title: Comparison of SpectraCell RA typing and multilocus sequence typing for extended-spectrum-β-lactamase-producing Escherichia coli.
abstract: Multilocus sequence typing (MLST) is one of the most reliable methods for typing of Escherichia coli, including extended-spectrum-β-lactamase-producing E. coli (ESBL-EC). We investigated the performance of a new typing method, SpectraCell RA (River Diagnostics, Madison, WI), in comparison on MLST on a well-defined collection of ESBL-EC isolates obtained from chicken meat and humans. Ninety-two ESBL-EC isolates obtained from meat and 59 ESBL-EC isolates obtained from human rectal swabs and clinical blood cultures were typed using MLST and SpectraCell RA. The sensitivity and specificity of SpectraCell RA were calculated, using MLST as a reference method. Subsequently, the results of SpectraCell RA were used to determine the relatedness of ESBL-EC isolates from chicken and humans. Using MLST as the gold standard, the performance of SpectraCell RA was evaluated for 3 different cutoff values: 0.99975, 0.99955, and 0.99935. Depending on the cutoff value, the sensitivity was mediocre to unacceptably low, with values of 9.4%, 43.9%, and 66.7%, respectively. When sensitivity increased, the specificity decreased rapidly, from 95.6% to 69.8% and 34.4%, respectively. Also, the number of clusters containing both human and meat samples varied from 0 (0.0%) to 14 (38.9%). Our study shows that SpectraCell RA is not a suitable typing method for ESBL-EC when evaluating relationships of ESBL-EC at the population level.
authors.affiliation: Department of Medical Microbiology and Immunology, St. Elisabeth Hospital, Tilburg, The Netherlands. i.overdevest@elisabeth.nl
authors.forename: I T M A
authors.initials: IT
authors.lastname: Overdevest
authors.forename: M
authors.initials: M
authors.lastname: Heck
authors.forename: K
authors.initials: K
authors.lastname: van der Zwaluw
authors.forename: I
authors.initials: I
authors.lastname: Willemsen
authors.forename: J
authors.initials: J
authors.lastname: van de Ven
authors.forename: C
authors.initials: C
authors.lastname: Verhulst
authors.forename: J A J W
authors.initials: JA
authors.lastname: Kluytmans
mesh_terms: D000818:Animals; D002645:Chickens; D004926:Escherichia coli / Q000145:classification* / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D006801:Humans; D008460:Meat / Q000382:microbiology; D017720:Molecular Epidemiology / Q000379:methods; D058889:Molecular Typing / Q000379:methods*; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D001618:beta-Lactamases