Case Presentation: A 66-year-old male with a history of hypertension and end-stage renal disease (ESRD) on home peritoneal dialysis (PD) was admitted to an outside hospital for abdominal pain and a cancer workup. During hospitalization, he inadvertently removed his PD catheter. The catheter was replaced and he was started on intraperitoneal cefepime and vancomycin at discharge due to non-sterile catheter removal. Due to unknown circumstances, he was discharged without antibiotics.Three days later, he presented to the emergency department with worsening abdominal pain, shortness of breath, subjective fevers, and altered mental status. He was hypertensive (161/112 mmHg), tachycardic (106 bpm), with diffuse abdominal pain and distension. Labs showed leukocytosis (11.6 x 109/L; reference range 3.6-11.2 x 109/L) and stable ESRD-associated lab abnormalities. Blood cultures were drawn and intravenous cefepime and vancomycin was started. Peritoneal fluid revealed 449 neutrophils. MRI abdomen showed a 5.6 cm heterogenous mass in the distal duodenum concerning for gastrointestinal stromal tumor and mild peritoneal thickening. On day 4, repeat peritoneal fluid had 64 neutrophils. On day 5, peritoneal fluid cultures grew acid-fast bacilli and he was switched to imipenem, levofloxacin, and TMP/SMX. On hospital day 11, Mycobacterium fortuitum was identified, prompting PD catheter removal, insertion of a new right internal jugular hemodialysis catheter, and initiation of intermittent hemodialysis. Culture of the PD catheter and repeat peritoneal cultures grew M. fortuitum. He received 8 weeks of therapy with combinations of imipenem, levofloxacin, TMP-SMX, linezolid, and azithromycin. He was discharged with 6 additional months of oral linezolid, levofloxacin, and azithromycin.
Discussion: Mycobacterium fortuitum is a rare, nontuberculous mycobacterium classified in Runyon group IV, typically found in soil, sewage, and water (Figure 1).1-3 It can infect both immunocompetent and immunocompromised individuals through contaminated water or penetrating injuries.2 Although uncommon, patients with ESRD are ten times more likely to develop this mycobacterial infection compared to those with normal renal function.4 Peritonitis caused by M. fortuitum is even rarer, with the true prevalence remaining unclear due to the limited number of case reports.4,6 Symptoms generally mirror those of typical peritonitis, including diffuse abdominal tenderness and fever.4,6Diagnosing M. fortuitum peritonitis can be challenging because the bacterium often remains culture-negative for several days and grows slowly, with poor response to initial empiric antibiotic therapy.5,6,7 Acid-fast staining is crucial in the initial gram stain analysis for correct identification of the pathogen, and cultures must be observed longer than the standard timeframe, due to the slow-growing nature of the organism.4 Treatment requires timely catheter removal, conversion to hemodialysis, and a prolonged course of antibiotics.5 In this case, M. fortuitum peritonitis was likely acquired through a contaminated PD catheter, as the bacteria has a proclivity to infect tunneled lines.5
Conclusions: This case highlights the need for internists to consider M. fortuitum in ESRD patients with culture-negative, refractory peritonitis, to avoid delayed diagnosis and associated adverse outcomes.
