非阻塞性無精症患者睪丸液微生物群特徵及

其與精子取出結果之關聯

林子翔¹、黃奕燊^1,2

¹台北榮民總醫院 泌尿部；²書田泌尿學研究中心

Testicular Fluid Microbiome Profiles and Their Association with Sperm Retrieval Outcomes in Non-Obstructive Azoospermia Patients

Tzu-Hsiang Lin^1,, I-Shen Huang^1,2

¹ Department of Urology, Taipei Veterans General Hospital;

² Department of Urology, School of Medicine and Shu-Tien Urological Science Research Center, National Yang Ming Chiao Tung University,

Taipei, Taiwan

Purpose:

Non-obstructive azoospermia (NOA), defined as the absence of sperm in the ejaculate due to intrinsic testicular dysfunction, remains one of the most challenging forms of male infertility to treat, despite advances in testicular sperm extraction (TESE). Sperm retrieval rates are approximately 50%, underscoring the need for reliable predictors of successful retrieval. The bacterial microbiome (BM), a key component of the sperm microenvironment, plays an important role in various physiological processes. However, its impact on TESE outcomes in patients with NOA remains poorly understood. In this study, we present our findings on the association between BM and sperm retrieval success.

Materials and Methods:

Male-factor infertility and azoospermia were defined according to World Health Organization (WHO) criteria. Patients with non-obstructive azoospermia (NOA) were dichotomized based on microdissection testicular sperm extraction (microTESE) outcomes into sperm retrieval–positive (NOA[+]) and sperm retrieval–negative (NOA[–]) groups. Demographic and clinical data, including age, body mass index (BMI), and baseline hormone levels, were collected.

The bacterial microbiome (BM) was characterized to the species level using 16S rRNA gene amplification and sequencing. Within-sample diversity (α-diversity) was assessed using the Chao1, Shannon, and Simpson indices. Between-sample diversity (β-diversity) was evaluated using non-metric multidimensional scaling (NMDS) plots in conjunction with analysis of similarities (ANOSIM). Linear discriminant analysis effect size (LEfSe) was performed to identify differences in microbial composition between NOA(–) and NOA(+) testicular fluid samples.

Results: 

Analysis of the testicular fluid microbiome in patients with non-obstructive azoospermia (NOA), stratified by sperm retrieval status, revealed no statistically significant differences in α-diversity (Chao1, Shannon, and Simpson indices) at the phylum, genus, or species levels. Similarly, β-diversity analysis using non-metric multidimensional scaling (NMDS) demonstrated no distinct clustering between groups. Across comparisons among obstructive azoospermia (OA), NOA(–), and NOA(+), all p-values exceeded 0.05, indicating no significant differences in overall microbial composition.

Taxonomic profiling showed that the microbial community was predominantly composed of the phyla Proteobacteria and Firmicutes, with commonly detected genera including Ralstonia, Klebsiella, and Acinetobacter. Despite this apparent compositional similarity, linear discriminant analysis effect size (LEfSe) identified specific taxa that differentiated the groups at a finer resolution. The phylum Verrucomicrobia and the genus Stenotrophomonas were enriched in the NOA(–) group, whereas the NOA(+) group demonstrated a higher relative abundance of Helicobacter. At the species level, Klebsiella africana and Helicobacter pylori were more prevalent in the NOA(+) group.

Conclusion: 

The enrichment of taxa such as Verrucomicrobia and Stenotrophomonas in NOA(–) patients, and Helicobacter, Klebsiella africana, and Helicobacter pylori in NOA(+) patients suggests that while the broad microbial composition remains stable between groups, specific low-abundance taxa may still serve as indicators of retrieval success.