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Biomedical subjects

I D Paul

Publications and source records attributed to I D Paul.

15 recordsLinked to original sources
PubMed1992

The laboratory diagnosis of male Chlamydia trachomatis infections--a time for change?

We carried out a two-phased study comparing the effectiveness of first-catch early morning urine (FCU) samples against urethral swabs for the detection of C. trachomatis in men. Four hundred and seventeen new and re-booked consecutive men, who attended the Department of Genito-Urinary Medicine, Bristol, having held their urine overnight, were recruited. Patients who had received antimicrobial chemotherapy in the preceding 2 months were excluded. Early morning FCU samples were obtained from 208 men followed by urethral swabs for the detection of C. trachomatis (phase I) and this order of collection was reversed for the remaining 209 patients (phase 2). A last-catch urine (LCU) was also obtained from all patients. All urethral and urine samples were examined by an amplified enzyme immunoassay (IDEIA, Dako Diagnostics Ltd). Initially, discordant samples were critically examined by direct immunofluorescence (Syva, 'Microtrak') which was used as the 'gold' standard in this study. We have shown that overall 42 and 4.7% of our symptomatic and asymptomatic male patients respectively were positive for C. trachomatis antigen by IDEIA. Furthermore 86.4 and 91.0% (phases 1 and 2) of the total C. trachomatis positive samples were detected by examination of an FCU sample. In contrast only 66.0 and 65.5% (phases 1 and 2) of the total positives were identified by examination of an urethral swab. These results show that an FCU sample not only has the advantage of being a non-invasive procedure but is also a very sensitive method, compared to swabbing the urethra for the detection of C. trachomatis.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Bacterial↗
PubMed1992

The differentiation of Chlamydia species by antigen detection in sputum specimens from patients with community-acquired acute respiratory infections.

An amplified enzyme immunoassay (IDEIA III: Dako Diagnostics Ltd) for detecting genus-specific chlamydia antigen was evaluated prospectively on 286 respiratory specimens from 275 patients presenting with community-acquired pneumonia or persistent chest infection. Nineteen patients had evidence of recent chlamydial infection, having two or more positive sputum or serological markers. Sputa from two other patients were ELISA-positive in the absence of other positive criteria and were regarded as false-positive results. When compared with a direct immunofluorescence test for chlamydial elementary bodies (EBs) using a genus-specific monoclonal antibody, the ELISA gave a positive predictive value of 91% and a negative predictive value of 99%. Non-specific problems with a wide variety of other micro-organisms isolated from the sputa were not encountered. Attempts to differentiate between Chlamydia psittaci, Chlamydia pneumoniae and Chlamydia trachomatis using genus-specific lipopolysaccharide reactive--and species-specific major outer membrane protein--monoclonal antibodies were encouraging and results were substantiated, in most patients, by the species-specific serological assays of the whole-cell-inclusion immunofluorescence or micro-immunofluorescence assays. The study demonstrated that antigen detection techniques offer scope for routine laboratories to diagnose chlamydial respiratory infections rapidly and reliably and may enable differentiation to species level. Although immunofluorescence offers marginally greater sensitivity and specificity when compared with ELISA, the latter is less subjective and less demanding. Sixty-eight per cent of these infections would have remained undiagnosed despite the general availability of ELISA tests.

Adult↗
PubMed1990

Chlamydia trachomatis, tubal disease and the incidence of symptomatic and asymptomatic infection following hysterosalpingography.

The risk of causing or reactivating pelvic infection by hysterosalpingography (HSG) was assessed in 118 infertile women. Serological evidence of Chlamydia trachomatis infection was sought before, and 10 days and 4 weeks after HSG, using the single-antigen whole-inclusion immunofluorescence (WIF) test for species-specific antibody and the complement fixation test (CFT) for group antibody. Chlamydia antigen was detected using an ELISA. There was a close correlation between the finding of occlusive tubal damage and serum antibodies to C.trachomatis detected by both tests (P less than 0.001). Of 60 patients with WIF antibody titres greater than or equal to 1/64, 65% had evident tubal damage compared with only 16% of patients without a raised titre. Clinically suspected sepsis after HSG occurred in 4% of cases both with and without antibodies to C.trachomatis but only in those with tubal damage (10%). There was no serological evidence of C.trachomatis involvement in symptomatic or asymptomatic patients and anaerobic pathogens were isolated more commonly than C.trachomatis in those symptomatic cases. Isolation of C.trachomatis in two cases from the endocervix and also from the endometrium in one of these only after HSG was compatible with reactivation but not reinfection. Mycobacterium tuberculosis was isolated in two out of three cases with unsuspected tubal disease without antibodies to C.trachomatis. The risk of infection from HSG appears to be confined to patients with existing tubal damage, and in those unexpected cases without serological evidence of previous chlamydial infection, tuberculosis seems to be a likely cause.

Chlamydia Infections↗
PubMed1990

Evaluation of three Chlamydia trachomatis immunoassays with an unbiased, noninvasive clinical sample.

First-catch early morning urine samples from patients attending a genitourinary medicine clinic were tested by three different enzyme immunoassays. The results suggest significant differences in the sensitivities and specificities of the different assays. The direct visualization of elementary bodies in urine deposits by direct immunofluorescence was used as the "gold standard," using a monoclonal antibody with a different epitope specificity from those of antibodies used in the enzyme-linked immunosorbent assays. We report for the first time that urine specimens represent an unbiased sample, free of the inherent sampling errors associated with other genital specimens. We feel that urine is a valid specimen for use in any evaluation study of new assays directed towards the detection of Chlamydia trachomatis.

Antigens, Bacterial↗
PubMed1988

The development and evaluation of a mu-capture ELISA detecting Chlamydia-specific IgM.

A mu-capture enzyme-linked immunosorbent assay (ELISA) for detecting chlamydia-specific IgM was developed by use of the heat stable, lipopolysaccharide group-specific antigen and an alkaline phosphatase-labelled anti-chlamydia group-specific monoclonal antibody conjugate. The test was used to study the serological response in chlamydial respiratory tract infection among patients with acute respiratory tract symptoms in Cambridgeshire during the past 7 years. Results were compared with those of the complement fixation test (CFT) in routine use as well as those of a whole inclusion indirect immunofluorescence (WIF) test for IgM. Correlation between results of the mu-capture ELISA and those of the WIF test was 87.5%. The percentage of patients in whom specific IgM was found fell with increasing age. This may be due to lack of recall of IgM as a response to reinfection. Chlamydia-specific IgM was more likely to be detected when the CFT titre was greater than or equal to 64 and was rarely detected more than 6 months after the onset of symptoms. However, several patients less than 20 years of age were found to have specific IgM with CF antibody titres less than 64. We have found the mu-capture ELISA a useful test for the diagnosis of respiratory tract chlamydial infections, particularly in younger patients.

Adolescent↗
PubMed1986

Rapid diagnosis of Chlamydia trachomatis infection in patients attending an ophthalmic casualty department.

Direct immunofluorescence (DIF) techniques were compared with conventional cell culture for the diagnosis of ocular infections with Chlamydia trachomatis. The DIF test was found to have a sensitivity of 100% and a specificity of 97.5%. Of 178 patients studied, 19 patients (11%) were positive by DIF and 15 (8.4%) by conventional cell culture technique. Four patients who had previous treatment with chloramphenicol eye drops were negative by cell culture but positive by the DIF test. The DIF test is considered to be a rapid, accurate test with a number of advantages over culture techniques for the detection of C. trachomatis. The importance of appropriate referral of positive patients to prevent more serious sequelae due to C. trachomatis infection is discussed.

Adolescent↗
PubMed1985

Enzyme amplified immunoassay: a novel technique applied to direct detection of Chlamydia trachomatis in clinical specimens.

Endocervical swabs from 212 women and urethral swabs from 100 men were tested by the routine methods for McCoy cell culture and simultaneously by a novel enzyme amplified immunoassay test to detect chlamydia antigen. Overall correlation of the amplified test with culture was 96.5%. The test proved to be a suitable screening procedure for genital chlamydial infection, particularly for large numbers of specimens or in cases in which culture was not available.

Antigens, Bacterial↗
PubMed1985

Evaluation of a genus reactive monoclonal antibody in rapid identification of Chlamydia trachomatis by direct immunofluorescence.

This study compared the direct visualisation of elementary bodies in urogenital smears by the direct immunofluorescence test with the isolation of Chlamydia trachomatis in McCoy cell cultures treated with cytochalasin B. C trachomatis was isolated from 41 (16.4%) of 250 unselected specimens in McCoy cell cultures treated with cytochalasin B. Of the 41 culture positive specimens 37 (90%) were diagnosed by direct visualisation of elementary bodies in the smears using the direct immunofluorescence test. Four specimens were positive by isolation only and a further seven were positive by the direct immunofluorescence test only. Overall the direct immunofluorescence test had a sensitivity of 90% and a specificity of 97%. The presence of red blood cells or mucus or the use of barrier creams did not appear to interfere with the normal visualisation of elementary bodies using the direct immunofluorescence test.

Antibodies, Monoclonal↗
PubMed1984

Isolation of Chlamydia psittaci from cases of conjunctivitis in a colony of cats.

This report describes the isolation in cell cultures of Chlamydia psittaci from cases of conjunctivitis in a colony of cats. The organism was identified in McCoy cell monolayers by staining the intracytoplasmic chlamydial inclusions with a fluorescent antibody technique, and serological evidence of chlamydial infection in cats was obtained by indirect immunofluorescence. The possible role of C psittaci as an ocular, upper respiratory and reproductive tract pathogen in cats is discussed.

Animals↗
PubMed1980

Value and feasibility of screening women attending STD clinics for cervical chlamydial infections.

A chlamydial screening service was provided in Bristol over a three-month period for women attending the sexually transmitted disease (STD) clinic either for the first time or with a new complaint. Isolation of Chlamydia trachomatis was attempted in cytochalasin-treated McCoy cells. Of 919 specimens, valid results were obtained in 796. Chlamydial infections were identified and treated in 154 (19%) of these 796 women. Chlamydia were isolated from 52 (37%) of 152 female partners of men with nongonococcal urethritis (NGU); these patients already routinely receive treatment with tetracylcines in this clinic. The remaining 102 infections (34 (48%) of 71 women with gonorrhoea and 68 (12%) of the other 573 women) would have been unrecognised and usually untreated without chlamydial isolation studies. These figures confirm the need to provide chlamydial diagnostic services for selected STD clinic attenders.

Bacteriological Techniques↗