Growth of Acinetobacter baumannii impacted by iron chelation

Acinetobacter baumannii (AB) has become multidrug-resistant (MDR) in recent years, and, currently, there are limited effective treatment options. Nutrient metals (e.g. iron) are essential to the metabolic functions of AB. This study examined the impact of iron chelation on the growth of AB in vitro and in vivo. Susceptible and MDR-AB bloodstream isolates (n = 9) were recovered from different patients between 2011 and 2018. Clonal diversity was ascertained by Fourier-transform infrared spectroscopy. In vitro bacterial densities were measured over 20 h to determine growth profiles. Variable amounts of a chelating agent [deferiprone (DFP)] were added to create a concentration gradient. Galleria mellonella larvae were inoculated with an isolate, with and without DFP. Quantitative culture was used to ascertain the bacterial burden of aggregate larvae immediately and 4 h post-infection. Increasing concentrations of DFP caused a transient and concentration-dependent hindrance to in vitro growth, compared to the no-treatment group. In vivo bacterial burden immediately post-infection in both groups was comparable. After 4 h, the burden was much higher in the control group comparatively (8.7 and 6.7 log CFU g-1). These results support that micro-nutrient limitation has the potential of being a novel approach for treating high-risk infections due to MDR-AB.