973 Utility of Gram Stain in the Diagnosis and Management of Spontaneous Bacterial Peritonitis: Promoting High Value Care

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INTRODUCTION: The diagnostic criteria for spontaneous bacterial peritonitis (SBP) and culture negative neutrocytic ascites depends largely on neutrophil counts of more than 250 cells / mm3. A positive ascitic fluid culture makes the diagnosis of SBP versus CNNA. In general clinical practice gram stain (GS) and culture are routinely sent for suspected SBP. The yield of microbe from ascitic fluid is low possibly because SBP and CNNA are known to happen with very small concentrations of bacteria, whereas bacterial loads as high as 10^5 organisms/ml are required for a positive GS. The aim of this study was to determine the utility of GS in the diagnosis and management of suspected SBP as an impetus to decrease overall burden of healthcare cost and unnecessary testing. METHODS: We retrospectively reviewed patients with ascites and cirrhosis, who underwent paracentesis with body fluid analysis at a large tertiary care hospital in a 1-year period. Patients were identified using institutional procedural codes and ICD 9 and ICD 10 codes for ascites and cirrhosis. We included all adult patients with cirrhosis who had underwent paracentesis in 2017 and had both a culture and a GS sent for analysis. We excluded patients who had any evidence of recent or current source of intra-abdominal infection or had partial labs sent. Variables of interest were date of ascitic fluid studies sent, date of GS results, date of culture results, date of initiation of empiric antibiotics and the date and name of the second antibiotic used. Descriptive statistics were used to analyze data. Costs for GS, culture and body fluid cell count & differential were obtained from the coding and reimbursement department. RESULTS: 767 patients underwent ascitic fluid testing in our study period. 43 had a positive GS (5.6%). 21 of these had SBP (PMN > 250 and positive culture), one patient had CNNA (PMN > 250 and no culture growth), 20 patients had bacteracitis (PMN < 250 and positive culture) and one patient had PMNs < 250 and no culture growth. Management was changed in 3 cases (0.4%) based on GS alone (Table 1). In one of these patients, therapy was changed again after the culture grew a different organism. Total healthcare cost calculated to be at least $36,672 each year at our center based on $48 per ascitic fluid gram stain sample alone. CONCLUSION: Carrying out GS on all ascitic fluid samples is not cost effective and rarely leads to changes in management.