The cost-effectiveness of ESBL detection: towards molecular detection methods?

Abstract

Correct detection of extended-spectrum beta-lactamases (ESBLs) is crucial for infection control and antibiotic choice. We performed a study to determine the cost-effectiveness of phenotypical testing, which can be inaccurate, and genotypical tests, which are considered to be more reliable but also more expensive. All patients that had been in isolation in the Amphia hospital because of the detection of ESBL according to the ESBL Etest were included in the survey. All strains were retested using the double disk confirmation test (DDCT) and a genotypical method. This was a commercially available microarray (Check-Points). Discordant results were confirmed by PCR and sequencing. In total 174 patients were included. In 24 of 174 (14%) patients, ESBL carriage could not be confirmed with the microarray. This was verified with PCR and sequencing. The mean duration of isolation was 15 days, adding up to a total number of isolation days of 2571. False-positive results according to the microarray resulted in a total of 279 days of unnecessary isolation for the Etest and 151 days for the DDCT. Using Etest to detect the presence of ESBL results in a false-positive outcome in 14% of the cases. This results in unnecessary isolation of patients, which can be omitted by using a genotypic method.

Multiplex High-Resolution Melting Analysis as a Diagnostic Tool for Detection of Plasmid-Mediated AmpC β-Lactamase Genes

“…These data could be very useful in determining the risk of a potential outbreak in a hospital setting and the need for patient isolation. As technology allows further development of phenotypic and molecular diagnostic assays, it is to the benefit of the clinical laboratory to have options to choose from that best fit the working operation of the individual laboratory (9,14,15).…”

The Changing Role of the Clinical Microbiology Laboratory in Defining Resistance in Gram-negatives

“…107,[115][116][117][118] One of these platforms (Check KPC/ESBL) was used to detect ESBL and KPC genes directly in positive blood cultures, reducing the reporting time of ESBL and/or KPC production by 18 to 20 hours. 119,120 Check-MDR CT101 assay, which detects ESBL, KPC, pAmpCs, and NDM genes, showed 100% agreement with standard PCR/DNA sequencing. 114 Check-MDR CT102, which detects ESBLs and the most important carbapenemase (VIM, IMP, OXA-48-like, KPC, and NDM) genes, showed an agreement with PCR/DNA sequencing of 99%.…”

Diagnosis and antimicrobial treatment of invasive infections due to multidrug-resistant Enterobacteriaceae. Guidelines of the Spanish Society of Infectious Diseases and Clinical Microbiology

“…18 ESBL Etest ® strips are less efficacious and more expensive than CDDST since MIC values of cephalosporins in some ESBL-producing isolates can be out of the range of the strip 19 or yield false positive results. 19 For ESBL confirmation, the best option is probably the use of CDDST with cefotaxime, ceftazidime, and cefepime. In AmpC co-producers the best method to confirm ESBL production is CDDST assay in agar containing cloxacillin 17 or the use of commercially available cefotaxime and ceftazidime disks containing 3-aminophenylboronic acid (APBA).…”