Drug-induced crystalluria attributable to tosufloxacin in children.

BACKGROUND: Drug-induced crystalluria is reportedly caused by a large number of drugs. Tosufloxacin (TFLX), a second-generation fluoroquinolone antibiotic, is reported to cause kidney injury and crystalluria. We retrospectively analyzed patients with crystalluria caused by TFLX to clarify the clinical course of TFLX-induced crystalluria in children. METHODS: This study was designed as a retrospective case series using the database of the National Center for Global Medicine covering the period from January 1, 2020 to March 31, 2021. We enrolled pediatric patients aged 15 years or younger with crystalluria attributable to TFLX treated in our pediatric department and collected clinical data. RESULTS: Thirteen patients were diagnosed with crystalluria attributable to TFLX. The median age of the patients at diagnosis was 4.0 years (range, 0.8-15 years; interquartile range = 1.2-8.8 years), and five patients (38%) were male. Six patients (46%) had gastrointestinal symptoms such as vomiting and abdominal pain, and 12 patients (92%) had decreased oral intake. The median time to diagnosis after TFLX administration was 4 days (range, 2-7 days; interquartile range = 3-6 days). All patients received TFLX at the appropriate dose. Two patients (17%) were diagnosed with acute kidney injury, and both had gastrointestinal symptoms such as vomiting and abdominal pain. CONCLUSIONS: Crystalluria induced by TFLX occurred despite administration of the appropriate dose of TFLX. Physicians should recognize crystalluria and renal injury attributable to TFLX. It may be possible to prevent renal injury by discontinuing drug therapy.

Diazotrophic Anaeromyxobacter Isolates from Soils.

Biological nitrogen fixation is an essential reaction in a major pathway for supplying nitrogen to terrestrial environments. Previous culture-independent analyses based on soil DNA/RNA/protein sequencing could globally detect the nitrogenase genes/proteins of Anaeromyxobacter (in the class Deltaproteobacteria), commonly distributed in soil environments and predominant in paddy soils; this suggests the importance of Anaeromyxobacter in nitrogen fixation in soil environments. However, direct experimental evidence is lacking; there has been no research on the genetic background and ability of Anaeromyxobacter to fix nitrogen. Therefore, we verified the diazotrophy of Anaeromyxobacter based on both genomic and culture-dependent analyses using Anaeromyxobacter sp. strains PSR-1 and Red267 isolated from soils. Based on the comparison of nif gene clusters, strains PSR-1 and Red267 as well as strains Fw109-5, K, and diazotrophic Geobacter and Pelobacter in the class Deltaproteobacteria contain the minimum set of genes for nitrogenase (nifBHDKEN). These results imply that Anaeromyxobacter species have the ability to fix nitrogen. In fact, Anaeromyxobacter PSR-1 and Red267 exhibited N2-dependent growth and acetylene reduction activity (ARA) in vitro Transcriptional activity of the nif gene was also detected when both strains were cultured with N2 gas as a sole nitrogen source, indicating that Anaeromyxobacter can fix and assimilate N2 gas by nitrogenase. In addition, PSR-1- or Red267-inoculated soil showed ARA activity and the growth of the inoculated strains on the basis of RNA-based analysis, demonstrating that Anaeromyxobacter can fix nitrogen in the paddy soil environment. Our study provides novel insights into the pivotal environmental function, i.e., nitrogen fixation, of Anaeromyxobacter, which is a common soil bacterium.IMPORTANCEAnaeromyxobacter is globally distributed in soil environments, especially predominant in paddy soils. Current studies based on environmental DNA/RNA analyses frequently detect gene fragments encoding nitrogenase of Anaeromyxobacter from various soil environments. Although the importance of Anaeromyxobacter as a diazotroph in nature has been suggested by culture-independent studies, there has been no solid evidence and validation from genomic and culture-based analyses that Anaeromyxobacter fixes nitrogen. This study demonstrates that Anaeromyxobacter harboring nitrogenase genes exhibits diazotrophic ability; moreover, N2-dependent growth was demonstrated in vitro and in the soil environment. Our findings indicate that nitrogen fixation is important for Anaeromyxobacter to survive under nitrogen-deficient environments and provide a novel insight into the environmental function of Anaeromyxobacter, which is a common bacterium in soils.