Clinical features:
(1) signs and symptoms of peritonitis
(2) negative cultures of peritoneal fluid
Differential diagnosis of culture-negative peritonitis:
(1) concurrent antibiotic therapy that suppresses bacterial growth (static agent)
(2) bacteria with special culture requirements
(3) improper culturing of the peritoneal fluid (related to sample, handling, etc)
(4) acid fast bacillus
(5) fungus
(6) drug-induced or chemical peritonitis
(7) retroperitoneal infection or inflammation
(8) intra-peritoneal infection without bacterial release
(9) splenic disorder such as infarction
(10) allergic reaction to peritoneal dialysis catheter
(11) parasitic infection
(12) hemoperitoneum
(13) intra-abdominal malignancy
(14) increased triglycerides in the peritoneal fluid (chylous ascites)
(15) strenuous exercise
A high index of suspicion may be necessary to diagnose bacterial peritonitis when initial cultures are negative. Review of Gram stain, reculture with large volume, PCR, peritoneal biopsy or other technique may be necessary to identify a pathogen.
