The past, present, future of Listeria monocytogenes: Understanding the molecular pathways, antibiotic resistance and public health implications

Antibiotic resistance is a grave, potential threat to global health due to the continuing difficulty in treating bacterial infections. Misuse and overuse of antibiotics in humans and animals increase this resistance by creating "superbugs" impervious to multiple drug therapies. One pathogen that is acquiring resistance is Listeria monocytogenes , a gram-positive bacterium responsible for listeriosis, mainly in immunocompromised individuals. This pathogen's potential for biofilm formation in food processing environments enhances the threat even more, since such biofilms protect the bacteria from standard cleaning procedures and enhance its resistance to antibiotics. Listeria monocytogenes has several mechanisms of resistance against antibiotics by genetic alternations, efflux pumps, and biofilm formation, which exclude the antibiotic, and enzymatic degradation. These mechanisms make the bacteria successful in surviving a hostile environment and resisting several classes of antibiotics; hence, listeriosis is increasingly difficult to treat. It is, therefore, very important to understand the molecular dynamics of Listeria monocytogenes and its strategies of resistance if the design of new therapeutic approaches is to be successful and public health measures are to be effective in controlling the spread of the pathogen. Precisely, this paper attempts a detailed review of the mechanisms of Listeria monocytogenes pathogenesis and antibiotic resistance, together with public health implications that call for urgent innovative strategies in the war against this resilient pathogen. • L. monocytogenes exhibits multidrug resistance via efflux pumps, biofilms, and enzymes. • Genetic modifications enhance L. monocytogenes resistance to β-lactams and fluoroquinolones. • Biofilm formation protects L. monocytogenes from antibiotics in food processing environments. • Novel therapies include bacteriophages, antimicrobial peptides, and C-Met inhibitors. • Public health measures are essential to curb L. monocytogenes outbreaks and resistance spread.