Design
A retrospective review was performed of all stool cultures, ova and parasite examinations, and Clostridia difficile toxin assays performed on pediatric inpatients, aged 3 days to 18 years, at Thomas Jefferson University Hospital, Philadelphia, Pa, for 1 year. Medical records were reviewed for positive cases, each with 2 controls matched for age and test type. For this study, the term admission refers to the interval between the times each patient was admitted to and discharged from the hospital. Some patients had multiple stool tests sent to the laboratory during a single admission; some patients had more than 1 admission during the study period. Statistical analysis was performed using ² analysis and the Student 2-tailed t test with a commercially available statistical software package (Statworks, Cricket Software, Philadelphia).

Results
Of 250 patient admissions to the hospital for which stool was cultured, 7 cultures (2.8%) were positive. Of 63 patient admissions having ova and parasite testing, 1 (2%) had a positive result. Clostridia difficile toxin assays were performed on 40 patient admissions to the hospital, and 7 (18%) had a positive result. Only 18 (3.0%) of 598 of all test results reviewed were positive. Costs of negative test results totaled $26 084. More patients (71%) with positive stool cultures than control patients (21%) had a temperature higher than or equal to 38°C (², P<.05); however, relying on this sign missed 29% of the children with bacterial infection. A white blood cell band count of at least 0.10 was 100% sensitive and 79% specific in identifying patients with positive stool culture. There was no statistically significant relationship between stool culture results and age, total white blood cell count or white blood cell segmented neutrophil count, and no relationship between C difficile toxin assay results and any of the above characteristics. Clostrida difficile was the most common pathogen identified (6 of 9) in patients developing gastrointestinal symptoms after admission; however, Salmonella enteritidis and Shigella sonnei were also significant causes (3 of 9).

Conclusions
There is low yield from stool testing of pediatric inpatients; C difficile toxin assay has the highest yield. Clostridia difficile testing is most valuable for children with nosocomial gastrointestinal symptoms, although other bacterial pathogens do cause nosocomial symptoms in children. More selective stool testing could help us be more efficient with our patient care resources.

Arch Pediatr Adolesc Med. 1997;151:142-145