Volume 5, Number 6—December 1999
Synopsis
Antimicrobial Resistance with Streptococcus pneumoniae in the United States, 1997–98
Gary V. Doern
, Angela B. Brueggemann, Holly Huynh, Elizabeth Wingert, and Paul Rhomberg
, Angela B. Brueggemann, Holly Huynh, Elizabeth Wingert, and Paul Rhomberg
Table 1
In vitro activity of 23 antimicrobial agents for 1,601 isolates of Streptococcus pneumoniae
| Antimicrobial agent | Penicillin-susceptible strains (n = 1,127) |
Penicillin-intermediate strains (n = 278) |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| MIC50 | MIC90 | MIC range | % I | % R | MIC50 | MIC90 | MIC range | % I | % R | ||
| Penicillin | 0.015 | 0.03 | <0.004 - 0.06 | -- | -- | 0.5 | 1 | 0.12 - 1 | -- | -- | |
| Amoxicillin | 0.015 | 0.03 | <0.004 - 0.12 | 0.0 | 0.0 | 0.5 | 2 | 0.015 - 4 | 34.5 | 14 | |
| Amox/clav | 0.015 | 0.03 | <0.004 - 0.12 | 0.0 | 0.0 | 0.5 | 2 | 0.015 - 4 | 31.7 | 16.9 | |
| Ceftriaxone | 0.015 | 0.03 | <0.008 - 0.5 | 0.0 | 0.0 | 0.5 | 1 | 0.015 - 4 | 20.1 | 0.7 | |
| Cefuroxime | 0.03 | 0.12 | <0.015 - 2 | 0.2 | 0.1 | 2 | 4 | 0.12 - 8 | 6.8 | 55.8 | |
| Cefpodoxime | 0.03 | 0.06 | <0.015 - 4 | – | – | 1 | 4 | 0.03 - 8 | -- | -- | |
| Cefprozil | 0.06 | 0.12 | <0.03 - 1 | – | – | 2 | 8 | 0.06 - 16 | – | – | |
| Cefixime | 0.25 | 0.5 | <0.06 - 16 | – | – | 8 | 16 | 0.25 - 32 | – | – | |
| Loracarbef | 0.5 | 1 | <0.06 - 4 | – | – | 16 | 128 | 0.25 - >128 | – | – | |
| Cefaclor | 0.5 | 2 | <0.06 - 2 | – | – | 8 | 64 | 0.12 - >128 | – | – | |
| Ceftibuten | 4 | 8 | <0.25 - >64 | – | – | 64 | >64 | 4 - >64 | – | – | |
| Clarithromycin | <0.03 | <0.03 | <0.03 - >64 | 0.5 | 5.2 | <0.03 | >64 | <0.03 - >64 | 2.2 | 35.3 | |
| Erythromycin | 0.06 | 0.06 | <0.03 - >64 | 0.3 | 5.7 | 0.06 | >64 | <0.03 - >64 | 0.7 | 37.4 | |
| Azithromycin | 0.06 | 0.12 | <0.03 - >64 | 0.2 | 5.6 | 0.12 | >64 | <0.03 - >64 | 0.7 | 37.8 | |
| Clindamycin | 0.06 | 0.06 | <0.008 - >8 | 0.1 | 1.1 | 0.06 | >8 | <0.008 - 8 | 0.0 | 12.9 | |
| Trovafloxacin | 0.06 | 0.12 | 0.015 - 8 | 0.0 | 0.2 | 0.06 | 0.12 | 0.015 - 0.25 | 0.0 | 0.0 | |
| Tetracycline | 0.12 | 0.25 | <0.03 - 64 | 0.2 | 2.5 | 0.25 | 32 | <0.03 - >64 | 0.7 | 27.7 | |
| TMP/SMX | 0.12 | 1 | 0.06 - 32 | 6.5 | 5.9 | 2 | 8 | <0.03 - >32 | 19.8 | 42.4 | |
| Chloramphenicol | 2 | 4 | <0.5 - 16 | – | 0.8 | 4 | 16 | <0.05 - 16 | – | 11.9 | |
| Rifampin | <0.12 | <0.12 | <0.12 - 0.5 | 0.0 | 0.0 | <0.12 | <0.12 | <0.12 - 2 | 0.7 | 0.0 | |
| Linezolida | 1 | 2 | 0.12 - 2 | – | – | 1 | 2 | 0.25 - 2 | – | – | |
| Quin/dalfo | 0.25 | 0.5 | 0.06 - 8 | 0.0 | 0.2 | 0.25 | 0.5 | 0.06 - 1 | 0.0 | 0.0 | |
| Vancomycin | 0.25 | 0.5 | 0.03 - 0.5 | 0.0 | 0.0 | 0.25 | 0.5 | 0.06 - 0.5 | 0.0 | 0.0 | |
| Antimicrobial | Penicillin-resistant strains
(n = 196) |
All strains
(n = 1,601) |
|||||||||
| agent |
MIC50 |
MIC90 |
MIC range |
% I |
% R |
MIC50 |
MIC90 |
MIC range |
% I |
% R |
|
| Penicillin | 2 | 4 | 2 - 8 | -- | -- | 0.015 | 2 | <0.004 - 8 | 17.4 | 12.1 | |
| Amoxicillin | 2 | 8 | 1 - 8 | 9.7 | 90.3 | 0.03 | 2 | <0.004 - 8 | 7.2 | 13.5 | |
| Amox/clav | 2 | 8 | 1 - 8 | 6.6 | 93.4 | 0.03 | 2 | <0.004 - 8 | 6.3 | 14.4 | |
| Ceftriaxone | 1 | 2 | 0.5 - 8 | 68.4 | 31.6 | 0.03 | 1 | <0.008 - 8 | 10.9 | 4 | |
| Cefuroxime | 4 | 8 | 2 - 32 | 0.0 | 100 | 0.03 | 4 | <0.015 - 32 | 1.3 | 22 | |
| Cefpodoxime | 4 | 8 | 1 - >32 | -- | -- | 0.06 | 4 | <0.05 - >32 | – | -- | |
| Cefprozil | 8 | 16 | 2 - 64 | – | – | 0.12 | 8 | <0.03 - 64 | – | -- | |
| Cefixime | 32 | 64 | 2 - 128 | – | – | 0.25 | 16 | <0.06 - 128 | – | -- | |
| Loracarbef | 128 | >128 | 32 - >128 | – | – | 1 | 128 | <0.06 - >128 | – | -- | |
| Cefaclor | 128 | >128 | 16 - >128 | – | – | 0.5 | 64 | <0.06 - >128 | – | -- | |
| Ceftibuten | >64 | >64 | <16 - >64 | – | – | 44 | >64 | <0.25 - >64 | – | – | |
| Clarithromycin | 2 | >64 | <0.03 - >64 | 3.6 | 64.8 | <0.03 | 4 | <0.03 - >64 | 1.2 | 17.7 | |
| Erythromycin | 4 | >64 | <0.03 - >64 | 0.5 | 68.4 | 0.06 | 8 | <0.03 - >64 | 0.4 | 18.9 | |
| Azithromycin | 8 | >64 | <0.03 - >64 | 1.5 | 67.3 | 0.12 | 16 | <0.03 - >64 | 0.4 | 18.7 | |
| Clindamycin | 0.06 | >8 | <0.008 - >8 | 0.5 | 21.4 | 0.06 | 0.06 | <0.008 - >8 | 0.1 | 5.6 | |
| Trovafloxacin | 0.06 | 0.12 | 0.03 - 4 | 0.5 | 0.5 | 0.06 | 0.12 | 0.015 - 8 | 0.1 | 0.2 | |
| Tetracycline | 16 | 32 | 0.06 - 64 | 0.5 | 51.5 | 0.12 | 16 | <0.03 - >64 | 0.3 | 12.9 | |
| TMP/SMX | 4 | 16 | 0.06 - 32 | 21.9 | 71.9 | 0.25 | 4 | <0.03 - 32 | 10.7 | 20.4 | |
| Chloramphenicol | 4 | 16 | <0.5 - >16 | – | 37.2 | 2 | 4 | <0.5 - >16 | – | 7.2 | |
| Rifampin | <0.12 | <0.12 | <0.12 - >4 | 0.0 | 0.5 | <0.12 | <0.12 | <0.12 - >4 | 0.1 | 0.1 | |
| Linezolid | 1 | 2 | 0.5 - 2 | – | – | 1 | 2 | 0.12 - 2 | – | -- | |
| Quin/dalfo | 0.25 | 0.5 | 0.12 1 | 0.0 | 0.0 | 0.25 | 0.5 | 0.06 - 8 | 0.0 | 0.1 | |
| Vancomycin | 0.25 | 0.5 | 0.06 - 0.5 | 0.0 | 0.0 | 0.25 | 0.5 | 0.03 - 0.5 | 0.0 | 0.0 | |
aBecause of the lack of NCCLS breakpoints for linezolid, resistance rates were not determined.
Amox/clav, amoxicillin/clavulanate; TMP/SMX, trimethoprim/sulfamethoxazole; Quin/dalfo, quinupristin/dalfopristin.
MIC, minimum inhibitory concentration; I, intermediate resistance; R, resistant.
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