Case Presentation: A 56 year old female smoker with history of progressive weight loss in the past 6-9 months and changes in urinary frequency for about a month, presented with confusion, generalized weakness, lower extremity edema and dysphagia. Physical examination revealed blood pressure 112/53 mmHg, hear rate 81 bpm, temperature 96.1 F, and 1+ bilateral lower extremity edema without CVA tenderness. Labs showed leukocytosis, anemia, elevated BUN/creatinine. Urinalysis showed pyuria. CT scan chest, abdomen, and pelvis showed a bladder mass 7.8 x 7.3 x7.3 cm, with bilateral hydroureteronephrosis, and a fluid collection inseparable from the left kidney. The patient underwent bilateral nephrostomy and left perinephric drainage placement. Gram stain from kidneys and the perinephric fluid drainage showed gram positive bacilli consistent with actinomycosis. Cystoscopy showed necrotic debris and bladder biopsy was positive for invasive urothelial carcinoma with extensive pelvic involvement. Patient was initially treated with piperacillin/tazobactam, and later transitioned to a long term antibiotic therapy with Amoxicillin/clavulanic acid and to continue with chemotheraphy for bladder cancer.

Discussion: Actinomycosis pathologic infections typically occur in the cervicofascial (50%), thoracic (15-20%) abdominal regions (20%), and rarely affect the kidneys. Renal involvement thought to be through a digestive route even though hematologic spread has been assumed in cases where there was no previous intra-abdominal disease. Predisposing factors include recent abdominal surgery, trauma, neoplastic, perforated viscus, chronic inflammatory disease, immunosuppression and use of intrauterine contraceptive devices. Renal actinomycosis can present with non-specific symptoms like fatigue, fever, weight loss and abdominal pain mimicking more common conditions such as malignancy or tuberculosis. It may resemble other kidney diseases such as pyelonephritis, renal abscesses, tumor like lesion and very rarely necrotizing papillitis. In our case the presence of invasive urothelial carcinoma of bladder with extensive pelvic involvement was the predisposing factor for actinomycosis. On imaging, actinomycotic infection can be seen as solid masses or cystic masses with thick enhancing walls. The diagnosis of Actinomycosis is made via culture or by microscopic detection of sulfur granules. Penicillin or ampicillin is the treatment of choice and this drug should be administered for at least 3 months. In cases of allergic reaction tetracycline, erythromycin or clindamycin may be used alternatively.

Conclusions: Actinomycosis is an uncommon chronic granulomatous disease, mainly caused by Actinomyces Israeli, a gram positive anaerobic organism that is normally present in the oral cavity and intestinal tract, which acquires pathogenicity through invasion of breached or necrotic tissue. Pathologic infections typically occur in the cervicofascial, thoracic and abdominal regions, and rarely affect the kidneys . In case of renal actinomycosis further workup should be done for possible neoplastic etiology if no history of trauma, abdominal surgery or intrauterine contraceptive device.