The evaluation of a rapid microfluidic immunofluorescence antigen test in detecting the infectiousness of COVID-19 patients.

BACKGROUND: A test-based strategy against coronavirus disease 2019 (COVID-19) is one of the measures to assess the need for isolation and prevention of infection. However, testing with high sensitivity methods, such as quantitative RT-PCR, leads to unnecessary isolation, whereas the lateral flow antigen test shows low sensitivity and false negative results. The purpose of this study was to evaluate the performance of the LumiraDx SARS-CoV-2 Ag test (Lumira Ag), a rapid microfluidic immunofluorescence method, in assessing infectivity. METHODS: This study was performed from March 2022 to July 2022. A pair of nasopharyngeal swab samples were obtained from each patient with mild COVID-19. One swab was used for Lumira Ag testing, and the other for quantitative RT-PCR testing and virus culture. RESULTS: A total of 84 patients were included in the study. Among them, PCR, Lumira Ag test, and virus culture indicated positivity for 82, 66, and 24 patients, respectively. When comparing the Lumira Ag test to virus culture, its sensitivity was 100.0% (24/24), specificity, 30.0% (18/60); positive predictive value, 36.3% (24/66); and negative predictive value (NPV), 100.0% (18/18). The positive sample for virus culture was observed until the ninth day from the onset of symptoms, while the Lumira Ag test was observed until day 11. CONCLUSIONS: The Lumira Ag test showed high sensitivity and NPV (100% each) compared to virus culture. A test-based strategy using the Lumira Ag test can effectively exclude COVID-19 infectiousness.

The fecal carriage rate of extended-spectrum ß-lactamase-producing or carbapenem-resistant Enterobacterales among Japanese infants in the community at the 4-month health examination in a rural city.

Background: Extended-spectrum ß-lactamase-producing Enterobacterales (ESBL-E) is a great public health concern globally not only in hospitals but also in the community. To our knowledge, there have been few studies on the prevalence of ESBL-E and much less about carbapenem-resistant Enterobacterales (CRE) among children in the community, and there is no such study in Japan despite such situations. This study aimed to clarify their carriage status among Japanese infants in the community by taking the opportunity of the 4-month health checkup. Methods: This prospective analysis was conducted from April 2020 to March 2021 in Shimabara City, Nagasaki Prefecture, Japan. The research-related items were mailed to all subjects with official documents for the checkup. The fecal samples were obtained from the diaper by guardians beforehand and were collected with the questionnaire and then screened for ESBL-E and CRE by a clinical laboratory company with selective agars followed by identification and confirmation. Only the positive samples were analyzed about resistant genotypes. Results: One hundred fifty infants aged 4-5 months, over half of the subjects, participated in this study. The overall ESBL-E carriage rate was 19.3% (n = 29), and no CRE carrier was detected among them. All identified ESBL-E were E. coli except for one K. pneumoniae. A significantly higher carriage rate was recorded among the infants born at "Hospital A" (25.0%) than the others (11.3%). Enterobacterales producing CTX-M-9 ± TEM were broadly distributed among the positive samples (65.5%), whereas the CTX-M-1 group was exclusively detected among those from "Hospital A". Recursive partitioning analysis suggested that delivery facilities might be an important factor for ESBL-E colonization, although the effect could be decreased as they grow. In contrast, no significant effect was observed for other factors such as parent(s) as healthcare worker(s), having a sibling(s), and the mode of delivery. Conclusion: This study revealed the ESBL-E and CRE carriage status of Japanese infants in the community for the first time, although the setting is somewhat limited. Our findings indicated that environmental factors, especially delivery facilities, influenced ESBL-E colonization among infants aged 4-5 months, implying the need for strengthening countermeasures against antimicrobial resistance at delivery facilities and communities outside the hospitals.

Clinical evaluation of cell-direct polymerase chain reaction-based nucleic acid lateral flow immunoassay for rapid detection of bacterial pathogens in clinically suspected sepsis: A multi-center study in Japan.

Blood culture, a method for identifying causative agents of bacterial sepsis, requires several days. The combination of cell-direct polymerase chain reaction and nucleic acid lateral flow immunoassay (cdPCR-NALFIA) is a simple and sensitive detection method for identifying pathogenic bacteria. Furthermore, this assay, when applied directly to blood samples yields results within 4.5 h, without requiring culture. This study was performed at five hospitals in Japan between 2013 and 2016. Blood samples from 73 patients with clinically suspected sepsis yielded 18 positive blood cultures, and the isolated bacterial species were detectable using cdPCR-NALFIA in nine samples. Thirteen samples were positive on cdPCR-NALFIA. In total, 17 samples confirmed to have bacterial species were detectable using cdPCR-NALFIA and/or blood culture with a true positive rate of 76.5% and 64.7%, respectively. The combination of blood culture and cdPCR-NALFIA could improve the rate of detection of bacterial sepsis.

The surveillance of colistin resistance and mobilized colistin resistance genes in multidrug-resistant Enterobacteriaceae isolated in Japan.

BACKGROUND: The plasmid-mediated bacterial colistin-resistant gene, mcr, is of global concern in clinical healthcare. However, there are few reports of surveillance for mcr in Japan. The aim of this study was to assess the prevalence of colistin resistance by identifying nine mcr genes in extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae and carbapenem-resistant Enterobacteriaceae (CRE) isolates in Japan. METHODS: A total of 273 ESBL and CRE clinical isolates were collected from patients in five tertiary hospitals from August 2016 to March 2017. Minimum inhibitory concentration (MIC) of colistin was measured using the microdilution method. Polymerase chain reaction (PCR) was performed to detect mcr-1 to mcr-9 genes in all strains. Whole-genome sequencing (WGS) analysis was conducted for any mcr-genes identified that had not been previously reported in patients from Japan. RESULTS: The rate of colistin resistance was 7.7% in all strains, with a higher rate in the CRE strains than in the ESBL-producing strains (20.4% versus 1.1%). The mcr-5 and mcr-9 gene were detected in one ESBL-producing Escherichia coli strain (1/273, 0.37%) and three CRE strains (3/273, 1.1%), respectively. As the ESBL-producing E. coli strain was the first clinical strain with mcr-5 in Japan, WGS analysis was performed for the strain. The sequence type of the mcr-5-positive strain was ST1642 and it carried two distinct plasmids, ESBL gene-carrying pN-ES-6-1, and mcr-5.1-carrying pN-ES-6-2. CONCLUSIONS: The results of this study showed that the frequency of colistin resistance and mcr-positive strains is not high in Japan. As the MIC for colistin was low in the mcr-5.1 and mcr-9 gene-positive strain, continuous monitoring of mcr genes is necessary.

Rapid detection and surveillance of cfiA-positive Bacteroides fragilis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

OBJECTIVES: To perform surveillance of cfiA-positive Bacteroides fragilis using new subtyping software module, MALDI Biotyper Subtyping Module (MBT Subtyping Module), on MALDI-TOF MS system, and to evaluate the detection ability of the module. METHODS: cfiA-positive strains were presumed using the module against B. fragilis isolated between 2006 and 2019. The cfiA gene was confirmed using PCR. In cfiA-positive B. fragilis, the insertion sequence (IS) elements were examined and the MBT STAR-BL assay was performed to examine meropenem hydrolysis activity. RESULTS: Of the 396 B. fragilis strains included, the MBT Subtyping Module detected 33 presumptive cfiA-positive strains (8.3%), of which 32 harbored the cfiA gene. The sensitivity and specificity of the MBT Subtyping Module for detecting cfiA-positive B. fragilis were 100.0% and 99.7%, respectively. Of the 32 strains harboring the cfiA gene, seven strains possessed IS elements, which were thought to induce high cfiA expression. Meropenem hydrolysis was detected in all seven strains that were positive for both cfiA and IS elements, and they exhibited resistance to meropenem and imipenem. The overall non-susceptibility rates to meropenem and imipenem were 84.8% and 36.4%, respectively, in the 33 presumptive cfiA-positive strains. CONCLUSION: The MBT Subtyping Module can detect cfiA-positive B. fragilis rapidly and accurately, supporting its use for surveillance of cfiA-positive B. fragilis in clinical settings.

A novel macrolide, solithromycin suppresses mucin overexpression induced by Pseudomonas aeruginosa LPS in airway epithelial cells.

Some macrolides such as 14- and 15-membered macrolides have immunomodulatory effects such as suppression of mucin overproduction. Because a novel macrolide, solithromycin, was developed, we examined whether it suppresses the overexpression of mucin in vitro. A human airway epithelial cell line NCI-H292 was stimulated by Pseudomonas aeruginosa lipopolysaccharides to induce the overproduction of a major mucin, MUC5AC. Treatment with 10 µg/mL of solithromycin significantly inhibited LPS-induced MUC5AC in both mRNA and protein levels as well as a 15-membered macrolide, azithromycin. These findings support that solithromycin has a potential immunomodulatory effect.

Detection of extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae using the MALDI Biotyper Selective Testing of Antibiotic Resistance-ß-Lactamase (MBT STAR-BL) assay.

The MALDI Biotyper Selective Testing of Antibiotic Resistance-ß-Lactamase (MBT STAR-BL) assay, which analyzes bacterial induced hydrolysis of cefotaxime using MALDI-TOF MS, correctly identified 100.0% of extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae as positive and 94.7% of non-ESBL producers as negative in 80 strains tested.

Performance evaluation of the MALDI Biotyper Selective Testing of Antibiotic Resistance-ß-Lactamase (MBT STAR-BL) assay for the detection of IMP metallo-ß-lactamase activity in Enterobacteriaceae.

The MALDI Biotyper Selective Testing of Antibiotic Resistance-ß-Lactamase (MBT STAR-BL) assay enables rapid detection of ß-lactamase activity using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. The assay is based on analysis of bacterially induced hydrolysis of ß-lactam antibiotics. We investigated the performance of the MBT STAR-BL assay for detecting IMP metallo-ß-lactamase (MBL) activity in Enterobacteriaceae. A total of 145 strains (30 Escherichia coli, 43 Klebsiella pneumoniae, and 72 Enterobacter cloacae complex) were evaluated using meropenem hydrolysis assays. The MBT STAR-BL correctly identified all 48 IMP MBL producers as positive, even those exhibiting a low minimal inhibitory concentration (MIC) (1 µg/mL) for meropenem. Conversely, all non-IMP MBL producers, including strains with higher MICs (4 or 8 µg/mL), were correctly identified as negative. The MBT STAR-BL is a rapid, accurate, and reliable system for detecting IMP MBL activity in Enterobacteriaceae.

Performance evaluation of BD Phoenix™, an automated microbiology system, for the screening of IMP-producing Enterobacteriaceae.

BD Phoenix™ is an automated bacterial identification and susceptibility testing system. Here, its performance in screening IMP-producing Enterobacteriaceae was evaluated. The system identified 97.8% of IMP producers as being nonsusceptible to imipenem or meropenem, which was higher than that identified by the broth microdilution method (91.3%, imipenem; 41.3%, meropenem).

TNF-α inhibits the growth of Legionella pneumophila in airway epithelial cells by inducing apoptosis.

BACKGROUND: TNF-α plays an important role in the pathogenesis of Legionella pneumophila (Lp)-induced pneumonia. Patients undergoing anti-TNF-α therapy are at an increased risk of Lp infection. Lp infects both phagocytic and non-phagocytic cells such as airway epithelial cells; however, the role of TNF-α in airway epithelial cells is unknown. METHODS: Human airway epithelial cell line NCI-H292 was infected with Lp NUL1 strain. After infection, both intracellular growth of Lp and cell death were evaluated after treating the cells with or without TNF-α. Apoptosis was examined by performing activated caspase-3/7 staining and by using a pan-caspase inhibitor. RESULTS: Lp infected and replicated in NCI-H292 cells in a time-dependent manner, and TNF-α treatment of Lp-infected NCI-H292 cells inhibited Lp replication. Inhibitory effects of TNF-α on Lp replication were suppressed after treatment with a TNF-α-neutralizing antibody. Lp infection increased extracellular lactate dehydrogenase levels and decreased the number of living cells. Increased number of Lp-infected NCI-H292 cells showed caspase-3/7 activation, indicating they underwent apoptosis. TNF-α treatment inhibited Lp replication by increasing the apoptosis of NCI-H292 cells. CONCLUSIONS: Thus, our results suggested that airway epithelial cells were involved in the pathogenesis of Lp infection and that TNF-α played a protective role by inhibiting the intracellular replication of Lp and by increasing the apoptosis of Lp-infected airway epithelial cells. However, Lp infection should be investigated further in patients undergoing anti-TNF-α therapy who develop pneumonia.