Comparison of clinical performance of antigen basedenzyme immunoassay (EIA) and major outer membrane protein (MOMP)-PCR for detection of genital Chlamydia trachomatis infection

Epidemiology of Chlamydia trachomatis in the Middle East and north Africa: a systematic review, meta-analysis, and meta-regression

BACKGROUND

The epidemiology of Chlamydia trachomatis in the Middle East and north Africa is poorly understood. We aimed to provide a comprehensive epidemiological assessment of C trachomatis infection in the Middle East and north Africa.

METHODS

We did a systematic review of C trachomatis infection as well as a meta-analysis and meta-regression of C trachomatis prevalence. We searched PubMed and Embase, as well as regional and national databases up to March 13, 2019, using broad search terms with no language or year restrictions. Any document or report including biological measures for C trachomatis prevalence or incidence was eligible for inclusion. We extracted all measures of current (genital or rectal), recent, and ever infection with C trachomatis. We estimated pooled average prevalence in different populations using random-effects meta-analysis. Factors associated with prevalence and sources of between-study heterogeneity were determined using meta-regression.

FINDINGS

We identified a total of 1531 citations, of which 255 reports contributed to 552 C trachomatis prevalence measures from 20 countries. No incidence measures were identified. Pooled prevalence of current genital infection was 3·0% (95% CI 2·3-3·8) in general populations, 2·8% (1·0-5·2) in intermediate-risk populations, 13·2% (7·2-20·7) in female sex workers, 11·3% (9·0-13·7) in infertility clinic attendees, 12·4% (7·9-17·7) in women with miscarriage, 12·4% (9·4-15·7) in symptomatic women, and 17·4% (12·5-22·8) in symptomatic men. Pooled prevalence of current rectal infection was 7·7% (4·2-12·0) in men who have sex with men. Substantial between-study heterogeneity was found. Multivariable meta-regression explained 29·0% of variation. Population type was most strongly associated with prevalence. Additional associations were found with assay type, sample size, country, and sex, but not with sampling methodology or response rate (about 90% of studies used convenience sampling and >75% had unclear response rate). There was no evidence for temporal variation in prevalence between 1982 and 2018.

INTERPRETATION

C trachomatis prevalence in the Middle East and north Africa is similar to other regions, but higher than expected given its sexually conservative norms. High prevalence in infertility clinic attendees and in women with miscarriage suggests a potential role for C trachomatis in poor reproductive health outcomes in this region.

FUNDING

National Priorities Research Program from the Qatar National Research Fund (a member of Qatar Foundation).

Diagnostic test evaluation methodology: A systematic review of methods employed to evaluate diagnostic tests in the absence of gold standard - An update

OBJECTIVE

To systematically review methods developed and employed to evaluate the diagnostic accuracy of medical test when there is a missing or no gold standard.

STUDY DESIGN AND SETTINGS

Articles that proposed or applied any methods to evaluate the diagnostic accuracy of medical test(s) in the absence of gold standard were reviewed. The protocol for this review was registered in PROSPERO (CRD42018089349).

RESULTS

Identified methods were classified into four main groups: methods employed when there is a missing gold standard; correction methods (which make adjustment for an imperfect reference standard with known diagnostic accuracy measures); methods employed to evaluate a medical test using multiple imperfect reference standards; and other methods, like agreement studies, and a mixed group of alternative study designs. Fifty-one statistical methods were identified from the review that were developed to evaluate medical test(s) when the true disease status of some participants is unverified with the gold standard. Seven correction methods were identified and four methods were identified to evaluate medical test(s) using multiple imperfect reference standards. Flow-diagrams were developed to guide the selection of appropriate methods.

CONCLUSION

Various methods have been proposed to evaluate medical test(s) in the absence of a gold standard for some or all participants in a diagnostic accuracy study. These methods depend on the availability of the gold standard, its' application to the participants in the study and the availability of alternative reference standard(s). The clinical application of some of these methods, especially methods developed when there is missing gold standard is however limited. This may be due to the complexity of these methods and/or a disconnection between the fields of expertise of those who develop (e.g. mathematicians) and those who employ the methods (e.g. clinical researchers). This review aims to help close this gap with our classification and guidance tools.

Chlamydia, gonorrhoea, trichomoniasis and syphilis: global prevalence and incidence estimates, 2016

OBJECTIVE

To generate estimates of the global prevalence and incidence of urogenital infection with chlamydia, gonorrhoea, trichomoniasis and syphilis in women and men, aged 15-49 years, in 2016.

METHODS

For chlamydia, gonorrhoea and trichomoniasis, we systematically searched for studies conducted between 2009 and 2016 reporting prevalence. We also consulted regional experts. To generate estimates, we used Bayesian meta-analysis. For syphilis, we aggregated the national estimates generated by using Spectrum-STI.

FINDINGS

For chlamydia, gonorrhoea and/or trichomoniasis, 130 studies were eligible. For syphilis, the Spectrum-STI database contained 978 data points for the same period. The 2016 global prevalence estimates in women were: chlamydia 3.8% (95% uncertainty interval, UI: 3.3-4.5); gonorrhoea 0.9% (95% UI: 0.7-1.1); trichomoniasis 5.3% (95% UI:4.0-7.2); and syphilis 0.5% (95% UI: 0.4-0.6). In men prevalence estimates were: chlamydia 2.7% (95% UI: 1.9-3.7); gonorrhoea 0.7% (95% UI: 0.5-1.1); trichomoniasis 0.6% (95% UI: 0.4-0.9); and syphilis 0.5% (95% UI: 0.4-0.6). Total estimated incident cases were 376.4 million: 127.2 million (95% UI: 95.1-165.9 million) chlamydia cases; 86.9 million (95% UI: 58.6-123.4 million) gonorrhoea cases; 156.0 million (95% UI: 103.4-231.2 million) trichomoniasis cases; and 6.3 million (95% UI: 5.5-7.1 million) syphilis cases.

CONCLUSION

Global estimates of prevalence and incidence of these four curable sexually transmitted infections remain high. The study highlights the need to expand data collection efforts at country level and provides an initial baseline for monitoring progress of the World Health Organization global health sector strategy on sexually transmitted infections 2016-2021.

Borrelia and Chlamydia Can Form Mixed Biofilms in Infected Human Skin Tissues

Our research group has recently shown that Borrelia burgdorferi, the Lyme disease bacterium, is capable of forming biofilms in Borrelia-infected human skin lesions called Borrelia lymphocytoma (BL). Biofilm structures often contain multiple organisms in a symbiotic relationship, with the goal of providing shelter from environmental stressors such as antimicrobial agents. Because multiple co-infections are common in Lyme disease, the main questions of this study were whether BL tissues contained other pathogenic species and/or whether there is any co-existence with Borrelia biofilms. Recent reports suggested Chlamydia-like organisms in ticks and Borrelia-infected human skin tissues; therefore, Chlamydia-specific polymerase chain reaction (PCR) analyses were performed in Borrelia-positive BL tissues. Analyses of the sequence of the positive PCR bands revealed that Chlamydia spp. DNAs are indeed present in these tissues, and their sequences have the best identity match to Chlamydophila pneumoniae and Chlamydia trachomatis. Fluorescent immunohistochemical and in situ hybridization methods demonstrated the presence of Chlamydia antigen and DNA in 84% of Borrelia biofilms. Confocal microscopy revealed that Chlamydia locates in the center of Borrelia biofilms, and together, they form a well-organized mixed pathogenic structure. In summary, our study is the first to show Borrelia-Chlamydia mixed biofilms in infected human skin tissues, which raises the questions of whether these human pathogens have developed a symbiotic relationship for their mutual survival.