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Few studies have compared CTX-M encoding plasmids identified in different ecological sources. This study aimed to analyze and compare the molecular epidemiology of plasmids encoding CTX-M-14 among strains from humans and animals. The CTX-M-14 encoding plasmids in 160 Escherichia coli isolates from animal faecal (14 pigs, 16 chickens, 12 cats, 8 cattle, 5 dogs and 3 rodents), human faecal (45 adults and 20 children) and human urine (37 adults) sources in 2002-2010 were characterized by molecular methods. The replicon types of the CTX-M-14 encoding plasmids were IncFII (n=61), I1-Iγ (n=24), other F types (n=23), B/O (n=10), K (n=6), N (n=3), A/C (n=1), HI1 (n=1), HI2 (n=1) and nontypeable (n=30). The genetic environment, ISEcp1 -bla(CTX-M-14) - IS903 was found in 89.7% (52/58), 87.7% (57/65) and 86.5% (32/37) of the animal faecal, human faecal and human urine isolates, respectively. Subtyping of the 61 IncFII incompatibility group plasmids by replicon sequence typing, plasmid PCR-restriction fragment length polymorphism and marker genes (yac, malB, eitA/eitC and parB/A) profiles showed that 31% (18/58), 30.6% (20/65) and 37.8% (14/37) of the plasmids originating from animal faecal, human faecal and human urine isolates, respectively, were pHK01-like. These 52 pHK01-like plasmids originated from diverse human (20 faecal isolates from 2002, 2007 to 2008, 14 urinary isolates from 2004) and animal (all faecal, 1 cattle, 1 chicken, 5 pigs, 9 cats, 1 dog, 1 rodent from 2008 to 2010) sources. In conclusion, this study highlights the importance of the IncFII group, pHK01-like plasmids in the dissemination of CTX-M-14 among isolates from diverse sources., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Objectives: 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., Methods: 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., Results: 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., Conclusions: 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.