PROSPECTIVE CASE-CONTROL STUDY OF ROLE OF INFECTION IN PATIENTS WHO RECONSULT AFTER INITIAL ANTIBIOTIC-TREATMENT FOR LOWER RESPIRATORY-TRACT INFECTION IN PRIMARY-CARE

Objective: To assess direct and indirect evidence of active infection which may benefit from further antibiotics in adults who reconsult wit hin 4 weeks of initial antibiotic management of acute lower respirator y tract infection in primary care. Design: Observational study with a nested case-control group. Setting: Two suburban general practices in Arnold, Nottingham, over 7 winter months. Subjects: 367 adults aged 16 years and over fulfilling a definition of lower respiratory tract inf ection and treated with antibiotics. 74 (20%) patients who reconsulted within 4 weeks for the same symptoms and 82 ''control'' patients who did not were investigated in detail at follow up. Main outcome measure s: Direct and indirect evidence of active infection at the time of the reconsultation or the follow up visit with nurse for the controls. In vestigations performed included sputum culture, pneumococcal antigen d etecting viral and atypical pathogens by culture and polymerase chain reaction, and chest radiographs. Results: Demographic and clinical fea tures of the groups were similar. Two thirds of the 74 patients who re consulted received another antibiotic because the general practitioner suspected continuing infection. Any evidence of infection warranting antibiotic treatment was uncommon at reconsultation. The findings for the two groups were similar for the occurrence of identified pathogens ; chest x ray changes ofinfection (present in 13%); and C reactive pro tein concentrations, which had nearly all fallen towards normal. Only three patients in the reconsultation group had concentrations greater than or equal to 40 mg/L. Pathogens identified at follow up in the 156 patients in both groups included ampicillin sensitive bacteria in six . Atypical infections diagnosed in 27 (Chlamydia pneumoniae in 22) and viral infections in 54 had probably been present at the initial prese ntation. Conclusion: Our study suggests that active infection, which m ay benefit from further antibiotics, is uncommon in patients who recon sult after a lower respiratory tract infection, and a repeat antibioti c prescription should be the exception rather than the rule. Other fac tors, such as patients' perception of their illness, may be more impor tant than disease and infection in their decision to reconsult.