Aetiological role of viral and bacterial infections in acute adult lower respiratory tract infection (LRTI) in primary care

• Published in: Thorax Vol. 61; no. 1; pp. 75 - 79
• Main Authors: Creer, D D, Dilworth, J P, Gillespie, S H, Johnston, A R, Johnston, S L, Ling, C, Patel, S, Sanderson, G, Wallace, P G, McHugh, T D
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and British Thoracic Society 01.01.2006; BMJ; BMJ Publishing Group LTD; BMJ Group
• Subjects: Acute Disease; Adult; Aged; Anti-Bacterial Agents - therapeutic use; Antibiotics; Bacteria; Bacterial infections; Bacterial Infections - complications; Bacterial Infections - drug therapy; Biological and medical sciences; Case-Control Studies; Chlamydophila pneumoniae; Community-Acquired Infections - microbiology; Community-Acquired Infections - virology; Coronaviruses; Etiology; Female; Humans; Influenza; influenza virus; Laboratories; Legionella pneumophila; lower respiratory tract infection; lower respiratory tract infections; LRTI; Male; Medical sciences; Middle Aged; Mycoplasma pneumoniae; Pathogens; Patients; Pneumology; polymerase chain reaction; Primary care; Respiratory Infection; Respiratory syncytial virus; Respiratory system : syndromes and miscellaneous diseases; Respiratory Tract Infections - drug therapy; Respiratory Tract Infections - microbiology; Respiratory Tract Infections - virology; Reverse Transcriptase Polymerase Chain Reaction; Rhinovirus; RSV; RT-PCR; Serology; Sputum - microbiology; Streptococcus infections; Streptococcus pneumoniae; Tuberculosis; Virus Diseases - complications; Virus Diseases - drug therapy; Viruses; United Kingdom > UK; Human; Lung disease; Pneumonia; Respiratory disease; Acute; Cardiovascular disease; Care; Infection; Viral disease; Primary; Bacteriosis; Adult; Pneumopathy
• ISSN: 0040-6376; 1468-3296
• DOI: 10.1136/thx.2004.027441

Background: Lower respiratory tract infections (LRTI) are a common reason for consulting general practitioners (GPs). In most cases the aetiology is unknown, yet most result in an antibiotic prescription. The aetiology of LRTI was investigated in a prospective controlled study. Methods: Eighty adults presenting to GPs with acute LRTI were recruited together with 49 controls over 12 months. Throat swabs, nasal aspirates (patients and controls), and sputum (patients) were obtained and polymerase chain reaction (PCR) and reverse transcriptase polymerase chain reaction (RT-PCR) assays were used to detect Streptococcus pneumoniae, Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila, influenza viruses (AH1, AH3 and B), parainfluenza viruses 1–3, coronaviruses, respiratory syncytial virus, adenoviruses, rhinoviruses, and enteroviruses. Standard sputum bacteriology was also performed. Outcome was recorded at a follow up visit. Results: Potential pathogens were identified in 55 patients with LRTI (69%) and seven controls (14%; p<0.0001). The identification rate was 63% (viruses) and 26% (bacteria) for patients and 12% (p<0.0001) and 6% (p = 0.013), respectively, for controls. The most common organisms identified in the patients were rhinoviruses (33%), influenza viruses (24%), and Streptococcus pneumoniae (19%) compared with 2% (p<0.001), 6% (p = 0.013), and 4% (p = 0.034), respectively, in controls. Multiple pathogens were identified in 18 of the 80 LRTI patients (22.5%) and in two of the 49 controls (4%; p = 0.011). Atypical organisms were rarely identified. Cases with bacterial aetiology were clinically indistinguishable from those with viral aetiology. Conclusion: Patients presenting to GPs with acute adult LRTI predominantly have a viral illness which is most commonly caused by rhinoviruses and influenza viruses.