Which test is best for chlamydia?

Validation of a New Duplex Real-Time Polymerase Chain Reaction for Chlamydia trachomatis DNA Detection in Ocular Swab Samples

Trachoma is the world-leading infectious cause of preventable blindness and is caused by the bacteria Chlamydia trachomatis. In developing countries, diagnosis is usually based on clinical evaluation. Serological-based tests are cheaper than molecular-based ones, but the latter are more sensitive and specific. The present study developed a new duplex qPCR which concomitantly detects the C. trachomatis cryptic plasmid and the human 18S rRNA gene, with an LOD95% for C. trachomatis DNA of 13.04 genome equivalents per reaction. The new qPCR was tested using 50 samples from an endemic area and 12 from a non-endemic area that were previously characterized using direct immunofluorescence assay (DFA) and clinical evaluation. Among the 50 endemic samples, 3 were found to be positive by clinical evaluation (6%), 18 were found to be positive by DFA (36%), and 48 were found to be positive by qPCR (96%). Next, the new duplex qPCR was validated using 50 samples previously characterized by qPCR. Validation was carried out on a benchtop instrument (ABI7500) or on a portable point-of-care instrument (Q3-Plus), showing 95% specificity and 100% sensitivity. The ubiquitous presence of C. trachomatis DNA in samples from the endemic region confirms that constant monitoring is of paramount importance for the effective measurement of the elimination of trachoma. The newly developed duplex qPCR presented in this study, along with its validation in a portable qPCR system, constitutes important tools toward achieving this goal.

Study of the prevalence and association of ocular chlamydial conjunctivitis in women with genital infection by Chlamydia trachomatis, Mycoplasma genitalium and Candida albicans attending outpatient clinic

AIM

To determine the association between chlamydial conjunctivitis and genital infection by Chlamydia trachomatis, Mycoplasma genitalium and Candida albicans, in addition to the possible relationship between cultured bacterial pathogens and oculogenital chlamydial infection.

METHODS

This study was performed on 100 (50 symptomatic and 50 asymptomatic) women attending the Gynecological and Obstetric outpatient clinic of Alzahra hospital, Alazhar University. Simultaneously a conjunctival swab was taken from these patients. Polymerase chain reaction (PCR) was done on DNA extracted from both vaginal and conjunctival swab samples. Culture for both vaginal and conjunctival swabs was also done.

RESULTS

Candida albicans was the predominant organism isolated by culture in 20% and 40% of conjunctival and vaginal swabs respectively. By the PCR method, ocular Chlamydia trachomatis was present in 60% of symptomatic women, while genital Chlamydia trachomatis infection was present in 30% of symptomatic women. The results of this method also indicated that 25/50 (50%) vaginal swabs were positive with PCR for Candida albicans versus 15/50 (30%) were PCR positive in conjunctival swab. Mycoplasma genitalium was present in only 10% of vaginal swabs. Concomitant oculogenital PCR positive results for Chlamydia trachomatis and Candida albicans were 30% and 28% respectively.

CONCLUSION

Ocular Chlamydia trachomatis was associated with genital Chlamydia trachomatis in a high percentage of women followed by Candida albicans. Cultured bacterial organisms do not play a role in enhancement of Chlamydia trachomatis infection.

Self-Collected versus Clinician-Collected Sampling for Chlamydia and Gonorrhea Screening: A Systemic Review and Meta-Analysis

BACKGROUND

The increases in STI rates since the late 1990s in Canada have occurred despite widespread primary care and targeted public health programs and in the setting of universal health care. More innovative interventions are required that would eliminate barriers to STI testing such as internet-based or mail-in home and community service testing for patients that are hard to reach, who refuse to go for clinician-based testing, or who decline an examination. Jurisdictions such as New Zealand and some American states currently use self-collected sampling, but without the required evidence to determine whether self-collected specimens are as accurate as clinician-collected specimens in terms of chlamydia and gonorrhea diagnostic accuracy. The objective of the review is to compare self-collected vaginal, urine, pharyngeal and rectal samples to our reference standard - clinician-collected cervical, urethral, pharyngeal and rectal sampling techniques to identify a positive specimen using nucleic acid amplification test assays.

METHODS

The hierarchical summary receiver operating characteristic and the fixed effect models were used to assess the accuracy of comparable specimens that were collected by patients compared to clinicians. Sensitivity and specificity estimates with 95% confidence intervals (CI) were reported as our main outcome measures.

FINDINGS

We included 21 studies based on over 6100 paired samples. Fourteen included studies examined chlamydia only, 6 compared both gonorrhea and chlamydia separately in the same study, and one examined gonorrhea. The six chlamydia studies comparing self-collection by vaginal swab to a clinician-collected cervical swab had the highest sensitivity (92%, 95% CI 87-95) and specificity (98%, 95% CI 97-99), compared to other specimen-types (urine/urethra or urine/cervix). Six studies compared urine self-samples to urethra clinician-collected samples in males and produced a sensitivity of 88% (95% CI 83-93) and a specificity of 99% (95% CI 0.94-0.99). Taking into account that urine samples may be less sensitive than cervical samples, eight chlamydia studies that compared urine self-collected verses clinician-collected cervical samples had a sensitivity of 87% (95% CI 81-91) and high specificity of 99% (95% CI 0.98-1.00). For gonorrhea testing, self-collected urine samples compared to clinician-collected urethra samples in males produced a sensitivity of 92% (95% CI 83-97) and specificity of 99% (95% CI 0.98-1.00).

CONCLUSION

The sensitivity and specificity of vaginal self-collected swabs compared to swabs collected by clinicians supports the use of vaginal swab as the recommended specimen of choice in home-based screening for chlamydia and gonorrhea. Urine samples for gonorrhea collected by men had comparably high sensitivity and specificity, so could be recommended as they can be left at room temperature for several days, allowing for the possibility of mail-in home-based testing. In populations that may not go for testing at all, do not have the option of clinical testing, or who refuse a clinical examination, self-collected screening would be a good alternative. We recommend that guidelines on how to self-collect gonorrhea and chlamydia urine, vaginal, rectal and pharyngeal specimens be published.

Self-collected versus clinician-collected sampling for sexually transmitted infections: a systematic review and meta-analysis protocol

BACKGROUND

Three meta-analyses and one systematic review have been conducted on the question of whether self-collected specimens are as accurate as clinician-collected specimens for STI screening. However, these reviews predate 2007 and did not analyze rectal or pharyngeal collection sites. Currently, there is no consensus on which sampling method is the most effective for the diagnosis of genital chlamydia (CT), gonorrhea (GC) or human papillomavirus (HPV) infection. Our meta-analysis aims to be comprehensive in that it will examine the evidence of whether self-collected vaginal, urine, pharyngeal and rectal specimens provide as accurate a clinical diagnosis as clinician-collected samples (reference standard).

INCLUSION AND EXCLUSION CRITERIA

Eligible studies include both randomized and non-randomized controlled trials, pre- and post-test designs, and controlled observational studies.

SEARCH STRATEGY

The databases that will be searched include the Cochrane Database of Systematic Reviews, Web of Science, Database of Abstracts of Reviews of Effects (DARE), EMBASE and PubMed/Medline.

DATA COLLECTION AND ANALYSIS

Data will be abstracted independently by two reviewers using a standardized pre-tested data abstraction form. Heterogeneity will be assessed using the Q2 test. Sensitivity and specificity estimates with 95% confidence intervals as well as negative and positive likelihood ratios will be pooled and weighted using random effects meta-analysis, if appropriate. A hierarchical summary receiver operating characteristics curve for self-collected specimens will be generated.

DISCUSSION

This synthesis involves a meta-analysis of self-collected samples (urine, vaginal, pharyngeal and rectal swabs) versus clinician-collected samples for the diagnosis of CT, GC and HPV, the most prevalent STIs. Our systematic review will allow patients, clinicians and researchers to determine the diagnostic accuracy of specimens collected by patients compared to those collected by clinicians in the detection of chlamydia, gonorrhea and HPV.

Diagnosis and follow-up of genital chlamydial infection by direct methods and by detection of serum IgG, IgA and secretory IgA

PURPOSE

To determine the prevalence of Chlamydia trachomatis infection in a high-risk population by direct and indirect methods and to evaluate the diagnosis of secretory immunoglobulin A (sIgA).

PATIENTS AND METHODS

Urethral or endocervical specimens from 78 patients (48 females and 30 males) were examined by cell culture, direct fluorescence assay, PCR Cobas Amplicor (Roche Molecular Diagnostics), and sIgA was detected by the recombinant lipopolysaccharide (LPS)-enzyme-linked immunoassay (rELISA). Serum from each patient was also obtained and analysed for the presence of IgG and IgA antibody by in-house microimmunofluorescence (MIF) and by the rELISA method (Medac, Hamburg, Germany).

RESULTS

The overall C. trachomatis prevalence determined by direct methods was 28%. The detection of sIgA antibodies was significantly higher in the group of patients with a positive direct detection (50%) than in the group of negative direct detection (10.7%). The Chlamydia-specific IgA antibodies were detected by the rELISA in 40.9 and 53.6% of group I (positive direct detection) and group II patients (negative direct detection), respectively. The species-specific IgA antibodies were detected by the MIF method in 18.2 and 16.1% of group I and II patients, respectively. Chlamydia genus-specific IgG antibodies were detected by the rELISA in 86.4 and 83.9% of group I and group II patients and, C. trachomatis specific IgG were present in 81.8 and 73.2% of group I and group II patients, respectively, as assessed by the MIF test.

CONCLUSION

Combining the positive direct methods and/or positive sIgA antibody results from cervical or urethral specimens had an indication of current C. trachomatis infection.

Guidelines for the laboratory diagnosis of Chlamydia trachomatis infections in East European countries

The present guidelines aim to provide comprehensive information regarding the laboratory diagnosis of infections caused by Chlamydia trachomatis in East European countries. These recommendations contain important information for laboratory staff working with sexually transmitted infections (STIs) and/or STI-related issues. Individual East European countries may be required to make minor national adjustments to these guidelines as a result of lack of accessibility to some reagents or equipment, or laws in a specific country.

Chlamydienerkrankungen des Auges – eine kurze Übersicht

In this short review, new data on the taxonomy of Chlamydia and the association of these pathogens with various ocular diseases are presented. Clinical diagnosis and laboratory tests for ocular C. trachomatis infection are discussed. The actual therapy consists in oral azithromycin.

Nonspecific urethritis and reactive arthritis

Nongonococcal urethritis (NGU) is a common sexually transmitted infection most often caused by Chlamydiae and Mycoplasmae. A few other organisms, as well as some nonsexual factors, also contribute to its etiology. NGU can result in considerable physical and psychological morbidity. In a few cases, it can lead to complications like reactive arthritis, and pelvic inflammatory disease, with their attendant morbidities. Correct diagnosis and treatment is therefore imperative in proper management of these cases. While earlier diagnostic support for these infections was limited and expensive, the advent of new methods like the nucleic acid amplification assays (NAA tests) has contributed significantly to better diagnosis. Treatment as per suggested guidelines and follow up of cases and contacts are all crucial in management. Counseling, including advice on behavior change, goes a long way in preventive strategies.

Chlamydial conjunctivitis (in adults), uveitis, and reactive arthritis, including SARA. Sexually acquired reactive arthritis

This chapter deals with Chlamydia -induced ocular and rheumatic diseases of the adult. All of these may follow a primary urogenital infection with Chlamydia trachomatis in genetically predisposed patients. Besides the infection with Chlamydia trachomatis, infections with Chlamydia pneumoniae and Chlamydia psittaci are also discussed as possible causative agents. Chlamydial conjunctivitis is frequently a secondary infection, and the organism is transferred from the urogenital tract to the eye by autoinoculation. Uveitis and reactive arthritis are believed to be triggered - among other infections - by a preceding urogenital infection. Both of them are closely associated with HLA-B27 positivity. The simultaneous occurrence of uveitis and reactive arthritis is termed Reiter's syndrome. We report on clinical characteristics, diagnosis and the role of Chlamydia in the pathogenesis of chlamydial conjunctivitis, uveitis and reactive arthritis as well as on the currently recommended treatment regimens.

PCR detection and molecular identification of Chlamydiaceae species

Recent taxonomic developments, based on 16s and 23s rRNA gene sequences, have divided the family Chlamydiaceae into two genera and nine species, of which five have been found to infect humans. Few simple methods are available to detect and identify all species sensitively and specifically. In this study the suitability of the omp2 gene as a target for molecular identification of Chlamydiaceae is demonstrated. Phylogenetic analysis of partial omp2 gene sequences from all nine species agrees with the recently published taxonomic changes based on the ribosomal genes. The use of a family-specific PCR primer pair, which is able to amplify the 5' end of the omp2 gene from all Chlamydiaceae except some Chlamydophila pecorum strains, is described. Identification of all nine species was achieved using restriction fragment length polymorphism analysis with a single enzyme, AluI, confirmed by DNA sequencing. A PCR enzyme-linked oligonucleotide assay was developed which can detect a single chlamydial genome and may be applied to DNA extracts from any specimen or culture for the detection of single or mixed human chlamydial infection.

Sexually transmitted infections in teenagers

Prevention of sexually transmitted infection in teenagers is a high priority. The introduction of non-invasive methods for diagnostic testing of Chlamydia trachomatis and Neisseria gonorrhoeae has enabled screening for these sexually transmitted micro-organisms in a range of community-based settings among populations at high risk, such as teenagers, who do not readily access existing sexual health services.

Molecular epidemiology of genital Chlamydia trachomatis infection in high-risk women in Senegal, West Africa

The prevalence and heterogeneity of Chlamydia trachomatis infections in a cohort of female sex workers in Dakar (Senegal) were determined by using endocervical-swab-based PCR DNA amplification assays. The overall prevalence of cervical chlamydial infection was 28.5% (206 of 722), and most of these infections were asymptomatic. An increased number of sexual partners was significantly associated with infection (adjusted odds ratio [AOR] = 1.37; 95% confidence interval [CI] = 1.06 to 1.77), while the presence of a yeast infection was negatively associated with chlamydial infection (AOR = 0.28; 95% CI = 0.10 to 0.83). Six different C. trachomatis genotypes were identified based on phylogenetic analysis of the omp1 gene sequences. Interestingly, genotype E predominated (47.6%) and was not associated with visible signs of cervical inflammation compared to non-E genotypes (P < 0.05). Overall, the high rate of asymptomatic C. trachomatis infection by genotype E may suggest genotype-specific properties that confer a transmission advantage in this high risk population.