 |
41.8 |
| Ceftriaxone |
0.06/1.0 |
0.03-4.0 |
93.0 |
4.7 |
2.3 |
4.1 |
8.9 |
| Erythromycin |
≤0.25/≥64.0 |
≤0.25- ≥ 64.0 |
53.1 |
0.0 |
46.9 |
36.7 |
53.2 |
| Clindamycin |
0.06/≥64.0 |
0.01- ≥ 64.0 |
66.4 |
0.8 |
32.8 |
22.4 |
40.5 |
| Levofloxacin |
1.0/1.0 |
0.5 - 2.0 |
100.0 |
0.0 |
0.0 |
0.0 |
0.0 |
| Tetracycline |
2.0/≥8.0 |
0.25- ≥ 8.0 |
50.8 |
0.8 |
48.4 |
46.9 |
50.6 |
| Chloramphenicol |
4.0/≥8.0 |
0.5- ≥ 8.0 |
84.4 |
- |
15.6 |
24.5 |
10.1 |
| Trimeth/Sulfameth | 2.0/≥4.0 | 0.06- ≥ 4.0 | 35.2 | 22.7 | 42.2 | 65.3 | 64.6 |
MICs-minimal inhibitory concentracions; MIC50/90, MICs for 50% and 90% of the isolates, respectively; R-resistant; I-intermediate; S-susceptible (Interpretation according to CLSI, 2010); NS- nonsusceptibility; The following breakpoints (μg/mL) for penicillin (oral penicillin V) were used: susceptible ≤ 0.06; intermediate ≥ 0.12 - 1.0; resistant ≥ 2; Trimethoprim/Sulfamethoxazole (1:19 ratio), MIC refers to trimethoprim value.