Inevitable Late Miscarriage Associated with Mycoplasma hominis Bacteremia Following Cervical Cerclage: A Case Report and Literature Review

Introduction

Mycoplasma represents a group of the smallest prokaryotic microorganisms characterized by their lack of cell walls.¹Mycoplasma is a significant pathogen associated with sexually transmitted diseases and is among the most prevalent microorganisms responsible for reproductive tract infections.^2–4 Notably, Mycoplasma hominis (M. hominis) are the most commonly identified species within this group.⁵ Furthermore, M. hominis infections have been implicated in adverse pregnancy outcomes, including miscarriage, endometritis, premature birth, embryonic arrest, chorioamnionitis, and intrauterine growth restriction.^6,7 M. hominis infections have also been documented in various anatomical sites, including the central nervous system, thoracic cavity, and musculoskeletal system.^8–11

Attributable to M. hominis fastidious nutritional requirements, this organism is infrequently detected by conventional blood culture systems. Moreover, the inherent absence of a cell wall confers resistance to numerous first-line antimicrobial agents, thereby complicating both the diagnosis and clinical management of M. hominis bloodstream infections in pregnant patients.^6,12,13 This article presents a case study of an 18-week pregnant woman who developed a bloodstream infection due to M. hominis following a cervical cerclage procedure, which resulted in an unavoidable late miscarriage. A retrospective analysis of the case, including the pathogenic characteristics of M. hominis and its antibiotic resistance profile, has been conducted to offer insights for clinical diagnosis and management.

Case Presentation

The patient experienced menarche at the age of 13, with regular 30-day menstrual cycles and 5-day bleeding duration. Her last menstrual period was on February 23, 2022. She married at 26 years old and had only one long-term sexual partner, with no history of unprotected or high-risk sexual intercourse. Her husband was healthy and had no family history of hereditary diseases, yet he had never received any genital tract microbial screening or culture tests. The couple did not use contraceptive measures. She had an obstetric history of gravida 4, para 1. In 2014, she delivered a full-term male infant weighing 3900 g via cesarean section with unremarkable postpartum recovery. She underwent medical abortion at 7+ weeks of gestation in 2015 and artificial abortion at 7+ weeks in 2020, with satisfactory recovery after both procedures. One month after her missed current menstrual cycle, a urine pregnancy test confirmed gestation, and she denied obvious discomforts or typical early pregnancy symptoms at initial presentation.

Routine prenatal examinations revealed no abnormalities. On June 26, 2022, at 17 weeks and 4 days of gestation, the patient experienced irregular lower abdominal pain without any noticeable vaginal bleeding or fluid discharge. At an external hospital, the cervical canal was measured at 11 mm in length, exhibiting a slight V-shape and a separation of 3 mm. Cervical secretion culture, chlamydia, mycoplasma, and gonorrhea examinations showed no obvious abnormalities. The patient was treated with oral Duphaston and intravenous magnesium sulfate; however, uterine contractions did not show significant improvement. Irregular uterine contractions persisted on the night of June 28, at 17 weeks and 6 days of gestation, prompting the patient to seek emergency care at our hospital on June 29, at 18 weeks of gestation.

Protocol Upon admission, the patient received magnesium sulfate, progesterone, and drotaverine to support fetal health, while cefoxitin sodium was administered as a prophylactic measure against infection. Ultrasound imaging indicated that the cervical canal of the pregnant patient was dilated in a “Y” shape, with the closed segment measuring approximately 1.2 cm in length. In response to “cervical incompetence during pregnancy,” a transvaginal cervical cerclage was performed under epidural anesthesia on July 4, 2022, at 18 weeks and 5 days of gestation, with the procedure being deemed successful. On the same day, an examination of cervical secretions for pathogenic microorganisms revealed a positive result for Ureaplasma urealyticum DNA, with a concentration of 149,000 copies, while tests for Chlamydia trachomatis DNA and Neisseria gonorrhoeae DNA were negative, each with fewer than 500 copies detected (Fluorescence Quantitative PCR, Sansure Biotech, China). Azithromycin is used to treat this positive pathogen. On July 6, 2022, at 19 weeks of gestation, the patient’s body temperature was recorded at 38.1°C, although no additional symptoms were reported. Consequently, Cefoperazone sulbactam sodium was administered for infection control. On July 7, a microbial culture of vaginal secretions indicated a substantial growth of Candida albicans (Sabouraud Dextrose Agar, Zhengzhou Antu Biology, China). To address fungal infections, Nifuratel Nystatin is utilized. On July 8, 2022, at 19 weeks and 2 days of gestation, laboratory results indicated a white blood cell count of 12.0×10^9/L, a neutrophil percentage of 87.7%, and a high-sensitivity C-reactive protein level of 74.7 mg/L. In light of the intrauterine infection and increased uterine contractions during pregnancy, it was advised to remove the cervical cerclage suture and discontinue efforts to protect the fetus, to which the pregnant woman consented. Three hours following the removal of the cerclage suture, the patient’s body temperature increased to 38.6°C. (Figure 1) Consequently, oxytocin was administered intravenously to enhance uterine contractions and facilitate the termination of the pregnancy. The patient was informed of her scarred uterus and the associated risk of uterine rupture during labor. At 17:52 on July 8, 2022, a fetus weighing 350g was delivered vaginally. The placenta was expelled spontaneously, with intact fetal membranes, and the estimated blood loss during childbirth was approximately 100mL, with an additional 30mL of vaginal bleeding observed postpartum. Postoperative placental histopathological results: chorioamnionitis. (Figure 2) On July 8, a microbial culture of cervical secretions demonstrated the presence of M. hominis (Columbia Blood Agar, Zhengzhou Antu Biology, China). M. hominis was found to be resistant to macrolide antibiotics and responsive to doxycycline, tetracycline, and quinolone antibiotics according to susceptibility tests. (Table 1) Additionally, a blood culture set was obtained at 16:22 on the same day. A positive result was obtained from the anaerobic bottle on July 10, indicating the growth of M. hominis as identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. (MALDI-TOF MS) (MALDI Biotyper Sirius/microflex, Bruker Daltonics GmbH & Co. KG, Germany) (Figure 3).

Table 1 Antibiotic Sensitivity of the M. hominis

Figure 1 Dynamic changes of inflammatory markers and vital signs during the patient’s hospitalization. The chart shows the trends of C-reactive protein (CRP), white blood cell (WBC) count, body temperature, pulse rate, and the timeline of antibiotic administration during admission. 1–6.

Figure 2 Histopathological features of placental chorioamnionitis. (a) Panoramic view of the placental tissue, HE staining, total magnification ×100, scale bar=200 μm. (b) High-magnification view of the lesion area, HE staining, total magnification ×400, scale bar=50 μm. Abundant inflammatory cell infiltration in the chorionic and amniotic membranes is indicated by the arrow. 1–6.

Figure 3 Identification and antibiotic susceptibility testing of M. hominis. (A) Needle-tip colonies of M. hominis after 48 h of anaerobic incubation. (B) Positive signal of the anaerobic blood culture bottle at 48 h, with a flat growth curve of the automated culture system. (C) Antibiotic susceptibility testing results of the M. hominis isolate. (D) M. hominis identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). 1–6.

After a miscarriage, the patient’s body temperature was recorded at 37.5°C, and her vital signs remained stable Cefoperazone sulbactam sodium was continued for its anti-infective properties. On the second day following the miscarriage, the patient experienced minimal vaginal bleeding without any associated symptoms such as fever. Laboratory tests indicated an improvement in the white blood cell count and other parameters, although levels of high-sensitivity C-reactive protein remained elevated. Doctors select moxifloxacin for oral administration for one week after obtaining the M. hominis drug susceptibility results. After receiving appropriate medical treatment, the patient was discharged from the hospital.

Discussion

Mycoplasma hominis (M. hominis) is a prevalent colonizing bacterium of the urogenital tract, frequently isolated from sexually mature women.¹⁴ Approximately 21% to 53% of asymptomatic women are colonized with M. hominis, and the colonization rate in the male urethra can reach up to 20%.^15,16 Under certain conditions, M. hominis can lead to urogenital tract infections, such as pelvic inflammatory disease and cervicitis.¹⁷ Typically, it causes infections confined to the mucosal surfaces of the genital tract and does not invade tissues or the bloodstream.¹⁸ We reviewed cases of M. hominis bloodstream invasion reported in the literature from 1994 to 2005 and synthesized this information with our findings (Table 2).

Table 2 Summary of Published Cases of M. hominis Bloodstream Infections (1994–2025)

This case is clinically important because M. hominis bacteremia following cervical cerclage during pregnancy is extremely rare but can cause life-threatening intrauterine infection and inevitable late miscarriage.

In this case, persistent cervical structural damage caused by multiple prior pregnancy events, including one cesarean delivery and two first-trimester induced abortions, gradually impaired cervical tissue elasticity and mechanical integrity over time. Such cumulative injury significantly weakened the cervical barrier function and resulted in cervical insufficiency during the current gestation. The unique virulence characteristics of M. hominis mediate immune evasion and tissue invasion, and this risk is further amplified by cervical cerclage—a necessary invasive procedure for treating cervical incompetence. As an invasive intervention, cervical cerclage inevitably disrupts the integrity of the cervical mucosal epithelium, which not only impairs the local physical barrier but also creates an additional pathway for pathogen invasion, thereby increasing the chance of infection. M. hominis can adhere to genital epithelial cells via surface adhesins and secrete a variety of virulence factors, including phospholipase C, aminopeptidase, and hydrogen peroxide. These factors not only further damage the already impaired epithelial cell barrier (exacerbated by cerclage-related trauma) but also induce the release of pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, triggering a sustained inflammatory cascade. Unlike other common genital pathogens, M. hominis lacks a rigid cell wall, enabling it to evade phagocytosis by host immune cells and survive in both intracellular and extracellular environments, leading to persistent infection that is difficult to clear.¹⁴ This physiological immune adaptation, combined with the pre-existing cervical structural damage, significantly reduces the host’s ability to control the proliferation and invasion of colonizing M. hominis, making pregnant women more susceptible to the progression from asymptomatic colonization to invasive infection. In this case, the sustained elevation of inflammatory markers after surgery not only reflects the failure of the host immune system to limit the spread of M. hominis infection but also correlates with the placental inflammatory changes induced by the pathogen.

Other than that, the diagnostic approach failed to encompass common pathogens of the lower reproductive tract, such as bacterial vaginosis (BV), fungi, and Group B Streptococcus (GBS), and notably omitted screening for M. hominis. Consequently, the clinician was unable to administer precise treatment for the pathogens actually present in the patient in a timely manner, resulting in reliance on empirical treatment strategies. This oversight allowed M. hominis to persist and continue infecting the patient. By this stage, the patient had developed a severe infection, and the miscarriage was irreversible.

Additionally, the antibiotic resistance characteristics of M. hominis present a significant challenge.²⁸ It is evident that M. hominis is neither a well-recognized nor a common pathogen in clinical practice. Therefore, understanding its drug resistance profile is essential for the appropriate application of antibiotics in its treatment. It is well established that Mycoplasma species exhibit intrinsic resistance to β-lactam antibiotics due to the absence of a cell wall in Mycoplasma.²⁹ Doxycycline and moxifloxacin are commonly used in the literature to treat M. hominis infections.^8,26 In the present case, oral administration of Azithromycin tablets was employed for a duration of three days to address the Ureaplasma urealyticum infection, while Cefoperazone and Sulbactam were utilized as prophylactic agents. However, the M. hominis strain in this instance demonstrated resistance to macrolide antibiotics, rendering the empirical treatment regimen ineffective against this pathogen.

Several limitations of this study should be noted. First, as a single-case report from a single center, the generalizability of our findings is inherently limited, and a definitive causal link between M. hominis bacteremia and post-cerclage late miscarriage cannot be established. Second, comprehensive pre-operative genital pathogen screening (including M. hominis) and sexual partner pathogen detection were not performed, so the baseline colonization status and transmission source of the pathogen could not be clarified. Third, we did not apply mNGS or other sensitive molecular methods for early pathogen detection, nor did we obtain direct pathological evidence of placental M. hominis infection. Finally, our literature review only included English-language reports, with no long-term follow-up of the patient, which may lead to incomplete data summary and insufficient evaluation of the long-term prognosis of the disease.

In conclusion, this case highlights that Mycoplasma hominis bloodstream infection is a life-threatening complication of cervical cerclage that can lead to life-threatening late miscarriage. For pregnant patients with cervical insufficiency, routine screening for M. hominis and timely pathogen identification should be prioritized. Mastery of its unique antimicrobial resistance profiles enables prompt targeted therapy, replacing ineffective empirical treatment. This clinical paradigm is critical for reducing infectious complications, improving the prognosis of cervical cerclage, and ultimately protecting the health and safety of pregnant women and their fetuses.