Coverage of atypical pathogens for hospitalised patients with community-acquired pneumonia is not guided by clinical parameters

BACKGROUND: Although most experts recommend empirical antibiotic treatment, covering also atypical bacteria, for patients admitted to an intensive care unit (ICU), the data are not clear for patients admitted to a general ward. European guidelines recommend starting empirical treatment with a beta-lactam antibiotic with or without a macrolide, but the with/without is not clarified. We investigated whether the use of antibiotic coverage for atypical pathogens was guided by clinical parameters. METHODS: We retrospectively analysed 300 patients hospitalised with community-acquired pneumonia. Four parameters for possible atypical pneumonia (age < 55 years, abdominal symptoms, sodium < 130 mmol/l, immunosuppression) and three for pneumonia severity (pneumonia severity index [PSI], ICU admission, pO(2) < 8 kPa (60 mm Hg) or O-2 saturation < 90%) were defined and correlated with the probability of coverage for atypical pathogens. Correlations were calculated using the chi-square test for 2 x 2 tables. RESULTS: Patients younger than 55 years significantly more likely to receive coverage for atypical pathogens than older patients (odds ratio [OR] 2.68; 95% confidence interval [CI] 1.3-5.5, p = 0.009). In patients with a PSI > III the proportion receiving coverage for atypical bacteria was even smaller than in patients with less severe pneumonia (OR 0.77; 95% CI 0.60-0.99, p = 0.03), but no difference was found for PSI > IV compared with PSI = IV (OR = 1.03; 95% CI 0.61-1.74, p = 0.9). The other clinical parameters had no effect on antibiotic coverage: ICU admission (OR = 1.39; 95% CI 0.87-2.4, p = 0.15); pO(2) > 8 kPa or O-2-Saturation > 90% (OR 1.36; 95% CI 0.85-2.17, p = 0.19); abdominal symptoms (OR 1.06; 95% CI 0.51-2.25, p = 0.88); sodium < 130 mmol/l (OR 0.63; 95% CI 0.29-1.36, p = 0.2) or immunosuppression (OR 1.007; 95% CI 0.462-44, p = 1). There was also no correlation between the number of clinical parameters present and the coverage of atypical pathogens (r = 0.48). Mortality was no different between patients in whom atypical pathogens were covered compared with those with beta-lactam therapy alone (OR 1.2; 95% CI 0.66-2.25, p = 0.43). CONCLUSION: Physicians have difficulties deciding when to cover atypical pathogens in hospitalised patients with community-acquired pneumonia. Guidelines should clarify under what circumstances combination therapy is warranted.