Biology subjects

Fukano, H.

Publications and source records attributed to Fukano, H..

4 recordsLinked to original sources

bioRxiv2025

Plasmid-mediated macrolide resistance among rapidly growing mycobacteria in Japan

ObjectivesThe spread of a transmissible plasmid carrying the 23S rRNA methylase gene erm(55), which confers inducible macrolide resistance in rapidly growing mycobacteria (RGM), has raised significant clinical concerns. The aim of this study was to investigate the prevalence of erm(55)-carrying plasmids in clinically isolated RGM strains in Japan. MethodsIn total, 607 RGM clinical isolates, representing 32 species or complexes, collected between 2019 and 2023 in Japan were examined. To detect the presence of erm(55)-carrying plasmids, we conducted PCR screening, minimum inhibitory concentration testing for clarithromycin, and whole-plasmid genome sequencing. Comparative genomic analyses were performed to characterise the plasmids. ResultsAmong the 607 RGM isolates, 0.8% (5/607) possessed the plasmid with the erm(55) gene and exhibited inducible macrolide resistance, with ratios of 100% (1/1) in Mycobacterium murale, 50% (3/6) in M. obuense, and 0.8% (1/125) in M. chelonae. The erm(55)-carrying plasmids ranged from 126,187 to 170,220 bp in size. Pairwise BLASTn comparisons of the erm(55)-carrying plasmids showed weighted percent identity values ranging from 99.5% to 99.9%, with query and subject coverage values ranging from 74.2% to 100%. All erm(55) sequences (813 bp) were identical and located within a horizontal gene transfer region. ConclusionsThis study confirmed the presence of macrolide-resistant RGMs related to the erm(55)-carrying plasmid in Japan, although the overall prevalence remains low. These findings emphasise the need to consider plasmid-mediated resistance when treating infections caused by the RGM species.

microbiology↗

bioRxiv2022

A case of mycobacteriosis associated with Mycobacterium pseudoshottsii in aquarium-reared fish in Japan

In 2019, several aquarium-reared fish died at a sea life park in Japan. Necropsy revealed micronodules on the spleen in the dotted gizzard shad (Konosirus punctatus). Seven of 16 fish exhibited microscopic multifocal granulomas associated with acid-fast bacilli in the spleen, kidney, liver, alimentary tract, mesentery, gills, and/or heart. Bacterial cultures yielded isolates from the dotted gizzard shad and a Japanese sardine (Sardinops melanostictus). Microbiological examination, multilocus sequence typing analysis, and variable number of tandem repeats analysis with a newly proposed 6-loci set revealed the isolates as Mycobacterium pseudoshottsii. To our knowledge, this is the first isolation of M. pseudoshottsii from aquarium-reared fish.

microbiology↗

bioRxiv2021

Comparative analysis of Mycobacterium abscessus clinical isolate virulence using an invertebrate infection model

Mycobacterium abscessus causes chronic skin infections, lung diseases, and systemic or disseminated infections. Here we investigated whether the virulence of M. abscessus clinical isolates could be evaluated by calculating the median lethal dose (LD50) in a silkworm infection model. M. abscessus subsp. abscessus cells were injected into the silkworm hemolymph. When reared at 37{degrees}C, the silkworms died within 2 days post-infection with M. abscessus subsp. abscessus. Viable cell numbers of M. abscessus subsp. abscessus increased in the hemolymph of silkworms injected with M. abscessus subsp. abscessus. Silkworms were not killed by injections with heat-killed M. abscessus subsp. abscessus cells. The administration of clarithromycin, an antibacterial drug used to treat the infection, prolonged the survival time of silkworms injected with M. abscessus subsp. abscessus. The LD50 values of 7 clinical isolates were determined using the silkworm infection model and differed by up to 9-fold. The Mb-17 isolate, which was identified as a pathogenic strain in the silkworm infection model, induced more detachment of human THP-1-derived macrophages during infection than the Mb-10 isolate. These findings suggest that the silkworm M. abscessus infection model with can be used to quantitatively evaluate the virulence of M. abscessus clinical isolates in a short time period.

microbiology↗

bioRxiv2020

A Novel DNA Chromatography Method to Distinguish M. abscessus Subspecies and Macrolide Susceptibility

RationaleThe clinical impact of infection with Mycobacterium abscessus complex (MABC), a group of emerging non-tuberculosis mycobacteria (NTM), is increasing. Mycobacterium abscessus subsp. abscessus/bolletii frequently shows natural resistance to macrolide antibiotics, whereas Mycobacterium abscessus subsp. massiliense is generally susceptible. Therefore, rapid and accurate discrimination of macrolide-susceptible MABC subgroups is required for effective clinical decisions about macrolide treatments for MABC infection. ObjectivesTo develop a simple and rapid diagnostic that can identify MABC isolates showing macrolide susceptibility. MethodsWhole genome sequencing (WGS) was performed for 148 clinical or environmental MABC isolates from Japan to identify genetic markers that can discriminate three MABC subspecies and the macrolide-susceptible erm(41) T28C sequevar. Using the identified genetic markers, we established PCR based- or DNA chromatography-based assays. Validation testing was performed using MABC isolates from Taiwan. Measurements and Main ResultsWe identified unique sequence regions that could be used to differentiate the three subspecies. Our WGS-based phylogenetic analysis indicated that M. abscessus carrying the macrolide-susceptible erm(41) T28C sequevar were tightly clustered, and identified 11 genes that were significantly associated with the lineage for use as genetic markers. To detect these genetic markers and the erm(41) locus, we developed a DNA chromatography method that identified three subspecies, the erm(41) T28C sequevar and intact erm(41) for MABC in a single assay within one hour. The agreement rate between the DNA chromatography-based and WGS-based identification was 99.7%. ConclusionsWe developed a novel, rapid and simple DNA chromatography method for identification of MABC macrolide susceptibility with high accuracy.

microbiology↗