First evaluation of six nucleic acid amplification tests widely used in the diagnosis of Chlamydia trachomatis in Russia

Background  In Russia, nationally developed nucleic acid amplification tests (NAATs), which have never been validated to international commercially available NAATs, are mainly used in the diagnosis of Chlamydia trachomatis infection.
Objective  To evaluate the performance characteristics of six NAATs widely used to diagnose C. trachomatis infection in Russia.
Materials and methods   In total, 446 consecutive symptomatic patients (319 females and 127 males) were included. Five polymerase chain reaction (PCR) assays and one real-time nucleic acid sequence-based amplification (NASBA) assay were evaluated on cervical and vaginal samples from females and on urethral and first voided urine samples from males. As reference methods, the Cobas Amplicor PCR, as the main 'gold standard' method, and LightMix 480HT PCR were used.
Results  The overall prevalence of C. trachomatis infection was 12.6%. The Russian NAATs and the reference methods displayed a high level of concordance (97.9% to 99.2%). In comparison with the reference methods, the sensitivities, specificities, positive predictive values and negative predictive values of the Russian tests in different specimens ranged from 86.1% to 100%, 99.1% to 100%, 92.3% to 100% and 98.2% to 100%, respectively.
Conclusions  According to the reference methods, C. trachomatis NAATs developed and used in Russia have relatively good performance characteristics for both invasive and non-invasive samples. However, larger studies that include symptomatic and asymptomatic patients as well as genital and extra-genital samples, and in comparison with other internationally well-recognized, validated, and ideally Food and Drug Administration–approved C. trachomatis NAATs performed strictly according to the manufacturer's instructions, need to be conducted.

Conflicts of interest

None declared     

First evaluation of polymerase chain reaction assays used for diagnosis of Mycoplasma genitalium in Russia

Background  Diagnosis of Mycoplasma genitalium is entirely based on nucleic acid amplification tests (NAATs). In Russia, several M. genitalium polymerase chain reaction (PCR) assays have been developed; however, any evaluation of their performance has never been performed.
Objective  To assess the performance of five PCRs developed and currently used in Russia for diagnosis of M. genitalium .
Materials and methods  Vaginal swabs and first voided urine samples (FVUs) from 281 females and urethral swabs and FVUs from 125 males were analysed using three conventional PCRs and two real-time PCRs developed by three Russian companies. As reference tests, a real-time PCR targeting the MgPa adhesin gene was used; positive results were confirmed by two conventional PCRs targeting the 16S rRNA gene and MgPa gene, respectively. For evaluation of detection limits and analytical specificities, a blinded control panel consisting of dilutions of six strains of M. genitalium and 14 other Mycoplasma species was tested.
Results  The prevalence of M. genitalium was 2.5% among females and 9.6% among males. The highest sensitivity (71.4–100% in different specimens) was exhibited by one real-time PCRs. Conventional PCRs from two manufacturers failed to detect M. genitalium in any of the seven positive female FVUs. All tests had a 100% clinical specificity; however, one cross-reacted with Mycoplasma pneumoniae .
Conclusions  Only one of the five Russian PCRs displayed reasonable sensitivity for all specimen types, but the specificities of all assays were high. Accordingly, improvements regarding sensitivity of all the tests are needed. However, larger studies, including other populations, evaluating these assays are crucial.