Abscess of the seminal vesicle in a kidney allograft recipient: a clinical case report

Introduction

Seminal vesicle abscess (SVA) is a rare urogenital infection, first described by J. Rajfer et al. in 1978 [1]. To date, only 66 cases have been reported in the literature, with a single case occurring in a post-organ transplant recipient. Predisposing factors commonly include chronic genitourinary infections, prior urological instrumentation, diabetes mellitus, and immunosuppression [2].

Early-stage SVA is frequently underdiagnosed due to nonspecific clinical manifestations, such as fever, lower urinary tract symptoms, perineal or rectal discomfort, and scrotal pain, none of which are pathognomonic [3]. Consequently, a high index of suspicion is essential in at-risk populations. Imaging plays a pivotal role in both detection and characterization of SVA, with transrectal ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI) representing the primary diagnostic modalities.

Given the rarity of SVA, standardized treatment guidelines are lacking. While isolated reports have described successful management with antimicrobial therapy alone, most cases require abscess drainage. Transperineal, transrectal, and transurethral approaches have all been reported, with the choice of modality typically guided by abscess characteristics, anatomical considerations, and clinical response to initial therapy [2].

Patient information

A 45-year-old male presented to the emergency department with high-grade fever, malaise, and severe scrotal pain. His medical history was notable for end-stage chronic kidney disease secondary to diabetic nephropathy diagnosed in 2017. He underwent right-sided deceased-donor kidney transplantation in December 2017. Progressive allograft dysfunction with recurrent end-stage disease was documented in 2022, and a second deceased-donor kidney transplant was performed on the left side in April 2024. In January 2025, a right transplant nephrectomy was performed due to persistent, recurrent pyelonephritis and abscess formation in the nonfunctioning graft. The postoperative course was uneventful, with stable creatinine and inflammatory markers. No antimicrobial therapy was prescribed upon discharge.

Case report

On 13 February 2025 (20 days post-nephrectomy), the patient developed worsening fever up to 39 °C, generalized weakness, and left testicular pain. He was transported by emergency medical services and admitted to the nephrology department. Clinical evaluation indicated acute bilateral orchiepididymitis. Laboratory testing showed leukocytosis (13.52 × 10⁹/L) and elevated C-reactive protein (221.46 mg/L). Scrotal ultrasonography confirmed bilateral epididymo-orchitis.

Empiric therapy consisted of cefepime/sulbactam 1 + 1 g q.i.d. (as a continuous infusion following a loading dose 1 + 1 g) combined with colistimethate sodium (6 million IU loading dose, then 3 million IU b.i.d.), adjusted to graft function. The regimen was selected based on previous microbiological data demonstrating a carbapenem-resistant Klebsiella pneumoniae strain susceptible only to colistin. The patient initially improved, with reduction of fever to subfebrile levels and normalization of leukocyte count.

Three days after initiation of therapy, fever recurred. Computed tomography of the chest and abdomen revealed no abnormalities. Pelvic MRI demonstrated transplant pyelonephritis with small apostemes (up to 2.5 mm) and an inflammatory fluid collection within the right seminal vesicle measuring 31 × 25 mm (Fig. 1).

Urgent transperineal drainage under transrectal ultrasound guidance was performed. Approximately 5 mL of thick purulent material was aspirated, and an 8Ch pig-tail catheter was inserted (Fig. 2). Rapid clinical and laboratory improvement followed: body temperature normalized and CRP decreased from 246.98 mg/L to 76.93 mg/L (Table 1).

Culture of the operative specimen yielded carbapenem-resistant K. pneumoniae (104 CFU/mL), susceptible only to polymyxins (Table 2). Real-time PCR identified the blaOXA-48 gene, consistent with the observed carbapenem resistance (Table 3). Microbiological analysis demonstrated that the isolated organism was susceptible to polymyxins. As the patient showed clinical improvement, the antimicrobial therapy was continued without modification.

Drain output remained minimal. Follow-up transrectal ultrasonography on postoperative days 3 and 5 showed progressive reduction of the abscess cavity and normalization of seminal vesicle echotexture. Drains were removed on postoperative day 6. Antimicrobial therapy was discontinued after 12 days. The patient was discharged in good condition with recommendations for herbal urinary antiseptics (centaury herb, lovage root, and rosemary leaf). No antibiotics were prescribed.

At the two-month follow-up, imaging confirmed complete resolution of the abscess without recurrence (Fig. 3). Renal allograft function remained stable (creatinine 124.7 µmol/L; urea 5.7 mmol/L).

Discussion

SVA is characterized as a purulent-inflammatory process involving the formation and accumulation of purulent exudate within the seminal vesicle cavity. The etiopathogenesis of this condition remains insufficiently elucidated. Existing literature provides only sporadic reports regarding potential predisposing factors, which include diabetes mellitus, HIV infection, alcoholic liver cirrhosis, immunosuppressive therapy, recurrent urinary tract infections, prolonged urethral catheterization, previous urological interventions, and vasectomy [2][4]. The clinical presentation is highly variable and may include fever, dysuria, recurrent episodes of epididymo-orchitis, rectal discomfort, urinary frequency, hematuria, abdominal, lumbar, pelvic or inguinal pain, and hematospermia [3]. To date, only 66 cases of SVA have been reported in the literature. Of particular interest is the case described by Wadei et al. (2008), in which SVA developed in a post-renal transplant patient, presenting with severe testicular pain comparable to that observed in our patient [5]. In a systematic review by Pandey et al., epididymo-orchitis was noted in 6 of 18 patients with SVA [3]. These findings suggest that clinical manifestations of epididymo-orchitis in post-renal transplant patients should raise suspicion for SVA and prompt diagnostic exclusion.

The diagnosis of SVA is often challenging due to its nonspecific clinical manifestations, necessitating a high degree of clinical suspicion. Imaging plays a pivotal role in establishing the diagnosis and guiding management. TRUS commonly reveals hypoechoic, heterogeneous lesions within the seminal vesicle region, providing a rapid and minimally invasive initial assessment [6]. MSCT offers a more comprehensive evaluation, delineating the extent of the abscess, its spatial relationships with adjacent pelvic structures, and potential complications such as fistula formation. MRI with its superior soft tissue contrast, is particularly valuable for detecting small or subtle abscesses that may be missed on TRUS or MSCT [7]. In the present case, given the atypical clinical presentation, MRI was specifically employed to assess both the transplanted kidney and surrounding pelvic structures, allowing early identification of lesions not visualized on MSCT and facilitating timely intervention.

Although successful conservative management of SVA with antibiotics alone has been reported, most cases require abscess drainage to achieve complete resolution [8]. Antimicrobial therapy should target urogenital pathogens and be guided by culture and sensitivity results from urine and purulent material. In this case, the choice of antimicrobials was limited by prior colonization with an extensively drug-resistant Enterobacterales strain, pharmacokinetic challenges in reaching the infection site, and the presence of a renal allograft, necessitating careful dosing considerations. The combination of cefepime/sulbactam and colistimethate sodium was selected based on pharmacokinetic and microbiological properties: cefepime demonstrates greater stability against OXA-48-like carbapenemases than penicillins or carbapenems, while sulbactam protects cefepime from hydrolysis by plasmid-mediated (SHV, CTX-M) and chromosomal beta-lactamases, including AmpC, thereby restoring activity against Enterobacteriaceae [9]. Colistimethate sodium is a preferred agent for urinary tract infections caused by multidrug-resistant Gram-negative bacteria, with dosing tailored to renal function or allograft status [10][11].

This case underscores the limitations of conservative therapy alone: despite appropriate antibiotic administration, the patient continued to exhibit fever and elevated C-reactive protein, indicating ongoing inflammation. Therefore, adequate abscess drainage remains a cornerstone of successful treatment. Drainage may be performed transrectally or transperineally under TRUS guidance, or via transurethral vesiculoscopic techniques, as recently demonstrated [8][12]. In our patient, we elected to place a pigtail catheter for continuous drainage, rather than performing a single aspiration. This decision was supported by evidence that one-time drainage frequently leads to early recurrence, particularly in patients with associated epididymo-orchitis or persistent infectious foci. Continuous drainage ensured sustained decompression of the abscess cavity, allowing complete evacuation of purulent material and minimizing the risk of re-accumulation. Furthermore, in the context of immunosuppression following renal transplantation, maintaining effective drainage was critical to prevent ongoing infection and protect allograft function.

Conclusion

Seminal vesicle abscess is a rare condition, with immunosuppression following renal transplantation representing a significant risk factor. In patients with predisposing factors who present with testicular pain or epididymo-orchitis, SVA should be suspected and evaluated using appropriate imaging techniques. Management should combine minimally invasive drainage with targeted antimicrobial therapy. A multidisciplinary approach enables favorable outcomes, prevents complications, and preserves renal allograft function.