The article discusses the emergence and spread of CTX-M extended-spectrum β-lactamases (ESBLs), which are a group of β-lactamases that confer resistance to a wide range of β-lactam antibiotics, including cefotaxime and ceftazidime. These enzymes are classified into four classes based on their amino acid sequences, with classes A and C being the most common in bacteria. The CTX-M enzymes, first identified in the late 1980s, have since spread globally, becoming a major concern in regions such as South America, the Far East, and Eastern Europe. The CTX-M enzymes are derived from natural β-lactamases found in species such as Kluyvera ascorbata, Kluyvera georgiana, and Kluyvera cryocrescens, and have been transferred to plasmids through various genetic mechanisms, including insertion sequences and integrons. CTX-M enzymes are known for their high resistance to cefotaxime, but their susceptibility to ceftazidime varies depending on the specific enzyme. The CTX-M enzymes are often found in clinical strains of Enterobacteriaceae, including Escherichia coli, Klebsiella pneumoniae, and Citrobacter freundii, and are associated with nosocomial infections. The spread of CTX-M enzymes is thought to be driven by the overuse of β-lactam antibiotics, particularly cefotaxime and ceftriaxone, which has led to the emergence of resistant strains. The CTX-M enzymes are also implicated in community-acquired infections, such as those caused by non-typhoid Salmonella and Shigella species. The CTX-M enzymes are characterized by their ability to hydrolyze a wide range of β-lactam antibiotics, including cefotaxime and ceftazidime, and are often resistant to β-lactamase inhibitors such as clavulanate and tazobactam. The CTX-M enzymes have been shown to evolve over time, with some variants exhibiting increased activity against ceftazidime. The spread of CTX-M enzymes is a significant public health concern, as they can lead to treatment failures and the emergence of more resistant strains. The article highlights the importance of monitoring the spread of CTX-M enzymes and developing new strategies to combat their resistance.The article discusses the emergence and spread of CTX-M extended-spectrum β-lactamases (ESBLs), which are a group of β-lactamases that confer resistance to a wide range of β-lactam antibiotics, including cefotaxime and ceftazidime. These enzymes are classified into four classes based on their amino acid sequences, with classes A and C being the most common in bacteria. The CTX-M enzymes, first identified in the late 1980s, have since spread globally, becoming a major concern in regions such as South America, the Far East, and Eastern Europe. The CTX-M enzymes are derived from natural β-lactamases found in species such as Kluyvera ascorbata, Kluyvera georgiana, and Kluyvera cryocrescens, and have been transferred to plasmids through various genetic mechanisms, including insertion sequences and integrons. CTX-M enzymes are known for their high resistance to cefotaxime, but their susceptibility to ceftazidime varies depending on the specific enzyme. The CTX-M enzymes are often found in clinical strains of Enterobacteriaceae, including Escherichia coli, Klebsiella pneumoniae, and Citrobacter freundii, and are associated with nosocomial infections. The spread of CTX-M enzymes is thought to be driven by the overuse of β-lactam antibiotics, particularly cefotaxime and ceftriaxone, which has led to the emergence of resistant strains. The CTX-M enzymes are also implicated in community-acquired infections, such as those caused by non-typhoid Salmonella and Shigella species. The CTX-M enzymes are characterized by their ability to hydrolyze a wide range of β-lactam antibiotics, including cefotaxime and ceftazidime, and are often resistant to β-lactamase inhibitors such as clavulanate and tazobactam. The CTX-M enzymes have been shown to evolve over time, with some variants exhibiting increased activity against ceftazidime. The spread of CTX-M enzymes is a significant public health concern, as they can lead to treatment failures and the emergence of more resistant strains. The article highlights the importance of monitoring the spread of CTX-M enzymes and developing new strategies to combat their resistance.