A Rare Case of Stenotrophomonas maltophilia-Refractory Peritonitis in a Patient on Automated Peritoneal Dialysis

Introduction: Stenotrophomonas maltophilia is a multidrug-resistant gram-negative bacillus common among the severely immunocompromised population and is associated with a high morbidity and mortality. Additionally, S. maltophilia in peritoneal dialysis (PD) population is also associated with loss of PD catheter and poor prognosis. We present a case of S. maltophilia refractory peritonitis in a PD patient. Case Description: An 85 year-old woman with end stage kidney disease on peritoneal dialysis was admitted for refractory peritonitis and PD catheter dysfunction. Four weeks prior, the patient was diagnosed with S. maltophilia peritonitis. Initial effluent cell count was 800/uL (51% neutrophils, 38% monocytes). Treated with empiric intra-peritoneal vancomycin and cefepime followed by cefpodoxime for 4-weeks. Despite symptomatic improvement, repeat peritoneal effluent analysis showed greater than 600 WBC/uL (74% neutrophils, 25% monocytes) suggestive of refractory peritonitis. Antibiotics were changed to trimethoprim/sulfamethoxazole and levofloxacin, and PD catheter was removed. She transitioned to temporary thrice weekly hemodialysis with plan to return to PD. Discussion: S. maltophilia is an emerging multidrug-resistant opportunistic pathogen; it can be found in water, soils, and on rhizomatous plants. S. maltophilia peritonitis is a rare finding in patients on peritoneal dialysis. Its presence poses a therapeutic challenge and is often associated with poor prognosis. We present here a case of an elderly patient found to have refractory S. maltophilia peritonitis. S. maltophila infections commonly present in patients who are immunocompromised although our patient was immunocompetent. Interestingly, this patient is an avid vegetable gardener, and thus touch-contamination may have been the source. International guidelines recommend dual antibiotic coverage for environmental gram-negative bacteria such as Pseudomonas and Stenotrophomonas; special attention was paid to treatment of Stenotrophomonas in most recent guideline update. This case highlights the importance of considering this organism in patients with PD peritonitis regardless of their immunocompetence, the importance of hand hygiene, and also spotlights the resistant nature of the organism prompting us to be more vigilant when presented with such case.