Time to reconsider moxifloxacin anti-anaerobic activity?

Large data on moxifloxacin activity on anaerobes are old. Moxifloxacin is often used for empiric therapy therefore the knowledge of current epidemiologic data is fundamental. We analyzed 69 anaerobic strains, from a recent multicenter Italian study, for moxifloxacin susceptibility. Using EUCAST criteria 81% of Bacteroides spp. and 48% of anaerobes other than Bacteroides were resistant to moxifloxacin. Using CLSI criteria moxifloxacin resistance rates decrease to 35% for all anaerobes, and to 41% for Bacteroides spp. We reported an alarming increase in moxifloxacin resistance among anaerobes in Italy.