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

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.

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, pO2 <8 kPa (60 mm Hg) or O2 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.

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); pO2 >8 kPa or O2-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).

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.