Evaluation of the Xpert Xpress SARS-CoV-2/Flu/RSV Assay for Simultaneous Detection of SARS-CoV-2, Influenza A and B Viruses, and Respiratory Syncytial Virus in Nasopharyngeal Specimens.

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A (flu A), influenza B (flu B), and respiratory syncytial virus (RSV) have overlapping clinical presentations, but the approaches to treatment and management of infections caused by these viruses are different. Therefore, rapid diagnosis in conjunction with infection prevention measures is important to prevent transmission of the diseases. Recently, a new Xpert Xpress SARS-CoV-2/Flu/RSV (Xpert 4-in-1) assay enables the detection and differentiation of SARS-CoV-2, flu A, flu B, and RSV in upper respiratory tract specimens. In this study, we evaluated the performance of the Xpert 4-in-1 assay by comparing it with that of the Xpert Xpress SARS-CoV-2 and Xpert Xpress Flu/RSV assays for the detection of the four viruses in nasopharyngeal (NP) specimens. A total of 279 NP specimens, including 66, 56, 64, and 53 specimens positive for SARS-CoV-2, flu A, flu B, and RSV, respectively, were included. The Xpert 4-in-1 assay demonstrated high concordance with the comparator assays, with overall agreement for SARS-CoV-2, flu A, flu B, and RSV at 99.64%, 100%, 99.64%, and 100%, respectively, and a high Cohen's kappa (κ) value ranging from 0.99 to 1.00, indicating an almost perfect correlation between assays. The cycle threshold value association between positive samples also showed a good correlation between assays. In conclusion, the overall performance of the Xpert 4-in-1 assay was highly comparable to that of the Xpert SARS-CoV-2 and Xpert Flu/RSV assays for the detection and differentiation of SARS CoV-2, flu A, flu B, and RSV in NP specimens.

Deep throat saliva as an alternative diagnostic specimen type for the detection of SARS-CoV-2.

Nasopharyngeal swabs (NPS) are widely accepted as specimens for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the current pandemic of coronavirus disease 2019. However, the collection procedures for NPS specimens causes sneezing and coughing in most patients, which generate droplets or aerosol particles that are hazardous to the healthcare workers collecting these specimens. In this study, 95 patient-matched paired deep throat saliva (DTS) and NPS specimens from 62 patients were analyzed. Samples were tested for SARS-CoV-2 by reverse-transcription polymerase chain reaction (RT-PCR). The rates of detection for DTS (53.7%) and NPS (47.4%) samples were comparable (P = .13). It is important to note that the patients should be clearly instructed or supervised during DTS collection. In conclusion, SARS-CoV-2 detection by RT-PCR was equivalent in DTS and NPS specimens.

Admission Screening of Methicillin-Resistant Staphylococcus aureus with Rapid Molecular Detection in Intensive Care Unit: A Three-Year Single-Centre Experience in Hong Kong.

Background. The admission screening of methicillin-resistant Staphylococcus aureus (MRSA) by rapid molecular assay is considered to be an effective method in reducing the transmission of MRSA in intensive care unit (ICU). Method. The admission screening on patients from ICU once on their admissions by BD GeneOhm MRSA assay has been introduced to Prince of Wales Hospital, Hong Kong, since 2008. The assay was performed on weekdays and reported on the day of testing. Patients pending for results were under standard precautions until the negative screening results were notified, while contact precautions were implemented for MRSA-positive patients. In this study, we compared the MRSA transmission rate in molecular screening periods (2008 to 2010) with the historical culture periods (2006 to 2007) as control. Results. A total of 4679 samples were tested; the average carriage rate of MRSA on admission was 4.45%. By comparing with the historical culture periods, the mean incidence ICU-acquired MRSA infection was reduced from 3.67 to 1.73 per 1000 patient bed days. Conclusion. The implementation of admission screening of MRSA with molecular method in intensive care unit could reduce the MRSA transmission, especially in the area with high MRSA prevalence situation in Hong Kong.

Enterovirus infection among patients admitted to hospital in Hong Kong in 2010: epidemiology, clinical characteristics, and importance of molecular diagnosis.

The activity of hand, foot, and mouth disease (HFMD) in Hong Kong was high in 2010. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) had been performed routinely for diagnosis of enterovirus (EV) infection among hospitals in a geographical cluster. The aim of the study was to describe the epidemiology and the clinical pattern of EV-related hospital admission in 2010, and evaluate the impact of RT-PCR compared to conventional method. This was a retrospective study and patients with laboratory confirmed EV infection were included. Demographic information, clinical features, complications, and laboratory findings were analyzed. Among the 113 patients identified, HFMD was the most common presentation (84/113, 74%), followed by meningitis (10/113, 9%). Respiratory (52/113, 46%) and gastrointestinal symptoms like vomiting (36/113, 32%) and diarrhea (15/113, 13%) were quite common. For cases with central nervous system (CNS) or myocardial complications, there were significantly fewer oral ulcer and rash over hands and feet compared to their counter group. Serious infection mainly affected children younger than 1-year old and adults. Dual infection was noted among seven patients (6%). Compared to RT-PCR, conventional virus isolation detected only 14-16% of the infections. The relative low culture positive rate could be explained by the circulation of Coxsackie A6 in 2010 which was difficult to be isolated by cell culture. Diagnosis of EV infection among hospitalized patients may not be straightforward. EV RT-PCR significantly improved laboratory diagnosis and delineation of epidemiology of EV infection compared to conventional methods.