The genus Peptostreptococcus has now nine species all of which are commensal bacteria, but some cause infections in soft tissues, pneumonia, appendicitis, sinusitis, periodontitis, dental plaque, superficial and deep infections in the neck, arthritis, abscesses, vaginitis, and urinary infections. Two species, P. anaerobicus and P. indolicum, cause similar infections in animals.1,3

Peptostreptococcus species are the most frequently isolated anaerobic bacteria from brain abscesses, along with Fusobacterium nucleatum and Bacteroides intermedius.2

It is estimated that approximately 20% of animal bites or scratches cause infections in humans. Bacterial culturing from pet bite infections in humans is found to be smilar to the oral microbiota of the pets. Infections in dog bite wounds are usually dominated by aerobic bugs, however, Peptostreptococcus species are also isolated from infected wounds.5 Peptostreptococcus has been found to be more prevalent in the throats of laryngeal cancer patients than healthy individuals.6 Recently a link between chronic periodontitis and Alzheimer disease has been confirmed. Tumor necrosis factor-α, a cytokine that is elevated in response to stimulations from periodonto-pathogens such as Peptostreptococcus micros has been implicated for initiation and the development of the disease.7


  1. Diagnostic Procedure in Veterinary Bacteriology and Mycology. Grace R. Carter, John R. Cole, Jr.
  2. Risk Factors Associated with Poor Outcomes in Patients with Brain Abscesses
  3. Oral Fluid Based Biomarkers in Periodontal Disease: Part 1. Saliva
  4. Odontogenic infections: Microbiology and management
  5. Review: The Important Bacterial Zoonoses in “One Health” Concept
  6. Microbiota in the Throat and Risk Factors for Laryngeal Carcinoma
  7. The effect of chronic periodontitis on serum levels of tumor necrosis factor-alpha in Alzheimer disease



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