Scandinavian Journal of Infectious Diseases, 2014; 46: 348–353
ORIGINAL ARTICLE
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Distribution and perinatal transmission of bacterial vaginal infections in pregnant women without vaginal symptoms HO-SUAP HAHN1∗, KI-HEON LEE1∗, YU-JIN KOO1, SOON-GYU KIM1, JEE EUN RHEE2, MOON YOUNG KIM1, SOO-JIN HWANG3, JAE HO LEE3, IN-HO LEE1, KYUNG-TAEK LIM1, JAE-UK SHIM1 & TAE-JIN KIM1 From the 1Department of Obstetrics and Gynecology, Cheil General Hospital and Women’s Healthcare Center, Kwandong University College of Medicine, 2Division of AIDS, Korea Centers for Disease Control and Prevention, Korea National Institute of Health, and 3Laboratory of Molecular Oncology, Cheil General Hospital and Women’s Healthcare Center, Kwandong University College of Medicine, Seoul, Korea
Abstract Background: We evaluated the distribution and vertical transmission of bacterial vaginal infections in asymptomatic pregnant women. Methods: We performed multiplex PCR on secretions collected on cervical swabs from pregnant women at over 36 weeks of gestation and on oral secretions collected from their neonates immediately after delivery. We detected sexually transmitted infections (STIs) with the following 6 species: Trichomonas vaginalis, Mycoplasma hominis, Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, and Ureaplasma urealyticum. Results: Infectious agents were detected in 64 of 455 pregnant women (14.1%) and in 11 neonates (2.4%). The rate of vertical transmission was 17.2% and all the infectious agents detected in neonates were concordant with those found in their mothers. U. urealyticum was the most frequently detected in the maternal genitalia, followed by M. hominis. Women who were in labor for a longer period of time had a higher risk of vertically transmitting STI agents to their neonates. Conclusions: Vertical transmission of bacterial STIs from mothers to their infants is possible at delivery and influenced by the duration of labor. STIs should be diagnosed in pregnant women to prevent vertical transmission from the mother to the infant at the time of delivery.
Keywords: Vertical transmission, STI, bacterial infection, STD
Introduction Sexually transmitted diseases (STD) comprise illnesses that have a significant probability of transmission between humans by means of vaginal, oral, and anal intercourse. Sexually transmitted infection (STI) is a broader term than STD, because the term STD refers only to infections that cause symptoms or problems [1]. STIs are caused by various pathogens, such as bacteria, viruses, fungi, parasites, and protozoa [2–6]. Vertical transmission, also known as mother-tochild transmission, is the transfer of an infection or other disease from mother to child before and after birth. Infants born to mothers with an untreated STI may develop various infectious diseases, such as
conjunctivitis or pneumonia [7]. Therefore, the rates of STI during pregnancy and vertical transmission need to be evaluated. In this prospective study, we aimed to evaluate the rate of bacterial STIs in pregnant women without any vaginal symptoms and the risk factors associated with vertical transmission. Perinatal STI transmission was defined as detection of a microbe in the newborn identical to that found in the mother. We performed multiplex PCR to detect infections with the following microbial species: Trichomonas vaginalis, Mycoplasma hominis, Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, and Ureaplasma urealyticum.
∗H.-S. Hahn and K.-H. Lee contributed equally to this article. Correspondence: T.-J. Kim, Cheil General Hospital and Women’s Healthcare Center, Kwandong University College of Medicine, 1–19 Mukjeong-dong, Jung-gu, Seoul 100-380, Korea. Tel: 82 2 2000 7577. Fax: 82 2 2000 7183. E-mail: [email protected] (Received 25 July 2013 ; accepted 19 December 2013) ISSN 0036-5548 print/ISSN 1651-1980 online © 2014 Informa Healthcare DOI: 10.3109/00365548.2014.880183
Vertical transmission of STIs Materials and methods
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Study population We recruited pregnant women past 36 weeks of gestation, who did not have any vaginal symptoms and were expected to give birth at Cheil General Hospital and Women’s Healthcare Center between March 2010 and April 2011. We excluded women with severe intrauterine growth restriction, severe oligohydramnios, severe hypertension during pregnancy, history of malignancy within 5 y, liver cirrhosis, renal failure, chronic diseases affecting materno-fetal immunity, a history of psychological disease, and alcoholism. The rate of vertical transmission, demographic and reproductive characteristics associated with vertical transmission, and the distribution of causative microbial species were analyzed. The study was approved by the institutional review board, and all the participants gave informed consent.
349
to one of 2 groups according to the presence or absence of an STI. Continuous variables were compared using the Student’s t-test, while discrete variables were compared with the Chi-square test. Two-sided p-values of 0.05 were considered significant.
Results
DNA isolated from the specimens was subjected to multiplex PCR. PCR was performed using Seeplex STI Master Panel 1 (Seegene Inc., Seoul, Korea) in accordance with the manufacturer’s instructions. PCR products were visualized via 2% agarose gel electrophoresis.
A total of 500 pregnant women without any vaginal symptoms were enrolled during the study period, and 455 patients with available neonate samples were included in our study. Two hundred ninety-four of the 455 women (64.6%) gave birth through vaginal delivery and 161 women (35.4%) through cesarean section.The rate of maternal STI was 14.1% (64/455) and there were no statistically significant differences between STI-positive and STI-negative women with regard to age, gravidity, parity, number of abortions, presence of gestational diabetes mellitus, or mode of delivery (Table I). U. urealyticum was the most frequent species detected in the maternal genitalia (n 36, 50.0%), followed by M. hominis (n 16, 22.2%). C. trachomatis, M. genitalium, and N. gonorrhoeae followed in order of detection frequency. Dual infections were noted in 8 cases (12.5%). T. vaginalis was not detected in our study (Table II). Reproductive characteristics including birth weight, premature rupture of the amniotic membrane, mode of delivery, and number of infectious species detected in the maternal genitalia were not significantly different in the comparison of STI-positive women according to neonatal STI status (Table III). Women who labored longer had a higher risk of vertical transmission to their neonates (p 0.006). The rate of pathogen detection in neonates was 2.4% (11/455). The microbes detected in these 11 neonates were all transmitted from their mothers, thus the rate of vertical transmission was 17.2% (11/64). No babies born to STI-negative women were STI-positive. Vertical transmission was confirmed if the species detected in the baby corresponded to that found in the mother. All the mother and neonate pairs in our study showed concordance of bacterial species (Table IV). These results suggest that all the infections detected in the neonates were acquired from their mothers through vertical transmission. U. urealyticum was detected most frequently in neonates (8/11 cases; 72.7%), followed by M. hominis (3/11 cases; 27.3%). None of the other species were detected in the neonates.
Statistical analysis
Discussion
To identify the factors associated with STIs in pregnant women and their neonates, participants were assigned
STIs are spread by sexual contact, and people with an STI may not have any symptoms and may be
Samples Maternal cervical swabs collected using Cervex Brush™ (Rovers, Boonton, NJ, USA) were placed into tubes containing 2 ml of phosphate-buffered saline (PBS) to detect infections by T. vaginalis, M. hominis, M. genitalium, C. trachomatis, N. gonorrhoeae, and U. urealyticum. Immediately after delivery, oral secretions of the neonates were collected by mouth suction and swabs for microbial detection. The specimens were centrifuged at 13,000 rpm for 10 min, and pellets were resuspended in 1 ml of PBS. Ultimately 200 μl of each suspended sample were used for subsequent experiments. Isolation of DNA Nucleic acids from the maternal cervical swab and neonatal oral secretions were isolated using a QIAamp DNA Mini Kit (Qiagen Inc., Valencia, CA, USA) in accordance with the manufacturer’s instructions. Multiplex PCR and detection of microbes
350
H.-S. Hahn et al. Table I. Demographic characteristics according to maternal STI status (n 455).a
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Characteristics Age (y) 30 31–35 36 Gravida 1 2 3 Para 0 1 Abortion 0 1 GDM Negative Positive Mode of delivery CS VD
STI-positive (n 64)
(%)
STI-negative (n 391)
(%)
p-Value
21 28 15
(16.4) (13.3) (12.8)
107 182 102
(83.6) (86.7) (87.2)
0.663
28 20 16
(14.2) (12.0) (17.6)
169 147 75
(85.8) (88.0) (82.4)
0.463
39 25
(13.7) (14.6)
245 146
(86.3) (85.4)
0.792
43 21
(13.9) (14.5)
267 124
(86.1) (85.5)
0.861
61 3
(14.0) (16.7)
376 15
(86.0) (83.3)
0.746
22 42
13.7 14.3
139 252
86.3 85.7
0.855
STI, sexually transmitted infection; GDM, gestational diabetes mellitus; CS, cesarean section; VD, vaginal delivery. aSexually transmitted infection in this study was defined as genital infection by any of the following 6 species: Trichomonas vaginalis, Mycoplasma hominis, Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, and Ureaplasma urealyticum.
unaware of their infection. Symptoms occur only if the disease becomes more advanced. Untreated infections can cause pelvic inflammatory disease, which can lead to infertility and ectopic pregnancy. Furthermore, persistent STIs may cause cancer, as evidenced by the high-risk types of HPV that have been found to be causative agents of cervical cancer [8,9]. STDs in pregnancy can cause adverse outcomes, such as abortion, premature delivery, and intrauterine infection. M. hominis and U. urealyticum are both associated with preterm rupture of the membranes, premature labor, intra-amniotic infection, and chorioamnionitis. U. urealyticum is thought to be the
Table II. Distribution of genital infection by STI-related microorganism (n 64). STI-related bacteria species Trichomonas vaginalis Mycoplasma hominis Mycoplasma genitalium Chlamydia trachomatis Neisseria gonorrhoeae Ureaplasma urealyticum Infection by single species Infection by multiple species STI, sexually transmitted infection.
Number of infected pregnant women (%) 0 16 8 10 2 36 56 8
(0.0) (22.2) (11.1) (13.9) (2.8) (50.0) (87.5) (12.5)
more virulent of these 2 opportunistic organisms [10]. Vertical transmission of Ureaplasma species is associated with premature infant bronchopulmonary dysplasia and sepsis [11]. In the present study, we dealt with bacterial STIs with 6 microbial species, and the rates of U. urealyticum and M. hominis detection in pregnant women with STIs were 50.0% and 22.2%, respectively. Only these 2 species of the 6 analyzed were transmitted vertically. U. urealyticum was detected in 8 of 11 neonates, suggesting that it is easily transmitted vertically. Fortunately, none of the infants in whom infectious agents were detected in our study showed symptoms such as pneumonitis, fever, or conjunctivitis. STIs affect the process of parturition in pregnant women. This process includes uterine activity, cervical effacement, and rupture of the fetal membrane. Proinflammatory substances are released and are important mediators of these mechanical actions. Inflammatory cells invade the amnion and chorion during labor and are a source of inflammatory mediators. Stress to the mother or fetus, placental infection, a short cervix, over-distention of the uterus, and an altered vaginal flora are thought to be other sources of inflammatory mediators [12]. Elevated concentrations of proinflammatory microorganisms seem to alter the vaginal flora and induce preterm labor or vertical transmission from mother to fetus through an inflammatory process. Our study focused
Vertical transmission of STIs
351
Table III. Reproductive characteristics associated with neonatal STI status in STI-positive women (n 64).a STI-positive (n 11)
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Characteristics Birth weight (g) Length of labor (min) (n 51) PROM Negative Positive Mode of delivery CS VD Number of species Single Dual
3434 1137
(SD or %) (200) (885)
STI-negative (n 53) 3397 583
(SD or %)
p-Value
(401) (434)
0.660 0.006
4 7
(13.3%) (20.6%)
26 27
(86.7%) (79.4%)
0.443
2 9
(10.0%) (20.5%)
18 35
(90.0%) (79.5%)
0.304
9 2
(16.4%) (25.0%)
46 6
(83.6%) (75.0%)
0.548
STI, sexually transmitted infection; SD, standard deviation; PROM, premature rupture of the membranes; CS, cesarean section; VD, vaginal delivery. aSexually transmitted infection in this study was defined as genital infection by 1 or more of the following 6 species: Trichomonas vaginalis, Mycoplasma hominis, Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, and Ureaplasma urealyticum.
on the distribution and vertical transmission of bacterial STIs and we recruited pregnant women past 36 weeks of gestation. Thus our study could not evaluate preterm labor induced by the inflammation associated with microorganisms. Nonetheless, uterine contractions driven by prostaglandins in the setting of inflammation have been well documented in previous reports [10,13]. The rate of maternal bacterial STIs in pregnancy was 14.1% in our study. Chugh and Gaind reported that 10–20% of adult patients in developing countries have STIs. Increasing urbanization, illiteracy, poverty, sexual promiscuity, and lack of health education account for the high prevalence of STIs [14]. Vallely et al. reported that the prevalence of C. trachomatis, N. gonorrhoeae, Treponema pallidum, and T. vaginalis in Papua New Guinea were 26.1%, 33.6%, 33.1%, and 39.3%, respectively [15]. Our study excluded patients under 36 weeks of gestation, and since STIs may induce preterm labor and deliv-
ery, the prevalence of STIs in pregnant women may actually be higher than 14.1%. Of note, T. vaginalis, which is a common cause of STIs, was not detected in any women in our study. Chico et al. reported that the prevalence of STI with T. vaginalis in pregnant women was 29.1% in East and Southern Africa and 17.8% in West and Central Africa [16]. There may be an explanation for the absence of T. vaginalis in our study. The flagellated, pear-shaped trophozoite of Trichomonas can be seen on a wet-mount slide, and the diagnostic test for this organism is performed routinely in early pregnancy at our institute. Thus, pregnant women with Trichomonas may have been treated with metronidazole before 36 weeks of pregnancy. Further epidemiological surveillance in pregnant women in a multicenter study is necessary to determine the actual frequency of Trichomonas infections. The rate of vertical transmission of bacterial STIs was 17.2%, and a longer duration of labor was significantly associated with vertical transmission. Prema-
Table IV. Concordance of STI-related bacterial species in mother–neonate pairs (n 11). Mother infection (Genital sampling)
Newborn infection (Oral sampling)
Mycoplasma hominis Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma hominis Ureaplasma urealyticum Mycoplasma hominis, Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma genitalium, Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma hominis Ureaplasma urealyticum
Mycoplasma hominis Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma hominis Ureaplasma urealyticum Ureaplasma urealyticum Ureaplasma urealyticum Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma hominis Ureaplasma urealyticum
Participant 28 47 84 98 102 189 244 303 308 317 349
STI, sexually transmitted infection.
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352
H.-S. Hahn et al.
ture rupture of the amniotic membrane, mode of delivery, and number of pathogenic species were not significantly related to vertical transmission (Table III). Yu et al. reported that the prevalence of Chlamydia in 300 pregnant women in Chongqing, China was 11% (33/300) and that of vertical transmission was 24.2% (8/33). They also reported that the prevalence of vertical transmission with cesarean section was lower than with vaginal delivery [17]. This result is in disagreement with our findings. Chlamydia was detected in 10 of 455 pregnant women (2.2%, 10/455), with 6 of them delivering vaginally and the remaining 4 delivering via cesarean section. Chlamydia was not detected in any of the babies, thus no vertical transmission of Chlamydia was found. The small number of pregnant women with Chlamydia made it difficult to evaluate the factors influencing vertical transmission, thus we included a total of 64 samples positive for 1 of 6 species of microorganism in our analysis (Table III). Of 64 women with an STI, 44 delivered vaginally and the remaining 20 via cesarean section. The mode of delivery did not influence the prevalence of vertical transmission in our study (p 0.304). However, the 2 mothers of 2 STI-positive babies who were delivered by cesarean section had attempted vaginal delivery before surgery. No baby was STI-positive after a pure cesarean section without at least an attempt at vaginal delivery. Therefore, vaginal delivery appears to be more risky in the vertical transmission of STIs. Longer labor times had an influence on the vertical transmission of bacterial STIs. It is speculated that the reason for this is that infectious agents have a better opportunity to proliferate in pregnant women with a longer duration of labor because these women likely undergo pelvic examinations and rupture of membranes during labor. It is known that microbial stimuli can lead to inflammatory reactions in the pregnant uterus, and they may elicit adverse pregnancy outcomes that lead to preterm labor, birth, and precipitous delivery [10]. Paradoxically, preterm labor and delivery may be the defense mechanism by which the fetus can protect itself from STIs. The fetus can shorten the length of labor and gestational period by precipitous and preterm delivery, thereby evading microbial infections present in the mother. Our data excluded preterm delivery before 36 gestational weeks, thus we cannot present and compare the rates of vertical transmission between term and preterm deliveries. Further evaluations including those of preterm babies would be necessary to demonstrate our hypothesis. This study has several limitations. First, the number of mothers with STIs was small. Second, this study was based on data from a single institute. Third, pregnant women at less than 36 gestational weeks
were excluded. Despite these limitations, it is meaningful to evaluate vertical transmission of bacterial STIs between pregnant women and their babies for the benefit of both the mothers and their offspring. In conclusion, vertical transmission of bacterial STIs from mothers to their infants may occur at delivery and is influenced by the duration of labor. Therefore, to prevent vertical transmission of STIs from mothers to their infants at the time of delivery, STIs in pregnant women should be diagnosed appropriately. Acknowledgements This work was supported by grants from the Korea Center for Disease Control and Prevention (No 2010-E51007-00) and the Korean Healthcare Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (A10206510111250100). Declaration of interest: We declare that we have no conflicts of interests.
References [1] Schneede P, Tenke P, Hofstetter AG. Sexually transmitted diseases (STDs)—a synoptic overview for urologists. Eur Urol 2003;44:1–7. [2] Diez M, Diaz A. sexually transmitted infections: epidemiology and control. Rev Esp Sanid Penit 2011;13:58–66. [3] Manikam L, Rogstad K, Singh G, Lakhanpaul M. Management of sexually transmitted infections in pubertal children. Arch Dis Child Educ Pract Ed 2012;97:132–42. [4] Apers L, Crucitti T, Verbrugge R, Vandenbruaene M. Sexually transmitted infections: what’s new? Acta Clin Belg 2012;67:154–9. [5] Fairley CK, Read TR. Vaccination against sexually transmitted infections. Curr Opin Infect Dis 2012;25:66–72. [6] Ballini A, Cantore S, Fatone L, Montenegro V, De Vito D, Pettini F, et al. Transmission of nonviral sexually transmitted infections and oral sex. J Sex Med 2012;9:372–84. [7] Koumans EH, Rosen J, van Dyke MK, Zell E, Phares CR, Taylor A, et al. Prevention of mother-to-child transmission of infections during pregnancy: implementation of recommended interventions, United States, 2003–2004. Am J Obstet Gynecol 2012;206:158.e1–158.e11. [8] Nuranna L, Aziz MF, Cornain S, Purwoto G, Purbadi S, Budiningsih S, et al. Cervical cancer prevention program in Jakarta, Indonesia: see and treat model in developing country. J Gynecol Oncol 2012;23:147–52. [9] Lee JM. Screening of uterine cervical cancer in low-resource settings. J Gynecol Oncol 2012;23:137–8. [10] Larsen B, Hwang J. Mycoplasma, Ureaplasma, and adverse pregnancy outcomes: a fresh look. Infect Dis Obstet Gynecol 2010;2010. pii: 521921. [11] Breugelmans M, Vancutsem E, Naessens A, Laubach M, Foulon W. Association of abnormal vaginal flora and Ureaplasma species as risk factors for preterm birth: a cohort study. Acta Obstet Gynecol Scand 2010;89:256–60. [12] Bjartling C, Osser S, Persson K. The association between Mycoplasma genitalium and pelvic inflammatory disease after termination of pregnancy. BJOG 2010;117:361–4.
Vertical transmission of STIs
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[13] Blanchard A, Hamrick W, Duffy L, Baldus K, Cassell GH. Use of the polymerase chain reaction for detection of Mycoplasma fermentans and Mycoplasma genitalium in the urogenital tract and amniotic fluid. Clin Infect Dis 1993; 17(Suppl 1):S272–9. [14] Chugh TD, Gaind R. Sexually transmitted infections. Clin Lab Med 2012;32:143–58. [15] Vallely A, Page A, Dias S, Siba P, Lupiwa T, Law G, et al. The prevalence of sexually transmitted infections in Papua
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New Guinea: a systematic review and meta-analysis. PLoS One 2010;5:e15586. [16] Chico RM, Mayaud P, Ariti C, Mabey D, Ronsmans C, Chandramohan D. Prevalence of malaria and sexually transmitted and reproductive tract infections in pregnancy in Sub-Saharan Africa: a systematic review. JAMA 2012;307:2079–86. [17] Yu J, Wu S, Li F, Hu L. Vertical transmission of Chlamydia trachomatis in Chongqing China. Curr Microbiol 2009;58:315–20.
ORIGINAL ARTICLE
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Distribution and perinatal transmission of bacterial vaginal infections in pregnant women without vaginal symptoms HO-SUAP HAHN1∗, KI-HEON LEE1∗, YU-JIN KOO1, SOON-GYU KIM1, JEE EUN RHEE2, MOON YOUNG KIM1, SOO-JIN HWANG3, JAE HO LEE3, IN-HO LEE1, KYUNG-TAEK LIM1, JAE-UK SHIM1 & TAE-JIN KIM1 From the 1Department of Obstetrics and Gynecology, Cheil General Hospital and Women’s Healthcare Center, Kwandong University College of Medicine, 2Division of AIDS, Korea Centers for Disease Control and Prevention, Korea National Institute of Health, and 3Laboratory of Molecular Oncology, Cheil General Hospital and Women’s Healthcare Center, Kwandong University College of Medicine, Seoul, Korea
Abstract Background: We evaluated the distribution and vertical transmission of bacterial vaginal infections in asymptomatic pregnant women. Methods: We performed multiplex PCR on secretions collected on cervical swabs from pregnant women at over 36 weeks of gestation and on oral secretions collected from their neonates immediately after delivery. We detected sexually transmitted infections (STIs) with the following 6 species: Trichomonas vaginalis, Mycoplasma hominis, Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, and Ureaplasma urealyticum. Results: Infectious agents were detected in 64 of 455 pregnant women (14.1%) and in 11 neonates (2.4%). The rate of vertical transmission was 17.2% and all the infectious agents detected in neonates were concordant with those found in their mothers. U. urealyticum was the most frequently detected in the maternal genitalia, followed by M. hominis. Women who were in labor for a longer period of time had a higher risk of vertically transmitting STI agents to their neonates. Conclusions: Vertical transmission of bacterial STIs from mothers to their infants is possible at delivery and influenced by the duration of labor. STIs should be diagnosed in pregnant women to prevent vertical transmission from the mother to the infant at the time of delivery.
Keywords: Vertical transmission, STI, bacterial infection, STD
Introduction Sexually transmitted diseases (STD) comprise illnesses that have a significant probability of transmission between humans by means of vaginal, oral, and anal intercourse. Sexually transmitted infection (STI) is a broader term than STD, because the term STD refers only to infections that cause symptoms or problems [1]. STIs are caused by various pathogens, such as bacteria, viruses, fungi, parasites, and protozoa [2–6]. Vertical transmission, also known as mother-tochild transmission, is the transfer of an infection or other disease from mother to child before and after birth. Infants born to mothers with an untreated STI may develop various infectious diseases, such as
conjunctivitis or pneumonia [7]. Therefore, the rates of STI during pregnancy and vertical transmission need to be evaluated. In this prospective study, we aimed to evaluate the rate of bacterial STIs in pregnant women without any vaginal symptoms and the risk factors associated with vertical transmission. Perinatal STI transmission was defined as detection of a microbe in the newborn identical to that found in the mother. We performed multiplex PCR to detect infections with the following microbial species: Trichomonas vaginalis, Mycoplasma hominis, Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, and Ureaplasma urealyticum.
∗H.-S. Hahn and K.-H. Lee contributed equally to this article. Correspondence: T.-J. Kim, Cheil General Hospital and Women’s Healthcare Center, Kwandong University College of Medicine, 1–19 Mukjeong-dong, Jung-gu, Seoul 100-380, Korea. Tel: 82 2 2000 7577. Fax: 82 2 2000 7183. E-mail: [email protected] (Received 25 July 2013 ; accepted 19 December 2013) ISSN 0036-5548 print/ISSN 1651-1980 online © 2014 Informa Healthcare DOI: 10.3109/00365548.2014.880183
Vertical transmission of STIs Materials and methods
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Study population We recruited pregnant women past 36 weeks of gestation, who did not have any vaginal symptoms and were expected to give birth at Cheil General Hospital and Women’s Healthcare Center between March 2010 and April 2011. We excluded women with severe intrauterine growth restriction, severe oligohydramnios, severe hypertension during pregnancy, history of malignancy within 5 y, liver cirrhosis, renal failure, chronic diseases affecting materno-fetal immunity, a history of psychological disease, and alcoholism. The rate of vertical transmission, demographic and reproductive characteristics associated with vertical transmission, and the distribution of causative microbial species were analyzed. The study was approved by the institutional review board, and all the participants gave informed consent.
349
to one of 2 groups according to the presence or absence of an STI. Continuous variables were compared using the Student’s t-test, while discrete variables were compared with the Chi-square test. Two-sided p-values of 0.05 were considered significant.
Results
DNA isolated from the specimens was subjected to multiplex PCR. PCR was performed using Seeplex STI Master Panel 1 (Seegene Inc., Seoul, Korea) in accordance with the manufacturer’s instructions. PCR products were visualized via 2% agarose gel electrophoresis.
A total of 500 pregnant women without any vaginal symptoms were enrolled during the study period, and 455 patients with available neonate samples were included in our study. Two hundred ninety-four of the 455 women (64.6%) gave birth through vaginal delivery and 161 women (35.4%) through cesarean section.The rate of maternal STI was 14.1% (64/455) and there were no statistically significant differences between STI-positive and STI-negative women with regard to age, gravidity, parity, number of abortions, presence of gestational diabetes mellitus, or mode of delivery (Table I). U. urealyticum was the most frequent species detected in the maternal genitalia (n 36, 50.0%), followed by M. hominis (n 16, 22.2%). C. trachomatis, M. genitalium, and N. gonorrhoeae followed in order of detection frequency. Dual infections were noted in 8 cases (12.5%). T. vaginalis was not detected in our study (Table II). Reproductive characteristics including birth weight, premature rupture of the amniotic membrane, mode of delivery, and number of infectious species detected in the maternal genitalia were not significantly different in the comparison of STI-positive women according to neonatal STI status (Table III). Women who labored longer had a higher risk of vertical transmission to their neonates (p 0.006). The rate of pathogen detection in neonates was 2.4% (11/455). The microbes detected in these 11 neonates were all transmitted from their mothers, thus the rate of vertical transmission was 17.2% (11/64). No babies born to STI-negative women were STI-positive. Vertical transmission was confirmed if the species detected in the baby corresponded to that found in the mother. All the mother and neonate pairs in our study showed concordance of bacterial species (Table IV). These results suggest that all the infections detected in the neonates were acquired from their mothers through vertical transmission. U. urealyticum was detected most frequently in neonates (8/11 cases; 72.7%), followed by M. hominis (3/11 cases; 27.3%). None of the other species were detected in the neonates.
Statistical analysis
Discussion
To identify the factors associated with STIs in pregnant women and their neonates, participants were assigned
STIs are spread by sexual contact, and people with an STI may not have any symptoms and may be
Samples Maternal cervical swabs collected using Cervex Brush™ (Rovers, Boonton, NJ, USA) were placed into tubes containing 2 ml of phosphate-buffered saline (PBS) to detect infections by T. vaginalis, M. hominis, M. genitalium, C. trachomatis, N. gonorrhoeae, and U. urealyticum. Immediately after delivery, oral secretions of the neonates were collected by mouth suction and swabs for microbial detection. The specimens were centrifuged at 13,000 rpm for 10 min, and pellets were resuspended in 1 ml of PBS. Ultimately 200 μl of each suspended sample were used for subsequent experiments. Isolation of DNA Nucleic acids from the maternal cervical swab and neonatal oral secretions were isolated using a QIAamp DNA Mini Kit (Qiagen Inc., Valencia, CA, USA) in accordance with the manufacturer’s instructions. Multiplex PCR and detection of microbes
350
H.-S. Hahn et al. Table I. Demographic characteristics according to maternal STI status (n 455).a
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Characteristics Age (y) 30 31–35 36 Gravida 1 2 3 Para 0 1 Abortion 0 1 GDM Negative Positive Mode of delivery CS VD
STI-positive (n 64)
(%)
STI-negative (n 391)
(%)
p-Value
21 28 15
(16.4) (13.3) (12.8)
107 182 102
(83.6) (86.7) (87.2)
0.663
28 20 16
(14.2) (12.0) (17.6)
169 147 75
(85.8) (88.0) (82.4)
0.463
39 25
(13.7) (14.6)
245 146
(86.3) (85.4)
0.792
43 21
(13.9) (14.5)
267 124
(86.1) (85.5)
0.861
61 3
(14.0) (16.7)
376 15
(86.0) (83.3)
0.746
22 42
13.7 14.3
139 252
86.3 85.7
0.855
STI, sexually transmitted infection; GDM, gestational diabetes mellitus; CS, cesarean section; VD, vaginal delivery. aSexually transmitted infection in this study was defined as genital infection by any of the following 6 species: Trichomonas vaginalis, Mycoplasma hominis, Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, and Ureaplasma urealyticum.
unaware of their infection. Symptoms occur only if the disease becomes more advanced. Untreated infections can cause pelvic inflammatory disease, which can lead to infertility and ectopic pregnancy. Furthermore, persistent STIs may cause cancer, as evidenced by the high-risk types of HPV that have been found to be causative agents of cervical cancer [8,9]. STDs in pregnancy can cause adverse outcomes, such as abortion, premature delivery, and intrauterine infection. M. hominis and U. urealyticum are both associated with preterm rupture of the membranes, premature labor, intra-amniotic infection, and chorioamnionitis. U. urealyticum is thought to be the
Table II. Distribution of genital infection by STI-related microorganism (n 64). STI-related bacteria species Trichomonas vaginalis Mycoplasma hominis Mycoplasma genitalium Chlamydia trachomatis Neisseria gonorrhoeae Ureaplasma urealyticum Infection by single species Infection by multiple species STI, sexually transmitted infection.
Number of infected pregnant women (%) 0 16 8 10 2 36 56 8
(0.0) (22.2) (11.1) (13.9) (2.8) (50.0) (87.5) (12.5)
more virulent of these 2 opportunistic organisms [10]. Vertical transmission of Ureaplasma species is associated with premature infant bronchopulmonary dysplasia and sepsis [11]. In the present study, we dealt with bacterial STIs with 6 microbial species, and the rates of U. urealyticum and M. hominis detection in pregnant women with STIs were 50.0% and 22.2%, respectively. Only these 2 species of the 6 analyzed were transmitted vertically. U. urealyticum was detected in 8 of 11 neonates, suggesting that it is easily transmitted vertically. Fortunately, none of the infants in whom infectious agents were detected in our study showed symptoms such as pneumonitis, fever, or conjunctivitis. STIs affect the process of parturition in pregnant women. This process includes uterine activity, cervical effacement, and rupture of the fetal membrane. Proinflammatory substances are released and are important mediators of these mechanical actions. Inflammatory cells invade the amnion and chorion during labor and are a source of inflammatory mediators. Stress to the mother or fetus, placental infection, a short cervix, over-distention of the uterus, and an altered vaginal flora are thought to be other sources of inflammatory mediators [12]. Elevated concentrations of proinflammatory microorganisms seem to alter the vaginal flora and induce preterm labor or vertical transmission from mother to fetus through an inflammatory process. Our study focused
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351
Table III. Reproductive characteristics associated with neonatal STI status in STI-positive women (n 64).a STI-positive (n 11)
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Characteristics Birth weight (g) Length of labor (min) (n 51) PROM Negative Positive Mode of delivery CS VD Number of species Single Dual
3434 1137
(SD or %) (200) (885)
STI-negative (n 53) 3397 583
(SD or %)
p-Value
(401) (434)
0.660 0.006
4 7
(13.3%) (20.6%)
26 27
(86.7%) (79.4%)
0.443
2 9
(10.0%) (20.5%)
18 35
(90.0%) (79.5%)
0.304
9 2
(16.4%) (25.0%)
46 6
(83.6%) (75.0%)
0.548
STI, sexually transmitted infection; SD, standard deviation; PROM, premature rupture of the membranes; CS, cesarean section; VD, vaginal delivery. aSexually transmitted infection in this study was defined as genital infection by 1 or more of the following 6 species: Trichomonas vaginalis, Mycoplasma hominis, Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, and Ureaplasma urealyticum.
on the distribution and vertical transmission of bacterial STIs and we recruited pregnant women past 36 weeks of gestation. Thus our study could not evaluate preterm labor induced by the inflammation associated with microorganisms. Nonetheless, uterine contractions driven by prostaglandins in the setting of inflammation have been well documented in previous reports [10,13]. The rate of maternal bacterial STIs in pregnancy was 14.1% in our study. Chugh and Gaind reported that 10–20% of adult patients in developing countries have STIs. Increasing urbanization, illiteracy, poverty, sexual promiscuity, and lack of health education account for the high prevalence of STIs [14]. Vallely et al. reported that the prevalence of C. trachomatis, N. gonorrhoeae, Treponema pallidum, and T. vaginalis in Papua New Guinea were 26.1%, 33.6%, 33.1%, and 39.3%, respectively [15]. Our study excluded patients under 36 weeks of gestation, and since STIs may induce preterm labor and deliv-
ery, the prevalence of STIs in pregnant women may actually be higher than 14.1%. Of note, T. vaginalis, which is a common cause of STIs, was not detected in any women in our study. Chico et al. reported that the prevalence of STI with T. vaginalis in pregnant women was 29.1% in East and Southern Africa and 17.8% in West and Central Africa [16]. There may be an explanation for the absence of T. vaginalis in our study. The flagellated, pear-shaped trophozoite of Trichomonas can be seen on a wet-mount slide, and the diagnostic test for this organism is performed routinely in early pregnancy at our institute. Thus, pregnant women with Trichomonas may have been treated with metronidazole before 36 weeks of pregnancy. Further epidemiological surveillance in pregnant women in a multicenter study is necessary to determine the actual frequency of Trichomonas infections. The rate of vertical transmission of bacterial STIs was 17.2%, and a longer duration of labor was significantly associated with vertical transmission. Prema-
Table IV. Concordance of STI-related bacterial species in mother–neonate pairs (n 11). Mother infection (Genital sampling)
Newborn infection (Oral sampling)
Mycoplasma hominis Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma hominis Ureaplasma urealyticum Mycoplasma hominis, Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma genitalium, Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma hominis Ureaplasma urealyticum
Mycoplasma hominis Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma hominis Ureaplasma urealyticum Ureaplasma urealyticum Ureaplasma urealyticum Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma hominis Ureaplasma urealyticum
Participant 28 47 84 98 102 189 244 303 308 317 349
STI, sexually transmitted infection.
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ture rupture of the amniotic membrane, mode of delivery, and number of pathogenic species were not significantly related to vertical transmission (Table III). Yu et al. reported that the prevalence of Chlamydia in 300 pregnant women in Chongqing, China was 11% (33/300) and that of vertical transmission was 24.2% (8/33). They also reported that the prevalence of vertical transmission with cesarean section was lower than with vaginal delivery [17]. This result is in disagreement with our findings. Chlamydia was detected in 10 of 455 pregnant women (2.2%, 10/455), with 6 of them delivering vaginally and the remaining 4 delivering via cesarean section. Chlamydia was not detected in any of the babies, thus no vertical transmission of Chlamydia was found. The small number of pregnant women with Chlamydia made it difficult to evaluate the factors influencing vertical transmission, thus we included a total of 64 samples positive for 1 of 6 species of microorganism in our analysis (Table III). Of 64 women with an STI, 44 delivered vaginally and the remaining 20 via cesarean section. The mode of delivery did not influence the prevalence of vertical transmission in our study (p 0.304). However, the 2 mothers of 2 STI-positive babies who were delivered by cesarean section had attempted vaginal delivery before surgery. No baby was STI-positive after a pure cesarean section without at least an attempt at vaginal delivery. Therefore, vaginal delivery appears to be more risky in the vertical transmission of STIs. Longer labor times had an influence on the vertical transmission of bacterial STIs. It is speculated that the reason for this is that infectious agents have a better opportunity to proliferate in pregnant women with a longer duration of labor because these women likely undergo pelvic examinations and rupture of membranes during labor. It is known that microbial stimuli can lead to inflammatory reactions in the pregnant uterus, and they may elicit adverse pregnancy outcomes that lead to preterm labor, birth, and precipitous delivery [10]. Paradoxically, preterm labor and delivery may be the defense mechanism by which the fetus can protect itself from STIs. The fetus can shorten the length of labor and gestational period by precipitous and preterm delivery, thereby evading microbial infections present in the mother. Our data excluded preterm delivery before 36 gestational weeks, thus we cannot present and compare the rates of vertical transmission between term and preterm deliveries. Further evaluations including those of preterm babies would be necessary to demonstrate our hypothesis. This study has several limitations. First, the number of mothers with STIs was small. Second, this study was based on data from a single institute. Third, pregnant women at less than 36 gestational weeks
were excluded. Despite these limitations, it is meaningful to evaluate vertical transmission of bacterial STIs between pregnant women and their babies for the benefit of both the mothers and their offspring. In conclusion, vertical transmission of bacterial STIs from mothers to their infants may occur at delivery and is influenced by the duration of labor. Therefore, to prevent vertical transmission of STIs from mothers to their infants at the time of delivery, STIs in pregnant women should be diagnosed appropriately. Acknowledgements This work was supported by grants from the Korea Center for Disease Control and Prevention (No 2010-E51007-00) and the Korean Healthcare Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (A10206510111250100). Declaration of interest: We declare that we have no conflicts of interests.
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