Serological tests in the differentiation of staphylococcal and tuberculous bone disease

Spondylodiscitis: update on diagnosis and management

Spondylodiscitis, a term encompassing vertebral osteomyelitis, spondylitis and discitis, is the main manifestation of haematogenous osteomyelitis in patients aged over 50 years. Staphylococcus aureus is the predominant pathogen, accounting for about half of non-tuberculous cases. Diagnosis is difficult and often delayed or missed due to the rarity of the disease and the high frequency of low back pain in the general population. In this review of the published literature, we found no randomized trials on treatment and studies were too heterogeneous to allow comparison. Improvements in surgical and radiological techniques and the discovery of antimicrobial therapy have transformed the outlook for patients with this condition, but morbidity remains significant. Randomized trials are needed to assess optimal treatment duration, route of administration, and the role of combination therapy and newer agents.

Antibody response to teichoic acid and peptidoglycan in Staphylococcus aureus osteomyelitis

An enzyme-linked immunosorbent assay was used to evaluate the immunoglobulin G (IgG) response to Staphylococcus aureus crude teichoic acid (TA) and peptidoglycan (PG) in both rabbits and patients with osteomyelitis. In rabbits with experimental S. aureus osteomyelitis, elevated levels of IgG to TA were present in 13/18 (72%) of the serum samples obtained at 4 and 10 weeks postinfection. In contrast, only 5/18 (28%) of these sera were found to be positive for antibodies to PG. Of a total of 39 patients with confirmed S. aureus osteomyelitis (11 acute, 28 chronic), IgG to TA was elevated in 17 (44%), whereas antibodies to PG were found to be increased in only 1 (3%). Cross-reacting antibodies to S. aureus TA were detected in only 1/18 (6%) of the patients with osteomyelitis caused by organisms other than S. aureus. These studies indicate that IgG to TA is more prevalent than IgG to PG in patients with staphylococcal osteomyelitis. Although these results are encouraging, a larger number of patients is required for an adequate evaluation of the TA enzyme-linked immunosorbent assay for the diagnosis and management of suspected S. aureus osteomyelitis.

Enzyme-linked immunosorbent assay for detection of antibodies to Staphylococcus aureus cell walls in experimental osteomyelitis

An enzyme-linked immunosorbent assay was used to evaluate and compare the immunoglobulin G antibody response to Staphylococcus aureus cell walls of rabbits with either chronic staphylococcal osteomyelitis or subcutaneous abscesses. Osteomyelitis of the femur was produced by the intramedullary application of a sclerosing agent (3% sodium tetradecyl sulfate) and S. aureus. Radiographic evidence of osteomyelitis was observed in 10 of the 13 animals that survived the 10-week experimental period, and the diagnosis was confirmed by histopathology in 8 of the 10 instances. Abscess formation was initiated in a separate group of rabbits by the subcutaneous injection of S. aureus cells. All 10 of these rabbits subsequently developed abscesses, which usually resolved spontaneously within 3 to 5 weeks. Elevated levels of immunoglobulin G antibodies to the cell wall antigen were detected in 7 of 10 rabbits with osteomyelitis at 21 days postinfection, and these animals continued to display high antibody levels even at 59 days postinfection. In contrast, elevated levels of anti-cell-wall antibodies were only detected in 1 of 10 rabbits with subcutaneous abscesses. The enzyme-linked immunosorbent assay was found to be a rapid and sensitive serological technique for the detection of cell wall antibodies in this experimental osteomyelitis model and may be useful for the diagnosis of staphylococcal bone infections in humans.

Assay of teichoic acid antibodies and antistaphylolysin in the diagnosis of Staphylococcal osteomyelitis

Teichoic acid antibodies (TAA), measured by gel diffusion, and antistaphylolysin (ASa) values were determined in 46 osteomyelitis patients and 200 healthy controls. A positive TAA titer (greater than or equal to 4) was seen in 4/16 patients with acute hematogenous osteomyelitis caused by Staphylococcus aureus and in 7/22 patients with chronic staphylococcal osteomyelitis, while ASta was positive (greater than or equal to 2.0 IU/ml) in 9 patients in both groups all except 2 exceeding 4.0 IU/ml. No positive TAA titres or ASta values were seen in 8 patients with chronic nonstaphylococcal osteomyelitis. The rate of positive test results in 200 controls was 7% for TAA and 4% for ASta. Basing diagnosis on a positive value in either of the tests gave 21 positive results in 38 patients with staphylococcal osteomyelitis; 18 by ASta alone and 11 by TAA alone. Both tests were positive at the same time in 3 patients with acute and in 5 patients with chronic staphylococcal osteomyelitis but never in controls.

Anti-staphylococcal gamma hemolysin antibodies in rabbits with staphylococcal osteomyelitis

Titers of antibodies against staphylococcal gamma hemolysin were estimated in 23 rabbits with experimental staphylococcal osteomyelitis and in 32 control animals. In all but three infected animals from 2- to 64-fold increases of the antibody titers were detected. Most of the control animals showed no changes in anti-gamma toxin antibody titers, but in two animals some increase was noted. The possible significance of these differences is discussed.