Community-Onset Disease Caused by Citrobacter freundii Producing a Novel CTX-M β-Lactamase, CTX-M-30, in Canada

Strains of Citrobacter freundii intermediate to cefotaxime but sensitive to ceftazidime were isolated from four different patients in Canada. Sequencing of PCR products by use of CTX-M-specific primers revealed a new combination of four amino acid substitutions. This new gene was designated bla(CTX-M-30) and was encoded on a 3-kb plasmid. The pI of CTX-M-30 was 8.0.