Diagnostic strategy for STIs

Author

Sangrak Bae ( Department of Urology, The Catholic University of Korea, Uijeongbu St.Mary's Hospital, Uijeongbu, Korea)

Gilho Lee (Department of Urology, Dankook University College of Medicine, Cheonan, Korea)

Executive summary

Introduction

Which target is more appropriate for the diagnostic strategy:STDs or STIs ?

Choice of tests for STIs

STI diagnostic strategy's Target

Multidimensional approach and Consideration

Screening of STI

Another important issue is that “Which STIs we should impose the weight

Diagnosis

1. Diagnostic methods for Trichomonas vaginalis: Direct microscopic examination, Swab, and NAAT 2. Diagnostic methods for Neisseria Gonorrhoea: gram staining, culture, and NAAT 3. Diagnostic methods for Chlamydia trachomatis: culture, DFA (Direct immunofluorescence assay), EIA (Enzyme immunoassay), Rapid test, and NAAT.

How to evaluate the male urethritis patient?

1. Symptomatic patients 2. Asymptomatic people or risk groups

Conclusion

Introduction

World Health Organization(WHO) declared STI as "one of five types of disease for which adults around the world most commonly seek medical help." According to WHO report, there were several key facts in Sexually Transmitted infection, STI) More than one million STI occur every day, an estimated 376 million chlamydia, gonorrhoea, syphilis and trichomoniasis infections occur each year. ^[1] More than 500 million people have genital infection with herpes simplex virus(HSV1 or HSV2).^[2] Approximately 300 million women have a human papilloma virus(HPV) infection and this number is likely similar in men.^[3] The majority of STIs are occur without symptoms. Some STIs can increase the risk of HIV acquisition three-fold or more. STIs can have serious consequences beyond the immediate infection itself, trough mother-to-child transmission of infections or conditions such as infertility and cervical cancer. Drug resistance, for gonorrhoea is a major threat to control this STI worldwide.

STIs are caused by different pathogen such as virus, bacteria, parasites and the symptoms and lesions appear in various parts of the human body. Most STIs have atypical symptoms, signs and lesions by disease. However, symptomatic as well as asymptomatic carriers and asymptomatic carriers are important because they can be transmit the infection to other people. So in the case of STI, it can be said that the specific screening test is important. The strategies for diagnosis of STIs in Asian countries are very important for the following reasons: curable STIs are frequently found in Asians; STIs can result in serious physical complications in some patients; and deplete a developing nation’s economic reservoir for controlling the infections^[4]. Practically, untreated early syphilis will result in a stillbirth rate of 25% and be responsible for 14% of neonatal deaths. Untreated gonococcal and chlamydia infections in women will result in pelvic inflammatory disease in up to 40% of cases. One in four of these cases will result in infertility.^[5]

STIs are not only medical problems, but also social, political, behavioral and economical problems. Tests with high accuracy arewidely used in rich countries in developed countries, and are also very useful in detecting asymptomatic infections. However, in thelow-income and middle-income countries, many parts of the examination are impractical beacuae they are expensive or geographically inaccessible. Therefore, proper treatment through accurate diagnosis may take time and money in such countries. For a number ofreasons, there are many efforts to reduce the cost of tests and increase their convenience to perform these screening or confirmatory tests. For example, tests such as rapid dual HIV / syphilis blood test and single rapid test forsyphilis are accurate through 15-20 minutes to confirm the results , and the examiner does not require high proficiency.To solve these complicated and entangled problems, we must explore more comprehensive approaches as follows; internationalco-operation, national supports or international supports, and governmental or community supports. Furthermore, the strategies fordetection of STIs should be designed within one’s national ability or budget. ^[6]

Clinical guidelines must be based on evidence and be of value to medical practitioners. From the review of previous guidelines, we can find that the ideal guidelines are not often practice^[7][8]. Additionally, while there are very good STI or sexually transmitted diseases (STDs) guidelines around the world, STIs or STDs still thrive today.

The basic concept of a guideline is one rule for one fact with limited exceptions. However, a universal or multi-national guideline must capture the diversity of people across the Asian countries. To get an ideal STI guideline for Asian people, we must review some discrepant parts.

Accurate diagnostic tests for STIs are widely used in high-income countries but in low- and middle-income countries, the diagnostic testsare largely unavailable. So inexpensive and rapidresult for STI is needed and especially in resource-limiting environment. Several rapid tests for STIs are under development which can be potentially efficient tests for STI diagnosis and treatment , especially in resource-limited settings. ^[9]

Which target is more appropriate for the diagnostic strategy:STDs or STIs ?

STIs have broader meaning than STDs. The STDs get a small portion on the top of STIs ice bug. Unfortunately, some people who are STI incubators or asymptomatic can spread the pathogens to others as well as hurt themselves.Recently, the term “STIs”has been used more commonly in medical journals. Scientifically, the concept of STIs is more reasonablerather than the concept of STDs. However, while this inference is ideal in the medical sector, it is not always true in an economical perspective. In addition, etiological approach for STIs is problematic for some general health care providers in clinical setting because thisapproach may increase the medical costs and reduce accessbility. Setting for STDs may be simple and beneficial, and the patients may show higher compliance to treatment. If the strategy’s target is STIs, however , this approach may complicate ; the medical or social costs are very expensive because we would require highly sensitive laboratory or screening tests to detect non-symptomatic pathogens by qualified personnels after adequate training for performing technically demanding procedures. Therefore , diagnostic tests for STI differ in suitability according to the socioeconomic status of each country. The high-income country can use various tests but the low-to-mid income country has limitations on the tests. There are many methods for etiological diagnosis of STIs. While the standard bacterial culture method for Neisseria gonohoeae or Trichomonas vaginalis are well established around the world, the culture method for cryptic organisms such as Chlamydia trachomatis or Mycoplasma genitalium are difficult to set up, time-consuming, and demanding highly qualified cell culture techniques. Many health care facilities in Asian countries may lack the cell culturing equipment and trained personnel for STI approaching . The screening tests on the base of pathogens, nucleic acid amplification technique (NAAT), can be alternative method for etiological detection of STIs. Though it is customized and the whole procedures can be automatically performed, the cost is expensive to cover all person who wants to check for STIs. Practically, wide use of NAAT is not acceptable in less developed Asian countries.However, we cannot overlook serious complications of asymptomatic STIs in Asian countries. Hence, I propose a mixed step for diagnosing the STIs or STDs in Asian countries: the STI concept for the core groups or people with the high complication risk of STIs. In contrast, the STDs concept for lower prevalence groups for STIs and people with lower complication risk of STIs.I strongly recommend that the STIs core group or people with potentially serious risks after STIs infection should be tested with STIs screening tests regardless of symptoms. We should provide the NAAT for all symptomatic patients whatever the risk for STIs (Fig. 1).^{[10] [11] [12]}To successfully implement this concept, we must decide “Who should be tested for screening tests in each country?” and “Who are the STI core groups in each country?”

Choice of tests for STIs

There is no single or independent test to diagnose the causative agent that causes STI. However, there are some considerations for each country and region in selecting various tests. Various considerations exist, including the cost of the examination and the prevalence of STIs in specif region. Table 1 shows considerations for each test.^[13]

Multidimensional approach and Consideration

There are many things to consider about STI. It is necessary to distinguish whether it is a treatable STI or a preventable STI. Depending on each, an appropriate selection should be made between screening and confirm diagnosis.

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In addition, it is necessary to distinguish whether it is high risk or low risk through risk management, and for complications of STI itself, priority should be given to diagnosis by considering no complication, mild complication, severe or irreversible complication.

Education for disease prevention, diagnosis, treatment, etc. also has many points to be considered depending on how and what is delivered to whom. Education that considers all aspects such as national characteristics, demographic characteristics, and economic and social characteristics is necessary. In addition, in establishing a strategy based on these considerations, it is important to establish a strategy for each country or administrative unit, but international, regional and global strategy must be considered and established.

Screening of STI

The screening of curable STI is summarized by the CDC US Preventive Service Task Force (USPSTF) in 2019. The screening recommendations for each disease are summarized as follows for each disease.^[14]

1. CHLAMYDIA TRACHOMATIS AND NEISSERIA GONORRHOEAE

SYPHILIS

HUMAN IMMUNODEFICIENCY VIRUS

Another important issue is that “Which STIs we should impose the weight"

There are many defined STIs in the literatures. The common pathogens or diseases are bacterial vaginosis, Chlamydia trachomatis (CT), genital herpes, Neisseria gonohoeae (NG), hepatitis B and C viral infections, human papillomavirus, HIV/AIDS, pubic lice, syphilis, and Trichomonas vaginalis(TV)^[15].The three pathogens (CT, NG, TV) are very well known organisms for male urethritis.

Today, we can definitively add on Mycoplasma genitalium as a urethritis pathogen, while there are many disputes that the Ureaplsma pavum or Ureaplasma urealyticum can be pathogens for urethritis^{[16] [17] [18] [19]}.

In the urology area, urethritis can be performed as a confirmation test, and in the obstetrics area, vaginitis can be mainly targeted for examination, and these diseases can be said to be curable. So, from the next paragraph, we will examine various test methods for Tricomonas / Chlamydia trachomatis / Neisseria gonorrhoea / Mycoplasma genitalium.

Diagnostic methods for urethritis pathogens

We need valid laboratory assays to confirm STDs from the symptomatic patients, to detect infections in asymptomatic high STIs risk individuals, and to investigate the cases of resistance to empirical treatment or to monitor the changes of antibiotics resistance patterns. The ideal diagnostic methods for STIs must be simple to perform, highly sensitive and highly specific, reproducible, rapid, and inexpensive. However, there is no one rule for covering all pathogens.

Medical practitioners must understand the feasibility and weakness of each test for each pathogen within their national ability or budget. In recent years, new methods have been developed, using molecular biology techniques. Even though the newly developed NAATs meet the criteria of optimal test for STIs, they also some disadvantages for general use in Asian countries. Additionally, we must understand the limitation of not validated in-house NAATs in Asian markets. Furthermore, the genetic sequence mutations in the target area are a critical issue or serious limitation for NAATs^[20]. Interestingly, some old fashioned tests are still valid and used as a gold standard for detecting the STIs pathogens.

Trichomoniasis

Direct microscopic examination

Direct microscopic examination by medical exporters is made from a swab or urethral discharges.

One drop of a physiological saline is placed into a sample on slide and immediately examined under a light microscope (x100).

Swab

A swab of secretions is taken from the urethral orifice within six hours of sample collection to inoculate a tube of Diamond’s modified medium.The culture is incubated at 35°C for 3-4 days with daily examination by wet prep for motile trichomonas. Recently, a culture system with a two-chambered bag is available^[21].

NAAT

Even though some assays are commercially available, the feasibility has not scientifically evaluated.

Table 1. Diagnostic methods for Trichomonas vaginalis

Chlamydia trachomatis

Culture

Chlamydia culture is labor-intensive, time-consuming and expensive. It also needs considerable technique to perform. For these reasons, culture techniques are not generally recommended for clinicians. Practically, some national research laboratories may be required for monitoring of antibiotics resistance or genetic mutations.

DFA (Direct immunofluorescence assay)

The urethral secretion is collected with cotton swabs,and rolled on glass slides. Fixed and stained with fluorescein-labelled antibodies for major outer membrane protein of Chlamydia trachomatis.

The stained Chlamydia trachomatis can be detected with immuno fluorescence microscopy by the trained person.

EIA (Enzyme immunoassay)

The common target of EIA for diagnosing the Chlamydia trachomatis is chlamydial genus-specific lipopolysaccharide (LPS) antigen. Because of sharing the structure of LPS in chlamydial genus or other Gram-negative bacteria, blocking process are needed for enhancing the specificity. The basic equipments for successful performance are commercial kits by certain companies and a microwell plate reader.

Rapid test

The main advantage for rapid test is simple and rapid in chlamydial detecting process. In addition, rapid detection and onsite treatment can be an ideal method to stop spreading the infection. However, major drawback of this test is very lower sensitivity. Furthermore, the cost for doing the test is expensive. For these reasons, we do not recommend the test for diagnosing chlamydia infection anymore.

NAAT

Today, the NAAT for Chlamydia trachomatis is a newly developed gold standard for detecting the infection. While the major disadvantage of the NAAT is a complicated procedure, requiring training or expertise for successful operation; today, the drawback has been solved with a semior full automated format. With high sensitivity for detecting the organisms, we can use various clinical samples such as urine, tampons, swabs, and direct smeared samples. With the multiple targeting ability, we can detect many STIS pathogens in one sample. However, we still consider the disadvantages of NAATs for molecular diagnosis of STIs. First of all, the cost is very expensive for routinely performing in under developed countries. Second, we must consider the technical failure with amplification inhibitors and cross-over contamination. Finally, if genetic mutation in the targeted area happens during genetic evolution, we cannot detect the infection with NAATs system.

Table 2. Diagnositc methods for Chlamydia trachomatis

Neisseria Gonorrhoea

Gram staining

A direct Gram staining on the urethral discharge and examining under an oil immersion (X1000) has been a traditional laboratory test for Neisseria gonorrhoeae detection. The presence of Gram-negative diplococcic inside polymorphonuclear leukocytes is a significant diagnostic critera for Neisseria gonorrhoeae infection. The main advantages of Gram staining are rapid and inexpensive. This is the first recommended evaluation test for the male urethritis.

Culture^[22]

Inoculating the urethral secretion on Neisseria Gonorrhoea selective media such as Thayer-Martin or blood agar plate is the next step after a direct Gram smear. Typical colonies are tested with Gram-stain, oxidase and catalase and/or superoxal tests for presumptive identification of N.gonorrhoeae. Additionally, the minimal inhibitory concentration (MIC) of antibiotics such as cefixime, ceftriaxone, fluoroquinolone, azithromycin, spectinomycin and et al are determined to establish the antimicrobial susceptibility of the strain.

NAAT

The NAATs systems are designed to combo types for detecting Neisseria Gonorrhoea and Chlamydia trachomatis. Target genes are both DNA and RNA, and the molecular techniques are polymerase chain reaction (PCR) and ligase chain reaction (LCR). Please see the section of Chlamydia trachomatis for understanding advantages and disadvantages.

Table 3. Diagnostic methods for Nesisseria Gonorrhoea

Mycoplasma genitalium

Only culture and NAAT method can detect the organism for diagnosis of this infection. However, unfortunately, the culture method is very difficult, time-consuming, and expensive. In addition, while there are many NAATs methods for detecting the organism, we do not have authorized commercial kits to diagnose the infection^[13]. Mycoplasma genitalium has ability for genetic mutation under evolutional pressure. One of frequent mutation sites is determining areas for antimicrobial resistance. For this reason, we must consider unique national laboratory research center for tracking the mutation and antimicrobial susceptibility. If it is not available due to either some technical problems or national medical budget problems, we can consider one or two Asian reference centers.

How to evaluate the male urethritis patient?^[23][24]

Symptomatic patients

All male patients with urethral discharge must examine the gonococal infection. The first step is a Gram smear that is simple and rapid test. If Gram-negative diplococci in PMN cells are detected, we should do Neisseria Gonorrhoea culture. NAATs can be available to detect STIs from various samples. If NAATs test are positive in gonococal infection, we must do Neisseria Gonorrhoea culture.

Asymptomatic people or risk groups

Screening tests for STIs can be indicated in pregnant women, sexually active adolescents, persons in correction facility, homeless adolescents, and sex workers. While they have not shown symptoms, the risk of vertical STIs infection transmission is underestimated. In addition, the potential risk of STIs core groups for spreading the infections into bridging people must be considered. In conclusion, to establisha good Asian STIs guideline, we must consider the heterogeneous characteristics of Asian countries, and the draft must be reviewed by wide spectrums of national specialists to adjust their performance. In near future, we should set up regional or international central laboratories to support the diagnosis and treatment of STIs.

Conclusion

Sex is essential component of all human. But more than 1 million sexually transmitted infections occur every day. Diagnosis of disease is important for both treatable and non-curable diseases. Whether it is a confirmation test or a screening test should be applied differently according to the socioeconomic status of each region or country, and where the focus is placed will also vary. Early diagnosis and early treatment are also important for STI. Also, STI is a simple not only national problem, But also regional and worldwide.

Abbreviations

STIs: sexually transmitted infections, STDs: sexually transmitted diseases, NAAT: nucleic acid amplification technique, CT: Chlamydia trachomatis, TV: Trichomonas vaginalis, NG: Neisseria gonohoeae, MIC: minimal inhibitory concentration, PCR: polymerase chain reaction, LCR: ligase chain reaction

Reference

1. Jump up↑ Rowley J, Vander Hoorn S, Korenromp E, Low N, Unemo M, Abu-Raddad LJ, et al. Global and Regional Estimates of the Prevalence and Incidence of Four Curable Sexually Transmitted Infections in 2016. WHO Bulletin. June 2019. Report on global sexually transmitted infection surveillance, 2018. Geneva: World Health Organization; 2018. Licence: CC BY-NC-SA 3.0 IGO]

2. Jump up↑ Looker KJ, Magaret AS, Turner KM, Vickerman P, Gottlieb SL ,Newman LM. Global estimates of prevalent and incident herpes simplex virus type 2 infections in 2012. PLoS One. 2015 Jan 21;10(1):e114989

3. Jump up↑ Worldwide prevalence and genotype distribution of cervical human papillomavirus DNA in women with normal cytology: a meta-analysis. de Sanjosé S, Diaz M, Castellsagué X, Clifford G, Bruni L, Muñoz N, et al. Lancet Infect Dis. 2007 Jul;7(7):453-9

4. Jump up↑ Prevalence and incidence of selected sexually transmitted infections Chlamydia trachomatis, Neisseria gonorrhoeae, syphilis and Trichomonas vaginalis Methods and results used by WHO to generate 2005 estimates. WHO 2011 http://whqlibdoc.who.int/publications/2011/9789241502450_eng.pdf

5. Jump up↑ Aral SO, Holmes KK. Social and behavioral determinants of the spidemiology of STDs:Industrialized and developing countries. In: Holmes KK, Sparling PF, Mardh P, Lemon SM, Stamm WE, Piot P, et al, editors. Sexually transmitted diseases. 3rd ed. New York: McGrawHill; 1999:39-76.

6. Jump up↑ Aral SO, Holmes KK. Social and behavioral determinants of the spidemiology of STDs:Industrialized and developing countries. In: Holmes KK, Sparling PF, Mardh P, Lemon SM, Stamm WE, Piot P, et al, editors. Sexually transmitted diseases. 3rd ed. New York: McGrawHill; 1999:39-76

7. Jump up↑ Lugtenberg M, Burgers JS, Zegers-van Schaick JM, Westert GP. Guidelines on uncomplicated urinary tract infections are difficult to follow: perceived barriers and suggested interventions. BMC Fam Pract. 2010 ;11:51.

8. Jump up↑ Cabana MD, Rand CS, Powe NR, Wu AW, Wilson MH, Abboud PA, Rubin HR. Why don't physicians follow clinical practice guidelines? A framework for improvement. JAMA. 1999;282:1458-65.

9. Jump up↑ WHO FACT SHEETs Sexually transmitted infections (STIs) https://www.who.int/news-room/fact-sheets/detail/sexually-transmitted-infections-(stis)

10. Jump up↑ Swartz SL, Kraus SJ, Herrmann KL, Stargel MD, Brown WJ, Allen SD. Diagnosis and etiology of nongonococcal urethritis. J Infect Dis. 1978 ;138:445-54.

11. Jump up↑ Workowski KA, Berman S; Centers for Disease Control and Prevention (CDC). Sexually transmitted diseases treatment guidelines, 2010. MMWR Recomm Rep. 2010;59(RR-12):1-110.

12. Jump up↑ Choi JY, Cho IC, Lee GI, Min SK. Prevalence and associated factors for four sexually transmissible microorganisms in middle-aged men receiving general prostate health checkups: a polymerase chain reaction-based study in Korea. Korean J Urol. 2013;54:53-8.

13. Jump up↑ Laboratory diagnosis of sexually transmitted infections, including human immunodeficiency virus

14. Jump up↑ Shoshana B Levy, Jyothi Gunta , Peter Edemekong. Screening for Sexually Transmitted Diseases. Prim Care 2019 Mar;46(1):157-173. doi: 10.1016/j.pop.2018.10.013. Epub 2018 Dec 24.

15. Jump up↑ Markle W, Conti T, Kad M. Sexually transmitted diseases. Prim Care. 2013 ;40:557-87. 29.

16. Jump up↑ Choi JY, Cho IC, Lee GI, Min SK. Prevalence and associated factors for four sexually transmissible microorganisms in middle-aged men receiving general prostate health checkups: a polymerase chain reaction-based study in Korea. Korean J Urol. 2013;54:53-8.

17. Jump up↑ Daley G, Russell D, Tabrizi S, McBride J. Mycoplasma genitalium: a review. Int J STD AIDS. 2014 ;25:475-487.

18. Jump up↑ Cazanave C, Manhart LE, Bébéar C. Mycoplasma genitalium, an emerging sexually transmitted pathogen. Med Mal Infect. 2012 ;42:381-92

19. Jump up↑ Hamasuna R. Mycoplasma genitalium in male urethritis: diagnosis and treatment in Japan. Int J Urol. 2013 ;20:676-84.

20. Jump up↑ Unemo M, Clarke IN. The Swedish new variant of Chlamydia trachomatis. Curr Opin Infect Dis. 2011 ;24:62-9.

21. Jump up↑ Levi MH, Torres J, Pina C, Klein RS. Comparison of the In Pouch TV culture system and Diamond’s modified medium for detection of Trichomonas vaginalis. Journal of Clinical Microbiology, 1997, 35:3308-10.

22. Jump up↑ http://www.wpro.who.int/publications/pub_9290611480/en/

23. Jump up↑ 日本性感染症学会. 性感染症診断・治療ガイドライン 2011. 日本性感染症学会誌 2011;22(Supplement 1): 10

24. Jump up↑ http://www.uti.or.kr/include/pdf/sexually-transmitted-infection-2016.pdf