title: Human polymicrobial infections.
abstract: BACKGROUND
  Polymicrobial diseases, caused by combinations of viruses, bacteria, fungi, and parasites, are being recognised with increasing frequency. In these infections, the presence of one micro-organism generates a niche for other pathogenic micro-organisms to colonise, one micro-organism predisposes the host to colonisation by other micro-organisms, or two or more non-pathogenic micro-organisms together cause disease.
  
  
  BACKGROUND
  Recently, Gili Regev-Yochay (JAMA 2004; 292: 716-20) and Debby Bogaert (Lancet 2004; 363: 1871-72), and their colleagues, suggested another interaction: microbial interference-the ability of Streptococcus pneumoniae carriage to protect against Staphylococcus aureus carriage, and the inverse effect of pneumococcal conjugate vaccination on the increased carriage of Staph aureus and Staph-aureus-related disease. Strep pneumoniae carriage protected against Staph aureus carriage, and the bacterial interference could be disrupted by vaccinating children with pneumococcal conjugate vaccines that reduced nasopharyngeal carriage of vaccine-type Strep pneumoniae.
  
  
  CONCLUSIONS
  The medical community is recognising the significance of polymicrobial diseases and the major types of microbial community interactions associated with human health and disease. Many traditional therapies are just starting to take into account the polymicrobial cause of diseases and the repercussions of treatment and prevention.
authors.affiliation: Department of Periodontics and Dows Institute for Dental Research, College of Dentistry, University of Iowa, Iowa City, IA 52242, USA. kim-brogden@uiowa.edu
authors.forename: Kim A
authors.initials: KA
authors.lastname: Brogden
authors.forename: Janet M
authors.initials: JM
authors.lastname: Guthmiller
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Taylor
mesh_terms: D000898:Antibiosis; D001424:Bacterial Infections / Q000382:microbiology; D006801:Humans; D007239:Infections / Q000175:diagnosis / Q000382:microbiology* / Q000628:therapy; D014762:Viral Interference