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

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

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 clini-cal 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 hospi-tals 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 identi-fied 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 theESBL-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

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

a b s t r a c t Background: TNF-a plays an important role in the pathogenesis of Legionella pneumophila (Lp)-induced pneumonia. Patients undergoing anti-TNF-a 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-a 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-a. Apoptosis was examined by performing activated caspase-3/7 staining and by using a pancaspase inhibitor. Results: Lp infected and replicated in NCI-H292 cells in a time-dependent manner, and TNF-a treatment of Lp-infected NCI-H292 cells inhibited Lp replication. Inhibitory effects of TNF-a on Lp replication were suppressed after treatment with a TNF-a-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-a 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-a 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-a therapy who develop pneumonia

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)

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 fow 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 microfuidic immunofuorescence 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), specifcity, 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 testbased strategy using the Lumira Ag test can efectively exclude COVID-19 infectiousness.BMC Infectious Diseases, 23(1), art. no. 823; 202