U.S. Department of Defense


Date of this Version



Antimicrobial Agents and Chemotherapy 57(5) pp. 2434 (May 2013)


In their letter, Visca et al. have shown that P. aeruginosa can use deferiprone as an iron “carrier,” which in turn promotes bacterial growth in a low-iron M9 minimal medium (1). Since our initial publication, we have also observed that the presence of deferiprone (and some other iron chelators) at sub-MICs can promote the growth of clinical isolates of Acinetobacter baumannii in M9 minimal medium (our unpublished results). However, while these data are in agreement with the results published by de Léséleuc et al. with respect to deferiprone and A. baumannii (2), in our hands, they were also strain and chelator dependent. For example, we did not observe growth promotion with VK28 and A. baumannii (unpublished results). We agree with Visca et al. that the consequences of growth promoted by iron chelators at sub-MIC levels in minimal media need to be considered before clinical application. However, it is unclear how relevant these findings would be in vivo if a high-enough concentration of a chelator can be achieved (≥1× MIC). With systemic applications, these concentrations are not possible because of toxicity concerns, but for wound infections, a topical, nonsystemic application could be considered and was also highlighted in a recent review (3).