TABLE 3.
Etest results for all Bacillus species tested
| Antibiotic | Species | No. of isolates | MIC (μg/ml)
|
Breakpointsa
|
Interpretation (%)b
|
|||||
|---|---|---|---|---|---|---|---|---|---|---|
| Range | 50% | 90% | S (≤) | R (≥) | S | I | R | |||
| Amoxicillin-clavulanic acid | B. anthracis | 48c | 0.016-0.5 | 0.032g | 0.047 | 4 | 8 | 100 | ||
| B. cereus | 67 | 0.5-64 | 8 | 12 | 22 | 18 | 60 | |||
| B. thuringiensis | 12 | 4-96 | 12 | 24 | 8 | 8 | 84 | |||
| B. mycoides | 4 | 8-24 | 8 | 24 | 100 | |||||
| S. aureus 29213 | 0.4 (0.25-1)d | |||||||||
| Azithromycin | B. anthracis | 73 | 1-12 | 3 | 6 | 2a | 8a | 26 | 64 | 10 |
| B. cereus | 67 | 0.094-6 | 0.38 | 3 | 84 | 16 | ||||
| B. thuringiensis | 12 | 0.094-3 | 0.19 | 3 | 84 | 16 | ||||
| B. mycoides | 4 | 0.19-0.38 | 0.19 | 0.38 | 100 | |||||
| S. aureus 29213 | 1.5 (1.5-4)d | |||||||||
| Cefotaxime | B. anthracis | 76 | 3->32 | >32 | >32 | 8a | 64a | 1 | 1 | 98e |
| B. cereus | 67 | 0.1->32 | >32 | >32 | 29 | 71e | ||||
| B. thuringiensis | 12 | >32 | >32 | >32 | 100e | |||||
| B. mycoides | 4 | >32 | >32 | >32 | 100e | |||||
| S. aureus 29213 | 2 (1.5-2)d | |||||||||
| Ciprofloxacin | B. anthracis | 76 | 0.032-0.094 | 0.064 | 0.094 | 0.5f | 100 | |||
| B. cereus | 67 | 0.047-0.5 | 0.19 | 0.25 | 1a | 4a | 100 | |||
| B. thuringiensis | 12 | 0.094-0.19 | 0.125 | 0.19 | 100 | |||||
| B. mycoides | 4 | 0.125-0.25 | 0.125 | 0.25 | 100 | |||||
| S. aureus 29213 | 0.5 (0.25-0.5)d | |||||||||
| Erythromycin | B. anthracis | 69 | 0.5-4 | 1 | 1.5 | 0.5a | 8a | 15 | 85 | |
| B. cereus | 67 | 0.032-3 | 0.064 | 1.5 | 78 | 21 | 1 | |||
| B. thuringiensis | 12 | 0.032-1 | 0.094 | 1 | 84 | 16 | ||||
| B. mycoides | 5 | 0.064-0.38 | 0.125 | 0.25 | 100 | |||||
| S. aureus 29213 | 0.38 (0.25-0.5)d | |||||||||
| Gentamicin | B. anthracis | 75 | 0.064-0.5 | 0.25 | 0.38 | 4a | 16a | 100 | ||
| B. cereus | 67 | 0.094-0.75 | 0.38 | 0.75 | 100 | |||||
| B. thuringiensis | 12 | 0.047-0.5 | 0.19 | 0.5 | 100 | |||||
| B. mycoides | 5 | 0.19-0.38 | 0.25 | 0.25 | 100 | |||||
| S. aureus 29213 | 0.8 (0.5-1.5)d | |||||||||
| Penicillin | B. anthracis | 74c | <0.016-≥32 | <0.016 | 0.023 | 0.12af | 0.25af | 97 | 3 | |
| B. cereus | 67 | 0.012->32 | >32 | >32 | 1 | 99 | ||||
| B. thuringiensis | 12 | >32 | >32 | >32 | 100 | |||||
| B. mycoides | 4 | >32 | >32 | >32 | 100 | |||||
| S. aureus 29213 | 0.4 (0.25-0.38)d | |||||||||
| Tetracycline | B. anthracis | 71 | 0.016-0.094 | 0.023 | 0.032 | 1 | 100 | |||
| B. cereus | 67 | 0.05-32 | 1 | 6 | 4a | 16a | 84 | 9 | 6 | |
| B. thuringiensis | 12 | 0.5-24 | 2 | 6 | 84 | 8 | 8 | |||
| B. mycoides | 4 | 0.125-2 | 0.5 | 2 | 100 | |||||
| S. aureus 29213 | 0.17 (0.094-0.38)d | |||||||||
| Vancomycin | B. anthracis | 74 | 0.75-5 | 2 | 3 | 4a | 32a | 99 | 1 | |
| B. cereus | 67 | 1-16 | 3 | 6 | 85 | 15 | ||||
| B. thuringiensis | 12 | 0.75-4 | 2 | 4 | 100 | |||||
| B. mycoides | 4 | 1.5-4 | 2 | 100 | ||||||
| S. aureus 29213 | 1.8 (1.5-2)d | |||||||||
NCCLS MIC interpretive standards for gram-positive and/or aerobic bacteria (NCCLS documents M100-S6, M7-A3, and M11-A3 [1995]; M100-S7, M7-A4, and M11-A3 [1997]; M100-S8 and M7-A4 [1998], and M100-S9 and M7-MIC [1999]), as given in the manufacturer's insert.
S, susceptible; I, intermediate; R, resistant.
Penicillin-resistant cultures ASC 32, ASC 70, and ASC 183 are treated here as one strain.
The values given for S. aureus ATCC 29213 are the means and ranges of 5 to 7 repeat tests.
Resistance inferred. The highest level on the strips used was 32 μg/ml.
NCCLS approved standard M100-S13 (27). No tetracycline- or ciprofloxacin-resistant strains were available for establishing the standards; only susceptible breakpoints were established for these drugs.
MIC at which 50% of the isolates tested are inhibited.