"A REVIEW ON ANTIBIOTIC RESISTANCE & THEIR MECHANISM"

Antibiotic resistance (AR) has escalated into a global health crisis, threatening the very foundations of modern clinical medicine.[1] This review provides an in-depth exploration of how bacterial pathogens have evolved to withstand once-lethal chemical agents. The study begins by tracing the historical timeline from the "Golden Age" of discovery to the current "Post-Antibiotic Era," where common infections once again pose a fatal risk.[2] We examine the classification of antibiotics based on their chemical structure and analyze the intricate molecular mechanisms, such as efflux pumps and enzymatic inactivation, that bacteria employ to survive.[3] Furthermore, the role of horizontal gene transfer via plasmids is highlighted as a primary driver for the rapid dissemination of resistance across diverse bacterial species.[4] The review also addresses the critical impact of socio-economic factors, specifically the irrational use of drugs in healthcare and growth promoters in the livestock industry.[5] Statistical data presented herein underlines the rising mortality rates associated with multi-drug resistant (MDR) organisms like MRSA and Carbapenem-resistant Enterobacteriaceae.[6] Finally, the paper evaluates emerging therapeutic frontiers, including bacteriophage therapy and CRISPRbased antimicrobials, emphasizing that a multidisciplinary "One Health" approach is essential to mitigate this escalating biological threat.[7]