ABSTRACT
Extended-spectrum ß-lactamases (ESBLs) are emerging worldwide, making rapid and adequate ESBL detection crucial for infection control measures as well as for the choice of correct antimicrobial therapy. The aim of this study was to compare the performance of a novel rapid ligation-mediated real-time PCR (LM-PCR) with a combination disc test (CDT). In total, 172 prospective putative ESBL-positive Enterobacteriaceae isolates from clinical specimens based on VITEK2 results were included in this study and tested with the phenotypic CDT and the LM-PCR. Positive ESBL results were obtained in 100 and 95 isolates using CDT and LM-PCR, respectively. The sensitivity, specificity, negative predictive value and positive predictive value of the LM-PCR were 99.0, 92.2, 98.6 and 94.0â%, respectively, compared with the CDT. The LM-PCR technique provides an important reduction in turnaround time (~4.5 h versus overnight incubation using CDT) for ESBL confirmation. As a consequence, all ESBL results are available within the same day, making this assay an important tool for rapid and accurate ESBL detection.
Subject(s)
Enterobacteriaceae/enzymology , Real-Time Polymerase Chain Reaction/methods , beta-Lactamases/genetics , beta-Lactamases/metabolism , Anti-Bacterial Agents/pharmacology , DNA, Bacterial/genetics , DNA, Bacterial/isolation & purification , Drug Resistance, Multiple, Bacterial/genetics , Enterobacteriaceae/drug effects , Enterobacteriaceae/genetics , Genetic Variation , Phenotype , Predictive Value of Tests , Real-Time Polymerase Chain Reaction/economics , Reproducibility of Results , Sensitivity and Specificity , Time FactorsABSTRACT
A proof of principle of a multi-target assay for genotyping Salmonella has been developed targeting 62 genomic marker sequences of Salmonella related to pathogenicity. The assay is based on multiplex ligation detection reaction (LDR) followed by customized ArrayTube® microarray detection. The feasibility of the developed assay was verified in a method comparison study with conventional PCR using 16 Salmonella 'test' strains comprising eight serovars. Subsequently, the feasibility of the LDR microarray assay was also tested by analyzing 41 strains belonging to 23 serovars. With the exception of four serovars each serovar was characterized by a unique virulence associated gene repertoire. The LDR microarray platform proved to be a convenient, rapid and easy to use tool with potential in tracing a Salmonella contamination in the food chain, for outbreak studies, and to provide data for risk assessors that support bio-traceability models.
Subject(s)
Oligonucleotide Array Sequence Analysis/methods , Salmonella enterica/classification , Abattoirs , Animals , Genotype , Polymerase Chain Reaction , Salmonella enterica/genetics , Salmonella enterica/isolation & purification , SwineABSTRACT
A new commercial system based on genetic profiling and aimed at identifying Salmonella enterica serovars was evaluated by comparing its performance with classical serotyping on 443 strains. Within 62 serovars represented, 60 gave unique genetic profiles while 2 were undistinguishable. Results were obtained within 8 h, were reproducible and clear-cut. The system allowed single-tube processing of the samples and required no peculiar technical skill. It showed interesting potential for routine laboratory testing.
