Novel therapy of Pseudomonas aeruginosa in the stallion: A case report

A 14 y-o Holsteiner stallion was presented for infectious disease screening prior to semen cryopreservation. Penile screening with bacteriology samples from urethral fossa (UF), urethral orofice (UO), penile sheath (PS) and pre-ejaculatory fluid (PF) was performed for Taylorella equigenitalis, Pseudomonas aeruginosa (PA) and Klebsiella pneumoniae. Positive growth of PA from UF, UO and PF was revealed with antimicrobial sensitivity only to amikacin. Screening of abdominal wall, scrotum and inner thighs revealed no PA. Penile treatment with warm water cleansing, rinsing with 0.03% hypochlorous acid (LEUcillin Ⓡ , Lyvlee UK), followed by application of 1% silver sulfadiazine cream (Flamazine Ⓡ , Smith - Nephew Pharmaceuticals, UK) was performed under light sedation (4 µg/kg of both detomidine hydrochloride and butorphanol), once daily for 7 consecutive days. On the 4th day repeat bacteriology isolated PA from UO only. On the 5th day chemically-induced ejaculation revealed pyospermia and pure growth of PA with identical antimicrobial sensitivity. Transrectal ultrasound of accessory sex glands and urinary bladder suggested seminal vesiculitis. Four days after cessation of penile therapy repeat screening revealed positive PCR and growth of PA from all 4 sites. Urethroscopy of the genitourinary tract with trans-endoscopic catheterisation of the left and right seminal vesicles in sequence was done. The vesicles were first infused with sterile Hartman's solution followed by aspiration for cytology and culture. The catheter was replaced between sides with the endoscope in situ. Post-aspiration each seminal vesicle was lavaged with 100-200 ml Hartman's solution followed by infusion of a prepared gelified buffered solution of 1.0g amikacin sulphate (20ml Amikin Ⓡ Injection 50mg/ml), 1.68g sodium bicarbonate (20ml Sodium Bicarbonate solution 8.4% w/v) and 40ml of sterile 1.5% sodium carboxymethylcellulose, with combined pH 7.3. Fluid aspirated from the left yielded occasional extracellular bacteria, moderate neutrophils and erythrocytes; no growth was returned. The right yielded moderate amounts of extracellular bacteria, numerous active neutrophils and few erythrocytes; a positive culture of PA was returned confirming seminal vesiculitis. Further treatments were performed 3, 5 and 7 days after with repeat sampling of the vesicles immediately prior to the 4th treatment, returning a negative growth from both vesicles; mild inflammation and presence of occasional extracellular bacteria persisted. Three days later penile screening revealed a positive growth of PA from 3 sampled sites (UF, UO - PS); sampling from the proximal sheath, scrotum and semen returned no PA growth. Six days of penile treatment was performed as described previously, followed by 3 days application of a commensal bacterial culture broth (Rossdales Laboratories, UK) gelified with galactomannan polysaccharide (Guar gum) powder in a 2% w/v solution. On the final day, repeat genital screening was performed from UF, UO and PS and was culture and PCR negative for PA. Semen collection resumed and semen remained negative by PCR at last sampling 53 days later. This case represented therapeutic challenges given the location and sensitivity of the bacteria, yet it was safely eradicated utilizing novel local special preparations.