Evaluation of the Wider system, a new computer-assisted image-processing device for bacterial identification and susceptibility testing.
The Wider system is a newly developed computer-assisted image-processing device for both bacterial identification and antimicrobial susceptibility testing. It has been adapted to be able to read and interpret commercial MicroScan panels. Two hundred forty-four fresh consecutive clinical isolates (138 isolates of the family Enterobacteriaceae, 25 nonfermentative gram-negative rods [NFGNRs], and 81 gram-positive cocci) were tested. In addition, 100 enterobacterial strains with known beta-lactam resistance mechanisms (22 strains with chromosomal AmpC beta-lactamase, 8 strains with chromosomal class A beta-lactamase, 21 broad-spectrum and IRT beta-lactamase-producing strains, 41 extended-spectrum beta-lactamase-producing strains, and 8 permeability mutants) were tested. API galleries and National Committee for Clinical Laboratory Standards (NCCLS) microdilution methods were used as reference methods. The Wider system correctly identified 97.5% of the clinical isolates at the species level. Overall essential agreement (+/-1 log(2) dilution for 3,719 organism-antimicrobial drug combinations) was 95.6% (isolates of the family Enterobacteriaceae, 96.6%; NFGNRs, 88.0%; gram-positive cocci, 95.6%). The lowest essential agreement was observed with Enterobacteriaceae versus imipenem (84.0%), NFGNR versus piperacillin (88.0%) and cefepime (88.0%), and gram-positive isolates versus penicillin (80.4%). The category error rate (NCCLS criteria) was 4.2% (2.0% very major errors, 0.6% major errors, and 1. 5% minor errors). Essential agreement and interpretive error rates for eight beta-lactam antibiotics against isolates of the family Enterobacteriaceae with known beta-lactam resistance mechanisms were 94.8 and 5.4%, respectively. Interestingly, the very major error rate was only 0.8%. Minor errors (3.6%) were mainly observed with amoxicillin-clavulanate and cefepime against extended-spectrum beta-lactamase-producing isolates. The Wider system is a new reliable tool which applies the image-processing technology to the reading of commercial trays for both bacterial identification and susceptibility testing.
Cantón
R
R
Servicio de Microbiología, Hospital Ramón y Cajal, Madrid 28034, Spain. rcanton@hrc.insalud.es
Pérez-Vázquez
M
M
Oliver
A
A
Sánchez Del Saz
B
B
Gutiérrez
M O
MO
Martínez-Ferrer
M
M
Baquero
F
F
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000145:classification* / Q000187:drug effects; D001424:Bacterial Infections / Q000382:microbiology*; D015373:Bacterial Typing Techniques / Q000295:instrumentation*; D004755:Enterobacteriaceae / Q000145:classification / Q000187:drug effects; D005069:Evaluation Studies as Topic; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D008826:Microbial Sensitivity Tests / Q000295:instrumentation*; D012015:Reference Standards; D018440:beta-Lactam Resistance
D000900:Anti-Bacterial Agents