PC1198: Opening the Flood Gates: Aerococcus UTI in a Pediatric Patient with Chronic Urinary Retention

Introduction: Aerococcus urinae is a rare, catalase-negative, gram-positive bacterium that has been underreported as a causative pathogen in urinary tract infections (UTI) with an estimated incidence of < 1% of all UTIs. It most commonly presents in elderly patients with prostatic hypertrophy, overactive bladder, and obstructive uropathy, and has not historically been thought to cause clinical disease in pediatric patients.

Case Description: A 16-year-old male with Trisomy 21, autism, and history of incontinence presented with hematuria and dysuria concerning for UTI. In the month prior, he had similar symptoms and urinalysis demonstrated hematuria, proteinuria, and pyuria. He was treated empirically with Sulfamethoxazole / Trimethoprim (SMX/TMP). Urine culture grew >100,000 CFU Aerococcus, which was attributed to colonization. Symptoms slightly improved then recurred after completing SMX/TMP, prompting admission and empiric ceftriaxone. Repeat urine culture grew Aerococcus alone, increasing suspicion for Aerococcus UTI. After special request to the laboratory, sensitivities were reported to penicillin, ceftriaxone, and vancomycin. The patient transitioned to amoxicillin with gradual resolution of his symptoms. Test of cure one week later showed normalized urinalysis and absence of Aerococcus. Uroflow/EMG testing subsequently demonstrated staccato voiding and high post void residuals and he was ultimately diagnosed with bladder dyssynergy. Further treatment included behavioral modification with timed voiding schedule, Pyridium for dysuria with UTI, and alpha blocker therapy.

Discussion: Aerococcus may be dismissed as a true pathogen as it rarely causes clinical disease except in patients with specific risk factors such as advanced age. Our patient was atypically young for this infection and had no structural urologic abnormalities, however he exhibited incontinence, withholding behaviors, and straining with urination which had been difficult to evaluate due to his intellectual disability, but which resulted in chronic retention and recurrent UTIs. Additionally, males with Trisomy 21 have an increased association with non-neurologic neurogenic bladder, increasing their potential for clinically significant voiding dysfunction and predisposing to infection.

Conclusion: In pediatric patients with chronic urinary retention, including behavioral, genetic, and structural urologic etiologies, additional consideration may be warranted for growth of urinary pathogens like Aerococcus which may otherwise be considered non-virulent. Selection of empiric antibiotics should consider known resistance patterns extrapolated from adult literature. Although typically sensitive to penicillins, high Aerococcus MICs to cephalosporins, sulfamethoxazole, and fluoroquinolones may complicate empiric treatment options, and labs should be prompted to complete sensitivity testing where appropriate. Thus, an increased index of suspicion on the part of the ordering physician is needed to recognize and appropriately treat this UTI cause. To our knowledge, this is the first reported case of Aerococcus UTI in a pediatric patient from a primarily behavioral etiology.