Peritoneal fluid cultures rarely alter management in patients with ascites

Study objective: The objective of this study is to determine if the peritoneal fluid culture results in the ascites patient being evaluated for spontaneous bacterial peritonitis (SBP) in the Emergency Department (ED) are used by the inpatient physician to appropriately alter empiric antibiotic treatment.

Methods: We performed a retrospective study of all ascitic fluid samples sent from the ED between January 1, 2002 and December 31, 2004. Exclusion criteria included peritoneal fluid samples sent from peritoneal dialysis patients and those undergoing diagnostic peritoneal lavage for trauma. Medical records were examined to determine culture results, initial antibiotic choices, and subsequent changes in antibiotics by the inpatient physician in response to the culture results. The primary outcome measure was the percentage of cases in which ED peritoneal fluid culture results caused inpatient physicians to appropriately change antibiotic coverage.

Results: There were 201 ascitic fluid samples, of which 7 (3.5%; 95% confidence interval [CI] 1.4%-7.0%) had a pathogen identified. Of these, only 1 (0.5%; 95% CI .01%-2.4%) resulted in an appropriate change in empiric antibiotic therapy. Although there were additional opportunities for appropriately using the culture results to change the antibiotic coverage in 2 (1%; 95% CI 0.1%-3.6%) patients, coverage was not changed. In fact, it was changed inappropriately in these 2 patients, and in an additional patient on appropriate empiric therapy.

Conclusions: The yield from ascitic fluid cultures was low, and when positive, did not appropriately change management according to microbiologic criteria.