title: Chronic rhinosinusitis and antibiotics: the good, the bad, and the ugly.
abstract: BACKGROUND
  Despite the recognition that bacteria are universally present in the sinuses of patients with chronic rhinosinusitis (CRS) no compelling role for a primary infectious etiology of CRS has been elucidated. CRS is a constellation of inflammatory diseases that typically involve either noneosinophilic or eosinophilic processes, distinct conditions that must be treated individually.
  
  
  METHODS
  The bacteria that are present in the sinuses may be innocuous bystanders but alternatively may contribute to the presence and severity of the disease through their ability to influence immune responses, function as immune adjuvants, provide antigens or superantigens that contribute to adaptive immune activation, or in forming the basis for the frequent acute superinfections. However, those bacteria that do contribute to the persistence and severity of CRS primarily reside in biofilms, and, as such, are not capable of being eradicated with antibiotics at the doses at which they can be used, even when local irrigation is considered.
  
  
  RESULTS
  Biofilms create an inhospitable environment for antibiotic potency by down-regulating the metabolic activity of their "core" bacteria, decreasing the oxygen concentration, and altering the pH at the core of the biofilm.
  
  
  CONCLUSIONS
  Ultimately, if topical antibiotics are considered, they should be primarily focused on treating acute exacerbations and choices of antibiotics should optimally be based on endoscopic culture. This should be done with the recognition that while under certain circumstances antibiotics can ameliorate the severity of CRS, even if bacterial eradication were possible, this would not eliminate the underlying primary pathogenic mechanism or the natural history of these conditions.
authors.affiliation: Department of Medicine, Asthma and Allergic Disease Center, Carter Immunology Center, University of Virginia Health System, Charlottesville, Virginia, USA.
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Kennedy
authors.forename: Larry
authors.initials: L
authors.lastname: Borish
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001419:Bacteria / Q000302:isolation & purification; D018441:Biofilms; D002908:Chronic Disease; D006801:Humans; D009297:Nasal Mucosa / Q000382:microbiology; D012220:Rhinitis / Q000209:etiology* / Q000382:microbiology; D012852:Sinusitis / Q000209:etiology* / Q000382:microbiology; D013210:Staphylococcus / Q000276:immunology; D018089:Superantigens / Q000276:immunology
chemical_list: D000900:Anti-Bacterial Agents; D018089:Superantigens