[Choice of antimicrobial therapy for Legionnella infection]

Legionella pneumophila is an intracellularly-growing microorganism and the causative agent of Legionnaires' disease; this disease owes its name to the epidemic among American war veterans in Philadelphia in 1976. The analysis ofthe epidemic in Philadelphia revealed--retrospectively--that unlike beta-lactam antibiotica, erythromycin and tetracyclines provided protection against an unfavourable outcome. Despite the absence of prospective, blinded, randomised clinical trials, a well-founded choice for the antibiotic treatment of patients with a Legionella infection can be made using the evidence from in-vitro and cell culture studies, as well as studies in animal models. Although erythromycin, either or not in combination with rifampicin, is still recommended, there is not enough scientific evidence to support this as a first choice drug treatment. The available evidence suggests that quinolones (the most researched are ciprofloxacin and levofloxacin) are the treatment of choice in the case of severe Legionella pneumonia. Newer macrolides (especially azithromycin) have been shown to have some additional beneficial effect. However, the lack of an intravenous formulation limits the use of newer macrolides in severely ill patients.