Table 3.
Performance of the PCR-MCA assay for identification of pathogens compared to the results of blood culture.
| Pathogens | Blood culture/PCR-MCA | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | Agreement rate (%) | Kappa value | |||
|---|---|---|---|---|---|---|---|---|---|---|
| +/+a | +/−b | −/+c | −/−d | |||||||
| Pathogens on the PCR-MCA List | ||||||||||
| Gram negative | ||||||||||
| E. coli | 95 | 0 | 1 | 2,748 | 100.00 | 99.96 | 99.00 | 100.00 | 99.96 | 0.995 |
| K. pneumoniae | 38 | 2 | 1 | 2,803 | 95.00 | 99.96 | 97.40 | 99.93 | 99.89 | 0.961 |
| A. baumannii | 9 | 0 | 2 | 2,833 | 100.00 | 99.93 | 81.80 | 100.00 | 99.93 | 0.900 |
| P. aeruginosa | 9 | 0 | 0 | 2,835 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| E. cloacae | 5 | 0 | 0 | 2,839 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| K. oxytoca | 2 | 0 | 0 | 2,842 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| E. aerogenes | 2 | 0 | 0 | 2,842 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| H. parainfluenzae | 1 | 0 | 0 | 2,843 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| Citrobacter | 1 | 0 | 0 | 2,843 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| S. marcescens | 0 | 0 | 0 | 2,844 | n.a. | 100.00 | n.a. | 100.00 | 100.00 | n.a. |
| P. mirabilis | 0 | 0 | 0 | 2,844 | n.a. | 100.00 | n.a. | 100.00 | 100.00 | n.a. |
| Gram positive | ||||||||||
| S. aureus | 22 | 0 | 0 | 2,822 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| S. epidermidis | 16 | 0 | 0 | 2,828 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| S. pneumoniae | 9 | 0 | 1 | 2,834 | 100.00 | 99.96 | 90.00 | 100.00 | 99.96 | 0.947 |
| S. capitis | 7 | 0 | 0 | 2,837 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| E. faecium | 6 | 0 | 0 | 2,838 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| E. faecalis | 6 | 0 | 1 | 2,837 | 100.00 | 99.96 | 85.70 | 100.00 | 99.96 | 0.923 |
| S. dysgalactiae | 3 | 0 | 0 | 2,841 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| S. anginosus | 3 | 0 | 0 | 2,841 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| S. haemolyticus | 2 | 0 | 0 | 2,842 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| S. mutans | 1 | 0 | 0 | 2,843 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| S. pyogenes | 0 | 0 | 0 | 2,844 | n.a. | 100.00 | n.a. | 100.00 | 100.00 | n.a. |
| L. monocytogenes | 0 | 0 | 0 | 2,844 | n.a. | 100.00 | n.a. | 100.00 | 100.00 | n.a. |
| Fungus | ||||||||||
| C. albicans | 8 | 0 | 0 | 2,836 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| C. glabrata | 1 | 0 | 0 | 2,843 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 1.000 |
| C. parapsilosis | 0 | 0 | 0 | 2,844 | n.a. | 100.00 | n.a. | 100.00 | 100.00 | n.a. |
| C. krusei | 0 | 0 | 0 | 2,844 | n.a. | 100.00 | n.a. | 100.00 | 100.00 | n.a. |
| A. fumigatus | 0 | 0 | 0 | 2,844 | n.a. | 100.00 | n.a. | 100.00 | 100.00 | n.a. |
| Pathogens not on the PCR-MCA List | ||||||||||
| Streptococcus constellatus | 0 | 4 | 0 | 2,840 | 0.00 | 100.00 | n.a. | 99.86 | 99.86 | n.a. |
| Burkholderia cepacia | 0 | 3 | 0 | 2,841 | 0.00 | 100.00 | n.a. | 99.89 | 99.89 | n.a. |
| Bacteroides fragilis | 0 | 2 | 0 | 2,842 | 0.00 | 100.00 | n.a. | 99.93 | 99.93 | n.a. |
| Salmonella typhimurium | 0 | 2 | 0 | 2,842 | 0.00 | 100.00 | n.a. | 99.93 | 99.93 | n.a. |
| Staphylococcus hominis | 0 | 2 | 0 | 2,842 | 0.00 | 100.00 | n.a. | 99.93 | 99.93 | n.a. |
| Streptococcus mitis | 0 | 2 | 0 | 2,842 | 0.00 | 100.00 | n.a. | 99.93 | 99.93 | n.a. |
| Aeromonas hydrophila | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Atopobium | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Clostridium difficile | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Corynebacterium striatum | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Enterococcus avium | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Enterococcus casselifavus | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Kingella denitrificans | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Micrococcus | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Non-fermenter | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Staphylococcus cohnii | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Staphylococcus lugdunensis | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Stenotrophomonas maltophilia | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
| Streptococcus intermedius | 0 | 1 | 0 | 2,843 | 0.00 | 100.00 | n.a. | 99.96 | 99.96 | n.a. |
PCR-MCA, real-time polymerase chain reaction coupled with multiplex probe melting curve analysis; PPV, positive predictive value; NPV, negative predictive value; n.a., not applicable.
a
+/+ represents the number of episodes in which both blood culture and PCR-MCA were positive.
b
+/− represents the number of episodes in which blood culture was positive but PCR-MCA was negative.
c
−/+ represents the number of episodes in which blood culture was positive but PCR-MCA was negative.
d
−/− represents the number of episodes in which both blood culture and PCR-MCA were negative.