TABLE 1.
Comparison of titers of IgM antibodies against SSPA, expressed as ELISA units, in sera from subjects with an ongoing staphylococcal late-onset infection of orthopedic prostheses and in controls
| Group (no. of samples) | Mean (SD) IgM titer (EU) | % (no.) of positive tests for an IgM titer: |
|
|---|---|---|---|
| ≥0.35 EU | ≥0.40 EU | ||
| Prosthesis infectiona (29) | 0.72 (0.55) | 89.7 (26) | 69.0 (20) |
| Prosthesis, no infection (34) | 0.21 (0.09)b | 8.8 (3) | 5.9 (2) |
| No prosthesis, no infection (27) | 0.20 (0.05)b | 0 (0) | 0 (0) |
| All controls (61) | 0.21 (0.07)b | 4.9 (3) | 3.3 (2) |
a
Prosthesis infection is defined by subjects with an ongoing prosthetic infection caused by Staphylococcus epidermidis (n = 15), Staphylococcus aureus (n = 8), coagulase-negative staphylococci other than S. epidermidis (n = 2), and mixed infection by one or more staphylococcal species plus enterococci, Pseudomonas aeruginosa, or Escherichia coli (n = 4).
b
P < 0.001 versus infected subjects (Kruskal-Wallis test).