Prevalence of aetiological pathogens of vaginal discharge and male urethritis syndromes in the Tshwane region

Abstract

Sexually transmitted infections (STIs) continue to present major health, social and economic challenges in developing countries. The prevalence rate is higher in developing countries where STI treatment is less accessible. Sexually transmitted infections are caused by a large number of microbial agents that cause considerable morbidity, mortality and stigma worldwide. In South Africa, the burden of STI is high and the most common STI presentations to the public healthcare are male urethritis syndrome (MUS) and vaginal discharge syndrome (VDS). Male urethritis account for over 60% of STIs annually, reported at healthcare facilities in the Gauteng province of South Africa. The main STI pathogens responsible for these two syndromes are Chlamydia trachomatis, Neisseria gonorrhoeae and Trichomonas vaginalis. Bacterial vaginosis, candidiasis, Mycoplasma genitalium, Ureaplasma species and viruses [Epstein-Barr virus (EBV), Herpes simplex virus (HSV-1, HSV-2), cytomegalovirus (CMV)] cause a small percentage of the vaginal discharge seen in clinical practice. Sexually transmitted infections facilitate the transmission of the human immunodeficiency virus (HIV). This interaction may be a major factor in the rapid spread of HIV in sub-Saharan Africa. Hence, the control of STIs can lead to a substantial reduction in the transmission of HIV. However, antimicrobial resistance is making the clinical management of STIs such as gonorrhoea difficult. The treatment options for gonococcal infections have reduced over time because of the emergence and spread of gonococci resistant to all antibiotics previously used as first-line empirical treatment. Currently, extended-spectrum cephalosporins (ESCs) are the only antibiotics recommended as first-line treatment of gonococcal infections. However, N. gonorrhoeae strains with reduced susceptibility or resistant to ESC and treatment failures with these agents has been reported. Thus, continued monitoring is mandatory to ensure that the optimal agent for empirical therapy is in use. Ideally, resistance monitoring should be combined with a highly discriminatory typing scheme; this will permit the detection of sexual networks and offers the potential for early detection of multidrug resistance (MDR) isolates. In South Africa, STI treatment services are provided by both the public and private sectors. In the former, treatment for STIs is reliant on syndromic management. The success of this depends on early detection and constant monitoring of the aetiological pathogens. The aim of this study was to determine the prevalence of N. gonorrhoeae, T. vaginalis, C. trachomatis and M. genitalium as aetiological pathogens of MUS and VDS using a multiplex real-time polymerase chain reaction assay. Furthermore, the antimicrobial resistance of N. gonorrhoeae clinical isolates to eight antibiotics (penicillin, cefoxitin, ceftriaxone, cefpodoxime, tetracycline, ciprofloxacin, ofloxacin and spectinomycin) and the corresponding minimum inhibitory concentrations (MICs) were determined by using the Kirby Bauer disc diffusion and E-test methods. Finally, N. gonorrhoeae multi-antigen sequence typing (NGMAST) was used to determine the genetic relatedness of N. gonorrhoeae clinical isolates. The prevalence of MUS and VDS pathogens in this study was 57% (113/200). Pathogens responsible for urethritis were detected in 77% (48/62) of male participants while VDS were found in 47% (65/138) of the female participants. Resistance to quinolones increased by tenfold (7% in 2004 up to 70% in 2013) and it correlates with MDR isolates. All isolates were susceptible to third-generation cephalosporins. The NG-MAST method revealed novel as well as previously described sequence types (ST). The NG-MAST ST 11715, 11716, 11717 and 11718 are novel STs and have been registered at: (www.ngmast.net). This study showed that N. gonorrhoeae is the most common cause of urethritis and vaginal discharge in the Tshwane region. The real-time multiplex PCR assay was rapid and suitable for the detection of all four pathogens at relatively low cost. This study supports cefixime as the current first-line treatment for N. gonorrhoeae in the Tshwane region, Gauteng, South Africa. The findings of this study further support the testing of more than one pathogen in a PCR assay for the laboratory diagnosis of MUS and VDS.