INTRODUCTION
One of the groups of pathogens responsible for genitourinary infections are atypical bacteria, such as Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum and Ureaplasma parvum. They can be found both in the normal bacterial flora of the vagina in sexually active women and may be the causative agent of chorioamnionitis, inflammation of the appendages, bacterial vaginosis or endometritis in the puerperium [1–3]. They often cause infections with an asymptomatic course, making diagnosis and treatment difficult.
Ureaplasma bacteria are present in the vaginal secretions of about 50% of pregnant women, but only a fraction of them become infected by the ascending route, leading to intrauterine infection and preterm labor [4–6]. Each year, about 15 million babies worldwide are born prematurely, accounting for about 11% of all births. In Europe, the number of births before 37 weeks of pregnancy is gradually increasing [7]. Although Ureaplasma infection is an independent risk factor for adverse pregnancy outcome, the greatest risk is in patients with additional aggravating factors, such as bacterial vaginosis in pregnancy [8] or a previous history of preterm labor [9].
The exact mechanism of this phenomenon is not known. Abnormal vaginal bacterial flora can pave the way for ascending infection by Ureaplasma bacteria by weakening local immunity in the lower parts of the reproductive tract as well as affect the increase in the number of atypical bacteria [4]. At the same time, the urease produced by Ureaplasma breaks down urea to ammonia and Mycoplasma produces ammonia from arginine. These reactions lead to an increase in the pH of vaginal secretions and facilitate genital tract infections with other pathogens facilitating the development of, for example, bacterial vaginosis [10].
Ureaplasma are the most isolated pathogens in cervical secretions and of the amniotic cavity in patients who have had a preterm delivery or PPROM [11–13]. These pathogens found in upper respiratory tract secretions, blood serum or cerebrospinal fluid in premature babies, increase the risk of bronchopulmonary dysplasia, open ductus arteriosus, chronic lung disease, intraventricular brain hemorrhage leading to severe complications and increasing neonatal and child mortality [14, 15].
The gold standard in identification of Ureaplasma is the microbiological culture, which allows simultaneous determination of an antibiogram when the pathogen is found in the material under examination. A more modern and accurate method of pathogen identification uses polymerase chain reaction (PCR), which is particularly applicable for the determination of a specific bacterial species. The disadvantage of the method is the inability to perform an antibiogram. Treatment of asymptomatic vaginal infections in pregnancy remains a contentious issue. Given the prevalence of Ureaplasma infections in pregnant women, it seems that the intervention group should be more carefully selected [4]. At the same time, studies on the treatment of vaginal infections in pregnancy have shown that the inclusion of oral or vaginal antibiotic therapy prolongs the duration of pregnancy [16, 17]. The drugs of choice in pregnant women and children remain macrolides including erythromycin, azithromycin and clarithromycin [18–22].
Purpose
The purpose of our study is to analyze the impact of lower genital tract infections with Ureaplasma or Mycoplasma bacteria in pregnant patients with symptoms of threatened miscarriage or threatened preterm labor illustrated by pregnant women hospitalized at the Obstetrics and Gynaecology Department at Regional Hospital in Poznan in 2019–2022. We will retrospectively analyze the frequency of genital tract infections with atypical bacteria in the study group based on available medical records. We will check whether infection with Ureaplasma/Mycoplasma bacteria affects the subsequent course of pregnancy, including the incidence of preterm labor or premature preterm rupture of membranes (PPROM). We will compare the type of delivery, number of past pregnancies and type of pregnancy (single or multiple) in patients with positive and negative cultures for atypical bacteria. We will determine the prevalence of infections with aerobic, anaerobic bacteria or fungi in the lower genital tract in both groups of patients and their impact on the timing of delivery. We will also evaluate whether the lack of treatment for Ureaplasma/Mycoplasma in a swab taken from the external os area of the cervical canal significantly affects the subsequent course of pregnancy.
MATERIAL AND METHODS
In this study, we retrospectively analyzed the cases of 201 pregnant patients. hospitalized in the Obstetrics and Gynecology Department of Poznan Regional Hospital in 2019–2022, who were swabbed for atypical bacteria — Ureaplasma and Mycoplasma — from the external orifice of the cervical canal due to symptoms of threatened miscarriage or threatened preterm labor. These patients manifested the following clinical symptoms: lower abdominal pain, spotting or bleeding from the genital tract, uterine contraction activity, cervical shortening, dilation of the cervical canal or preterm premature rupture of the membranes.
Our department belongs to the second level of referral of perinatal care.
The analysis was based on medical records — results of bacteriological cultures and electronic records, including discharge cards available in the hospital integrated information system, as well as information obtained directly from patients whose deliveries took place outside our center. The group of patients included both primiparous and multiparous women, in single and twin pregnancies.
Microbiological tests were performed in the hospital laboratory using the Mycoplasma IST 3 test from Biomerieux. The antibiogram included the reaction to:
- azithromycin, clarithromycin, erythromycin, ciprofloxacin, ofloxacin, doxycycline;
- tetracycline, iosamycin, and pristinamycin in tests performed in 2019 and 2020;
- erythromycin, levofloxacin, moxifloxacin, telithromycin, and tetracycline in tests performed in 2021 and 2022.
Microbiologists interpreted the antibiogram according to The European Committee on Antimicrobial Susceptibility Testing (EUCAST) bacteria v 9.0, 10.0, 11.0 and 12.0 depending on when the test was performed (2019–2022).
Positive culture results were considered those in which bacteria were present at the level of ≥ 104/mL.
Statistical significance p was calculated using Pearson’s Chi-square test or Fisher’s exact test, depending on whether the relevant assumptions were met. A p ≤ 0.05 value was considered as the cutoff point.
RESULTS
During the analyzed years (2019–2022), bacterial cultures were performed from the area of the external os of the cervical canal for Ureaplasma and Mycoplasma in 236 pregnant women. The inclusion criterion for the study was the known type and time of delivery. The studies of 61 positive and 140 negative (Fig. 1, 2) patients were used for further analysis (Fig. 1, 2). The remaining 35 patients were excluded from the study, due to incomplete data on the course of the pregnancy. In 4 patients at the time of writing the paper the pregnancy was still ongoing.
The gestational age of positive patients ranged from 13-36 completed weeks of pregnancy. Patients with threatened miscarriage accounted for 9.8% and the remaining 90.2% of cases included pregnant women with features of threatened preterm labor. The gestational age of the patients in whom we obtained a negative result for Ureaplasma/Mycoplasma was in the range of 12–36 weeks. In this group, signs of threatened miscarriage affected 11.4% and threatened preterm labor affected 88.6% of women (Tab. 1).
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Table 1. Comparison of characteristics in groups of patients with positive and negative cultures for Ureaplasma/Mycoplasma. Groups were compared using Pearson’s Chi-square test or Fisher’s exact test (F), depending on whether assumptions were met |
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|
Attribute |
Culture result for Ureaplasma/Mycoplasma |
p value (statistical significance) |
|||
|
Positive |
Negative |
||||
|
Number of cultures performed in 2019–2022 |
61 (100.0) |
140 (100.0) |
– |
||
|
Gestational age at which culture was performed |
< 22 |
6 (9.8) |
16 (11.4) |
0.931 |
|
|
> 21 + 6 |
55 (90.2) |
124 (88.6) |
|||
|
Type of antibiotics used |
Azithromycin |
36 (59.0) |
– |
– |
|
|
Clarithromycin |
2 (3.3) |
– |
|||
|
Clindamycin |
2 (3.3) |
– |
|||
|
Azithromycin + clarithromycin |
1 (1.6) |
– |
|||
|
Azithromycin + clindamycin |
1 (1.6) |
– |
|||
|
No information available |
19 (31.1) |
– |
|||
|
Time of pregnancy completion |
< 22 |
2 (3.3) |
2 (1.4) |
0.098 (F) |
|
|
> 21 + 6 and < 37 |
19 (31.1) |
28 (20.0) |
|||
|
> 36 + 6 |
40 (65.6) |
110 (78.6) |
|||
|
Time of pregnancy completion |
Patients treated |
< 37 |
15 (24.6) |
– |
– |
|
> 36 + 6 |
27 (44.3) |
– |
|||
|
Patients who did not take treatment |
< 37 |
6 (9.8) |
– |
||
|
> 36 + 6 |
13 (21.3) |
– |
|||
|
Type of delivery |
Vaginal delivery |
35 (59.3) |
77 (55.8) |
0.764 |
|
|
Caesarean section |
24 (40.7) |
61 (44.2) |
|||
|
Cervical culture result for aerobic bacteria, anaerobic bacteria and fungi |
Positive |
49 (80.3) |
118 (84.3) |
0.063 (F) |
|
|
Negative |
8 (13.1) |
21 (15.0) |
|||
|
Not performed |
4 (6.6) |
1 (0.7) |
|||
|
The result of the cervical culture for aerobic bacteria, anaerobic bacteria and fungi, and the week of pregnancy in which the delivery occurred* |
Positive |
< 37 |
13 (23.2) |
26 (19.0) |
0.007 |
|
> 36 + 6 |
35 (62.5) |
91 (66.4) |
|||
|
Negative |
< 37 |
6 (10.7) |
2 (1.5) |
||
|
> 36 + 6 |
2 (3.6) |
18 (13.1) |
|||
|
Obstetric history (number of current pregnancy) |
I |
24 (39.3) |
61 (43.6) |
0.687 |
|
|
> I |
37 (60.7) |
79 (56.4) |
|||
|
Type of current pregnancy |
Singelton pregnancy |
55 (90.2) |
133 (95.0) |
0220 (F) |
|
|
Multiple pregnancy |
6 (9.8) |
7 (5.0) |
|||
|
Time of delivery |
< 22 |
2 (3.3) |
2 (1.4) |
0.139 |
|
|
> 21 + 6 i < 37 |
19 (31.1) |
28 (20.0) |
|||
|
> 36 + 6 |
40 (65.6) |
110 (78.6) |
|||
|
Time of delivery |
< 22 and > 21 + 6 and < 37 |
21 (34.4) |
30 (21.4) |
0.077 |
|
|
> 36 + 6 |
40 (65.6) |
110 (78.6) |
|||
|
Cervical culture result for aerobic bacteria, anaerobic bacteria and fungi* |
Positive |
48 (85.7) |
117 (85.4) |
> 0.999 |
|
|
Negative |
8 (14.3) |
20 (14.6) |
|||
|
The week of pregnancy in which the delivery occurred* |
< 37 |
19 (33.9) |
28 (20.4) |
0.072 |
|
|
> 36 + 6 |
37 (66.1) |
109 (79.6) |
|||
|
Positive: Cervical culture results for aerobic bacteria, anaerobic bacteria and fungi, and the week of pregnancy in which the delivery occurred* |
< 37 |
13 (27.1) |
26 (22.2) |
0.641 |
|
|
> 36 + 6 |
35 (72.9) |
91 (77.8) |
|||
|
Negative: The result of the cervical culture for aerobic bacteria, anaerobic bacteria and fungi, and the week of pregnancy in which the delivery occurred* |
< 37 |
6 (75.0) |
2 (10.0) |
0.002 |
|
|
> 36 + 6 |
2 (25.0) |
18 (90.0) |
|||
|
*Excludes patients with miscarriage and patients without aerobic and anaerobic bacterial cultures |
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In the microbiological results obtained, Ureaplasma was responsible for the infection of the lower genital tract (96.7% of positive results), in two cases Mycoplasma was cultured (3.3% of positive results).
Among the analyzed group, preterm labor between 22 and 36 + 6 weeks of gestation occurred in 19 patients, representing 31.1% of pregnant women with positive smear results for atypical bacteria and known course of pregnancy. 3.3% of Ureaplasma positive patients had a miscarriage, in both cases at 17 weeks of pregnancy. Timely deliveries, above 36 + 6 weeks’ gestation, occurred in 40 patients, accounting for 65.6% of cases (Tab. 1).
Patients were treated within the department or included in outpatient treatment. The most used drug was azithromycin — 36 cases, clarithromycin in two patients or clindamycin in two patients. In two cases, two drugs were used in therapy — azithromycin with clarithromycin and azithromycin with clindamycin. In 19 patients, no information was found regarding the included treatment, which was mainly due to the lack of final culture results before discharge from the ward and failure to report for the test result within the indicated timeframe, transfer of the pregnant woman to a higher referral center, or the occurrence of miscarriage or preterm labor within a short period of time after the swab collection (Tab. 1).
We performed a similar analysis in patients with negative cultures from the area of the external os of the cervical canal for atypical bacteria. In the analyzed group, preterm labor occurred in 28 out of 140 patients with a known week and method of delivery, which is 20% of the group (Tab. 1).
Ureaplasma/Mycoplasma-positive patients. Our observations shows that regardless of the inclusion of treatment in patients with confirmed infection with atypical bacteria, the incidence of preterm labor or miscarriage in both groups is similar and it is, interestingly, 35.7% in the treated group and 31.6% in the group without antibiotic therapy (Tab. 1).
To broaden the diagnosis and try to determine the cause of symptoms of threatened miscarriage or preterm labor, we additionally performed cultures from the area of the external orifice of the cervical canal for aerobic bacteria, anaerobic bacteria and fungi. The positive results were obtained in 49 Ureaplasma/Mycoplasma-positive pregnant women, which accounted for 80.3%. results. In the group of Ureaplasma/Mycoplasma-negative patients, we found genital tract infection with other types of bacteria or fungi in 118 pregnant women which was 84.3%. In addition, we contrasted the above data with the weeks of gestation in which delivery occurred. In the group of Ureaplasma/Mycoplasma-positive patients, preterm labor occurred in 13 out of 48 cases of established infection with other types of bacteria and fungi (27.1%) and in 6 of 8 cases with monoinfection (75%). In the Ureaplasma/Mycoplasma-negative group, preterm labor occurred in 26 out of 117 patients with infection with aerobic bacteria, anaerobic bacteria or fungi (22.2%) and 2 out of 20 patients without genital tract infection (10%). When comparing these three characteristics, we obtained statistical significance at the level of p = 0.007. For the group with negative cultures for aerobic bacteria, anaerobic bacteria and fungi (Ureaplasma/Mycoplasma negative and positive, split by week of delivery), we achieved significance at the level p = 0.002 (Tab. 1).
On analyzing the medical records, it was found that Ureaplasma/Mycoplasma- positive patients had the complication of PPROM with subsequent delivery before 37 weeks of gestation, accounting for 47.4% of preterm deliveries in the group under study. In all of them, the delivery occurred between 33–36 weeks of gestation. In 3 cases, the situation involved twin pregnancies. Accordingly, in the Ureaplasma/Mycoplasma-negative group, PPROM occurred in 12 cases, of which in 11 patients’ delivery occurred before 37 weeks of pregnancy, which accounts for 39.3% of preterm deliveries in this group. The situation in 3 cases involved twin pregnancies. In one of the pregnant women with PPROM found at 24 weeks of gestation, delivery took place on time (38 weeks of gestation).
When interpreting the results of the study, Ureaplasma/Mycoplasma-positive patients were also divided according to their obstetric history — 24 pregnant women were primiparous (39.3%), for the remaining 37 women it was a second or subsequent pregnancy (60.7%). The youngest of the analyzed patients was 16-years-old at the time of the study, while the oldest was 43. Among Ureaplasma/Mycoplasma-negative patients, the majority were also, accounting for 56.4% of patients in this group, 43.6% were primiparous. The age range in this group of patients was 22–46 years. No significant statistical difference was obtained in the compared groups (p = 0.687) (Tab. 1).
The group with positive cultures for atypical bacteria included both patients with single pregnancies — 90.2% and twin pregnancies — 9.8%. One of the multiple pregnancies was a monochorionic diamniotic twins, while the other 5 were dichorionic diamniotic twins. All multiple pregnancies ended prematurely (between 33–36 weeks).
In the group of Ureaplasma-negative patients, among the 7 dichorionic diamniotic twins (5% of the study group), 4 ended between 34–36 weeks of gestation, 3 patients gave birth after 36 + 6 weeks of gestation. Patients with singleton pregnancies made up 95% of the Ureaplasma-negative group (Tab. 1).
DISCUSSION
In the group of 201 of analyzed patients, which were hospitalized at the Obstetrics and Gynecology Department of Poznan Regional Hospital in 2019–2022, for threatened miscarriage or threatened preterm labor, there were 61 positive cultures from the area of the external outlet of the cervical canal for Ureaplasma/Mycoplasma and 140 negative results. Cases with a known course of pregnancy were included in the analysis. Patients with positive cultures accounted for about one-third of all pregnant women on the ward with a risk of preterm labor or pregnancy loss. In the literature, the percentage of at-risk of infection, pregnant women were as high as 57% [23]. A positive vaginal Ureaplasma/Mycoplasma culture is an independent predictive factor for preterm birth in patients with symptomatic threatened preterm labor and short cervix [23].
Ureaplasma accounted for 96.7% of positive culture results. The tests we use do not differentiate between Ureaplasma for U. urealyticum and U. parvum. Determination of the specific bacterial genus could provide additional relevant information, especially considering reports of a higher risk of pregnancy complications with U. parvum infection [24].
We mostly used azithromycin to treat genital tract infections with atypical bacteria. The decision on treatment was primarily made based on the antibiogram (2019 and 2020 cultures) and in view of the relative safety of macrolides in pregnant women [20]. Interestingly, we noted no significant difference in the incidence of miscarriage or preterm labor in Ureaplasma-positive patients receiving antibiotic therapy compared to pregnant women who did not receive treatment. A team investigating the effects of treatment for Ureaplasma/Mycoplasma infection in patients with high-risk factors for preterm birth came to similar conclusions [25]. This observation warrants further analysis. Data obtained in other previously described studies indicate a positive correlation of antibiotic therapy on prolongation of pregnancy duration and successful neonatal outcomes [26].
Approximately 30% of patients with positive cultures for atypical bacteria had a preterm delivery, of which nearly half of the pregnancies were complicated by PPROM. The percentage of preterm deliveries in the group of Ureaplasma/Mycoplasma-negative patients was lower, accounting for 20%, of which 40% were associated with PPROM.
There was a higher percentage of pregnant women with symptoms of threatened miscarriage or preterm labor who additionally had a genital tract infection with aerobic and anaerobic bacteria or fungi. In Ureaplasma/Mycoplasma-positive patients, co-infection with other types of microorganisms occurred in 80.3% of the studied population and in Ureaplasma/Mycoplsma-negative patients in 84.3%. The presence of aerobic and anaerobic bacteria in the genital tract may influence the facilitation of Ureaplasma or Mycoplasma expansion and the incidence of pregnancy complications [4, 8, 9]. In the group of patients that we have studied, the risk of preterm delivery was paradoxically higher in patients with known monoinfection of the genital tract with Ureaplasma bacteria compared to patients with additional infection with other types of pathogens (75% vs 27%). The least frequent delivery before 37 weeks occurred in the case of negative results of both types of cultures — 10%. We obtained a statistically significant difference in the compared groups (p = 0.007). And for the group with negative cultures for aerobic bacteria, anaerobic bacteria and fungi the differences were also significant (p = 0.002).
There was no significant predominance of either type of delivery in patients with positive or negative cultures for Ureaplasma/Mycoplasma. In both groups of patients, differentiated based on the presence of atypical bacteria in the genital tract, the vaginal route of pregnancy completion prevailed. Ureaplasma/Mycoplasma-positive patients had a lower percentage of deliveries by cesarean section, 40.7%, than representatives of the other group, 44.2%.
Ureaplasma/Mycoplasma-positive patients were predominantly women with second or subsequent pregnancy (61%) and in 12% of cases these were multiple pregnancies. All patients in twin pregnancies with positive cultures gave birth prematurely.
CONCLUSIONS
Infection with Mycoplasma/Ureaplasma bacteria of the reproductive tract has a significant impact on the course of pregnancy. It increases the risk of pregnancy loss and preterm labor preceded by, among others, cervical shortening or PPROM. Identification of pathogens in cervical canal secretions is particularly important in patients with pregnancy risk symptoms. Although we were not able to obtain better obstetric outcomes in Ureaplasma-positive patients receiving treatment compared to pregnant women not receiving therapy, this observation requires further analysis on a larger number of cases.
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Data availability statement
Available from the author.
Ethics statement
353/23.
Author contributions
Marcin Przybylski: concept, assumptions, study design, acquisition of data, analysis and interpretation of data, article draft, corresponding author. Ilona Wicher-Gozdur: concept, assumptions, study design, acquisition of data, analysis and interpretation of data, article draft. Joanna Kippen: concept, assumptions, study design, acquisition of data, analysis and interpretation of data, article draft. Sonja Millert-Kalinska: revised article critically. Agnieszka Zawiejska: revised article critically. Robert Jach: revised article critically. Dominik Pruski: concept, assumptions, study design, acquisition of data, analysis and interpretation of data, article draft.
Funding
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Acknowledgments
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Conflict of interest
All authors declare no conflict of interest.
Supplementary material
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