Background: Inflammatory illnesses are an indication for specific diagnostic studies and possible antimicrobial therapy. The presence of fecal leukocytes has been used as a marker of inflammatory diarrhea; however, microscopic examination of the fecal smear is unreliable if the specimen is transported, refrigerated, frozen, or collected by swab.
Objective: To evaluate a rapid, sensitive, semiquantitative test for detection of fecal leukocytes using antilactoferrin latex bead agglutination (LFLA), a test that remains sensitive even after specimens are refrigerated, frozen, or stored on swabs.
Methods: LFLA titers were determined in stool specimens from previously healthy volunteers before and after experimental infection with different enteric pathogens and from patients with nosocomial diarrhea caused by Clostridium difficile.
Results: Healthy controls and subjects with noninflammatory diarrhea caused by Vibrio cholerae consistently demonstrated LFLA titers less than 1:50. In contrast, subjects with inflammatory diarrhea caused by Shigella species and C difficile had markedly elevated titers. Titers for subjects with experimental shigellosis ranged from 1:50 to 1:3200, with seven (78%) of nine at 1:400 or greater. Titers for patients with C difficile enteritis ranged as high as 1:1200, with six (50%) of 12 at 1:400 or greater. Subjects with experimental enteropathogenic Escherichia coli infection also had elevated titers, ranging from 1:100 to 1:1600, with three (43%) of seven at 1:400 or greater. Titers for subjects with experimental enterotoxigenic E coli infection were moderately elevated, with nine (53%) of 17 ranging from 1:50 to 1:200 (only one [6%] of 17 was > or = 1:400), suggesting a mild inflammatory process.
Conclusions: The fecal LFLA assay distinguishes inflammatory from noninflammatory diarrhea, may provide new information on mildly inflammatory processes, and may be a useful, rapid test in a diagnostic algorithm for acute, infectious diarrheal illnesses.