TABLE 2.
Molecular- and culture-based microbiological results from 40 patients undergoing cardiac surgery with valve removal
| Method | Correct identification level of the causative pathogen | Causative pathogen in 34 infective endocarditis patients |
Total no. (% of IE patients) | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| S. aureus | Viridans streptococci | Coagulase-negative staphylococci | E. faecalis | P. acnes | C. burnetii | G. adiacens | Unknown | |||
| 16S rRNA PCR | Genus level | 0 | 3 | 1 | 0 | 0 | 0 | 0 | 0 | 4 (12) |
| Species level | 5 | 10a,b | 2 | 3 | 2c | 2 | 1 | 0 | 25 (74) | |
| False negative | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 3 | 5 (14) | |
| PCR-ESI-MS | Genus level | 0 | 6b | 0 | 0 | 0 | 0 | 0 | 0 | 6 (18) |
| Species level | 5 | 6a | 3 | 3 | 2c | 2 | 1 | 0 | 22 (65) | |
| Misidentification | 0 | 1d | 0 | 0 | 0 | 0 | 0 | 1e | 2 (6) | |
| False negative | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 2 | 4 (11) | |
| Blood culture | Growth and identification of causative pathogen | 4 | 12 | 4 | 3 | 0 | 0 | 1 | 0 | 24 (71) |
| Valve culture | Growth and identification of causative pathogen | 3 | 1 | 0 | 1 | 1 | 0 | 0 | 0 | 6 (18) |
| False positive results in six nonendocarditis patients |
Total no. (% of nonendocarditis patients) |
|||||||||
| 16S rRNA PCR | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 (17) | |
| PCR-ESI-MS | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 (17) | |
| Blood culture | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 (17) | |
| Valve culture | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 (0) | |
a
Both molecular techniques detected S. gallolyticus in one case of culture-negative infective endocarditis.
b
Both molecular techniques detected viridans Streptococcus spp. in one case of culture-negative infective endocarditis.
c
Both molecular techniques detected P. acnes in one case of culture-negative infective endocarditis.
d
This pathogen was identified as an Enterococcus spp.
e
This pathogen was identified as P. acnes (it is unknown if this is a misidentification or true-positive result).