SENSITIVITIES AND SPECIFICITIES OF PREMIER ESCHERICHIA-COLI O157 AND PREMIER EHEC ENZYME IMMUNOASSAYS FOR DIAGNOSIS OF INFECTION WITH VEROTOXIN (SHIGA-LIKE TOXIN)-PRODUCING ESCHERICHIA-COLI

This study describes the performance of two rapid enzyme immunoassays, Premier E. coli O157 and Premier EHEC (Meridian Diagnostics Inc., Cin cinnati, Ohio) for the detection in stools of Escherichia coil O157 an d verotoxins (Shiga-like toxins), respectively. Both tests were perfor med on stools from 876 children presenting to eight emergency departme nts with diarrhea. Standard culture, including E. coli O157:H7 isolati on, was performed, and paired sera were taken for anti-O157-lipopolysa ccharide antibody determination. Stools from patients enrolled in the study, and those yielding discordant results, were sent to a reference laboratory for repeat testing and further investigation, including cy totoxicity and non-O157 verotoxin-producing E. coli culture. Results w ere classified as field results (obtained in the eight site laboratori es) and resolved results (obtained after repeat testing in the central laboratory). The ''gold standard'' for sensitivity of both tests and for specificity of Premier E. coli O157 was isolation of E. coli O157: H7 or a fourfold anti-O157 antibody rise. Specimens positive by the Pr emier EHEC test and negative for E. coli O157 culture were examined fo r non-O157 verotoxin-producing E. coli. The field sensitivity of Premi er E. coli O157 was 86%, that of Premier EHEC was 89%, and the specifi city of Premier E. coli O157 was 98%. Ten of 13 discordant Premier E. coli O157 results were reassigned as true results after repeat testing . Ten non-O157 verotoxin-producing E. coli isolates were recovered fro m Premier EHEC-positive, E. coil O157 culture-negative stools. Only on e specimen gave an unequivocally false-positive Premier EHEC result. B oth tests are highly sensitive and are specific if correctly performed . The Premier EHEC test mill be particularly valuable as a practical r outine test for the detection of non-O157 verotoxin-producing E. coil.