Genomic and phylogenomic analysis of Fusobacteriaceae family and proposal to reclassify Fusobacterium naviforme Jungano 1909 into a novel genus as Zandiella naviformis gen. nov., comb. nov. and reclassification of Fusobacterium necrophorum subsp. funduliforme as later heterotypic synonym of Fusobacterium necrophorum subsp. necrophorum and Fusobacterium equinum as later heterotypic synonym of Fusobacterium gonidiaformans

The family Fusobacteriaceae is a large family within the phylum Fusobacteriota. The reclassification of F. naviforme as Zandiella naviformis gen. nov., comb. nov. is proposed because of the separate and distinct phylogenetic situation on the basis of the results of 16S rRNA gene sequence analysis, the genetic and genomic differences from all other species and subspecies in the Fusobacteriaceae family. The type strain is ATCC 25832; CCUG 50052; NCTC 13121. In phylogenetic trees drawn using complete genome sequences and 16S rRNA gene sequences, F. necrophorum subsp. funduliforme and F. equinum were clades together with F. necrophorum subsp. necrophorum and F. gonidiaformans, respectively. The average nucleotide identity, average amino acid identity, and digital DNA-DNA hybridization values between themes exceeded the cut-off values for species delineation. Based on these results, F. necrophorum subsp. funduliforme and F. equinum should be reclassified as later heterotypic synonyms of F. necrophorum subsp. necrophorum and F. gonidiaformans, respectively.

Leptotrichia Bacteremia: 10-Year Retrospective Clinical Analysis and Antimicrobial Susceptibility Profiles

Leptotrichia species are anaerobic, Gram-negative bacilli increasingly recognized as pathogens capable of causing invasive infections such as bloodstream infection (BSI), particularly among immunocompromised patients. However, there is a paucity of data regarding epidemiology, antimicrobial susceptibility, optimal treatment, and clinical outcomes among patients with Leptotrichia bacteremia. Patient risk factors, treatment approaches, and outcomes of a retrospective cohort of adult patients with Leptotrichia BSI at a tertiary medical center (Mayo Clinic Rochester [MCR]) were evaluated. Concurrently, species, temporal trends, and antimicrobial susceptibility testing (AST) results of Leptotrichia isolates submitted to a reference laboratory (Mayo Clinic Laboratories) over the past 10 years were examined. We identified 224 blood culture isolates of Leptotrichia species, with 26 isolates from patients treated at MCR. The most frequent species included L. trevisanii (49%), L. buccalis (24%), and L. wadei (16%). Leptotrichia species demonstrated >90% susceptibility to penicillin, metronidazole, ertapenem, and piperacillin-tazobactam. However, 96% (74/77) of isolates were resistant to moxifloxacin. For patients treated at MCR, the mean patient age was 55 years (standard deviation [SD], 17), with 9 females (35%), and all were neutropenic at the time of BSI. The primary sources of infection were gastrointestinal (58%), intravascular catheter (35%), and odontogenic (15%). Patients were treated with metronidazole (42%), piperacillin-tazobactam (27%), or carbapenems (19%). The mean duration of treatment was 11 days (SD, 4.5), with a 60-day all-cause mortality of 19% and no microbiologic relapse. Leptotrichia species are rare but important causes of BSI in neutropenic patients. Due to evolving antimicrobial susceptibility profiles, a review of AST results is necessary when selecting optimal antimicrobial therapy.

Update on Accepted Novel Bacterial Isolates Derived from Human Clinical Specimens and Taxonomic Revisions Published in 2020 and 2021

A number of factors, including microbiome analyses and the increased utilization of whole-genome sequencing in the clinical microbiology laboratory, has contributed to the explosion of novel prokaryotic species discovery, as well as bacterial taxonomy revision. This review attempts to summarize such changes relative to human clinical specimens that occurred in 2020 and 2021, per primary publication in the International Journal of Systematic and Evolutionary Microbiology or acceptance on Validation Lists published by the International Journal of Systematic and Evolutionary Microbiology. Of particular significance among valid and effectively published taxa within the past 2 years were novel Corynebacterium spp., coagulase-positive staphylococci, Pandoraea spp., and members of family Yersiniaceae. Noteworthy taxonomic revisions include those within the Bacillus and Lactobacillus genera, family Staphylococcaceae (including unifications of subspecies designations to species level taxa), Elizabethkingia spp., and former members of Clostridium spp. and Bacteroides spp. Revisions within the Brucella genus have the potential to cause deleterious effects unless the relevance of such changes is properly communicated by microbiologists to stakeholders in clinical practice, infection prevention, and public health.

Infection in a Young Immunocompetent Male Caused by Streptobacillus felis, a Putative Zoonotic Microorganism Transmitted by Cats

Rat bite fever (RBF) is predominantly caused by Streptobacillus moniliformis. We report a human infection with Streptobacillus felis. Clinical presentation was consistent with RBF, but serologic testing was negative for S moniliformis. Eventually, S felis-specific sequences were detected in skin lesions of the patient and in the oropharynx of local cats.