title: Bacterial interference in upper respiratory tract infections: a systematic review.
abstract: BACKGROUND
  Published definitions of bacterial interference (BI) differ, some focusing on changes in the normal flora and others on changes in subsequent infection. A need for consensus was identified at a roundtable discussion of BI in upper respiratory tract infections (URTI). We conducted a systematic review of the available data to justify a consensus definition of BI specific to URTI as "a dynamic, antagonistic interaction between at least 2 organisms that affects the life cycle of each, changes the microenvironment, and alters the organisms' colonization, invasiveness, and ability to affect the health of the host."
  
  
  METHODS
  Continued communication among the faculty postroundtable was used to identify and refine the search criteria to (1) in vitro and in vivo studies assessing bacterial URTI, (2) BI evaluated by response to treatment of URTI with antimicrobial agents, and (3) bacterial function in relation to interactions between normal (nonpathogenic) and pathological flora. The criteria were applied to systematic searches of MEDLINE (1950 onward), EMBASE (1974 onward), and the Cochrane Library (2007).
  
  
  RESULTS
  Twenty-nine studies met the inclusion criteria, most focused on children with recurrent infections. Qualitative analysis supports the consensus definition. Interfering organisms affected the life cycle of test pathogens and inhibited their colonization, invasiveness, and health outcomes. Data were insufficient for statistical analysis.
  
  
  CONCLUSIONS
  Interactions between interfering organisms and potential pathogens isolated from the same host can alter response to infection and treatment. More studies are needed, particularly in adults, to understand the role of interfering organisms, the influence of antibiotics, and the potential for recolonization posttreatment.
authors.affiliation: Head and Neck Institute, The Cleveland Clinic, Ohio, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Benninger
authors.forename: Itzhak
authors.initials: I
authors.lastname: Brook
authors.forename: Joel M
authors.initials: JM
authors.lastname: Bernstein
authors.forename: Janet R
authors.initials: JR
authors.lastname: Casey
authors.forename: Kristian
authors.initials: K
authors.lastname: Roos
authors.forename: Bradley
authors.initials: B
authors.lastname: Marple
authors.forename: Judith R
authors.initials: JR
authors.lastname: Farrar
mesh_terms: D000328:Adult; D000890:Anti-Infective Agents / Q000627:therapeutic use; D000898:Antibiosis / Q000187:drug effects; D001424:Bacterial Infections / Q000188:drug therapy / Q000382:microbiology*; D002648:Child; D032921:Consensus; D006801:Humans; D033183:Interdisciplinary Communication; D012008:Recurrence; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000382:microbiology*
chemical_list: D000890:Anti-Infective Agents