Post-Operative Wound Infection by Multiple Zoonotic Organisms

Rhodococcus hoagii (formerly Rhodococcus equi) is a Gram-positive, weakly acid-fast coccobacillus originally isolated from equine species. ¹ It has been recognized for its ability to cause severe, life-threatening opportunistic infection in immunocompromised patients including patients on chronic immunosuppressive treatment.^1,2 Rhodococcus is primarily transmitted through inhalation of contaminated aerosols (ie, dust) as well as direct inhalation of the breath of infected livestock. ² Human hosts often present with fever, lymphadenopathy, pneumonia, septic arthritis, meningitis, and soft tissue infections including abscesses. ²

Pasteurella multocida is Gram-negative coccobacillus and known cause of cellulitis in human hosts. It is commonly transmitted to humans from domesticated canine and feline bites.^3,4 In immunocompromised patients, these infections can become severe and spread systemically resulting in bacteremia, septic arthritis, meningitis, pneumonia, brain abscesses, spontaneous bacterial peritonitis, and intraabdominal abscesses.^3,4

This is the case of a 42-year-old female with a history of penetrating, small-bowel Crohn’s disease with several surgical explorations and small-bowel resections who subsequently developed a complex, low output enterocutaneous fistula. She had been maintained on several different systemic therapy treatments in the past, and was now on a single TNF-alpha antagonist. She had no recent administration of systemic corticosteroids.

After 12 months of medical and nutritional optimization, she was taken to the operating room for an elective exploratory laparotomy, extensive adhesiolysis, and excision of enterocutaneous fistula with creation of an end ileostomy. In the early post-operative period, she developed a rising leukocytosis, an elevated C-reactive protein, and systemic inflammatory response syndrome with tachycardia and fevers. Blood cultures and an IV- and PO-contrasted CT scan of the abdomen and pelvis were obtained and the patient was started empirically on broad spectrum antibiotics. The CT scan demonstrated a loculated pelvic fluid collection without any evidence of enteric leak. This was successfully managed with percutaneous drain placement by the interventional radiologist.

In the days following, both the peripheral and central venous access (PICC line) blood cultures grew multi-drug resistant Rhodococcus hoagie, while the percutaneous drain cultures grew Streptococcus anginosus, Pasteurella multocida, and Candida albicans. Once antibiotic susceptibilities had finalized, the patient appropriately completed a 14-day course of linezolid for Rhodococcus hoagie, ertapenem for the Streptococcus and Pasteurella species, and micafungin for Candida albicans. HIV testing was performed and was negative. The patient was later discharged following clinical improvement and subsequent negative post-treatment blood cultures.

During her inpatient workup, it was found that the patient is an enthusiast of exotic animals, specifically big cats, and has an occupational history of working as a zookeeper. She keeps a pet leopard (Panthera pardis) and also had recent exposure to zebras (Equus quagga) at work. This regular exposure to exotic animals in conjunction with her history of Crohn’s disease on systemic therapy likely predisposed her to developing these postoperative opportunistic infections with zoonotic pathogens.

This case demonstrates an unusual constellation of post-operative infections with two distinct zoonotic pathogens in an immunocompromised host who was successfully treated with anti-microbial medications tailored to the sensitivities of the individual organisms. This case also reiterates the importance of obtaining a thorough and accurate history and physical, specifically work history as it relates to patient occupational exposures.