Dear Editor,

Bacterial peritonitis is a common complication of peritoneal dialysis.¹ We report here a case presented with peritonitis attacks caused by rarely reported unusual pathogens, probably related with poor home environment and hygienic conditions.

A 57-year-old female patient had a history of end-stage renal disease secondary to hypertensive nephrosclerosis and undergone dialysis for 4 years. She was sharing a small house in poor hygienic conditions with eleven other family members with low socioeconomic status. Five months after the initiation of automated peritoneal dialysis (APD), the patient presented with abdominal pain and nausea to our PD clinic. She was febrile (38°C), had involuntary abdominal guarding and rebound tenderness on physical examination. Dialysate white blood cell count was 1100/mm³ (79% neutrophils). Empiric antibiotherapy was initiated with intraperitoneal cefazolin (1 g/day) and oral ciprofloxacin (250 mg every 12 h).

A pure growth of Serratia marcescens was obtained in both different culture media. The organism was resistant to cefazolin, ceftriaxone, piperacillin/tazobactam, but sensitive to cefepime. Cefazolin was stopped; cefepime could not be used due to a drug shortage; instead, intraperitoneal gentamicin (0.6 mg/kg/day). Oral ciprofloxacin was also continued based upon the susceptibility results. Following the treatment modification, high-sensitivity CRP level decreased from 240 mg/L to 9 mg/L. Peritoneal effluent became clear and drainage fluid leukocyte count was 100/mm³ (10% neutrophils) on the third week of admission.

The patient was readmitted to the hospital with similar complaints 7 months after the first peritonitis attack. Peritoneal fluid leukocyte count was found to be 17000/mm³ and empiric antibiotherapy was initiated with intraperitoneal cefazolin (1 g/day) and gentamicin (0.6 mg/kg/day). Dialysate cultures showed the growth of Morganella morganii, resistant to cefazolin, cefuroxime but sensitive to cefepime, gentamicin. Cefazolin was stopped and gentamicin was continued for 21 days. The clinical findings and laboratory results were improved during the follow-up.

The patient also had two more peritonitis attacks after this episode, both caused by Klebsiella oxytoca 4 and 8 months later, respectively. These attacks were treated successfully with cefazolin and gentamicin, as isolated pathogen was susceptible to both.

Enterobacteriaceae accounts for over 10% of cases of peritoneal dialysis associated peritonitis. Among all the gram-negative infections, S. marcescens peritonitis has the worst outcome. Serratia is an opportunistic pathogen causing nosocomial infections and is one of gram-negative organisms which have inducible beta-lactamase genes known as AmpC and summarized by the acronym SPICE (Serratia, Providencia/Pseudomonas, indole-positive Proteus species, Citrobacter, Enterobacter). Peritonitis by S. marcescens is not common and there are only few case reports in the literature, usually in diabetic patients.¹

Isolated organism during the first peritonitis attack of our patient had multiple drug resistance. In this case, adequate clinical response was only achieved with combination of gentamicin and ciprofloxacin, as reported in a previous report.²

M. morganii is a Gram-negative bacteria, also a rare cause of peritonitis. It has been reported as an opportunistic pathogen and associated mainly with urinary tract infections, bacteremia and sepsis. M. morganii is naturally sensitive to aminoglycosides as in our case. However, the widespread use led to increasing resistance to third-generation cephalosporins.³K. oxytoca peritonitis has been reported in a patient with cardiac ascites and another patient on continuous ambulatory PD (CAPD).⁴ Both M. morganii and K. oxytoca tend to cause peritonitis in a polymicrobial fashion.⁵ However in our case, they were both isolated as a single pathogen.

In summary, we present a rare case of peritonitis attacks caused by S. marcescens, M. morganii and K. oxytoca. Antibiotic options should be chosen carefully for peritonitis with these pathogens due to their ability to produce beta lactamase, which often complicates the therapy. We think that low socioeconomic status, poor home environment and hygienic conditions increase the peritonitis rates. Although modification of these factors may not be possible, we believe that more frequent and careful education of the patient and the family members under such conditions can improve patient care.