Pets are ‘risky business’ for patients undergoing continuous ambulatory peritoneal dialysis

The authors report the first case in Manitoba of a patient undergoing continuous ambulatory peritoneal dialysis who experienced three successive infections with Pasteurella multocida and Capnocytophaga species over an eight-month period. These zoonotic infections were believed to originate from contact with the patient’s household pets. To prevent such infections, the authors recommend the development and implementation of hygiene guidelines outlining the risks associated with owning domestic pets for continuous ambulatory peritoneal dialysis patients.


Pets are 'risky business' for patients undergoing continuous ambulatory peritoneal dialysis
Yahya Salim Yahya Al-Fifi MD 1 , Chris Sathianathan MD 2 , Brenda-Lee Murray MSc 3 , Michelle J Alfa PhD

CASE PrESEntAtIon
A 49-year-old man with end-stage renal failure secondary to type I diabetes undergoing continuous ambulatory peritoneal dialysis (CAPD) since August 2010 presented to the emergency room with severe abdominal pain in October 2011.Several days before presentation to the emergency room, the patient had been feeling unwell; this developed into localized, dull pain at the centre of the abdomen that extended to the flanks.Approximately 24 h to 48 h before presentation, the pains became sharp and diffuse throughout the abdomen; the pain escalated gradually and then became constant.The pain was aggravated by movement and eased by lying down on one side, but it did not radiate.The patient complained of fever, chills and rigors that were occasionally associated with nausea, vomiting and night sweats.
No other notable symptoms were reported.On physical examination, the patient was oriented and alert, with a blood pressure of 150/80 mmHg and a regular heart rate of 84 beats/min.He was pale but not jaundiced, and there was no sign of lymphadenopathy.His peritoneal dialysis (PD) catheter was in place and showed no signs of redness, discharge or leakage.
Five months earlier, in May 2011, the patient experienced similar symptoms and was diagnosed with PD-related peritonitis.Culture analysis of the PD fluid revealed Pasteurella multocida, a normal oropharyngeal flora of cats and dogs (1,2) (Table 1).This strain of P multocida was sensitive to numerous antibiotics (Table 2).The patient was treated empirically with vancomycin and tobramycin for two days followed by cefazolin for four days, and then given intraperitoneal (IP) ceftazidime for seven days and, finally, oral amoxicillin-clavulanate for seven days.Further questioning revealed that the patient had a dog and a cat at home; however, the patient was adamant that the animals were never in the vicinity while he was performing his dialysis.He did not recall any breaks or leaks in the dialysis tubing, although he did admit that he did not always use adequate hand hygiene when handling his catheter.
In August 2011, the patient acquired a PD infection secondary to Enterobacter cloacae (Table 1), which was characterized by cloudy dialysate and abdominal pain.The source of the infection was not likely zoonotic because this pathogen is commonly found in the human gastrointestinal tract.The patient was successfully treated with IP cefazolin and tobramycin for three days followed by IP ceftazidime and ciprofloxacin orally for 14 days.
Analysis of the dialysate in October 2011 (Table 1) revealed an elevated white blood cell (WBC) count of 13,631×10 6 cells/L with 89% polymorphonuclear neutrophils and 11% monocytes.Due to the patient's history and the fact that he owned household pets, this PD infection was suspected to be zoonotic in origin.The initial Gram stain revealed no bacteria; however, several days later, Capnocytophaga was recovered from liquid media that had been inoculated with PD fluid.Bacterial 16S ribosomal DNA (rDNA) sequencing was performed to determine the species, but was unable to differentiate between Capnocytophaga cynodegmi and Capnocytophaga canimorsus (both normal flora of domestic pets).Antibiotic treatment was initiated with IP cefazolin and tobramycin for 14 days.
The patient responded to antibiotic treatment and all subsequent CAPD bags were clear post-therapy until January 2012 when he presented again with cloudy dialysate and abdominal pain.As shown in Table 1, his CAPD fluid grew Capnocytophaga species.Bacterial 16S rDNA sequencing identified this isolate as C canimorsus.He was treated with IP cefazolin and tobramycin for three days followed by IP cefazolin and ciprofloxacin to complete 21 days of antibiotic therapy.It is possible that the same strain of Capnocytophaga was responsible for both infections; however, the second infection most likely occurred separately and was not a continuation of the first infection.
In March 2012, the patient developed a PD catheter exit site infection that grew Corynebacterium jeikeium and manifested as a 2 cm × 4 cm area of induration over the catheter tunnel.He was treated with IP cefazolin and the catheter was removed in April 2012.The exit site infection and the previous E cloacae CAPD infection are not likely related to the zoonotic infections, but they do further attest to the consequences of poor hand and catheter hygiene.
In view of the patient's history of multiple CAPD infections, in addition to his exit site infection, he was switched to hemodialysis after removal of his PD catheter.Since being switched, he has experienced no further issues and continues to do well.

Risks of owning pets while undergonig CAPD
Can J Infect Dis Med Microbiol Vol 24 No 3 Autumn 2013 e97

DISCUSSIon
P multocida is a small Gram-negative coccobacillus found in the oral cavity and upper respiratory tract of 70% to 90% of cats and 55% to 66% of dogs (1-3).It is a zoonotic pathogen and the most frequent causative agent in human pasteurella infection (4).P multocida can cause a variety of infectious diseases in humans such as sepsis, cellulitis, pulmonary infections and meningitis, among others (1,(4)(5)(6).The mechanisms of infection are not entirely clear and continue to be elucidated; however, the presence of a capsule and lipopolysaccharide have been identified as key virulence factors for avoiding the host immune system (5).Generally, P multocida is a rare cause of peritonitis in patients undergoing PD.Only 26 cases have been reported in the literature, three of which have involved children (3).Similar to our patient, 25 of the 26 cases of P multocida peritonitis can be linked to close contact with household cats (2,3).Very few cases have been associated with dogs compared with cats, which could be due to the fact that cats exhibit a higher prevalence of colonization with P multocida (2).It has been reported that approximately 20% of cats harbour Pasteurella species on their claws (4).In addition, cats are more likely to play with dialysis tubing; their sharper teeth and claws increase the probability of puncturing tubes or bags, thus transmitting the pathogen to the patient (2).Furthermore, cats are more of a self-grooming animal than dogs, which could result in the presence of the bacterium directly on the fur.Thus, even petting a domestic cat could result in transfer of the organism to the hands of PD patients or caregivers.
C canimorsus and C cynodegmi are slow-growing, thin, Gramnegative bacilli that are a part of the normal flora of dogs and, more rarely, cats (7).Generally, infections caused by Capnocytophaga species, especially C canimorsus, progress rapidly and are transmitted by dog bite.Symptoms of infection can vary and depend on the severity of the case (8).Infectious diseases caused by Capnocytophaga species in humans include, but are not limited to, septicemia, meningitis, osteomyelitis, purulent arthritis and endocarditis (7).Little is known about the pathogenesis of Capnocytophaga infection, but the clinical course of infection suggests the bacterium has the ability to avoid the immune system, particularly in the early stages of infection (7).
Capnocytophaga species causing peritonitis is even more rare than Pasteurella peritonitis, with only three cases being reported in the literature (9).Although C canimorsus and C cynodegmi are more common in dogs than cats, two of the three cases of Capnocytophaga species peritonitis reported were linked to close contact with cats (9,10).In one case, the patient's cat was allowed to sleep with him and punctured the dialysis tubing during the night (11), whereas the other case was a patient who had frequent visits from a neighbour's cat, who he periodically fed (9).
The fact that our patient was infected consecutively by P multocida and Capnocytophaga, but did not report any bites or scratches from his animals nor remember his cat playing with his dialysis tubing, emphasizes the importance of hand hygiene when dealing with PD equipment and bag changes.This is imperative for preventing infection in PD patients who are in close contact with domestic animals, especially cats.
Our data support the recommendations by Rondon-Berrios and Trevejo-Nunez (2), Weiss and Panesar (12), Pers et al (10), Schiller et al (6) and Sol et al (3) that PD patients who own pets be made aware of the need for proper hand hygiene before PD bag changes and the risk of zoonotic infection if these precautions are not taken.The need to ensure pet oral secretions do not come into contact with PD equipment and the threat of these infections should be clearly communicated to PD patients.We recommend strict hygiene guidelines be emphasized and periodically reviewed with PD patients who have pets.

TAble 1 History of Infection Date Peripheral WbC count*, ×10 9 /l Continuous ambulatory peritoneal dialysis fluid Therapy † WbC count, ×10 6 /l Gram stain Culture results
(13)al range 4.5×109cells/L to 11×109cells/L; † All antibiotics were administered by intraperitoneal route unless otherwise indicated; ‡ The recommended therapy for general Pasteurella multocida infections is penicillin G, ampicillin, amoxicillin, cefuroxime and cefpodoxime.Alternative therapies include doxycycline, levofloxacin, moxifloxacin and trimethoprim-sulfamethoxazole (13); § The recommended therapy for Capnocytophaga (typical infection from dog bite) is amoxicillin-clavulanate.Alternative therapies include piperacillin-tazobactam, clindamycin, imipenem-cilastatin, doripenem and meropenem(13).Note: There are no specified recommended therapies for Pasteurella and Capnocytophaga peritoneal dialysis-related peritonitis.Therapy is generally based on sensitivities and intraperitoneal administration of antibiotics is the preferred route.PO Per os (oral); WBC White blood cell *