Impact of simple screening criteria on utilization of low-yield bacterial stool cultures in a Children's Hospital.
OBJECTIVE
To determine diagnostic yield of stool cultures for Salmonella, Shigella, Campylobacter jejuni, Yersinia enterocolitica, and Escherichia coli O157:H7 (SSCYE) among hospitalized children and to develop guidelines for appropriate use of these tests. Setting. Tertiary care pediatric hospital.


METHODS
Computerized records from the Microbiology Laboratory from January 1992 to December 1996 were reviewed retrospectively to collect data on the number of stool cultures performed in inpatients and outpatients, the length of hospital stay at the time cultures were sent, and diagnostic yield of cultures in hospitalized patients. A detailed review of medical records of all patients with a stool pathogen isolated after 3 days of hospitalization was also undertaken. The results from this retrospective analysis were used to develop guidelines to reduce unwarranted stool cultures and to educate medical care providers in the appropriate use of these tests. The impact of these guidelines on reduction in the volume of stool cultures performed on hospitalized patients was measured prospectively from January 1998 to June 1998.


RESULTS
A total of 27 110 stool cultures for SSCYE were performed in the 5-year study period. Of the 14 125 cultures from inpatients, 174 (1.2%) were positive. Among the cultures from inpatients, 9378 (66%) were from patients hospitalized for >3 days. Only 13 (.14%) were positive. Of these 13 cultures, 4 represented nosocomial infections, whereas the remaining 9 cultures either were sent to document clearance from a patient known previously to be infected with an enteric pathogen (7), or were attributed to delayed testing in individuals admitted with a diarrheal illness (2). Introduction of guidelines to reject all SSCYE cultures from patients hospitalized for >3 days who did not meet specified criteria was associated with an overall reduction of 689 (43%) in the volume of tests performed in the 6-month period evaluated. This included 497 fewer cultures ordered and 192 cultures that were ordered but rejected because screening criteria were not met. Only 11 (5.4%) of 203 cultures sent >3 days after admission were processed because they met clinical criteria for testing. None were positive. Estimated cost savings were $50 163/year.


CONCLUSIONS
Stool cultures for SSCYE among hospitalized patients have very low diagnostic yield and are extremely overutilized. Simple guidelines, such as rejecting (with few exceptions) cultures from patients hospitalized for >3 days, can reduce substantially such unnecessary testing.
Zaidi
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AK
Division of Infectious Diseases, Department of Laboratory Medicine, Children's Hospital, Boston, Massachusetts, USA. zaidi_a@a1.tch.harvard.edu
Macone
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A
Goldmann
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AD
D001900:Boston; D002648:Child; D002675:Child, Preschool; D003955:Diagnostic Tests, Routine / Q000706:statistics & numerical data*; D005243:Feces / Q000382:microbiology*; D016905:Gram-Negative Bacterial Infections / Q000175:diagnosis* / Q000382:microbiology*; D006300:Health Services Misuse; D006776:Hospitals, Pediatric; D006801:Humans; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013997:Time Factors