Complete sequencing of the FII plasmid pHK01, encoding CTX-M-14, and molecular analysis of its variants among Escherichia coli from Hong Kong

• Published in: Journal of antimicrobial chemotherapy 2011-04, Vol.66 (4), p.752-756
• Main Authors: HO, P. L, LO, W. U, WONG, River C. W, YEUNG, M. K, CHOW, K. H, QUE, T. L, TONG, Amy H. Y, BAO, Jessie Y. J, LOK, Si, WONG, Samson S. Y
• Format: Article
• Language: English
• Subjects: Adult; Antibiotics. Antiinfectious agents. Antiparasitic agents; Bacterial proteins; beta -Lactamase; beta-Lactamases - genetics; Biological and medical sciences; Child; Child, Preschool; Colonization; Conjugation; Conjugation, Genetic; Cystitis; Cystitis - microbiology; Data processing; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; E coli; Escherichia coli; Escherichia coli - enzymology; Escherichia coli - genetics; Escherichia coli - isolation & purification; Escherichia coli Infections - microbiology; Female; Genotype; Homology; Hong Kong; Humans; Iron; Medical sciences; Molecular biology; Molecular Sequence Data; outer membrane proteins; Pharmacology. Drug treatments; Plasmids; Polymerase Chain Reaction; Polymorphism; Polymorphism, Restriction Fragment Length; Restriction fragment length polymorphism; Sequence Analysis, DNA; Studies; Toxins; Typing; Variable region
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkr010

We characterized plasmids encoding CTX-M-14 β-lactamase originating from Escherichia coli isolates recovered from patients with uncomplicated cystitis or individuals with faecal colonization in Hong Kong from 2002 to 2004. Plasmids carrying CTX-M-14 were studied by conjugation, replicon typing, S1 nuclease-PFGE and plasmid PCR-restriction fragment length polymorphism (RFLP). The complete sequence of pHK01, a 70 kb plasmid encoding CTX-M-14 from an E. coli strain, was determined and the results compared with reference plasmids and aligned with GenBank data. The blaCTX-M-14 plasmids could be transferred in 23 of 44 E. coli strains tested. Among the 23 transconjugants, the replicon types of the CTX-M-14-encoding plasmid were FII (n=13), I1-Iγ (n=4), F1B (n=2), FII and I1-Iγ (n=1), K (80 kb, n=1) and undetermined (n=2). Plasmid pHK01 (FII replicon) shares a high degree of homology with R100 except mainly for a 11 kb variable region containing blaCTX-M-14 (with an upstream ISEcp1 and a downstream truncated IS903), an iron transport system, an outer membrane protein (malB, maltoporin) and a putative toxin-antitoxin plasmid stability system (yacABC). It was highly related to blaCTX-M-14 (pKF3-70) and blaCTX-M-24 (pEG356) plasmids reported from mainland China in 2006 and Vietnam in 2007, respectively. Subtyping by a plasmid PCR-RFLP scheme showed that 10 of the 13 FII plasmids originating from isolates collected by multiple laboratories exhibited either identical or highly similar profiles. This study showed that narrow host-range FII plasmids play important roles in the dissemination of CTX-M-14. FII plasmids closely related to pHK01 have disseminated widely in the Hong Kong community.