Date Published: February 9, 2018
Publisher: Public Library of Science
Author(s): Katja Bogestam, Martin Vondracek, Mattias Karlsson, Hong Fang, Christian G. Giske, Karsten Becker.
Many countries using sensitive screening methods for detection of carriage of methicillin-resistant Staphylococcus aureus (MRSA) have a sustained low incidence of MRSA infections. For diagnostic laboratories with high sample volumes, MRSA screening requires stability, low maintenance and high performance at a low cost. Herein we designed oligonucleotides for a new nuc targeted hydrolysis probe PCR to replace the standard in-house nuc SybrGreen PCR assay. This new, more time-efficient, PCR assay resulted in a 40% increase in daily sample capacity, with maintained high specificity and sensitivity. The assay was also able to detect Staphylococcus aureus clonal cluster 75 (CC75) lineage strains, recently re-classified as Staphylococcus argenteus, with a sensitivity considerably increased compared to our previous assay. While awaiting consensus if the CC75 lineage of S. aureus should be considered as S. argenteus, and whether methicillin-resistant S. argenteus should be included in the MRSA definition, many diagnostic laboratories need to update their MRSA assay sensitivity/specificity towards this lineage/species. The MRSA screening assay presented in this manuscript is comprised of nuc oligonucleotides separately targeting S. aureus and CC75 lineage strains/S. argenteus, thus providing high user flexibility for the detection of CC75 lineage strains/S. argenteus.
Methicillin resistant Staphylococcus aureus (MRSA) is a multidrug resistant pathogen that causes both nosocomial and community-acquired infections worldwide. Rapid and accurate detection of MRSA is essential to enable early treatment and prevent further transmission of this pathogen. In Sweden, a relatively high percentage of patients admitted to hospitals are screened for the presence of MRSA. Although it is not possible to show a causative link between rigorous screening and the low incidence of MRSA in Sweden, it is still believed that the screening strategy has contributed to the favorable situation . As the largest diagnostic laboratory in northern Europe, this strategy results in high sample volumes with high demands in efficiency at low costs.
Herein, we describe the introduction of a new primary detection step nuc PCR, including novel oligonucleotides and hydrolysis probe. The assay allows screening of high sample volumes at a low cost with the ability to include or exclude detection of CC75 S. aureus/S. argenteus.