HOW USEFUL ARE FECAL NEUTROPHIL DETERMINATIONS

The microscopic examination of stool for neutrophils can he used as a screen to determine whether bacterial pathogens are present. We review ed a 1-year experience in a pediatric hospital laboratory to find out how often fecal neutrophil determinations were used, how useful these determinations were, and whether there were potential confounding fact ors. We found that only 654 (47%) of 1,398 stool cultures were evaluat ed for fecal neutrophils. If the presence of any number of neutrophils was considered positive, then the sensitivity was 69% and specificity 82%; if greater than five neutrophils per oil immersion field represe nted a positive determination, sensitivity was 48% and specificity 95% . Sensitivity and specificity differed for each bacterial pathogen spe cies. The test's usefulness therefore varied with definition of a posi tive test and with the mix of organisms encountered.