Bdellovibrio bacteriovorus: mechanisms, problems, and prospects against MDR respiratory infections

The rising rate of multidrug resistance (MDR) among bacteria is a real threat to public health across the globe, necessitating novel solutions that are beyond pharmacological approaches. The appearance of <i>Bdellovibrio bacteriovorus</i> as a predatory Gram-negative bacterium has become an alternative source to treat antibiotic-resistant infections, especially in cases of respiratory tract infections by pathogenic organisms like <i>Klebsiella pneumoniae</i> and <i>Pseudomonas aeruginosa</i>. <i>In vivo</i> studies demonstrate that intranasal administration of <i>Bdellovibrio bacteriovorus</i> reduces <i>Klebsiella pneumoniae</i> lung burden by more than 3 log₁₀ in rat models, while <i>in vitro</i> studies report significant disruption of <i>P. aeruginosa</i> biofilms and reduced epithelial invasion. The targeting of Gram-negative bacteria by this bacterium is the key to success, as this bacterium can prey upon Gram-negative bacteria and biofilm-forming bacteria. Nonetheless, Gram-positive bacteria have not been fully utilized in the application of <i>Bdellovibrio bacteriovorus</i>. In this review, our study aims to discuss antibiotic resistance, the <i>Bdellovibrio</i> life cycle, <i>Bdellovibrio bacteriovorus</i> against Gram-negative and Gram-positive bacteria, its shortcomings, and the way it could be applied, most especially against respiratory infections. However, important limitations remain, including incomplete eradication of prey populations, transient phenotypic resistance, and the absence of long-term or human clinical safety data. This review highlights the potential of <i>B. bacteriovorus</i> as an active antibacterial agent and draws attention to its clinical use to solve the current MDR respiratory infections.