Original article
Evaluation of VIASURE Sexually Transmitted Diseases Real Time PCR Detection kit (CerTest Biotec) for the diagnostic of sexually transmitted infectionsEvaluación de VIASURE® Sexually Transmitted Diseases Real-Time PCR Detection kit (CerTest Biotec) para el diagnóstico de las infecciones de transmisión sexual

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Abstract

Introduction

Sexually transmitted infections (STIs) are common in our environment, and trends have been increasing in the last few years. Different methods for STIs diagnosis have been applied by microbiology laboratories over years, but real-time PCR has improved this process. Our objective was to evaluate VIASURE Sexually Transmitted Diseases Real-Time PCR Detection kit (CerTestBiotec, S.L.) comparing with the real-time PCR technique used in our laboratory (Allplex™ STI7 Essential Assay, Seegene) which was considered as reference assay.

Methods

A total of 948 samples from different sites (vaginal, endocervical, urethral, rectal, pharyngeal swabs and urine samples) were analyzed from July to September 2018.

Results

A discordant result was obtained in 4.5% (43 samples). These discrepancies were mainly observed in threshold cycle (Ct) value next to the limit of detection. The k coefficient obtained shows a very high agreement between both methods with k values from 0.92 to 0.99.

Conclusions

VIASURE Sexually Transmitted Diseases Real-Time PCR Detection kit provides a very good correlation with Allplex STI7 and therefore, it's a good tool for the diagnostic of STIs. Positive results with Ct value obtained from 35 and low amplification signal should be applied with caution and should be interpreted based on the patient's clinical data.

Resumen

Introducción

Las infecciones de transmisión sexual (ITS) son frecuentes en nuestro entorno y con tendencia a aumentar. Las técnicas moleculares han mejorado su diagnóstico aportando sensibilidad y rapidez de resultados. Nuestro objetivo ha sido evaluar el nuevo kit de PCR a tiempo real VIASURE® Sexually Transmitted Diseases (CerTest Biotec, SL) comparándolo con la técnica de PCR a tiempo real empleada en nuestro laboratorio (AllplexTM STI7 Essential Assay, Seegene).

Métodos

Se analizaron prospectivamente un total de 948 muestras de diferente localización (exudado vaginal, endocervical, uretral, rectal, faríngeo y orina) recibidas en nuestro laboratorio desde julio hasta septiembre de 2018.

Resultados

En el 4,5% (43 muestras) se obtuvo un resultado discordante entre ambas técnicas. Estas discrepancias se observaron principalmente en ciclos próximos al límite de detección. El valor del coeficiente k osciló entre 0,92 a 0,99, mostrando una muy buena correlación entre técnicas.

Conclusiones

VIASURE® Sexually Transmitted Diseases Real-Time PCR Detection kit es una buena herramienta para el diagnóstico de las ITS. Muestras con señal de amplificación en ciclos a partir de 35 y baja señal de fluorescencia, deben ser tratados con precaución e interpretarse en función de los datos clínicos del paciente.

Introduction

Sexually transmitted infections (STIs) are common in our environment, and trends have been rising in the last few years.1, 2 STIs compromise quality of life as well as sexual and reproductive health and further facilitate the spread of infections such as human immunodeficiency virus infection (HIV), mainly in men who have sex with men (MSM). This situation not only represents an important individual problem, but also a Public Health issue. The patient can present a curable acute infection such as urethritis, cervicitis, proctitis and genital ulcers but this can also lead to serious complications such as cervical cancer, ease of HIV infection, and pelvic inflammatory disease (PID), which is a major cause of infertility, ectopic pregnancy, and chronic pelvic pain. The main objectives are focused on controlling and decreasing STIs transmission, and to improve the diagnosis in accordance to the guidelines of the Center Disease Control (CDC)3 and World Health Organization.4

There is a STIs work group in Catalonia that suggests, evaluates and develops screening programs. Work group consultants are sexually transmitted diseases (STD) clinicians of primary service and sexual and reproductive healthcare departments, representative members of the Public Health department, members of the Catalonia Center for HIV/AIDS, employees of sexual education center specific to children, and clinicians from different hospitals, such as microbiologist, dermatologist, infectologist and gynecologist. They make recommendations for the laboratory diagnosis and establish standard operating procedures to collect and process specimens, counsel and treat patients. Objectives of this group are to produce more rapid and accurate diagnosis, and to treat the patient as soon as possible ensuring quality. Furthermore, other efforts include having a critical role in prevention and this is why a screening program was implemented for all active individuals younger than 25 and everyone aged >25 with risk factors (e.g., those who have a new sexual partner or multiple partners).5

Most of the Clinical Microbiology laboratories use different methods for STIs diagnosis.6 Culture has all along been the reference standard for some pathogens but can have false negative results due to difficulties in maintaining the viability of organism during transport and storage or previous treatment. Serological tests are adequate for epidemiological purposes but could not distinguish between active and past infections in some cases. Due to nucleic acid amplification tests (NAATs), diagnosis has been improved. Molecular techniques provide faster results, more sensibility, do not require viable organism and additionally, they are the only available method for the detection of some microorganisms.7, 8, 9, 10

VIASURE Sexually Transmitted Diseases panel is a qualitative multiplex assay of real-time PCR able to detect and to identify 7 microorganisms related to genital pathology and/or STIs. Our objective was to evaluate VIASURE Sexually Transmitted Diseases Real-Time PCR Detection kit comparing with the real-time PCR technique used in our laboratory (Allplex™ STI7 Essential Assay, Seegene) which was considered as reference assay. Both assays detect Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, Ureaplasma parvum, Ureaplasma urealyticum, Mycoplasma genitalium and Mycoplasma hominis.

Section snippets

Patients and samples

This was a prospective study conducted from July to September 2018 at the Microbiology department of Laboratory Clinic Metropolitan Nord in Badalona (Barcelona, Spain). This laboratory receives samples from the North Metropolitan area that includes 106 primary health care facilities and 6 sexual and reproductive health centers; corresponding to more than 1,400,000 inhabitants. In our molecular biology Department next to 20,000 samples coming from different sites of symptomatic and asymptomatic

Results

A total of 948 samples were analyzed by two multiplex real-time PCR. Both assays have a comparable hands-on time and time to result (approximately 3.5 h). Furthermore, both companies have developed software to interpret the results easily.

Fully concordance was obtained in 905 (95.5%) specimens and discordant results were obtained in 4.5% (43 samples). Data for sensitivity, specificity, negative predictive value, positive predictive value and kappa index for each microorganism are shown in Table 1

Discussion

In the current study, the performance of a new multiplex real-time PCR assay (VIASURE Sexually Transmitted Diseases panel) was compared with the routine real-time PCR used in our laboratory (Allplex™ STI7 Essential Assay).

C. trachomatis and N. gonorrhoeae are the major causative agents of urethritis and cervicitis.11, 12 In our study, the degree of concordance was higher between both assays (0.96 vs 0.94). Unfortunately, due to the lack of sample and eluted, it was impossible to retest the

Conflict of interest

The authors declare no conflicts of interest.

Acknowledgments

We thank CerTestBiotec S.L. for providing the reagents and instrument used in this study.

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