Staphylococcus aureus and
coagulase-negative staphylococci are microorganisms most frequently isolated from orthopedic-implant-associated
infections. Their capacity to maintain these
infections is thought to be related to their ability to form adherent biofilms. Poly-N-acetyl-beta-(1,6)-glucosamine (PNAG) is an important constituent of the extracellular biofilm matrix of staphylococci. In the present study, we explored the possibility of using PNAG as an
antigen for detecting
antibodies in the blood sera of patients with staphylococcal orthopedic-
prosthesis-associated
infections. First, we tested the presence of anti-PNAG
antibodies in an animal model, in the blood sera of guinea pigs that developed an implant-associated
infection caused by biofilm-forming, PNAG-producing strains of Staphylococcus epidermidis. Animals infected with S. epidermidis RP62A showed levels of anti-PNAG
immunoglobulin G (
IgG) significantly higher than those of the control group. The comparative study of healthy individuals and patients with staphylococcal
prosthesis-related infections showed that (i) relatively high levels of anti-PNAG
IgG were present in the blood sera of the healthy control group, (ii) the corresponding levels in the infected patients were slightly but not significantly higher, and (iii) only 1 of 10 patients had a level of anti-PNAG
IgM significantly higher than that of the control group. In conclusion, the encouraging results obtained in the animal study could not be readily applied for the diagnosis of staphylococcal orthopedic-
prosthesis-related infections in humans, and PNAG does not seem to be an appropriate
antigen for this purpose. Further studies are necessary to determine whether the developed
enzyme-linked
immunosorbent assay method could serve as a complementary test in the individual follow-up treatment of such
infections caused by PNAG-producing staphylococci.