Available online 13 March 2023

Staphylococcus aureus bacteremia results in substantial mortality. Rapid identification and the determination of methicillin susceptibility are crucial for immediate treatment with appropriate antibiotics. In the present study, we aimed to evaluate the basic assay performance of GeneSoC®, a novel rapid quantitative polymerase chain reaction (qPCR) method, for the detection of methicillin-susceptible (MS) or -resistant (MR) S. aureus in blood culture (BC) bottles. qPCR pimers and probes were desinged for femA and mecA genes to diagnose S. aureus and its methicilline-resistance status. GeneSoC® system can detect target genes within 12 min per sample using microfludic thermal cycling. A total of 100 BC-positive samples, showing clusters of gram-positive cocci using microscopy, were tested. The analytical sensitivity was demonstrated for the target sequence of femA and mecA genes at 10 copies/μL, respectively. The detection limit of the MRSA bacterial burden using this system was 104 and 103 CFU/mL for femA and mecA, respectively. Compared with culture-based identification and susceptibility testing, the sensitivity and specificity for the detection of femA (+)/mecA (+) MRSA using GeneSoC® were 90.9 and 98.9%, respectively, whereas the sensitivity and specificity for detection of femA (+)/mecA (-) MSSA were 96.2% and 97.3%, respectively. In conclusion, although this was a small sample and pilot study, the GeneSoC® system is beneficial for rapid, reliable, and highly sensitive real-time testing of MRSA and MSSA in BC bottles.

Staphylococcus aureus infection is the leading cause of community- and hospital-acquired bacteremia, with a high mortality rate (20–40%) [1,2]. Prompt administration of pathogen-specific antibiotics can improve clinical outcomes [3]. Although blood culture (BC) test is the gold standard for the diagnosis of bacteremia, it is inconclusive when clusters of gram-positive cocci are detected. These could represent coagulase-negative Staphylococci (CoNS), often considered as a contaminant. The

All authors meet the ICMJE authorship criteria. TA and M Kaku conceived and desinged the experiments. MC and TA perfomed the experiments. TA, MY, and M Katsumi interaputed data. TA and MC wrote the manuscript. SF, YI, and KT perfomed a critical review of the manuscript. All authors have read and approved the final manuscript.

This study was funded by Kyorin Pharmaceutical Co., Ltd. The sponsor provided technical support for the GeneSoC® system examination, including system maintenance, during the study period. The sponsor had no control over the interpretation, writing, or publication of this work.

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© 2023 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.