The Microbiology laboratory does not perform microscopic analysis for fecal leukocytes without laboratory consultation. The presence of fecal leukocytes has only a 29% sensitivity and a 20% positive predictive value (PPV) for Shigella, Salmonella,and Campylobacter spp. (J. Clin Microbiol. 31: 2233, 1993). The sensitivity and PPV of fecal leukocytes in predicting the results of C. difficile toxin assay are only 28% and 27%, respectively (Diagn. Microbiol. Infect. Dis. 16: 313, 1993). For approval, contact the Clinical Pathology resident at 131-4903 Monday through Friday 0800-1700 and 131-3404 after 1700 and on weekends. If approved, specimens are analyzed daily 0800-2300.