Use of Macrolides for Q Fever

Gikas et al. report on the use of macrolides as empirical treatment for acute Q fever infection (1). This is of interest as few works have been performed to evaluate empirical therapy of Q fever pneumonia. However, I believe that one should be cautious before recommending erythromycin in this indication based on such results. In this work no patient treated with doxycycline was febrile after 4 days of treatment whereas more than 30% of those treated by erythromycin were. This difference was highly significant (P = 0.005). As stated by the authors, there are many discrepancies in the literature as to the clinical efficacy of erythromycin. We believe that this is correlated with a heterogeneity of susceptibility among Coxiella burnetii isolates. In our work testing 13 strains we found that 6 of the 13 were completely resistant to erythromycin (3). The discrepancies about erythromycin efficiency among the series could partly reflect the level of resistance of the local strains. Altogether these data are not in favor of the use of erythromycin for Q fever, and I believe that the role of the new macrolides for which no antibiotic resistance was detected, such as clarithromycin (2) and telithromycin (4), should be further investigated.