Evaluation of a Commercial Multiplex PCR for Rapid Detection of Multi Drug Resistant Gram Negative Infections



Ruchir Chavada*, Michael Maley*
Department of Microbiology and Infectious Diseases, Sydney South West Pathology Services(SSWPS), Corner Goulburn and Forbes Street, Liverpool Hospital, Liverpool, NSW-2170, Sydney, Australia


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© Chavada and Maley; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Department of Microbiology and Infectious Diseases, Sydney South West Pathology Services(SSWPS), Corner Goulburn and Forbes Street, Liverpool Hospital, Liverpool, NSW-2170, Sydney, Australia; Tel: +61-02-87385135; Fax: + 61-02-87385129; E-mail: ruchirchavda@gmail.com


Abstract

Introduction:

Community and healthcare associated infections caused by multi-drug resistant gram negative organisms (MDR GN) represent a worldwide threat. Nucleic Acid Detection tests are becoming more common for their detection; however they can be expensive requiring specialised equipment and local expertise. This study was done to evaluate the utility of a commercial multiplex tandem (MT) PCR for detection of MDR GN.

Methods:

The study was done on stored laboratory MDR GN isolates from sterile and non-sterile specimens (n=126, out of stored 567 organisms). Laboratory validation of the MT PCR was done to evaluate sensitivity, specificity and agreement with the current phenotypic methods used in the laboratory. Amplicon sequencing was also done on selected isolates for assessing performance characteristics. Workflow and cost implications of the MT PCR were evaluated.

Results:

The sensitivity and specificity of the MT PCR were calculated to be 95% and 96.7% respectively. Agreement with the phenotypic methods was 80%. Major lack of agreement was seen in detection of AmpC beta lactamase in enterobacteriaceae and carbapenemase in non-fermenters. Agreement of the MT PCR with another multiplex PCR was found to be 87%. Amplicon sequencing confirmed the genotype detected by MT PCR in 94.2 % of cases tested. Time to result was faster for the MT PCR but cost per test was higher.

Conclusion:

This study shows that with carefully chosen targets for detection of resistance genes in MDR GN, rapid and efficient identification is possible. MT PCR was sensitive and specific and likely more accurate than phenotypic methods.

Keywords: Commercial multiplex PCR, Gram negative infections, MDR GN resistance, Nucleic Acid Detection (NAD) tests, MT PCR, Primers, tandem PCR.