Siderophores and beyond: A comprehensive review of iron acquisition in Klebsiella pneumoniae.

Iron is an essential nutrient for Klebsiella pneumoniae, a significant opportunistic pathogen. The host's innate immune system attempts to limit iron availability through nutritional immunity; however, K. pneumoniae has evolved sophisticated strategies to circumvent these defenses. This review explores the intricate mechanisms employed by K. pneumoniae to acquire iron from the host environment. We focus on the roles of siderophores, TonB-dependent transporters (TBDTs), and other iron acquisition systems in K. pneumoniae. Additionally, we discuss the regulation of iron acquisition, emphasizing the importance of intracellular iron storage and the Ferric Uptake Regulator (Fur). Novel therapeutic approaches based on these iron acquisition systems, including siderophore-associated antimicrobials, the use of gallium as an iron analog, and vaccines targeting siderophores and TBDTs, offer new insights into curbing severe K. pneumoniae infections. By elucidating the mechanisms of iron acquisition in K. pneumoniae, this review provides valuable insights into the pathogenesis of this opportunistic pathogen and presents potential strategies to combat multidrug-resistant and hypervirulent strains of K. pneumoniae.