Streptobacillus hongkongensis sp. nov., isolated from patients with quinsy and septic arthritis, and emended descriptions of the genus Streptobacillus and Streptobacillus moniliformis

Abstract

Two bacterial strains, HKU33T and HKU34, were isolated in Hong Kong from the pus aspirated from the right peritonsillar abscess of a patient with quinsy and the left elbow joint fluid of another patient with tophaceous gout and left elbow septic arthritis, respectively. The bacteria were Gramstain-negative, non-motile, non-spore-forming, non-haemolytic pleomorphic bacilli. They grew best on Columbia agar with 5% defibrinated sheep blood in an anaerobic environment or aerobic environment with 5% CO2. They also grew on chocolate agar but not on MacConkey agar. They were catalase-and cytochrome oxidase-negative. They showed a unique profile of enzyme activities distinguishable from their closely related species. Phylogenetic analysis of the complete 16S rRNA gene, and partial groEL, gyrB and recA gene sequences showed the two isolates formed a distinct branch within the family Leptotrichiaceae, being related most closely to Streptobacillus moniliformis. Hierarchical cluster analysis of mass spectra of whole-cell protein contents showed that strains HKU33T and HKU34 were closely related to each other, but were distinct from Streptobacillus moniliformis, Sneathia sanguinegens and ‘Leptotrichia amnionii’. The DNA G+C content of strain HKU33T was 26.0±2.1 mol% (mean±SD; n=3). DNA-DNA hybridization demonstrated ≤45.02% DNA relatedness between the two isolates and Streptobacillus moniliformis CCUG 13453T. A novel species, Streptobacillus hongkongensis sp. nov., is proposed to accommodate strains HKU33T and HKU34, with HKU33T (=JCM 18691T=NCTC 13659T=DSM 26322T) designated the type strain. Emended descriptions of the genus Streptobacillus and Streptobacillus moniliformis are also given.