Testing for syphilis--rational use and interpretation.

Syphilis is a disease caused by a spiral organism, Treponema pallidum. Microscopy is useful in diagnosing syphilis in its primary stage while the serological tests are used for diagnosing primary secondary or latent stages of syphilis. The non specific serological tests are the non treponemal tests such as the Venereal Disease Laboratory Test (VDRL) and the Rapid Plasma Reagin Test (RPR). Both these tests are used as a screening test. The specific tests are the treponemal tests. The two common treponemal tests are fluorescent treponemal antibody absorption test (FTA/ABS) and the Microhaemagglutination assay for Treponema pallidum (MHA-TP). These two tests can be used to confirm the diagnosis of syphilis. The usefulness of laboratory tests in the diagnosis of syphilis depends on the selection of the appropriate standard tests.

Four patients in Singapore with anti-Golgi antibodies.

Serum specimens for anti-nuclear fluorescence tests are routinely received in our laboratory. Four specimens were spotted to be negative for anti-nuclear fluorescence but positive for fluorescence characteristic of that caused by anti-golgi antibodies. (a) Patient A had acute glomerulonephritis; (b) Patient B had acute viral hepatitis; (c) Patient C had deep vein thrombosis; and (d) Patient D had non-Hodgkin's lymphoma. The relevance and possible aetiology of anti-golgi antibodies are also discussed.

Anti-toxoplasma antibodies in healthy adults and in different patient categories.

This study analyzes the anti-toxoplasma sero-titres and prevalence rates in normal healthy adults and in patients presenting with different symptom-complexes. The study was based on sera from 80 normal healthy adults and 2,185 patient sera samples from 2,032 patients (from various clinics and hospitals in Singapore) being investigated for the diagnosis or exclusion of toxoplasmosis, over a 42-month study period. About 15% of the healthy adults were found to have low IgG antibody titres (1:64 to 1:256), while 3.8% had high IgG titres (1:1024 or higher). Interestingly, among the patients investigated for toxoplasmosis: i) more than 20% of those presenting with lymphadenopathy (usually cervical) had antibody titres more than or equal to 1:1024; ii) more than half of all patients with an antibody titre of 1:4096, and more than three-quarters of all patients with a titre exceeding 1:4096 had presented with lymphadenopathy; iii) about 20% of those presenting with ocular symptoms had low antibody titres of 1:64 or 1:256, whereas 7% had higher titres. Malay (p less than 0.01) and Indian (p less than 0.05) patients had significantly higher seropositive rates than the Chinese. In particular, the Malays (p less than 0.00001) and Indians (p less than 0.01) had significantly higher incidence of low-positive titres (1:64, 1:256); conversely the Chinese patients had a significantly higher (p less than 0.01) incidence of high-positive titres (1:4096 or higher). Finally, the epidemiology and clinical profiles of patients presenting with acute toxoplasmic lymphadenitis are contrasted with that of patients presenting with ocular manifestations of congenital toxoplasmosis.

Evaluation of an ELISA method for the measurement of antibodies to dsDNA.

Anti-dsDNA is found in 60-70% of patients with active, untreated systemic lupus erythematosus (SLE) and its detection serves as an important tool in the diagnosis and monitoring of these patients. This study evaluates the use of an Enzyme Linked Immunosorbent Assay (Elisa) to detect these antibodies. Its performance is also compared to the older, but established, method of detecting anti-dsDNA using Crithidia luciliae. The sera of the 56 normal healthy blood donors revealed a mean anti-dsDNA titre of 0.93mg% with a standard deviation of 0.23mg%. All 14 patients found to be negative by the Elisa method and 10 of the 11 patients found to have borderline anti-dsDNA Elisa titres were negative by immunofluorescence. 35 patients were found to harbour raised titres of anti-dsDNA by the Elisa method. All patients found to have anti-dsDNA titres exceeding 2mg% by the Elisa test were also positive by immunofluorescence. In fact, those with very high titres by the Elisa test were also strongly (titre greater than 1:100) positive by immunofluorescence. As a measurement of the kit's accuracy, the percentage of recovery of the activity of known amounts of antibody in a specimen fell within the range of about 89-104%. As a measurement of the kit's reproducibility, the coefficient of variation in the assayed titres of sample replicates was found to be 7.5% for within-batch assays and 9.7% for between-batch assays. The Elisa assay compared favourably to the immunofluorescence test in terms of enhanced sensitivity, quantitative approach with an objective end-point and the large number of samples that may be assayed simultaneously.

Evaluation of enzyme immunoassay for the detection of anogenital infections caused by Chlamydia trachomatis.

BACKGROUND--Infection caused by Chlamydia trachomatis is now recognised as the most prevalent sexually transmitted disease in many parts of the world. Anorectal infections caused by C. trachomatis is not uncommon. Enzyme-linked immunoassay (EIA) detects an antigen lipopolysaccharide (LPS) of C. trachomatis directly in clinical specimens. OBJECTIVE--Our aim was to compare an enzyme immunoassay, Wellcozyme Chlamydia (WZ04) with cell culture for the diagnosis of chlamydial infection of the anogenital tract. METHOD--Rectal swabs were taken from 100 prostitutes (80 females and 20 males) for chlamydia culture, WZ04 and direct immunofluorescence (DIF). In addition, endocervical specimens were obtained from the females for the above three tests. MAIN FINDINGS--All the positive rectal specimens were from females. Nine patients had a positive chlamydia culture from the rectum but negative WZ04 and DIF. Two patients had false positive results by WZ04 but negative culture and DIF. For cervical specimens, WZ04 identified 43% (3/7) of the culture positive cases. Specificity was 98.6%. WZ04 identified an additional specimen as positive which was also confirmed as positive by DIF. CONCLUSION--Our study shows that in our hands enzyme-linked immunoassays such as Wellcozyme Chlamydia are neither sensitive nor specific in detecting C. trachomatis infection of the rectum. For cervical infections, the sensitivity of WZ04 was 43% and the specificity 98.6% as compared to culture, with a positive predictive value of 75% and a negative predictive value of 94.7%.

Absence of retroviral antibodies in the sera of patients with systemic lupus erythematosus.

Retroviruses have been postulated as environmental triggers in the aetiopathogenesis of systemic lupus erythematosus. Sera from 100 lupus patients were screened for the presence of antibodies against recombinant HIV-1 core and envelope, and HIV-2 envelope antigens by an enzyme immunoassay. This will detect antibodies resulting from direct HIV-1 or HIV-2 infections or those generated as a result of antigenic similarities by other human retroviruses. The sera were obtained from 11 male and 89 female lupus patients. Retroviral antibodies were not detected in the sera of these lupus patients, thus contradicting published findings that up to 30% of lupus patients have antibodies against the p24 gag protein of HIV-1.

Endocervical chlamydial infection in women attending a sexually transmitted disease clinic in Singapore.

Two hundred women attending the sexually transmitted disease (STD) clinic at Middle Road Hospital were investigated. Chlamydia trachomatis was isolated from 32% of women who were contacts of men with nongonococcal urethritis, 15% of contacts of gonococcal urethritis, 27% of contacts of unspecified STD, and 13% of women without any history of STD in their sex partners. Overall, Chlamydia trachomatis was isolated from 17% of 200 women, Neisseria gonorrhoeae from 13% of 199 women, Candida albicans from 34% and Trichomonas vaginalis from 6% of 197 women. Three per cent of the patients had positive VDRL results. A history of bilateral lower abdominal pain and the presence of cervicitis were significantly associated with chlamydial infection. Forty one per cent of the 34 chlamydia-positive women were asymptomatic. The results of this study show that C. trachomatis infection is more common than infection with N. gonorrhoeae in women who attend STD clinics. The need for routine screening and treatment on the basis of epidemiological and clinical markers of infection has to be carefully examined.

Endocervical chlamydial infection in women with gonorrhoea.

Eighty six women attending Middle Road Hospital with endocervical gonococcal infection were evaluated. Chlamydia trachomatis was isolated in 27% of them. Women co-infected with C. trachomatis were similar to those with gonococcal infection alone in terms of demography, type of sexual contact, previous sexually transmitted disease, genitourinary symptoms, and clinical signs.

Chlamydial infection in female prostitutes in Singapore.

Three studies conducted in 1982, 1985 and 1988 investigated chlamydial infections in female prostitutes. In 1982, 115 prostitutes with culture-positive gonorrhoea were studied; 8% were coinfected with Chlamydia trachomatis. In 1985, 86 female prostitutes and in 1988, 100 female prostitutes attending for routine tests were examined. Chlamydia trachomatis was isolated in 12% and 9% of the cases, respectively. Gonorrhoea was detected in 10% and 11% of the cases. In the 1988 study, one (9%) of the 11 women with gonorrhoea had concomitant chlamydial infection. Syphilis was diagnosed in 3% of the female prostitutes investigated in 1988. Our findings indicate that concomitant chlamydial infection occurs in about 8-9% of female prostitutes with gonorrhoea and that 9-12% of the female prostitutes screened harboured Chlamydia trachomatis in their endocervices. A chlamydial control programme in prostitutes is desirable.

PIP: Studies conducted in 1982, 1985, and 1988 among female prostitutes in Singapore documented the need for a chlamydial control program in this population. In the 1982 study, which included 115 prostitutes infected with gonorrhea, Chlamydia trachomatis was recovered from 8%. In 1985 and 1988, the prevalence of endocervical chlamydia infection in prostitutes presenting for routine testing was 12% and 9%, respectively. The prevalence of gonorrhea in 1985 and 1988 was 10% and 11%, respectively. In the 1988 study, 1 of the 11 prostitutes with gonorrhea also harbored chlamydia. The prevalence of syphilis, ascertained only in the 1988 study, was 3%. These findings suggest that 8-9% of prostitutes with gonorrhea are co-infected with chlamydia. At present, prostitutes in Singapore are screened only for gonorrhea and syphilis. The high rate of C trachomatis infection recorded in this study indicates that chlamydia infection--on the increase in the West--should be added to this list. In addition, health education efforts are needed to stress the need for additional anti-chlamydial treatment. Currently utilized regimens for the treatment of gonorrhea are ineffective against C trachomatis.

Counterimmunoelectrophoresis in the rapid diagnosis of bacterial meningitis.

Cerebrospinal fluid from patients with clinically diagnosed meningitis was tested for meningococcal, pneumococcal, streptococcal Group B and Haemophilus influenzae antigens by counterimmunoelectrophoresis. Antigens were rapidly identified and the results compared favourably with that of bacteriological culture. In the case of pneumococcal meningitis counterimmunoelectrophoresis proved to be more sensitive than culture. The procedure was shown to be sensitive, specific, rapid and easily performed.

Bacterial meningitis--a five year review 1975--1979.

In a five year period 142 cases of bacterial meningitis were reported, of which 50 per cent were children under the age of four years and a third of the children were neonates. The commonest organism isolated was Streptococcus pneumoniae, there being 28 cases. The incidence of Klebsiella organism causing meningitis has been on the increase, and 20 cases were reported within this period. There has been a change in pattern of neonatal meningitis, with group B streptococcal infection predominating over the gram negatives.

Isolation of Legionella pneumophila from hospital cooling towers.

Water from twenty cooling towers from three major hospitals (A, B, C) were screened for the presence of Legionella pneumophila. Three of the water specimens were found to be positive for the organism. Serogroup 1 was isolated from the two cooling towers in Hospital A, while serogroup 4 was isolated from one of the cooling towers in Hospital B, this being the first time L. pneumophila has been isolated in Singapore.

A review of 58 patients in Singapore with significantly high anti-Toxoplasma serotitres.

Over a 42-month period, 58 patients presenting at the Singapore General Hospital were identified to have IgG anti-Toxoplasma serotitres of 1:1024 or higher by the indirect immunofluorescence test. This retrospective study examines the clinical presentation and management of these 58 patients. About 60% of these 58 patients had presented with lymphadenopathy, 20% with ocular symptoms and 14% with bad obstetric history. Almost all patients with IgG anti-Toxoplasma serotitres exceeding 1:1024 had presented with lymphadenopathy (with a modal titre of 1:4096). In contrast, most of the patients who presented with ocular symptoms or bad obstetric history had lower modal titres. The majority of patients who had presented with lymphadenopathy were Chinese, aged 21 to 35. Typically, they presented with a painless, mobile, solitary cervical node of three to four weeks duration as the only symptom, had biopsies where the histopathology was suggestive of toxoplasmosis, received no treatment and experienced no sequelae. The study concludes that: acute toxoplasmosis is common in Singapore and presents typically as asymptomatic cervical lymphadenopathy in a young Chinese; the incidence of congenital infection is also believed to be high, based on the number of cases presenting with fetal wastage and the prevalence of ocular toxoplasmosis; pigs in Singapore may constitute an important reservoir for the transmission of this disease to man.

Sero-survey for Legionella pneumophila antibodies--Singapore experience.

One hundred and fifty blood bank donors were sero-surveyed for legionella antibodies by indirect immunofluorescence test using a polyvalent antigen group (1 to 4). 20% of the group surveyed had an antibody titre greater than or equal to 16 to the organism. This paper also reports a study on 166 hospitalised acute pneumonia patients. The sera from these patients were screened for L. pneumophila antibodies; 5 of the patients had significant antibody titre greater than or equal to 256 which is diagnostic of legionellosis.

Newer methods for the detection of Chlamydia trachomatis in genital specimen.

Conventional culture isolation methods for detecting Chlamydia trachomatis infections are laborious, expensive, technically demanding and not widely available. Recently, non-culture methods which detect chlamydial antigens have been introduced. These methods utilise immunofluorescence (IF), enzyme immunoassay (EIA) or DNA hybridisation techniques. DNA hybridisation techniques are presently, still experimental. IF and EIA tests are widely available and are suitable alternatives to culture isolation for laboratories who wish to provide a chlamydia-service. The sensitivities and specificities, and advantages and disadvantages of these systems are discussed.

Relation of antinuclear fluorescence patterns and titres to autoantibody prevalence.

Different profiles of antinuclear antibodies (ANAs) have been found to be associated with different connective tissue diseases. Though several techniques have been developed to detect ANA, indirect antinuclear immunofluorescence (ANF) continues to be the most widely used and accepted. This study assesses the role of ANF as a screening test. The ANF patterns of 428 patients were studied. About 23% of patients with homogenous ANF patterns and 13% with speckled patterns were eventually shown to have raised anti-dsDNA titres. The percentage of patients harbouring raised titres of anti-dsDNA and the absolute titres were both seen to rise with the ANF titres. None of the patients with low ANF titres (1:40) harboured antibodies to extractable nuclea antigens (ENAs) whereas with increasing ANF titres the incidence of these autoantibodies was also seen to rise. Finally, it was noted that more than 80% of patients with high ANF titres demonstrated autoantibodies to ENA and/or dsDNA.

The role of counterimmunoelectrophoresis in the identification of antibodies to extractable nuclear antigens.

Antibodies to saline-extractable nuclear antigens are hallmarks of autoimmune diseases including systemic lupus erythematosus (SLE), mixed connective tissue disease, progressive systemic sclerosis and Sjogren's syndrome. In our laboratory, we use counterimmunoelectrophoresis as a screening test and immunodiffusion as a confirmatory test to identify these autoantibodies. This study examines the drawbacks of such an approach. Though 17 out of 19 sera that formed ribonuclease sensitive lines with rabbit thymus extract on counterimmunoelectrophoresis were confirmed to have anti-RNP by immunodiffusion, sera of several different autoantibody specificities were seen to form ribonuclease resistant precipitin lines with the thymus extract on counterimmunoelectrophoresis. Having screened sera to have autoantibodies by counterimmunoelectrophoresis, the identity of some of these autoantibodies were not confirmed because of the poor sensitivity of immunodiffusion or because inappropriate controls had been used for the confirmatory immunodiffusion test. To check these drawbacks and to obviate the need for a confirmatory test, a modification of the current approach is suggested.

Comparing the efficacy of pefloxacin and ciprofloxacin in the treatment of acute uncomplicated gonococcal urethritis in males.

The aim of this study was to compare the efficacy of single-dose pefloxacin 400 mg and ciprofloxacin 250 mg in the treatment of acute uncomplicated gonococcal urethritis in males. One hundred and twenty male patients with uncomplicated gonococcal urethritis were assigned alternately to receive single oral doses of either pefloxacin 400 mg or ciprofloxacin 250 mg. Forty-one out of 43 patients (95.3%) of the pefloxacin group and 46 of 47 (97.9%) of the ciprofloxacin group were cured of gonorrhoeae. The rates of post-gonococcal urethritis were 57.7% and 53.3% in the pefloxacin and ciprofloxacin groups respectively. There was a high incidence of penicillinase-producing gonococci (34.2%). High level resistance to pefloxacin (minimum inhibitory concentration [MIC] >1.0 mg/l) resulting in clinical failure on 400 mg stat dose was noted in 1 isolate. It also showed decreased susceptibility to ciprofloxacin (MIC 0.25 mg/l). Another isolate showed high-level resistance (MIC 0.06 mg/l) to ciprofloxacin 250 mg stat dose with concomitant decreased susceptibility to pefloxacin (MIC >1.0 mg/l). Ciprofloxacin 250 mg stat dose is still useful for the treatment of uncomplicated gonococcal urethritis in males. The cure rate of 95.3% with pefloxacin at 400 mg stat dose is acceptable, but needs to be monitored with caution. The emergence of a more resistant strain of Neisseria gonorrhoeae to fluoroquinolones calls for vigilance in the monitoring of antimicrobial susceptibility.