Performance of stool cultures before and after a 3-day hospitalization: fewer cultures, better for patients and for money.

We evaluated retrospectively the yield of stool culture (SC) depending on the length of hospitalization, and we characterized the patients missed by the 3-day rejection rule. SC detects bacterial enteric pathogens (Campylobacter spp., Salmonella enterica, Yersinia spp., Shigella spp.). During this 5-year study period, 13,039 SCs were requested, and 376 were positive (2.9%). The yield of SC dropped from 11.7% before 3 days of hospitalization to 0.7% after 3 days in children and 4.3% to 0.3% in adults. Finally, only 13 clinically relevant cases (0.2% of SC prescribed after 3 days) were undiagnosed by strict application of the 3-day rule. In conclusion, rejection of SC prescribed after 3 days of hospitalization allows to reduce workload by 37.8% for children and 65.7% for adults, representing a cost of €12,500 ($16,250) per year in our hospital.