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Table 1 Sensitivity and specificity of BACTEC TM using “gold standard” definition for infection

From: Use of an automated blood culture system (BD BACTEC™) for diagnosis of prosthetic joint infections: easy and fast

Incubation period “Gold standard”infection Cumulative number of patients % correctly identified by culture
Culture + ve Culture -ve Total Sensitivity (95% CI) Specificity (95% CI)
1 day Present 53 26 79 67.1 (55.6-77.3)  
  Absent 1 242 243   99.6 (97.7-100)
2 days Present 64 15 79 81.0 (70.6-89.0)  
  Absent 2 241 243   99.2 (97.1-99.9)
3 days Present 65 14 79 82.3 (72.1-90.0)  
  Absent 3 240 243   98.8 (96.4-99.7)
4 days Present 65 14 79 82.3 (72.1-90.0)  
  Absent 4 239 243   98.4 (95.8-99.5)
5 days Present 65 14 79 82.3 (72.1-09.0)  
  Absent 7 236 243   97.1 (94.2-98.8)
6 days Present 65 14 79 82.3 (72.1-90.0)  
  Absent 7 236 243   97.1 (94.2-98.8)
7 days Present 65 14 79 82.3 (72.1-90.0)  
  Absent 7 236 243   97.1 (94.2-98.8)
8 days Present 66 13 79 83.5 (73.5-90.9)  
  Absent 7 236 243   97.1 (94.2-98.8)
  1. Sensitivity and specificity for each time-point (incubation period) are shown in percentages with 95% confidence intervals. “Culture + ve” refers to patients with 2 or more samples positive with the same organism. “Culture –ve” refers to the rest.