Case Report|Articles in Press

A mixed infection involving Bacteroides denticanum, Lactobacillus salivarius, and Streptococcus anginosus as causative agents of abscess around a pharyngo-esophageal anastomosis and acute vertebral osteomyelitis: Identification by ribosomal RNA sequencing of bacterial isolates

Published:April 26, 2023DOI:


      Bacteroides denticanum” is an anaerobic, non-spore-forming, gram-negative bacterium with a rod morphology typical of canine, ovine, and macropod oral flora. There is only one report of bloodstream infection caused by “B. denticanum” from a dog bite in human. Here, we report a case with no history of animal contact who developed an abscess caused by “B. denticanum” around a pharyngo-esophageal anastomosis after undergoing balloon dilatation procedure for stenosis following laryngectomy. The patient was a 73-year-old man with laryngeal cancer, esophageal cancer, hyperuricemia, dyslipidemia, and hypertension with a 4-week history of cervical pain, sore throat, and fever. Computed tomography showed fluid collection on the posterior pharyngeal wall. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) identified Bacteroides pyogenes, Lactobacillus salivarius, and Streptococcus anginosus from abscess aspiration. 16S ribosomal RNA sequencing re-identified the Bacteroides species as “B. denticanum”. T2-weighted magnetic resonance images showed a high signal intensity adjacent to the anterior vertebral body of C3–C7. The diagnosis was peripharyngeal esophageal anastomotic abscess and acute vertebral osteomyelitis caused by “B. denticanum”, L. salivarius, and S. anginosus. The patient was treated with sulbactam ampicillin intravenously for 14 days and then switched to oral amoxicillin with clavulanic acid for 6 weeks. To our knowledge, this is the first report of a human infection caused by “B. denticanum” without a history of animal contact. Despite remarkable advancements facilitated by MALDI-TOF MS in microbiological diagnosis, the accurate identification of novel, emerging, or uncommon microorganisms and comprehending their pathogenicity, suitable therapy, and follow up necessitate sophisticated molecular approaches.



      16S rRNA (16S ribosomal RNA), CLSI (Clinical and Laboratory Standards), CVA/AMPC (amoxicillin clavulanic acid), MALDI-TOF MS (matrix-assisted laser desorption ionization-time-of-flight mass spectrometry), SBT/ABPC (ampicillin-sulbactam)
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Infection and Chemotherapy
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Wexler H.M.
        Bacteroides: the good, the bad, and the nitty-gritty.
        Clin Microbiol Rev. 2007; 20: 593-621
        • Hardham J.
        • Dreier K.
        • Wong J.
        • Sfintescu C.
        • Evans R.T.
        Pigmented-anaerobic bacteria associated with canine periodontitis.
        Vet Microbiol. 2005; 106: 119-128
        • Kitahara M.
        • Sakamoto M.
        • Ike M.
        • Sakata S.
        • Benno Y.
        Bacteroides plebeius sp. nov. and Bacteroides coprocola sp. nov., isolated from human faeces.
        Int J Syst Evol Microbiol. 2005; 55: 2143-2147
        • LPSN (List of Prokaryotic names with Standing in the Literature)
        Species “Bacteroides denticanum.
        • Dewhirst F.E.
        • Klein E.A.
        • Thompson E.C.
        • Blanton J.M.
        • Chen T.
        • Milella L.
        • et al.
        The canine oral microbiome.
        PLoS One. 2012; 7e36067
        • Riggio M.P.
        • Jonsson N.
        • Bennett D.
        Culture-independent identification of bacteria associated with ovine ‘broken mouth’ periodontitis.
        Vet Microbiol. 2013; 166: 664-669
        • Antiabong J.F.
        • Boardman W.
        • Moore R.B.
        • Brown M.H.
        • Ball A.S.
        The oral microbial community of gingivitis and lumpy jaw in captive macropods.
        Res Vet Sci. 2013; 95: 996-1005
        • Tkadlec J.
        • Krutova M.
        • Matejkova J.
        • Nyc O.
        • Drevinek P.
        Bloodstream infection caused by Bacteroides denticanum, a close relative of Bacteroides pyogenes, misidentified by MALDI TOF-mass spectrometry.
        Anaerobe. 2018; 54: 23-25
        • Fernández Vecilla D.
        • Oiartzabal Elorriaga U.
        • Urrutikoetxea Gutiérrez M.J.
        • Pérez Ramos I.S.
        • Díaz de Tuesta Del Arco J.L.
        Jaw osteomyelitis and myositis caused by Bacteroides pyogenes.
        Anaerobe. 2023; 79102670
        • Gual-de-Torrella A.
        • Suárez-Barrenechea A.I.
        • Del Toro M.D.
        Peptostreptococcus canis and Bacteroides pyogenes prosthetic joint infection.
        Enferm Infecc Microbiol Clín. 2019; 37 (English, Spanish): 347-348
        • Vecilla D.F.
        • Matheus M.P.R.
        • Hidalgo G.I.
        • de Tuesta Del Arco J.L.D.
        Osteomyelitis caused by Pasteurella multocida and Bacteroides pyogenes after cat bite.
        Eur J Clin Microbiol Infect Dis. 2023; 42: 125-128
        • Berbari E.F.
        • Kanj S.S.
        • Kowalski T.J.
        • Darouiche R.O.
        • Widmer A.F.
        • Schmitt S.K.
        • et al.
        Infectious Diseases Society of America (IDSA) clinical practice guidelines for the diagnosis and treatment of native vertebral osteomyelitis in adults.
        Clin Infect Dis. 2015; 61 (2015): e26-e46