WHEN BACTERIA FIGHT BACK: UNDERSTANDING MULTIDRUG RESISTANCE AND ITS GENETIC ROOTS IN PATHOGENIC BACTERIA

Background: Antibiotic resistance was once considered a distant threat; today it is a clinical reality reshaping how we treat even routine infections. Multidrug resistance (MDR)—defined as non-susceptibility to agents across three or more antibiotic categories—has taken hold in hospitals and communities worldwide, leaving clinicians with dangerously few options. Objective: This review explores the genetic machinery behind MDR, examining how bacteria acquire, store, and share resistance genes, and how those genes translate into the mechanisms that defeat our drugs. Methods: We searched Scopus, PubMed, and Web of Science for literature published between 2005 and 2024, prioritizing primary research and authoritative reviews on resistance genetics and mechanisms. Results: MDR arises through four principal strategies: enzymatic drug destruction, active drug expulsion via efflux pumps, alteration of the drug's binding target, and tightening of the bacterial membrane against drug entry. The genes driving these strategies—ranging from bla-family beta-lactamases to mcr colistin-resistance genes—travel efficiently between organisms on plasmids, transposons, and integrons. Conclusion: Addressing MDR demands more than new drugs; it requires an intimate understanding of how bacteria think genetically, because only then can we design interventions that are truly durable.

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