Severe peritonitis caused by Citrobacter freundii and successful treatment with double antibiotic coverage

Peritonitis from facultative anaerobic gram-negative bacilli likely due to translocation of bacteria from gut in a patient undergoing peritoneal dialysis

The peritonitis caused by gram-negative organisms is a serious complication encountered in patients undergoing peritoneal dialysis, often causing high morbidity and mortality. There has been recognition of peritonitis caused by uncommon organisms because of improved microbiological detection techniques. The healthcare providers involved in the management of these patients should be very vigilant. We report a rare case of peritonitis caused by Citrobacter freundii. A 42-year-old male on peritoneal dialysis for five years presented with abdominal pain and cloudy effluent. The peritoneal fluid analysis was consistent with peritonitis, and peritoneal fluid culture grew Citrobacter freundii. The patient was treated with two courses of double antibiotic coverage with intraperitoneal ceftazidime and oral ciprofloxacin, which failed to resolve the infection and hence resulted in the removal the peritoneal dialysis catheter and dialysis modality change.

Characterization of phiCFP-1, a virulent bacteriophage specific for Citrobacter freundii

Citrobacter freundii, a Gram-negative bacterium, causes many opportunistic infections. Bacteriophage phiCFP-1 was isolated and characterized by its ability to lyse the multidrug-resistant clinical C. freundii strain P10159. Transmission electron microscopy showed that the phage has an icosahedral head and a short tail, making it a Podoviridae family member. In a single-step growth experiment, phiCFP-1 exhibited an eclipse period of 20 min and a burst size of 100 particles per cell. Its genome assembled as a circular molecule when genomic sequencing was completed. However, based on genome content and organization, it was categorized as a classic T7-related phage, and such phages are known to have linear genomes with direct terminal repeats. With the quick and simple method established herein, the 38,625-bp linear double-stranded DNA with 229-bp direct terminal repeats was accurately identified. The genome contained 43 putative open reading frames and no tRNA genes. Using a proteomics-based approach, seven viral and two host proteins from purified phiCFP-1 particles were identified. Comparative genomics and recombination analyzes revealed close genetic relatedness among phiCFP-1, phiYeO3-12/vB_YenP_AP5 (from Yersinia enterocolitica O3), and phiSG-JL2 (from Salmonella enterica).