Advances in class I integron in extended-spectrum beta-lactamase producing bacteria

The multidrug resistance of ESBL-producing bacteria poses a serious problem in the clinical therapy. In recent years, some studies indicate that integrons are closely linked to the antibiotic resistance in bacterial pathogens. Class I integron is the most ubiquitous among clinical microbes and remains the focus of numerous investigations. Integrons are specialized genetic elements capable of capturing exogenous gene cassettes and ensuring their expression under the action of integrases. Integrons are natural cloning and expression systems in the function of integration and excision. It has been demonstrated that integrons can continuously capture and integrate multiple genes that confer resistance to antibiotics. The conjugative plasmids and transposons associated can serve as vehicles for the transmission of drug-resistance genes, leading to the serious trend of multidrug resistance. This paper reviews the structure of class I integron, the integration of gene cassettes by class I integron and the relationship between class I integron and multidrug resistance in ESBL-producing bacteria.