Characterisation of extended-spectrum β-lactamases of the SHV family using a combination of PCR-single strand conformational polymorphism (PCR-SSCP) and PCR-restriction fragment length polymorphism (PCR-RFLP)

Abstract

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) has been developed to extend the identification of SHV β-lactamases previously characterised by PCR-single strand conformational polymorphism (PCR-SSCP) analysis alone. Eight bacteria, each producing a different SHV β-lactamase, were used in this study. These bacteria harbour bla SHV-1, bla SHV-2a, bla SHV-3, bla SHV-4, bla SHV-5 (two strains), bla SHV-11 and bla SHV-12. All isolates were characterised by PCR-SSCP and PCR-RFLP with DdeI and NheI digestion. By a combination of these techniques, the genes encoding these β-lactamases could be differentiated from each other. In addition, the PCR-RFLP technique theoretically can be applied to distinguish the genes encoding SHV-7, SHV-9, SHV-10, SHV-15, SHV-17 and SHV-24 from those encoding other SHV variants. We report a simple PCR-RFLP technique that can be used in epidemiological studies to enable the rapid characterisation of known SHV β-lactamases in a combination with the previously published PCR-SSCP analysis.