Relationship between moxifloxacin use and increased antibiotic resistance and possible anaphylactic reactions

We read with interest the recently published paper by Arshinoff and Modabber.1 We wish to point out some relevant issues that the authors failed to include. In the discussion, the authors propose that the highest known reported minimum inhibitory concentration required to inhibit the growth of 90% of organisms (MIC90) of a staphylococcal strain to moxifloxacin is 32 mg/L, and they perform all their calculations on the basis of this value. However, Asbell et al.2 recently reported an MIC90 of moxifloxacin against moxifloxacin-resistant coagulase-negative Staphylococcus (CoNS) of 64 mg/L. Pondering this information, we reviewed the tables presented in the article. In the most optimistic scenario for persistence of the antibiotic in the anterior chamber over time, the optimum MIC90 for moxifloxacin-resistant CoNS of the moxifloxacin preparation proposed by the authors would last less than 1 hour. Considering moxifloxacin-resistant CoNS represented the 50.5% of the CoNS isolates in the aforementioned article,2 not to mention the existing evidence of moxifloxacin-resistant strains reported in TRUST3 (75% to 85% of methicillin-resistant Staphylococcus aureus resistant to fluoroquinolones) and more recently by Yannuzzi et al.4 (34% of tested isolates resistant to moxifloxacin), we find this information worth mentioning. Another issue not discussed in depth in this article is the possibility of moxifloxacin anaphylactic reactions. Noteworthy, a series of 3 cases of immediate hypersensitivity reactions to oral administration of moxifloxacin and more recently a case report of anaphylactic shock after topical administration of moxifloxacin for endophthalmitis prophylaxis before cataract surgery5 were published. Even though the moxifloxacin anaphylactic reactions are probably very rare, we believe that when proposing a universal prophylactic method based on this antibiotic, this evidence must be considered. In conclusion, we believe that when discussing the role of moxifloxacin as a universal antibiotic in endophthalmitis prophylaxis in cataract surgery, growing resistance to moxifloxacin and its infrequent, but serious, adverse effects must be contemplated.