Identification of CTX-M-14 extended-spectrum beta-lactamase in clinical isolates of Shigella sonnei, Escherichia coli, and Klebsiella pneumoniae in Korea

Abstract

CTX-M-14 beta-lactamase was identified in a stool isolate of Shigella sonnei and in blood isolates of Escherichia coli (one isolate) and Klebsiella pneumoniae (two isolates) from different parts of Korea. The amino acid sequence differed by one amino acid from CTX-M-9 (Ala-231--> Val) and was identical to that of beta-lactamases recently found in China and Japan.

FIG. 1

The nucleotide and deduced amino acid sequences of the CTX-M-14 β-lactamase identified in four strains found in Korea. The upstream and downstream sequences are shown in italics. ∗, termination codon.

FIG. 2

Plasmid agarose gel electrophoresis. Lanes: 1, plasmid size standards from E. coli strain V517 (5); 2, E. coli J53 Azi^r/pMG270; 3, E. coli J53 Azi^r/pMG269; 4, E. coli J53 Azi^r/pMG267; 5, S. sonnei 153; 6, S. sonnei 153 × E. coli J53 Azi^r transconjugant selected with cefotaxime; 7, S. sonnei 153 × E. coli J53 Azi^r transconjugant selected with ampicillin. The lack of cefotaxime resistance suggests that the cefotaxime resistance gene was carried on the missing 77-kb plasmid.