The aim of this study was to evaluate whether chronic endometritis (CE) and uterine endometrium microbiota were associated with repeated implantation failures (RIFs) and recurrent pregnancy losses (RPLs). In this prospective study, uterine endometrial specimens were obtained from 24 women with RIF, 27 with RPL, and 29 fertile control women. Immunohistochemical staining of CD138 for CE and 16S ribosomal RNA (rRNA) sequencing analysis for uterine endometrium microbiota were performed simultaneously. To assess CE, Liu’s method, McQueen scores and plasma cell count/10 mm² were used. The frequency of CE (plasma cells > 5.15/10 mm²) was higher in women with RPL (29.6%) than in fertile controls (6.8%, p < 0.05). The plasma cell count/10 mm² in women with RPL (median 1.53, range 0–252.6, p < 0.01) and women with RIF (median 0.6, range 0–6.98, p < 0.05) was higher than in fertile controls (median 0, range 0–29). The uterine endometrium microbiota in women with RPL or RIF was not significantly different from that in fertile controls. However, the relative dominance rate of Lactobacillus iners (median 4.7%, range 0–99.9 vs. median 0%, range 0–100, p < 0.001) and the positive rate of Ureaplasma species (36.3% vs. 8.6%, p < 0.05) were higher in 11 women with CE than in 69 women without CE. The results suggest that CE may be involved in the pathophysiology of RPL and RIF. Lactobacillus iners and Ureaplasma species may be associated with the etiology of CE.

Objectives: This prospective study evaluated whether endometriosis is associated with chronic endometritis (CE) and affects the uterine endometrium microbiome (UEM) in women with repeated implantation failure (RIF). Methods: Forty-three women with RIF were divided into 12 with endometriosis (EM) and 31 without endometriosis (non-EM). The UEM was examined by 16S ribosomal RNA (rRNA) sequencing, and CE was determined by CD 138 staining (plasma cells > 5.15/10 mm2) simultaneously. Results: The EM group had a higher bacterial number (EM vs. non-EM; median [range], 6.5 vs. 3 [3–11, 1–16], p = 0.009), while the frequency of Lactobacillus species did not change. The rates of presence of Dialister (41.7% [5/12] vs. 3.3% [1/31], p = 0.004) and Streptococcus species (58.3% [7/12] vs. 16.1% [5/31], p = 0.017) were higher in the EM group. The prevalence of CE did not differ between the two groups. Multivariable logistic regression analysis revealed that the presence of Dialister species (odds ratio, 10.97, 95% confidence interval, 1.17–249.37, p = 0.036) was associated with endometriosis. In the EM group, five women with Dialister species had a higher number of bacterial species (10 vs. 5 [6–11, 3–7], p = 0.021) and higher Shannon diversity index (0.50 vs. 0.20 [0.19–1.39, 0.03–0.46], p = 0.026) than seven without Dialister species. Conclusions: Dialister and Streptococcus species, and the increased number of bacterial species in UEM may be related to the pathogenesis of RIF complicated by endometriosis.

This study aimed to elucidate the molecular characteristics and antimicrobial resistance of Streptococcus agalactiae (group B streptococcus, GBS) colonizing pregnant women in Japan. GBS isolates obtained from screening of pregnant women from 2017 to 2021 were analyzed for capsular serotype, sequence type (ST), and antimicrobial susceptibility. For levofloxacin-resistant isolates, mutations in the quinolone resistance-determining regions (QRDRs) of the gyrA, gyrB, and parC genes were analyzed. Seventy-six GBS isolates were recovered from 1090 women (isolation rate: 7.0%). Of the 76 isolates, serotype III (31.6%) was the most prevalent, followed by V (19.7%), Ia (17.1%), and Ib (10.5%). Among the 22 STs identified, capsular serotype III/ST335-clonal complex (CC) 19 lineage was dominant (13.2%), followed by Ia/ST23, III/ST17, and V/ST1. Levofloxacin resistance was detected in 15.8% (n=12) of all the isolates, with serotype Ib being the most common. Most levofloxacin resistant isolates belonged to serotype Ib/CC10 or serotype V/CC19, with double mutations in the QRDRs, Ser81Leu in GyrA and Ser79Phe in ParC. The present study indicates the prevalence of the serotype III/ST335 (CC19) lineage, and the spread of serotype Ib/CC10 and serotype V/CC19 lineages, which are responsible for levofloxacin resistance in colonizing GBS in pregnant women in Japan.

Problem: Enhanced secretion of type-2 T-helper (Th2) cytokine is a characteristic feature in normal physiological pregnancy. A study has demonstrated defective production of interleukine-4 (IL-4) and other Th2 cytokine in women with recurrent pregnancy loss (RPL). Several studies have suggested that IL-4 variable number of tandem repeat (VNTR) gene polymorphism is probably associated with different IL-4 production. Methods of study: The IL-4 VNTR genotypes were assessed in 109 Japanese women with RPL and 210 ethnically matched women experiencing at least one live birth and no spontaneous abortion. Results: No significant differences in IL-4 VNTR genotype frequencies were found between the RPL and the control [B1B1 genotype (reference); B1/B2 and B2/B2 genotypes, odds ratio, 0.91; 95% confidence interval, 0.58–1.45]. Conclusion: The present study suggests that the IL-4 VNTR allele is not a major genetic regulator in RPL.

This prospective cohort study aimed to evaluate the performance of Flora select™ (FS), a newly developed real-time PCR test, for the assessment of the vaginal microbiome during early pregnancy. Five hundred and fifty-six pregnant women underwent examinations of FS, Nugent score—a Gram-staining scoring system for the diagnosis of bacterial vaginosis (BV)—and conventional bacterial culture between 8 weeks and 12 gestational weeks. Nugent scores of 0–3, 4–6, and ≥7 were found in 469 (84.2%), 41 (7.4%), and 47 (8.5%) of the women, respectively. Relative dominance rates of Lactobacillus species of high (≥80% medium (50%≤, <80%), and low (0.1≤, <50%), and no detection (<0.1%) were 63.0%, 8.8%, 17.1%, and 11.2%, respectively. Gardnerella, Prevotella, Atopobium, Streptococcus, Ureaplasma, and Mycoplasma species were detected in 23.9%, 17.6%, 17.1%, 7.0%, 23.0%, and 4.9% of the women, respectively. Gardnerella species were detected in all women with Nugent scores ≥7 and Ureaplasma were detected in 40.4% of them. BV-associated bacterial species were also detected in 70.7% of women with Nugent scores of 4–6. Gardnerella, Prevotella, Atopobium, Streptococcus, Ureaplasma, and Mycoplasma species were highly prevalent in women with Nugent scores ≥4 or Lactobacillus species <50%. FS detected Gardnerella, Prevotella, and Atopobium species more effectively than conventional bacterial culture. FS could determine relative dominance rates of Lactobacillus species in the vaginal microbiome, and simultaneously detect four kinds of BV-associated bacteria, Ureaplasma and Mycoplasma species. Therefore, FS may be clinically useful for the screening of the vaginal microbiome during pregnancy to prevent preterm birth and for the assessment of the vaginal microbiome after BV treatments.

Preterm birth is a major cause of perinatal mortality and morbidity in newborns, and its risk is increased by bacterial vaginosis (BV) during pregnancy. This multicenter prospective cohort study aimed to evaluate whether Flora select™ (FS), a newly developed real-time polymerase chain reaction test, is clinically useful for assessing the effectiveness of BV treatment during pregnancy. The vaginal microbiome characterized by relative dominance rates of Lactobacillus ≤ low (<50%), together with a positive test for Gardnerella, Prevotella, or Atopobium species, was defined as BV-FS A criterion. The vaginal microbiome characterized by Lactobacillus medium (50%≤, <80%), together with positive tests for Gardnerella plus either Prevotella species or Atopobium species, was defined as BV-FS B criterion. This study enrolled 25 pregnant women with classical BV (Nugent score ≥ 7) at initial examinations, and they met the BV-FS A (n = 23) and BV-FS B (n = 2) criteria. No woman with classical BV had a missed diagnosis of molecular BV. Treatments with metronidazole vaginal tablets resulted in the improvement of 88.0% (22/25) of classical BV, 65.2% (15/23) of BV-FS A, and 50.0% (1/2) of BV-FS B cases, whereas positive rates of Ureaplasma species in women with classical BV increased by 42.9%. Although most classical BV cases were cured following metronidazole treatments, a considerable proportion still harbored molecular BV detected by FS. Although the Nugent scoring system revealed that 80.0% (20/25) of women with classical BV (Nugent score ≥ 7) were sufficiently cured as BV-negative (Nugent scores 0–3), 5 (25%) of the 20 cured cases still met the BV-FS A/B criteria. FS particularly detected Ureaplasma species in 9 (45%) of the 20 cured cases. It could identify pregnant women who require additional treatments for residual molecular BV and Ureaplasma species. Therefore, the FS test may be clinically useful for assessing the vaginal microbiome and evaluating the effectiveness of BV treatments.