Biological false-positive venereal disease research laboratory test in cerebrospinal fluid in the diagnosis of neurosyphilis - a case-control study.

BACKGROUND: There is no clear consensus on the diagnosis of neurosyphilis. The Venereal Disease Research Laboratory (VDRL) test from cerebrospinal fluid (CSF) has traditionally been considered the gold standard for diagnosing neurosyphilis but is widely known to be insensitive. OBJECTIVE: In this study, we compared the clinical and laboratory characteristics of true-positive VDRL-CSF cases with biological false-positive VDRL-CSF cases. METHODS: We retrospectively identified cases of true and false-positive VDRL-CSF across a 3-year period received by the Immunology and Serology Laboratory, Singapore General Hospital. A biological false-positive VDRL-CSF is defined as a reactive VDRL-CSF with a non-reactive Treponema pallidum particle agglutination (TPPA)-CSF and/or negative Line Immuno Assay (LIA)-CSF IgG. A true-positive VDRL-CSF is a reactive VDRL-CSF with a concordant reactive TPPA-CSF and/or positive LIA-CSF IgG. RESULTS: During the study period, a total of 1254 specimens underwent VDRL-CSF examination. Amongst these, 60 specimens from 53 patients tested positive for VDRL-CSF. Of the 53 patients, 42 (79.2%) were true-positive cases and 11 (20.8%) were false-positive cases. In our setting, a positive non-treponemal serology has 97.6% sensitivity, 100% specificity, 100% positive predictive value and 91.7% negative predictive value for a true-positive VDRL-CSF based on our laboratory definition. HIV seropositivity was an independent predictor of a true-positive VDRL-CSF. CONCLUSION: Biological false-positive VDRL-CSF is common in a setting where patients are tested without first establishing a serological diagnosis of syphilis. Serological testing should be performed prior to CSF evaluation for neurosyphilis.

Interferon-gamma release assay as a diagnostic test for tuberculosis-associated uveitis.

BACKGROUND: To study the use of interferon-gamma release assay (IFN-γ) (IGRAs) as a diagnostic test for tuberculosis (TB)-associated uveitis (TAU). DESIGN: Prospective cohort study. PARTICIPANTS: Consecutive new patients (n=162) with clinical ocular signs suggestive of TAU, seen >1 year period at a single tertiary center. METHODS: All subjects underwent investigations to rule out underlying disease, including T-SPOT.TB and tuberculin skin test (TST). Twenty-one subjects with underlying disease and three with interdeterminate T-SPOT.TB results were excluded. Those with T-SPOT.TB- or TST-positive results were referred to infectious diseases physician for evaluation. Anti-TB therapy (ATT) was prescribed if required. Patients' treatment response and recurrence were monitored for six months after completion of ATT, if given; or 1 year if no ATT was given. MAIN OUTCOME MEASURE: Diagnosis of TAU. RESULTS: Mean age of study cohort (n=138) was 46.8 ± 15.3 years. Majority were Chinese (n=80, 58.0%) and female (n=75, 54.3%). TST was more sensitive than T-SPOT.TB (72.0% vs 36.0%); but T-SPOT.TB was more specific (75.0% vs 51.1%) for diagnosing TAU. Patients with either a T-SPOT.TB (1.44; 95% confidence intervals (CI), 0.86-2.42) or TST (1.47; 95% CI, 1.12-1.94)-positive result are more likely to have TAU. The accuracy of diagnosing TAU increases when both tests are used in combination (area under the receiver operator curve=0.665; 95% CI, 0.533-0.795). Patients with both tests positive are 2.16 (95% CI, 1.23-3.80) times more likely to have TAU. Negative T-SPOT.TB or TST results do not exclude TAU (negative likelihood ratios <1.0). CONCLUSIONS: We recommend using a combination of clinical signs, IGRA, and TST to diagnose TAU.

Eikenella corrodens discitis after spinal surgery: case report and literature review.

Eikenella corrodens is part of the normal flora of the mouth and upper respiratory tract and is usually associated with dental and head and neck infections. We report a case of Eikenella discitis occurring soon after spinal surgery in an otherwise healthy patient, review the literature on bone and joint infections unrelated to human bites and fist-fight injuries, and stress the importance of definitive diagnosis in post-operative spinal infections.

Epidemiology of beta-haemolytic group G streptococcal bacteraemia in Singapore (1996 to 1998).

INTRODUCTION: Group G streptococcus (GGS) accounted for 8% to 44% of all bacteraemias due to beta-haemolytic streptococci according to various reports. The aims of this study were 1) to describe the epidemiology of GGS bacteraemia in Singapore for which local data are lacking and 2) to compare its frequency of isolation to the other Lancefield groups. PATIENTS AND METHODS: The study period was from 1 January 1996 to 30 June 1998. The laboratory records of 2 large acute care hospitals were examined. There was a total of 85 patients. The medical records of 52 patients were available for analysis. In addition, laboratory microbiological data from 1993 to 1999 were reviewed and the number of blood cultures that were positive for beta-haemolytic streptococci groups A, B, C and G was collated. RESULTS: The majority involved the elderly. The mean age was 67 years. The skin was the major portal of entry. Local conditions predisposing the skin to infection occurred in 40.4%. Co-morbidity included malignancies in 28.8% of patients, diabetes mellitus in 11.5% and liver disease in 9.6%. Mortality was 15.4% including fatal septic shock. Recurrent bacteraemia occurred in 5.8% of the patients. The majority (90.4%) were community-acquired infections. GGS, along with group B streptococcus (GBS), was the most common streptococcus among the beta-haemolytic streptococci causing bacteraemia in these 2 hospitals.