Streptococcus mitis strains causing severe clinical disease in cancer patients

Samuel Shelburne, Pranoti Sahasrabhojane, Miguel Saldana, Hui Yao, Xiaoping Su, Nicola Horstmann, Erika Thompson, Anthony R. Flores

Research output: Contribution to journalArticlepeer-review

97 Scopus citations


The genetically diverse viridans group streptococci (VGS) are increasingly recognized as the cause of a variety of human diseases. We used a recently developed multilocus sequence analysis scheme to define the species of 118 unique VGS strains causing bacteremia in patients with cancer; Streptococcus mitis (68 patients) and S. oralis (22 patients) were the most frequently identified strains. Compared with patients infected with non-S. mitis strains, patients infected with S. mitis strains were more likely to have moderate or severe clinical disease (e.g., VGS shock syndrome). Combined with the sequence data, whole-genome analyses showed that S. mitis strains may more precisely be considered as ≥2 species. Furthermore, we found that multiple S. mitis strains induced disease in neutropenic mice in a dose-dependent fashion. Our data define the prominent clinical effect of the group of organisms currently classified as S. mitis and lay the groundwork for increased understanding of this understudied pathogen.

Original languageEnglish (US)
Pages (from-to)762-771
Number of pages10
JournalEmerging Infectious Diseases
Issue number5
StatePublished - May 2014

ASJC Scopus subject areas

  • Epidemiology
  • Microbiology (medical)
  • Infectious Diseases


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