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.

Correction to: mouse mammary tumour virus (MMTV) and human breast cancer with neuroendocrine differentiation.

[This corrects the article DOI: 10.1186/s13027-017-0135-8.].

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.

Molecular typing of multiresistant Streptococcus pneumoniae serogroup 19 in Singapore.

The prevalence of penicillin-resistant Streptococcus pneumoniae in clinical isolates from the Pathology Department of the Singapore General Hospital, in 1995, was 25%. Most of the resistant isolates belonged to serogroup 19 and were resistant to multiple antibiotics. Field-inversion gel electrophoresis (FIGE), after chromosomal digestion with the restriction enzymes Apal and Smal, was performed on all isolates of multiresistant serogroup 19 S. pneumoniae so as to determine whether they were of clonal origin. Twenty-six isolates, including six controls, were studied. Analysis of the FIGE patterns revealed three distinct clusters of closely related strains. The predominant clone comprised ten isolates of multiresistant serogroup 19 S. pneumoniae and also included two controls of a different serogroup. The presence of multiresistant serogroup 19 S. pneumoniae in Singapore, appears to be due to the spread of a small number of clones.

The effect of polyethylene glycol (PEG) on the isolation of Chlamydia trachomatis in H-1 HeLa cells.

One hundred and ninety-six urethral and endocervical swabs were processed for isolation of C. trachomatis, using H-1 HeLa cells on shell vials, in the presence and absence of 7% PEG in the chlamydial overlay medium. The results were divided into three evaluable groups based on the number of inclusions per coverslip in the shell vials without PEG. The number of inclusions were compared with that of PEG-treated cultures using the paired t-test. The ranges for the three evaluable groups were one to ten, 11-100 and 101-1000 inclusions per coverslip. All three groups showed a significant increase (2.8- to 3.8-fold) in the number of inclusion bodies in the PEG-treated cultures compared to the untreated cultures.

Update on techniques in the diagnosis of Chlamydia trachomatis infections.

There are two major advances in the laboratory diagnosis of Chlamydia trachomatis, one lies in the use of nucleic acid amplification techniques and the second in the evaluation of urine as an alternative to invasive sampling of urethral and cervical specimens. There is however, the problem of inhibitors in urine that needs to be addressed, in order for this method to achieve 100% sensitivity. The Q-beta (Q beta) replicase test, Gen-Probe transcription-mediated amplification (TMA) test and the nucleic acid sequence-based amplification (NASBA) test are some of the newer nucleic acid amplification methods being evaluated for the detection of C. trachomatis. These are RNA-based amplification techniques that can potentially achieve very high levels of sensitivity because of the presence of multiple RNA copies in microorganisms and may also be useful for detecting active infection. Q-beta has been found to be less subjected to inhibitory substances in urine than polymerase chain reaction (PCR). Cell culture remains the gold standard for the legal diagnosis of C. trachomatis infections and is the method of choice for the detection of infection at uncommon sites. It forms part of the expanded gold standard for the evaluation of nonculture methods that do not involve nucleic acid amplification, and is also a confirmatory test for such techniques. Notwithstanding, clinicians must remember the basic tenet of laboratory tests, that is, good specimen collection and handling, for any laboratory test to yield accurate information to guide their management of patients.

A shipyard outbreak of salmonellosis traced to contaminated fruits and vegetables.

A large outbreak of food poisoning occurred in September 1996 and involved at least 116 workers at a shipyard in Jurong. Salmonella weltevreden was isolated from the stool specimens of 24 hospitalised cases and three food handlers, giving a total of 27 bacteriologically confirmed cases (25 symptomatic and two asymptomatic) in this outbreak. Based on a case-control analysis, a number of food items consumed on 23 and 24 September 1996 were implicated in the outbreak, viz. a vegetable dish (P < 0.01), watermelon juice (P < 0.01) and cut watermelon (P < 0.001), papaya (P < 0.001) and pineapple (P < 0.05). The median incubation period was 38 hours and the median duration of illness was two days. Four samples of cut fruits obtained from a food stall at the canteen were found to be positive for Salmonella weltevreden. (The antibiogram of all the strains isolated from food samples and stool cultures was similar, consistent with a common source of infection.) Extensive investigation suggested that contamination may have occurred through unauthorised use of industrial water for washing the fresh produce. Early recognition of the outbreak and prompt implementation of control measures prevented further spread of infection.

Bacteroides fragilis meningitis.

Bacteroides fragilis is an obligate anaerobic bacillus residing in the normal intestinal flora of the colon. Anaerobic bacterial meningitis due to this pathogen is rarely diagnosed and if present, a predisposing source of infection should be actively sought for. Anaerobic cultures of cerebrospinal fluids should be done for patients with meningitis, especially those with concomitant pathologies that predispose to anaerobic infections. Two cases of anaerobic meningitis due to Bacteroides fragilis, one associated with cholesteotoma and the other with nasopharyngeal carcinoma, are reported. Both were successfully treated with metronidazole.

Enteropathogenic Escherichia coli as a cause of diarrhoea among children in Singapore.

Enteropathogenic Escherichia coli (EPEC) was isolated from 2.7% of 2983 children under 3 years of age with diarrhoea in Singapore. Of the nine serotypes identified, the most common were 0126:K71(B16), 086:K61(B7) and 0127:K63(B8). Infants were at the greatest risk of contracting gastroenteritis due to EPEC, and female children were slightly more susceptible than males. Antimicrobial susceptibility tests showed that the EPEC strains were generally resistant to ampicillin, streptomycin, tetracycline and triple sulpha, but highly sensitive to ceftriaxone and gentamicin.

Deep-vein thrombosis following hip surgery for fracture of the proximal femur.

This is a prospective study involving seventy-two consecutive admissions of patients with fractures of the proximal femur over a period of eleven months. It reviews the incidence, pattern and clinical course of deep vein thrombosis in this group of patients. The method of detection of deep vein thrombosis was that of ascending phlebography of the injured limb. Results show that the incidence of deep vein thrombosis is low and complications of thromboembolism and local complications secondary to venous stasis are nil. It appears that prophylaxis and active treatment of deep vein thrombosis in this group of patients may not be essential.