Rapid decrease in the prevalence of macrolide-resistant group A streptococci due to the appearance of two epidemic clones in Cantabria (Spain)

after launch, 61% of the tigecycline prescriptions were ’off label’, especially for patients with ventilator-associated pneumonia (VAP) due to MDR Acinetobacter spp. (D. Curcio, F. Fernández and F. Duret, unpublished data). The high concentration in alveolar cells (77.5-fold higher than serum), the increase in carbapenem-resistant Acinetobacter spp. in Argentina (54%), the lack of medical evidence to use colistin in pulmonary infections and the association between inappropriate initial antibiotic therapy with mortality in patients with VAP (defined as the susceptibility of cultured organisms to the antibiotics used) seem to be the main reasons for using tigecycline in this indication. Concerning tigecycline and Acinetobacter spp. several points should be taken into account: (i) definitive breakpoints of susceptibility are not available; (ii) results for Phase 3 clinical trials regarding clinical efficacy of tigecycline in nosocomial pneumonia and other infections produced by MDR microorganisms are not available; and (iii) we know that the overexpression of the intrinsic multidrug efflux pump (AdeABC) may decrease the susceptibility to tigecycline in Acineto-bacter spp. However, at least in Argentina, some physicians consider this new antibiotic as a possibility to treat microbiologically documented severe infections caused by MDR A. baumannii, in order to improve the patient outcome when the therapeutic options are limited (i.e. isolates only susceptible to colistin). Moreover, from a clinical point of view, until data on tigecycline clinical efficacy in severe Acinetobacter spp. infections become available, before treating a patient, physicians must consider the pharmacological and microbiological profile of tigecycline for each specific patient condition and carefully assess local susceptibility data to support its use. Finally, we agree with the authors, that the high MICs for A. baumannii found by them is a worrisome local phenomenon and requires further investigation.