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Published on: December 19, 2010
Ascitic fluid lactoferrin for diagnosis of spontaneous bacterial peritonitis
Mansour A Parsi1, Sherif N Saadeh, Nizar N Zein
1Digestive Disease Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA. parsim@ccf.org
Background & Aims:
The diagnosis of spontaneous bacterial peritonitis (SBP) is based on a manual count of ascitic fluid polymorphonuclear cells (PMNs). This procedure is operator-dependent and lysis of PMNs during transport to the laboratory may lead to false-negative results. Furthermore, ascitic fluid culture is insensitive and leads to delays in diagnosis. The aim of this study was to assess the utility of ascitic fluid lactoferrin (AFLAC) for the diagnosis of SBP and to identify a cut-off level that can be used for future development of a rapid bedside test.
Methods:
A total of 218 consecutive ascites samples from 148 patients (1-8 samples per patient) with cirrhosis at 2 tertiary care medical centers were examined for PMN count, bedside culture, and lactoferrin concentration. AFLAC concentrations were determined using a polyclonal antibody-based enzyme-linked immunosorbent assay. An ascitic fluid PMN count of 250 cells/mL or greater with or without a positive culture was used for diagnosis of SBP.
Results:
Twenty-two (10.1%) samples fulfilled diagnostic criteria for SBP. Samples with SBP had a significantly higher lactoferrin concentration (median, 3744 ng/mL; 25th-75th percentiles [P25-P75], 788-9617) compared with non-SBP samples (median, 31 ng/mL; P25-P75, 12-67; P < .001). By using a cut-off level of 242 ng/mL, the sensitivity and specificity of the assay for diagnosis of SBP were 95.5% and 97%, respectively. The area under the receiver operating characteristic curve was 0.98.
Conclusions:
AFLAC can serve as a sensitive and specific test for diagnosis of SBP. Qualitative bedside assays for the measurement of AFLAC can be developed easily and may serve as a rapid and reliable screening tool for SBP in patients with cirrhosis.
Insights
Ascitic fluid lactoferrin (AFLAC) shows high accuracy in diagnosing spontaneous bacterial peritonitis (SBP). This biomarker can be used to develop rapid bedside tests for SBP, improving patient care.
Area of Science:
- Hepatology
- Gastroenterology
- Clinical Chemistry
Background:
- Spontaneous bacterial peritonitis (SBP) diagnosis relies on manual polymorphonuclear cell (PMN) counts, which are operator-dependent and prone to false negatives due to cell lysis.
- Ascitic fluid culture for SBP is often insensitive and causes diagnostic delays.
Purpose of the Study:
- To evaluate ascitic fluid lactoferrin (AFLAC) as a diagnostic marker for SBP.
- To establish a cut-off level for AFLAC to facilitate the development of a rapid bedside test for SBP.
Main Methods:
- Analyzed 218 ascites samples from 148 cirrhosis patients.
- Measured ascitic fluid lactoferrin (AFLAC) concentrations using ELISA.
- Defined SBP based on ascitic fluid PMN count (≥250 cells/mL) with or without positive culture.
Main Results:
- 22 samples (10.1%) met SBP criteria.
- AFLAC concentrations were significantly higher in SBP samples (median 3744 ng/mL) vs. non-SBP samples (median 31 ng/mL) (P < .001).
- An AFLAC cut-off of 242 ng/mL yielded 95.5% sensitivity and 97% specificity for SBP diagnosis (AUC 0.98).
Conclusions:
- Ascitic fluid lactoferrin (AFLAC) is a sensitive and specific biomarker for SBP diagnosis.
- Easy-to-develop qualitative bedside assays for AFLAC can provide rapid and reliable SBP screening in cirrhosis patients.
