Do post-surgical multiresistant urinary infections occur in horses? Case of unilateral pyelonephritis caused by extended-spectrum beta-lactamase-producing bacteria as a complication of cystotomy

Abstract

Pyelonephritis is a serious condition that is rarely described in horses. In contrast, urinary tract infections are common in humans and small animals, and multi-drug-resistant urinary infections are an emerging threat. In this report, we describe a horse with unilateral pyelonephritis caused by extended-spectrum beta-lactamase-producing bacteria belonging to the Enterobacter cloacae complex. [Correction added on 9 August 2023, after first online publication: The preceding sentence was corrected.] An 11-year-old Swedish warmblood gelding was diagnosed with a cystolith and a cystotomy through an open left para-inguinal approach was performed. Seven days after surgery the horse presented with pyrexia, dullness and colic. Diagnostic testing and renal transabdominal ultrasonography confirmed the presence of a right-sided pyelonephritis. Culture and antimicrobial susceptibility testing revealed a pure growth of extended-spectrum beta-lactamases-producing E. cloacae complex bacteria with resistance against beta-lactams, aminoglycoside and trimethoprim-sulphonamide classes. Treatment included prolonged oral antimicrobials according to susceptibility testing results (enrofloxacin), judicious use of non-steroidal anti-inflammatory drugs, fluid therapy and gastric ulcer prophylaxis. The horse recovered successfully and is currently in good health (follow-up of 5 years). Once the infection resolved, unilateral renal scarring occurred. Multidrug-resistant upper-urinary infections occur in horses and should be considered in a post-surgical patient that develops fever. Early diagnosis, urine bacterial culturing and antimicrobial susceptibility testing were crucial in this case to successful management.

Keywords: ESBL-producing bacteria; cystotomy; horse; post-operative; pyelonephritis.

FIGURE 1

Image from a transurethral cystoscopy prior to surgery. A spiculated cystolith (white arrow) and secondary cystitis (white head arrow) were visualized.

FIGURE 2

Images in parts (a, b) from a transurethral cystoscopy performed 3 days after surgery showed a small cystolith (white arrow), inflamed bladder mucosa (white head arrow) and presence of fibrin (black arrow).

FIGURE 3

Transabdominal ultrasonographic image 10 days after surgery taken from the right, dorsal 15th intercostal space using an Esaote ultrasonographic machine and a 4 MHz convex probe, showing the right kidney in a longitudinal, latero‐medial plane. The kidney shows decreased cortex‐medulla demarcation (white arrow) and a severely dilated renal pelvis (diameter 7.1 cm, white arrow head).

FIGURE 4

Transurethral cystoscopy 10 days after surgery. Aspiration of thick, white mucus (white arrow) draining from the right ureter orifice (white arrow head) thought a transendoscopic catheter (black arrow).

FIGURE 5

Transabdominal ultrasonographic image taken during a revisit after discontinuing antibiotic treatment (2 months after surgery), image taken from the right, dorsal 15th intercostal space with a Esaote ultrasonographic machine and 4 MHz convex probe, imaging the right kidney in a longitudinal, latero‐medial plane. The kidney (14.1 cm diameter) shows cystic appearance and anechoic content (white arrow).