Chlamydia trachomatis infection positivity rates determined by nucleic acid amplification test in patients of hospitals in the northeastern region of Ukraine

Abstract

There are no accurate data regarding the prevalence of Chlamydia trachomatis infection in Ukraine. This study aims to estimate the prevalence in the northeastern region of the country through reviewing nucleic acid amplification test results in patients of medical institutions in the Kharkov region during 2014–2016. Samples from 6920 patients (5028 women and 1892 men) aged 12–76 years were tested. The overall positivity rate was 4.5% (95% CI 4.0–5.0): 3.9% (95% CI 3.4–4.5) in women and 6.1% (95% CI 5.1–7.3) in men. The highest prevalence was found in the 16–20 (8.5%, CI 6.3–11.4) and 21–25 (8.0%, CI 6.7–9.4) year age groups. The prevalence in men was higher than in women in all investigated groups. The results show the need for more attention to the prevention, diagnosis, and treatment of chlamydial infection in these age groups of women and men in this region.

Keywords

Sexually transmitted infections prevalence

Introduction

Chlamydia trachomatis is one of the most common sexually transmitted infections, which constitutes a substantial burden for health in many countries.^1,2 The prevalence of C. trachomatis infection in Ukraine was earlier estimated as 54–70 per 100,000 population.^3,4 Unfortunately, this estimate was obtained before the introduction of the nucleic acid amplification tests (NAATs) which greatly improved C. trachomatis screening.⁵ The aim of the present study was to estimate the prevalence of C. trachomatis infection in the northeastern region of Ukraine by using the positivity rate of NAATs in a representative group of patients, investigated in two medical institutions – SE ‘Institute of Dermatology and Venerology of the National Academy of Medical Sciences of Ukraine’ (IDV) and private diagnostic laboratory ‘Analytica’ (LA).

Diagnosis and treatment of C. trachomatis infection in Ukraine is not strictly regulated and is performed by different state and private medical institutions, including dermatovenerological, urological and gynecological clinics, private medical centers, and general practitioners. At the same time, the polymerase chain reaction (PCR) tests, especially important for chlamydia diagnosis, are performed almost exclusively in the private commercial laboratories to which clinical samples are sent. In connection with the diagnostic activities of such laboratories, LA being one of these, valuable information is provided on positivity rates of chlamydia infection in patients of more than ten different medical institutions in the Kharkov region. Patients’ samples (or patients themselves) are sent to LA from gynecological, obstetric, dermatovenerological, and urological clinics, private medical centers, and self-referrals. Unfortunately, some important data about patients whose clinical samples were sent to LA, including diagnoses, are missing. Diagnosis of chlamydial infection in this region is performed quite often, especially in patients of gynecology, urology, and fertility clinics; all pregnant women get a NAAT for chlamydial infection. Samples of patients from all these clinics are investigated in LA.

Another participant of this investigation, IDV, is a leading scientific center in the field of dermatovenerology in Ukraine, having investigated chlamydial infection for more than 40 years, with its own laboratory for PCR diagnostics and STI clinic. The number of people treated in the IDV was relatively small.

In this article we analyze the NAAT results in these groups of patients for estimation of the prevalence of C. trachomatis infection in the northeast region of Ukraine.

Methods

The study was conducted in the city of Kharkov (1,450,000 inhabitants), the center of the northeastern region of Ukraine, under the IDV’s supervision in the period between 1 January 2014 and 1 June 2016. The age of the patients ranged from 12 to 76 years. The persons examined in the IDV were clients of the urogenital clinic and high-risk group representatives; among which were men with urethritis (79.6%) and prostatitis (11.9%), infertility (4.2%), and arthritis (3.2%) and women with endocervicitis (81.5%), infertility (8.0%), adnexitis (3.4%), and cervical erosion (3.7%). LA samples sent from more than ten different medical institutions without specifying a diagnosis were investigated. These were divided into the following groups: women’s health clinics (as a rule it was impossible to discern gynecological and obstetrical patients), dermatovenerological clinics, urological clinics, medical centers, and ‘without referral’.

Urethral and cervical samples for investigation were taken by standard urogenital swabs.

The samples’ DNA was purified by the ‘Proba Rapid’ test kit (DNA technology, Russia). In IDV, C. trachomatis’ DNA detection was performed by a laboratory-designed seminested test for chlamydial cryptic plasmid DNA fragment⁶ with the ‘Tertsik’ thermocycler (DNA-technology, Russia). The PCR products were analyzed by electrophoresis in 2% agarose gel with ethidium bromide staining. In the LA, C. trachomatis DNA was detected by real-time PCR with the ‘Real Time Chlamydia trachomatis’ test kit and the ‘DT Light thermocycler’ (DNA technology, Russia).

The study was approved by the Ethics Committees of the IDV and the LA.

Statistical analysis

The Chi square test was used to compare percentages; Wilson score was calculated to estimate the confidence interval. The P value of < 0.05 was considered statistically significant. The EpiTools epidemiological calculators were used for the calculations.⁷

Results

The total number of screened patients was 6920, formed of 5028 women and 1892 men. 702 (324 women and 378 men) were examined in the IDV and 6218 (4704 women and 1514 men) in the LA. Average age of IDV patients was 34.9 years; 36.9 years for men and 32.7 years for women. For LA patients it was 31.4 years; 34.5 years for men and 30.3 years for women. The results of C. trachomatis testing (Table 1) show that the positivity rates in the LA and the IDV are similar; the IDV figures are a bit higher, but the difference is not significant, which makes it possible to combine data of the two institutions. In the joint group, C. trachomatis was detected in 311 of 6920 patients, with the overall prevalence of 4.5% (95% CI 4.0–5.0); 3.9% (95% CI 3.4–4.5) for women and 6.1% (95% CI 5.1–7.3) for men. The higher prevalence in men compared with women was statistically significant (p < 0.01).

Table 1.

Positivity rates of C. trachomatis testing in patients investigated in the IDV and the LA (%).

	Total				IDV				LA
	No.	CT+	(%)	95% CI	No.	CT+	(%)	95% CI	No.	CT+	(%)	95% CI
Total	6920	311	(4.5)	(4.0–5.0)	702	41	(5.8)	(4.3–7.8)	6218	270	(4.3)	(3.9–4.9)
Women	5028	195	(3.9)*	(3.4–4.5)	324	14	(4.3)	(2.5–7.1)	4704	181	(3.8)*	(3.3–4.4)
Men	1892	116	(6.1)*	(5.1–7.3)	378	27	(7.1)	(4.9–10.2)	1514	89	(5.9)*	(4.8–7.2)

CI: confidence interval; CT+: Chlamydia trachomatis positivity; IDV: Institute of Dermatology and Venerology of the National Academy of Medical Sciences of Ukraine; LA: laboratory ‘Analytica.’

*p < 0.05.

The youngest infected persons were aged 16, and the highest number of infection cases was observed in women aged 23–24 and in men aged 27–28 years. In the <26 year age group, the number of infected women was significantly higher than men (Figure 1).

The prevalence of chlamydial infection (Table 2) was highest in the 16–20 and 21–25 year age groups (8.5, 8.0%) and decreased to 1.9% in the 39–47 year age group; in all the groups, the prevalence in men was greater than in women.

Table 2.

Prevalence of C. trachomatis infection in different age groups.

Age (years)	Total				Men				Women
Age (years)	No.	CT+	(%)	95% CI	No.	CT+	(%)	95% CI	No.	CT+	(%)	95% CI
16–20	461	39	(8.5)	(6.3–11.4)	55	9	(16.4)	(8.9–28.3)	406	30	(7.4)	(5.2–10.4)
21–25	1556	124	(8.0)	(6.7–9.4)	302	34	(11.3)*	(8.2–15.3)	1254	90	(7.2)	(5.9–8.7)*
26–30	1810	75	(4.1)	(3.3–5.2)	440	36	(8.2)*	(6.0–11.1)	1370	39	(2.8)*	(2.1–3.9)
31–38	1738	50	(2.9)	(2.1–3.8)	505	23	(4.6)*	(3.1–6.7)	1233	27	(2.2)*	(1.5–3.2)
39–47	842	16	(1.9)	(1.1–3.1)	355	10	(2.8)	(1.5–5.1)	487	6	(1.2)	(0.6–2.7)

CI: confidence interval; CT+: Chlamydia trachomatis positivity.

*p < 0.05.

Information about positivity rates in different patients’ groups investigated in LA is presented in Table 3.

Table 3.

Positivity rates of C. trachomatis testing in LA patients from different clinics.

Samples sent from	Women				Men
Samples sent from	No.	CT+	(%)	95% CI	No.	CT+	(%)	95% CI
Women’s health clinics	2531	99	(3.9)	(3.2–4.7)*	186	22	(11.8)	(7.9–17.3)*
Dermatovenerological clinics	696	26	(3.7)	(2.6–5.4)	285	19	(6.7)	(4.3–10.2)
Urological clinics					656	26	(4.0)	(2.7–5.7)
Medical centers	1081	37	(3.4)	(2.5–4.7)	227	12	(5.3)	(3.0–9.0)
Without referral	396	19	(4.8)	(3.1–7.4)	160	10	(6.3)	(3.4–11.1)

CI: confidence interval; CT+: Chlamydia trachomatis positivity; LA: laboratory ‘Analytica.’

*p < 0.05.

A noticeable difference was found in positivity rates of the LA patients treated in the different medical institutions. In the patients from dermatovenerological clinics C. trachomatis positivity was very close to the figures obtained in the IDV, though slightly lower, which may be due to the greater number of the patients with more severe pathology in the latter group.

Almost half of the samples were sent to the LA from the women’s health clinics; positivity rates in women from these clinics were comparatively low, but this group was not homogenous. Low figures in women contrasted with high positivity rates in the men from this group.

Chlamydia positivity rates of the IDV patients with different pathology are presented in Table 4. Among women with endocervicitis and men with urethritis the frequency of positive results was 4.5% and 7.6%, respectively. Though other groups of patients were too small for statistically supported conclusions, the high positivity rates in women with cervical erosion and adnexitis and in men with infertility and arthritis are notable.

Table 4.

Positivity rates in IDV patients with different pathology.

Diagnosis	No.	CT+	(%)	95% CI
Women
Endocervicitis	264	12	(4.5)	(2.6–7.8)
Cervical erosion	12	1	(8.3)	(1.5–35.4)
Adnexitis	11	1	(9.1)	(1.6–37.7)
Infertility	26	1	(3.8)	(0.7–18.9)
Men
Urethritis	301	23	(7.6)	(5.1–11.2)
Prostatitis	45	2	(4.4)	(1.2–14.8)
Infertility	16	3	(18.7)	(6.6–43.0)
Arthritis	12	1	(8.3)	(1.5–35.4)

CI: confidence interval; CT+: Chlamydia trachomatis positivity; IDV: Institute of Dermatology and Venerology of the National Academy of Medical Sciences of Ukraine.

Discussion

There are scarce data regarding the prevalence of C. trachomatis infection in Ukraine and other countries of Eastern Europe, provided with NAAT. In 2008–2010 in Saint-Petersburg, С. trachomatis positivity in the group of patients with acute urogenital tract diseases was 12.6% in women and 18.0% in men. In patients with infertility these figures were correspondingly 29.3% and 19.6%, and in persons surveyed by contact 17.1% and 14.5%.⁸ In 2001–2002 in Novosibirsk, chlamydia was detected in 8.2% of women visiting a gynecologist, in 5.2% of healthy women, and 5.1% of pregnant women.⁹

In our study, positivity rates for similar groups were significantly lower than the data of these reports; it can be considered as evidence of a lower prevalence of chlamydial infection in our region. It is interesting to note that in the St. Petersburg study the rates of infection in men with acute inflammatory diseases exceeded those of the women. This trend in our study was more pronounced and appeared in the most of the groups examined.

The lower level of positivity was noted in the women treated in the medical centers (LA) – 3.4%. A higher rate was observed in patients of women’s health centers – 3.9%. It seems possible that the latter figure reflects the heterogeneity of this group, which could be illustrated by significant difference between the positivity in women and in men sent for investigation to the LA from the women’s health centers. Quite obviously this group of men belongs to the couples treated in these clinics for common problems and the female counterpart of these couples is responsible for the significant part of the positivity in this group of women. When excluding these high-risk persons from the general group of women surveyed by specialists we could obtain for the rest of the group a positivity rate as low as 3.1% (95% CI 2.5–3.8). Probably, this figure, quite comparable with 3.4% in women of medical centers, could be considered as an assessment of C. trachomatis prevalence in the low-risk female population in our region. The highest level of positivity could be seen in men who were patients of women's health clinics, similar to the 11.3% positivity in the high-risk group of 20–25 year-old men (Table 2).

There is a general agreement about the dependence of the prevalence of chlamydia infection on the age of the subjects. In our study, the highest positivity rates were found in the groups 16–20 and 21–25 years (Figure 1, Table 2). The maximum of the absolute number of positive results occurs in 20–25 year-old women. In all age groups the positivity rate in men was higher than in women.

The lower frequency of positive results in women compared to men does not correspond to the data of most literary sources, only rarely is higher prevalence in men found in the published articles. Probably, the results we obtained were due to the prevalence in our groups of patients of STI clinics. Some resemblance to this could be found in the results for the Australian population, reviewed by Lewis et al.¹⁰ The prevalence of chlamydial infection for persons under 25 attending community or general practice settings was 5.0% (95% CI 3.1–6.9) for women and 3.9% (95% CI 2.7–5.1) for men, but patients of sexual health, youth, or family planning clinics of the <25 age group demonstrated statistically higher prevalence of chlamydial infection in men: 10.2% (95% CI 9.5–10.9), than in women: 6.2% (95% CI 5.1–7.4).

It may also be partly due to higher testing rates in women, resulting in an increase in the number of women with low levels of infection among investigated persons. The overall number of women surveyed in our study was 2.6 times higher than men. At the same time there were more men than women among the IDV patients but this did not affect the ratio of the indicators.

Probably this may reflect recent trends in chlamydial infection distribution in men and women, reflected in recent articles from Sweden.¹¹

In any case, our results indicate a need for a more active approach to the prevention, detection, and treatment of C. trachomatis infection in the high-risk 16–30 years group, with as much attention to men as to women.

Conclusions

The positivity rate of C. trachomatis detection with NAAT in the whole group of patients of medical institutions in the northeastern region of Ukraine was 4.5% (95% CI 4.0–5.0); it varied from 3.1% for patients of women’s health clinics not connected with STIs to 11.3% in high-risk group of 21–25 year-old men. In all investigated groups, the positivity rates of C. trachomatis infection in men were higher than in women. Results of the study point to the need for more active prevention, diagnosis, and treatment of urogenital chlamydial infection in the high-risk 16–30 year age group of men and women.

Footnotes

Authors’ contributions

AB initiated the collaborative project, designed data collection tools, monitored data collection for IDV, analyzed the data, and drafted the paper. OF monitored data collection in LA; TC, EM, OS, RG, SU participated in the collection, design, and coordination of the material. Access to research materials for this study is available by request.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Funding from the National Academy of Medical Sciences of Ukraine, registration number 0114U001383

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