Predicting the presence of bacterial pathogens in the airways of primary care patients with acute cough.

BACKGROUND: Bacterial testing of all patients who present with acute cough is not feasible in primary care. Furthermore, the extent to which easily obtainable clinical information predicts bacterial infection is unknown. We evaluated the diagnostic value of clinical examination and testing for C-reactive protein and procalcitonin for bacterial lower respiratory tract infection. METHODS: Through a European diagnostic study, we recruited 3104 adults with acute cough (≤ 28 days) in primary care settings. All of the patients underwent clinical examination, measurement of C-reactive protein and procalcitonin in blood, and chest radiography. Bacterial infection was determined by conventional culture, polymerase chain reaction and serology, and positive results were defined by the presence of Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Bordetella pertussis or Legionella pneumophila. Using multivariable regression analysis, we examined the association of diagnostic variables with the presence of bacterial infection. RESULTS: Overall, 539 patients (17%) had bacterial lower respiratory tract infection, and 38 (1%) had bacterial pneumonia. The only item with diagnostic value for lower respiratory tract infection was discoloured sputum (area under the receiver operating characteristic [ROC] curve 0.56, 95% confidence interval [CI] 0.54-0.59). Adding C-reactive protein above 30 mg/L increased the area under the ROC curve to 0.62 (95% CI 0.59-0.65). For bacterial pneumonia, comorbidity, fever and crackles on auscultation had diagnostic value (area under ROC curve 0.68, 95% CI 0.58-0.77). Adding C-reactive protein above 30 mg/L increased the area under the ROC curve to 0.79 (95% CI 0.71-0.87). Procalcitonin did not add diagnostic information for any bacterial lower respiratory tract infection, including bacterial pneumonia. INTERPRETATION: In adults presenting with acute lower respiratory tract infection, signs, symptoms and C-reactive protein showed diagnostic value for a bacterial cause. However, the ability of these diagnostic indicators to exclude a bacterial cause was limited. Procalcitonin added no clinically relevant information.

Disease Course of Lower Respiratory Tract Infection With a Bacterial Cause.

PURPOSE: Bacterial pathogens are assumed to cause an illness course different from that of nonbacterial causes of acute cough, but evidence is lacking. We evaluated the disease course of lower respiratory tract infection (LRTI) with a bacterial cause in adults with acute cough. METHODS: We conducted a secondary analysis of a multicenter European trial in which 2,061 adults with acute cough (28 days' duration or less) were recruited from primary care and randomized to amoxicillin or placebo. For this analysis only patients in the placebo group (n = 1,021) were included, reflecting the natural course of disease. Standardized microbiological and serological analyses were performed at baseline to define a bacterial cause. All patients recorded symptoms in a diary for 4 weeks. The disease course between those with and without a bacterial cause was compared by symptom severity in days 2 to 4, duration of symptoms rated moderately bad or worse, and a return consultation. RESULTS: Of 1,021 eligible patients, 187 were excluded for missing diary records, leaving 834 patients, of whom 162 had bacterial LRTI. Patients with bacterial LRTI had worse symptoms at day 2 to 4 after the first office visit (P = .014) and returned more often for a second consultation, 27% vs 17%, than those without bacterial LRTI (P = .004). Resolution of symptoms rated moderately bad or worse did not differ (P = .375). CONCLUSIONS: Patients with acute bacterial LRTI have a slightly worse course of disease when compared with those without an identified bacterial cause, but the relevance of this difference is not meaningful.

Clinical relevance of bacterial resistance in lower respiratory tract infection in primary care: secondary analysis of a multicentre European trial.

BACKGROUND: The impact of antimicrobial resistance on clinical outcomes in patients with lower respiratory tract infection in primary care is largely unknown. AIM: To determine the illness course of infections with resistant bacteria in adults presenting to primary care with acute cough. DESIGN AND SETTING: Secondary analysis of a multicentre European trial in primary care. METHOD: A total of 2061 adults with acute cough (lasting ≤28 days) were recruited from primary care and randomised to amoxicillin or placebo. To reflect the natural course of disease, only patients in the placebo group (n = 1021) were eligible. Nasopharyngeal flocked swabs and/or sputa (when available) were analysed at baseline and Streptococcus pneumoniae and Haemophilus influenzae isolates underwent susceptibility testing. Patients recorded their symptoms in a diary every day for 4 weeks. Patients with and without resistant bacterial infection were compared with regards to symptom severity, duration of symptoms, worsening of illness, and duration of interference with normal activities or work. RESULTS: Of the 834 patients with diary records, 104 showed S. pneumoniae and/or H. influenzae infection. Of this number, 54 (52%) were resistant to antibiotics, while seven (7%) were resistant to penicillin. For the duration of symptoms rated 'moderately bad or worse' (hazard ratio 1.27, 95% confidence interval [CI] = 0.67 to 2.44), mean symptom severity (difference -0.48, 95% CI = -1.17 to 0.21), and worsening of illness (odds ratio 0.31, 95% CI = 0.07 to 1.41), there was no statistically significant difference between the antibiotic-resistant and antibiotic-sensitive groups. CONCLUSION: The illness course of antibiotic-resistant lower respiratory tract infection does not differ from that caused by antibiotic-sensitive bacteria.

Prevalence, diagnosis, and disease course of pertussis in adults with acute cough: a prospective, observational study in primary care.

BACKGROUND: Most cases of adult pertussis probably remain undiagnosed. AIM: To explore the prevalence, diagnosis, and disease course of acute pertussis infection in adult patients presenting with acute cough. DESIGN AND SETTING: Prospective observational study between 2007 and 2010 in primary care in 12 European countries. METHOD: Adults presenting with acute cough (duration of ≤28 days) were included. Bordetella pertussis infection was determined by polymerase chain reaction (from nasopharyngeal flocked swabs and sputa) and by measurement of immunoglobulin G antibodies to pertussis toxin (PT) in venous blood at day 28. An antibody titre to PT of ≥125 IU/ml or PCR positive result in a respiratory sample defined recent infection. Patients completed a symptom diary for 28 days. RESULTS: Serum and/or respiratory samples were obtained in 3074 patients. Three per cent (93/3074) had recent B. pertussis infection. Prior cough duration >2 weeks discriminated to some extent between those with and without pertussis (adjusted odds ratio 1.89, 95% confidence interval = 1.17 to 3.07; P = 0.010). Median cough duration after presentation was 17 and 12 days in patients with and without pertussis, respectively (P = 0.008). Patients with pertussis had longer duration of phlegm production (P = 0.010), shortness of breath (P = 0.037), disturbed sleep (P = 0.013) and interference with normal activities or work (P = 0.033) after presentation. CONCLUSION: Pertussis infection plays a limited role among adults presenting with acute cough in primary care, but GPs should acknowledge the possibility of pertussis in uncomplicated lower respiratory tract infection. As in children, pertussis also causes prolonged symptoms in adults. However, pertussis is difficult to discern from other acute cough syndromes in adults at first presentation.