THE USE AND ABUSE OF ROUTINE STOOL MICROBIOLOGY - A COLLEGE-OF-AMERICAN-PATHOLOGISTS Q-PROBES STUDY OF 601 INSTITUTIONS

Objective.-To examine the efficiency with which physicians use routine stool microbiology tests. Design.-Questionnaire and structured review of 100 consecutive stool bacteriology and parasitology examinations a t each participating institution. Setting.-Six hundred one institution s enrolled in the College of American Pathologists Q-Probes program. R esults.-Of 59500 bacteriology specimens, 3808 (6.4%) contained a patho gen. The vast majority (99%) of bacterial pathogens were detected in e ither the first or second specimen submitted. Almost 40% of inpatient specimens were collected after the third day of hospitalization, but o nly 0.6% of these specimens were positive for enteric pathogens that h ad not been previously recovered. More than half of the laboratories r eported having no limits on the number of bacteriology specimens per p atient that could be submitted for testing, and fewer than 8% of labor atories rejected specimens from inpatients after a certain number of d ays in the hospital. The frequency with which laboratories performed t ests for Clostridium difficile varied widely. Of 58500 parasitology sp ecimens, 1463 (2.5%) contained a pathogen; 97.6% of pathogens were det ected by the second stool specimen, and 99.8% were detected by the thi rd specimen. Only 0.7% of specimens from inpatients hospitalized more than 4 days contained a new pathogen. Conclusions. We recommend that n o more than two bacteriology specimens and no more than two or three p arasitology specimens be processed per patient without consultation. S tandard stool examination for bacterial pathogens has a low yield and should not be performed after 3 days of hospitalization. Likewise, par asitology examinations should not be performed after 4 days of hospita lization.