Antibacterial Effect of a 4x Cu-TiO2 Coating Simulating Acute Periprosthetic Infection-An Animal Model.

The purpose of our study was to investigate the antibacterial effect of a spacer (Ti6Al4V) coated with 4x Cu-TiO2 in an animal model simulating an acute periprosthetic infection by Staphylococcus aureus. Ti6Al4 bolts contaminated with Staphylococcus aureus were implanted into the femoral condyle of rabbits (n = 36) divided into 3 groups. After one week in group 1 (control) the bolts were removed without any replacement. In group2 Ti6Al4V bolts with a 4x Cu-TiO2 coating and in group 3 beads of a gentamicin-PMMA chain were imbedded into the borehole. Microbiological investigation was performed at the primary surgery, at the revision surgery and after scarification of the rabbits 3 weeks after the first surgery. Blood tests were conducted weekly. The initial overall infection rate was 88.9%. In group 2 and 3 a significant decrease of the infection rate was shown in contrast to the control group. The C-reactive protein (CRP) levels declined one week after the first surgery except in the control group where the CRP level even increased. This is the first in vivo study that demonstrated the antibacterial effects of a fourfold Cu-TiO2 coating. For the future, the coating investigated could be a promising option in the treatment of implant-associated infections.

A typically atypical tenosynovitis.

A 68-year-old woman developed tenosynovitis of the right second digit without a history of injury or animal bites. Apart from high titer anti-nuclear antibodies, serological studies were unremarkable. Tuberculin test and interferon gamma release assay were both negative. Several immunosuppressive therapies led only to partial relief of symptoms. Of note, clinical symptoms worsened significantly after introduction of adalimumab therapy. Tenosynovectomy was performed revealing a granulomatous inflammatory process. Seven weeks later, Mycobacterium malmoense could be cultured from the surgical specimen. A four drug antibiotic regimen was started and immunosuppressive therapy discontinued resulting in complete clinical remission. Our case highlights non-tuberculous mycobacterial (NTM) tenosynovitis as an important differential diagnosis of atypical arthritis. A negative tuberculin skin test as well as negative Ziehl-Neelsen stain does not argue against NTM infection. In fact, mycobacterial culture for extended periods remains the gold standard for diagnosis.

Is serological testing a reliable tool in laboratory diagnosis of syphilis? Meta-analysis of eight external quality control surveys performed by the german infection serology proficiency testing program.

The accuracy of diagnostic tests is critical for successful control of epidemic outbreaks of syphilis. The reliability of syphilis serology in the nonspecialist laboratory has always been questioned, but actual data dealing with this issue are sparse. Here, the results of eight proficiency testing sentinel surveys for diagnostic laboratories in Germany between 2000 and 2003 were analyzed. Screening tests such as Treponema pallidum hemagglutination assay (mean accuracy, 91.4% [qualitative], 75.4% [quantitative]), Treponema pallidum particle agglutination assay (mean accuracy, 98.1% [qualitative], 82.9% [quantitative]), and enzyme-linked immunosorbent assays (ELISAs) (mean qualitative accuracy, 95%) were more reliable than Venereal Disease Research Laboratory (VDRL) testing (mean accuracy, 89.6% [qualitative], 71.1% [quantitative]), the fluorescent treponemal antibody absorption test (FTA-ABS) (mean accuracy, 88% [qualitative], 65.8% [quantitative]), and immunoblot assays (mean qualitative accuracy, 87.3%). Clearly, immunoglobulin M (IgM) tests were more difficult to manage than IgG tests. False-negative results for samples that have been unambiguously determined to be IgM and anti-lipoid antibody positive accounted for 4.7% of results in the IgM ELISA, 6.9% in the VDRL test, 18.5% in the IgM FTA-ABS, and 23.0% in the IgM immunoblot assay. For negative samples, the mean percentage of false-positive results was 4.1% in the VDRL test, 5.4% in the IgM ELISA, 0.7% in the IgM FTA-ABS, and 1.4% in the IgM immunoblot assay. On average, 18.3% of participants misclassified samples from patients with active syphilis as past infection without indicating the need for further treatment. Moreover, 10.2% of laboratories wrongly reported serological evidence for active infection in samples from patients with past syphilis or in sera from seronegative blood donors. Consequently, the continuous participation of laboratories in proficiency testing and further standardization of tests is strongly recommended to achieve better quality of syphilis serology.

Quality of Lyme disease serology. Lessons from the German Proficiency Testing Program 1999-2001. A preliminary report.

OBJECTIVE: External quality control surveys are an important tool in regulating the quality of infection serology in general and of borreliosis serology in particular. We report on the results of a Lyme disease proficiency testing program which is regularly organised twice a year by our institutions in close cooperation with the Institute of Standardisation in the Medical Laboratory (INSTAND). METHODS: From 1999 to 2001, between 226 and 337 microbiological laboratories participated in each of the four surveys that have been held so far. In addition, between 23 and 30 laboratories from 13 other European countries also participated in each trial. In each survey two serum samples which had been unambiguously characterised by six reference laboratories to contain or not to contain antibodies against the Lyme disease spirochete were distributed in order to determine the accuracy of the diagnostic methods used in participating laboratories. The laboratories also reported interpretative statements of whether or not the test constellation suggested a possible borrelial infection and if an early or late phase of the specific antibody response was suspected. RESULTS: Test results were found to be in part highly variable and clearly correlated with the manufacturers and the applied test methodology. It was also clear that IgM tests were more difficult to handle than were IgG tests. ELISA-testing was more reproducible and proved to be more sensitive and specific than IFA and IHA testing. Quantification of test results and reporting of specific immunoblot bands also showed high variability. Moreover, for some assays a high number of false positive and false negative test results were reported by the participants. CONCLUSION: In view of our results further standardisation of Lyme disease serology is not just desirable but is urgently needed. Moreover, stronger criteria for the validation of available test kits must be applied.