Diagnostic Procedures to Detect Chlamydia trachomatis Infections.

Thomas Meyer

doi:10.3390/microorganisms4030025

Abstract

The intracellular life style of chlamydia and the ability to cause persistent infections with low-grade replication requires tests with high analytical sensitivity to directly detect C. trachomatis (CT) in medical samples. Nucleic acid amplification tests (NAATs) are the most sensitive assays with a specificity similar to cell culture and are considered the method of choice for CT detection. In addition, NAATs can be performed on various clinical specimens that do not depend on specific transport and storage conditions, since NAATs do not require infectious bacteria. In the case of lower genital tract infections, first void urine and vaginal swabs are the recommended specimens for testing males and females, respectively. Infections of anorectal, oropharyngeal and ocular epithelia should also be tested by NAAT analysis of corresponding mucosal swabs. In particular, anorectal infections of men who have sex with men (MSM) should include evaluation of lymphogranuloma venereum (LGV) by identification of genotypes L1, L2 or L3. Detection of CT antigens by enzyme immunoassay (EIAs) or rapid diagnostic tests (RDTs) are unsuitable due to insufficient sensitivity and specificity. Recent PCR-based RDTs, however, are non-inferior to standard NAATs, and might be used at the point-of-care. Serology finds application in the diagnostic work-up of suspected chronic CT infection but is inappropriate to diagnose acute infections.

Highlights

Reports from the WHO indicate a world-wide increase of sexually transmitted infections (STI) in recent years, with Chlamydia trachomatis (CT) and Neisseria gonorrhoeae being the most frequent bacterial STI pathogens, each causing an estimated 106 million new infections per year [1]
This review provides an overview of laboratory tests used to detect CT infections
Indirect methods depend on detection of antibodies against C. trachomatis that may be applied for diagnostic evaluation of chronic/invasive infection (PID, lymphogranuloma venereum (LGV)) and post infectious complications, like sexually acquired reactive arthritis (SARA)

Summary

Introduction

Reports from the WHO indicate a world-wide increase of sexually transmitted infections (STI) in recent years, with Chlamydia trachomatis (CT) and Neisseria gonorrhoeae being the most frequent bacterial STI pathogens, each causing an estimated 106 million new infections per year [1]. Acute infections present as conjunctivitis that, if left untreated, may become chronic and lead to trachoma These infections are rarely seen in Europe and North America, but are quite frequent in Africa and Asia, where they represent an important cause of blindness [6]. Most rectal and pharyngeal infections and many infections of the lower genital tract do not produce symptoms Both symptomatic and asymptomatic infections can cause sequelae, predominately affecting women. Since 2003 several outbreaks with genotype L2 were reported among MSM in Europe, North America and Australia [11] These patients predominately suffer from anorectal symptoms, in contrast to the classical inguinal syndrome of sporadic LGV [12]. LGV infections are not always symptomatic, further contributing to the constantly high incidence rates [13]

Diagnostic Procedures

Clinical Specimens for CT Testing

Serology

Findings

Conclusions