Urinary tract infection due to Staphylococcus schleiferi biofilm formation in the subcutaneous ureteral bypass system in a cat.

Abstract

Background: Staphylococcus schleiferi is mainly isolated from dogs and occasionally infects cats. We recently encountered a case of a biofilm-related urinary tract infection (UTI) caused by S. schleiferi in a cat with a subcutaneous ureteral bypass (SUB) system. This report presents a case of biofilm formation by S. schleiferi in the SUB system and discusses the causes of UTIs.

Case presentation: A 9-year-old female cat had been using the SUB system since 4 years-of-age. The cat had no significant clinical history or UTIs for 4 years after the first implantation of the SUB system. The SUB system was flushed once per month. When the cat was 8 years-of-age, the subcutaneous port of the SUB system was contaminated with Staphylococcus pseudintermedius and replaced with a new one. Subsequently, the SUB system had no particular problem for 8 months. The SUB system was flushed once every 2 months. However, the cat occasionally developed gross haematuria. Additionally, S. schleiferi was detected in urine. Although doxycycline was administered to the cat, 6 weeks later, the cat had cutaneous wounds with abscesses caused by excessive grooming of the skin in contact with the subcutaneous port of the SUB system. S. schleiferi was detected in a severe abscess in the cutaneous wound, and skin necrosis was observed. As bacterial contamination of the SUB system was suspected, the SUB system was removed from the cat. Scanning electron microscopy analysis revealed biofilm formation inside the locking loop catheters and outside the subcutaneous port of the SUB system. In an in vitro assay, S. schleiferi isolated from a catheter of the SUB system had low biofilm-forming ability. After the SUB system was removed, S. schleiferi was not detected in the urine and the infection was completely cured.

Conclusion: Considering these results, bacterial infections in cats with SUB systems should be carefully monitored, as contamination by biofilm-forming bacteria can occur regardless of flushing frequency.