TABLE 2.
Times to detection of aerobic BC positivity for BacT/Alert and Bactec culture bottlesa
| Microorganism(s) | No. of isolates | Times to detection (h) of aerobic BC positivity in: |
Pb | |||
|---|---|---|---|---|---|---|
| BacT/Alert bottles |
Bactec bottles |
|||||
| Median | Mean (IQRs) | Median | Mean (IQRs) | |||
| Monomicrobial cultures | 90 | 12.4 | 14.7 (8.2–19.9) | 12.3 | 15.4 (8.2–19.7) | NS |
| Gram-negative | 48 | 10.8 | 12.1 (7.0–15.3) | 10.2 | 12.7 (6.6–14.1) | NS |
| Escherichia coli | 17 | 6.5 | 6.8 (5.6–8.1) | 6.0 | 8.5 (4.3–9.0) | NS |
| Klebsiella pneumoniae | 10 | 10.8 | 10.8 (8.9–12.2) | 10.7 | 10.7 (8.3–13.1) | NS |
| Morganella morganii | 2 | 7.8 | 7.8 | 8.3 | 8.3 | NA |
| Pseudomonas aeruginosa | 19 | 17.3 | 18.0 (13.4–18.2) | 15.3 | 18.0 (12.2–21.2) | NS |
| Gram positive | 36 | 14.0 | 16.1 (10.7–22.0) | 14.8 | 16.5 (9.8–24.2) | NS |
| Enterococcus faecalis | 1 | 21.1 | 21.1 | NA | 15.6 | NA |
| Staphylococcus aureus | 14 | 10.8 | 10.8 (8.2–12.1) | 9.4 | 9.7 (7.9–12.7) | NS |
| Coagulase negative staphylococci | 16 | 19.9 | 21.6 (15.1–24.2) | 25.0 | 22.7 (16.9–28.6) | 0.003 |
| Streptococcus anginosus | 2 | 21.7 | 21.7 | 18.3 | 18.3 | NS |
| Streptococcus constellatus | 1 | NA | 21.4 | NA | 20.4 | NA |
| Streptococcus pneumoniae | 2 | 12.3 | 12.3 | 11.4 | 11.4 | NA |
| Yeasts | 6 | 21.8 | 23.3 (12.5–28.4) | 26.9 | 30.8 (14.5–51.3) | NS |
| Candida albicans | 4 | 22.4 | 28.4 (15.6–47.3) | 17.4 | 20.4 (13.1–30.7) | NS |
| Candida tropicalis | 2 | 27.7 | 27.7 | 52.0 | 51.6 | NA |
| Polymicrobial cultures | 12 | 15.2 | 21.5 (7.9–32.4) | 17.2 | 18.5 (7.2–28.5) | NS |
| Total isolates | 102 | 12.4 | 15.1 (8.3–20.8) | 12.3 | 15.6 (8.1–20.8) | NS |
| Treatment positive | 31 | 18.0 | 19.8 (10.2–25.4) | 15.2 | 18.7 (8.9–26.0) | NS |
| Treatment negative | 71 | 12.0 | 13.2 (8.0–18.0) | 12.1 | 14.3 (8.1–20.4) | NS |
a
Analysis was limited to the 192 aerobic bottles in which BacT/Alert and Bactec BC yields were concordant at the species level. The terms treatment negative and treatment positive refer to cultures drawn before and after initiation of empirical antimicrobial therapy, respectively (see Materials and Methods). Abbreviations: BC, blood culture; IQR, interquartile range (calculated only when ≥5 isolates were evaluated); NA, not applicable; NS, not significant (P > 0.05).
b
Statistical significance of differences between mean TTDs for BacT/Alert and Bactec bottles (Wilcoxon matched-pairs signed-rank test).