OBJECTIVE: We developed and validated a diagnostic nomogram for differentiating epididymal tuberculosis (TB) from bacterial epididymitis.
METHODS: In this retrospective study, we developed a prediction model based on demographics and clinical characteristics. Eligible patients were randomly divided into derivation and validation cohorts (ratio 7:3). Univariate and multivariate regression analyses were used to filter variables and select predictors. Multivariate logistic regression was used to construct the nomogram. Concordance index (C-index), calibration plots, and decision curves analysis (DCA) were used to assess the discrimination, calibration, and clinical usefulness of the nomogram.
RESULTS: We included 147 patients (epididymal TB, 93; bacterial epididymitis, 54). The derivation cohort included 66 patients with epididymal TB and 38 with bacterial epididymitis; the validation cohort included 27 patients with epididymal TB and 16 with bacterial epididymitis. One regression model was built from three differential variables: body mass index, purified protein derivative, and chronic infection. Accordingly, one nomogram was developed. The model had good discrimination and calibration. C-indexes of the derivation and validation cohorts were 0.89 and 0.98 (95% confidence intervals, 0.83-0.95 and 0.94-1.01), respectively. DCA showed that the proposed nomogram was useful for differentiation.
CONCLUSIONS: The nomogram can differentiate between epididymal TB and bacterial epididymitis.

Uropathogenic Escherichia coli (UPEC)-associated epididymitis is commonly diagnosed in outpatient settings. Although the infection can be successfully cleared using antimicrobial medications, 40% of patients unexplainably show persistent impaired semen parameters even after treatment. Our aim was to investigate whether pathogenic UPEC and its associated virulence factor hemolysin (hlyA) perturb the structural and functional integrity of both the epididymis and sperm, actions that may be responsible for the observed impairment and possibly a reduction of fertilization capabilities. Semen collected from patients diagnosed with E. coli-only related epididymitis showed that sperm counts were low 14 days postantimicrobial treatment regardless of hlyA status. At Day 84 following treatment, hlyA production correlated with approximately 4-fold lower sperm concentrations than in men with hlyA-negative strains. In vivo experiments with the hlyA-producing UPEC CFT073 strain in a murine epididymitis model showed that just 3 days postinfection, structural damage to the epididymis (epithelial damage, leukocyte infiltration, and edema formation) was present. This was more severe in UPEC CFT073 compared to nonpathogenic E. coli (NPEC 470) infection. Moreover, pathogenic UPEC strains prematurely activated the acrosome in vivo and in vitro. Raman microspectroscopy revealed that UPEC CFT073 undermined sperm integrity by inducing nuclear DNA damage. Consistent with these observations, the in vitro fertilization capability of hlyA-treated mouse sperm was completely abolished, although sperm were motile. These findings provide new insights into understanding the possible processes underlying clinical manifestations of acute epididymitis.