TABLE 1.
Results of MIC testing of B. pertussis isolates with the agar dilution reference method and Etest method on BGA and RL−Ca
| Antimicrobial agent | Growth method
|
Direct suspension method
|
|||
|---|---|---|---|---|---|
| Agar MICs on BGA (n)b | Etest MICs on BGA (n)c | Agar MICs on BGA (n) | Etest MICs on BGA (n) | Etest MICs on RL−C (n) | |
| Erythromycin | ≤0.06 (47) | 0.016 (1) | ≤0.06 (44) | ≤0.06 (47) | <0.016 (2) |
| >256 (4) | 0.03 (15) | 0.12 (3) | >256 (5) | 0.03 (40) | |
| 0.06 (30) | 64 (1) | 0.06 (5) | |||
| 0.12 (1) | >256 (4) | >256 (5) | |||
| >256 (4) | |||||
| Rifampin | ≤0.5 (51) | 0.25 (3) | ≤0.5 (52) | 0.125 (17) | 0.5 (29) |
| 0.5 (44) | 0.25 (19) | 1.0 (22) | |||
| 1.0 (4) | 0.5 (22) | 2.0 (1) | |||
| Chloramphenicol | ≤1.0 (51) | 0.5 (12) | ≤1.0 (52) | 0.25 (19) | 0.5 (26) |
| 1.0 (39) | 0.5 (30) | 1.0 (21) | |||
| 1.0 (3) | 2.0 (5) | ||||
| Trimethoprim-sulfamethoxazoled | ≤0.06 (4) | 0.12 (4) | ≤0.06 (4) | 0.004 (2) | 0.004 (4) |
| 0.12 (47) | 0.25 (40) | 0.12 (47) | 0.015 (16) | 0.06 (5) | |
| 0.5 (7) | 0.25 (1) | 0.03 (3) | 0.12 (28) | ||
| 0.06 (16) | 0.25 (14) | ||||
| 0.125 (15) | 0.5 (1) | ||||
a
MIC values given in micrograms per milliliter.
b
n, number of organisms tested in each category. The California isolate was tested by using the direct suspension method only.
c
Etest MIC results that were between standard doubling dilutions were rounded up to the next highest doubling dilution for analysis.
d
Number refers to the trimethoprim concentration in micrograms per milliliter.