title: Bacteria in the respiratory tract-how to treat? Or do not treat?
abstract: BACKGROUND
  Acute and chronic respiratory tract infections are a common cause of inappropriate antimicrobial prescription. Antimicrobial therapy leads to the development of resistance and the emergence of opportunistic pathogens that substitute the indigenous microbiota.
  
  
  METHODS
  This review explores the major challenges and lines of research to adequately establish the clinical role of bacteria and the indications for antimicrobial treatment, and reviews novel therapeutic approaches.
  
  
  RESULTS
  In patients with chronic pulmonary diseases and structural disturbances of the bronchial tree or the lung parenchyma, clinical and radiographic signs and symptoms are almost constantly present, including a basal inflammatory response. Bacterial adaptative changes and differential phenotypes are described, depending on the clinical role and niche occupied. The respiratory tract has areas that are potentially inaccessible to antimicrobials. Novel therapeutic approaches include new ways of administering antimicrobials that may allow intracellular delivery or delivery across biofilms, targeting the functions essential for infection, such as regulatory systems, or the virulence factors required to cause host damage and disease. Alternatives to antibiotics and antimicrobial adjuvants are under development.
  
  
  CONCLUSIONS
  Prudent treatment, novel targets, and improved drug delivery systems will contribute to reduce the emergence of antimicrobial resistance in lower respiratory tract infections.
authors: Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d'Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Ctra del Canyet s/n, 08916 Badalona, Barcelona, Spain; CIBER Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain. Electronic address: crisprat2010@gmail.com.
authors: Cristina
authors: C
authors: Prat
authors: Microbiology Department, Hospital Universitari Germans Trias i Pujol, Institut d'Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, Ctra del Canyet s/n, 08916 Badalona, Barcelona, Spain; CIBER Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.
authors: Alicia
authors: A
authors: Lacoma
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use; D000890:Anti-Infective Agents / Q000008:administration & dosage*; D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development / Q000472:pathogenicity; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D004337:Drug Carriers; D016503:Drug Delivery Systems; D054884:Host-Pathogen Interactions; D006801:Humans; D008168:Lung / Q000382:microbiology; D064307:Microbiota; D000071059:Phage Therapy; D012141:Respiratory Tract Infections / Q000188:drug therapy* / Q000382:microbiology; D037521:Virulence Factors / Q000032:analysis / Q000235:genetics / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D004337:Drug Carriers; D037521:Virulence Factors
keywords: Alternatives to antibiotics; Bacterial colonization; Lower respiratory tract infection; Novel therapeutic approaches; Prudent use of antibiotics