ESBLproducing

ESBL-producing refers to bacteria that carry and express extended-spectrum beta-lactamases (ESBLs), enzymes that hydrolyze many penicillins and expanded-spectrum cephalosporins, rendering these antibiotics ineffective. ESBLs are often located on plasmids, allowing rapid horizontal transfer between bacteria and contributing to the spread of resistance. The term is most commonly applied to members of the Enterobacterales, though other organisms can carry ESBLs.

The most frequent ESBL producers are Escherichia coli and Klebsiella pneumoniae; other Enterobacterales such as Klebsiella oxytoca, Proteus mirabilis, and Enterobacter spp. are also implicated. ESBL production is associated with infections acquired in hospitals and the community, including urinary tract infections, intra-abdominal infections, and bloodstream infections. Co-resistance to non–beta-lactam antibiotics is common due to linked resistance genes.

Genetic determinants include blaCTX-M, blaTEM, and blaSHV genes carried on plasmids. The spread of ESBLs is driven by antibiotic selection pressure and mobile genetic elements, enabling dissemination across regions and populations.

Diagnosis relies on phenotypic detection of ESBL activity through susceptibility testing and confirmatory methods, such as synergy or inoculum-based tests; molecular assays can identify specific ESBL genes.

Management focuses on selecting effective antimicrobial therapy based on susceptibility results. Carbapenems have traditionally been the treatment of choice for serious ESBL-producing infections, though newer beta-lactam–beta-lactamase inhibitor combinations and other agents may be appropriate in certain cases. Infection control measures, including contact precautions and rigorous hand hygiene, are essential to limit spread, and antimicrobial stewardship aims to minimize unnecessary antibiotic exposure.