Fluoroquinolone resistance in extended-spectrum β-lactamase-producing Klebsiella pneumoniae in a Japanese tertiary hospital: silent shifting to CTX-M-15-producing K. pneumoniae

Purpose. Fluoroquinolone resistance (FQ-r) in extended-spectrum β-lactamase (ESBL) producers is an urgent health concern in countries where ESBL-producing K. pneumoniae (ESBL-Kpn) is prevalent. We investigated FQ-r in Japan where ESBL-Kpn is less prevalent. Methodology. Clinical ESBL-Kpn isolates from 2011 to 2013 were collected in Nagasaki University Hospital. The ESBL genotypes included CTX-M-15, and the mechanisms of FQ-r through plasmid-mediated quinolone resistance (PMQR) and mutations in quinolone resistance-determining regions (QRDRs) were examined. Clonality was analysed by enterobacterial repetitive intergenic consensus (ERIC)-PCR and multi-locus sequence typing was performed on selected isolates. Results/Key findings. Thirty ESBL-Kpn isolates, including seven levofloxacin-resistant isolates, were obtained from different patients. An increase in CTX-M-15-producing strains was observed during the study period (0/11 in 2011, 3/8 in 2012, and 5/11 in 2013). PMQR was detected in 53.3?% of the isolates and aac-(6′)-Ib-cr was the most common (36.7?%). ST15 was observed in 60.0?% of the isolates, and for the most predominant ERIC-PCR profiles, 62.5?% of the isolates possessed the CTX-M-15 genotype and 71.4?% were levofloxacin-resistant. Levofloxacin-resistance was significantly more common in CTX-M-15 isolates (62.5?%) compared to non-CTX-M-15 isolates (9.1?%). Three QRDR mutations and aac(6′)-Ib-cr, but not qnrB and qnrS, were significantly enriched in the CTX-M-15 isolates (100.0?%) compared to the non-CTX-M-15 isolates (13.6?%). Conclusion. Cumulatively, these results indicate that the epidemic strain, the CTX-M-15-producing K. pneumoniae ST15, is covertly spreading even when ESBL producers are not prevalent. Monitoring these epidemic strains and ESBLs in general is important for quickly identifying health crises and minimizing future risks from FQ-r ESBL-Kpn

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

Evaluation of FilmArray respiratory panel multiplex polymerase chain reaction assay for detection of pathogens in adult outpatients with acute respiratory tract infection

Although viruses are the major pathogen that causes upper respiratory tract infection (URTI) and acute bronchitis, antibiotics have been prescribed. This was a prospective observational study in influenza epidemics that enrolled adult outpatients who visited a hospital with respiratory tract infection symptoms. In this study, we evaluated the usefulness of FilmArray respiratory panel (RP). Fifty patients were enrolled. FilmArray RP detected the pathogens in 28 patients. The common pathogens were influenza virus (n = 14), respiratory syncytial virus (n = 6), and human rhinovirus (n = 6). Of the 14 patients with influenza virus, 6 were negative for the antigen test. The physicians diagnosed and treated the patients without the result of FilmArray in this study. Of the patients with positive FilmArray RP, 9 were treated with antibiotics; however, bacteria were detected in only 3 patients. By implementing FilmArray RP, URTI and acute bronchitis would be precisely diagnosed, and inappropriate use of antibiotics can be reduced