Prenatal screening for infectious diseases, such as syphilis, hepatitis B, HIV and rubella, is already indicated in american protocols [37,38], however, microorganisms such as C. trachomatis, N. gonorrhoeae , M. genitalium and T. vaginalis have heterogeneity in how to perform screening to prevent unfavorable perinatal outcomes. The prevalence of at least one of the agents in the sample was 16.2% (N=24); C. trachomatis was 7.43%; M. genitalium, 8.7% and T. vaginalis, 2.03%, respectively. N. gonorrhoeae was not detected, and there were three cases of infection with more than one microorganism (2 CT + MG and 1 MG + TV). In the epidemiological associations, it found a lower rate of previous miscarriage in patients with positive CT (p-value = 0.023). Another significant associations brought forth were the detection of TV in patients with an earlier age at first pregnancy (p-value = 0.045), greater detection of MG in single patients (p-value=0.014); lower prevalence of TV in patients with fewer partners in the last year (p-value=0.042). This study provides Brazilian demographic data that we did not have access to until then, with emphasis on what can be considered a high prevalence of MG in pregnant women.
The found prevalence of 7.43% of C. trachomatis is within the range of 6.15 to 16.7% in pregnant women in Brazil [6,15,24,39] and Botswana [40], lower than 11.2% in pregnant women in Latin America [23], 14.7% in Haiti [5] and 22.9% in Papua New Guinea [22]. When compared to developed countries such as France, with a prevalence of 2.5% [21], we have a considerably higher rate, but in European pregnant women under the age of 25, CT was found in 7.6% [21] and 18.4% [41], in France and Spain, respectively. Among women who have some risk factor for STI, we have a prevalence of 10.7% in Brazilian women under 25 years old [42], 2.1% in HIV-positive Brazilian women [43], 4% in Spanish women under 30 years old [11] and 9% in female sex workers [44], which was not found when we stratified risk groups in our sample.
The non-detection of NG in the sample (n=0/148) was in line with the prevalence of 1.0% in Brazilian pregnant women [24,39] and 1,2% in Latin America [23]. Populations at risk, such as young women, sex workers and HIV positive people have a prevalence of 0.1%-1.5% [11,45], 3.3% [44] and 0.9% [46], respectively. Even in underdeveloped countries, NG detection rates during pregnancy are between 0.5 and 4.6% [5,23,40], with emphasis only on Papua New Guinea, with a rate 14.2% [22].
T. vaginalis was detected in 2.03% of the samples, lower than that found in Latin America (3.9%) [23] and Botswana (5.0%) [40]. Van Gerwen described an important variation in TV rates among pregnant women, from 3.9 to 24.6% [27]. In Brazil, the prevalence in pregnant adolescents (11-19 years old) was 4.3% [47], possibly higher than the value found in our research due to the age of the patients studied. The low rates found in our study can be attributed to the high human development index (HDI) in Joinville, in southern Brazil. The association between TV and younger age at first pregnancy and women with more sexual partners may be related to the lower use of condoms, attributed to this population [48], since they disregard barrier methods in long relationships and during the gestational period.
M. genitalium was identified in 13 pregnant women, 8.78% of the sample. This work is the first to describe the prevalence of MG in pregnant women in Brazil. Current literature report a prevalence of MG in pregnant women of 0.7% in England [49], 0.8% in France [21], 0.8% in Japan [50], 1.02% in Iran [28], 5.2% in Argentina [29], 11.9% in the Solomon Islands and 12.5% in Papua New Guine [51]. MG infection rates between 0.7-8.5% [10,12], with numbers ranging from 2.4 to 10% in young pregnant women, risky sexual behavior and low socioeconomic status [10]. In pregnant women under 30 years of age, M. genitalium was found in 1.3% of Spanish women [11] and 2.4% of French women [21].
Our prevalence (8.7%) is within the wide range found in Brazilian literature, not considering pregnant women, with a prevalence between 0.9% [8,52] and up to 28% in vaginal swab analysis by polymerase chain reaction (PCR) in postmenopausal women [25]. And it is lower when considering the high-risk population (15.9%) and sex workers (10.8%) [44].
In our study, MG was found more often in single women and was not related to age groups. Furthermore, no patient with MG presented leucorrhoea, dysuria, dyspareunia, pelvic pain or any other symptoms of genital infection when questioned. It highlights the importance of universal screening during pregnancy. Antimicrobial resistance associated with M. genitalium points to formulate new ways of population screening, diagnosis and treatment protocols in the United States [53], which should also be considered in Brazil, since treatment with a single dose of azithromycin is still widely used in medical practice and has been shown to be ineffective in recent studies [54].
Co-infection by more than one microorganism studied, observed in 16% of the sample, was higher than that found in the literature, between 1,02% [28,29] and 10% [30,43], close to the rate of 13.5%, in an African country [40]. There was no direct association with already known risk factors to STI such as young age and unfavorable socioeconomic situation [30] Among the epidemiological associations, we can highlight a lower rate of previous miscarriage in patients with positive CT (p-value = 0.023), this result may have been influenced by the sample size and has no cause-effect association. When comparing populations with positive CT and MG, there is no significant difference, which may point to a similarity in the risk factors for acquiring these STI, as Larsen already points out, in patients with cervicitis [2]. Twenty four patients (16.2% of the sample) presented a positive PCR for pathogens that cause cervicitis, a significant number compared to Korean data - 2.38%, including the same group of microorganisms [31].
This study is part of a multicenter project to screen microorganisms during pregnancy, that aims to evaluate possible implementation of these tests in the national territory. There were limitations related to the logistical difficulties between collection, storage, transportation and execution of NAAT exams, the sample size and the collection in a hospital environment, in the tertiary service, which may be associated with an increase in comorbidities in the population. Despite the relatively small number of patients evaluated, we highlight the prevalence of MG as well as the co-infection between CT and MG, which reinforces the importance of molecular biology tests in the assertive diagnosis of STI, mainly in special populations, such as pregnant women.
Expanding screening for C. trachomatis during prenatal care, given its high prevalence and the possibility of co-infection with other pathogens, also proves to be an important public health measure in Brazil, confirming data from the worldwide available literature. Even in asymptomatic pregnant women, cervicitis can cause preterm birth, premature rupture of membranes, fetal death, intrauterine growth restriction and puerperal endometritis [3-9]. Regarding the microorganisms to be tested, as there was no statistical difference between the populations, the data evaluated suggest screening for C. trachomatis and M. genitalium universally, for all pregnant women. Even though the region studied has a high human development index (HDI) compared to the rest of the country, we observed a high prevalence of CT and MG, which further alerts us to regions of greater vulnerability, such as young people, low socioeconomic status and precarious access to health services.
The prospects point to the need for a larger population study, evaluating risk groups for STI during the pregnant period, in order to verify the indication and feasibility of implantation, territorially, the screening of important pathogens to improve perinatal morbidity and mortality rates. Studies like this make it possible to measure data so that future strategies can have an impact on the health of developing countries like Brazil.