A B S T R A C T
CTX-M genes are the most prevalent ESBL globally, infiltrating nosocomial, community and
environmental settings. Wild and domesticated animals may act as effective vectors for the
dissemination of CTX-producing Enterobacteriaceae. This study aimed to contextualise blaCTX-M-14-
positive, cephalosporin-resistant Enterobacteriaceae human infections and compared resistance and
pathogenicity markers with veterinary isolates.
Epidemiologically related human (n = 18) and veterinary (n = 4) blaCTX-M-14-positive E. coli were fully
characterised. All were typed by XbaI pulsed
field gel electrophoresis and ST. Chromosomal/plasmidic
locations of blaCTX-M-14 were deduced by S1-nuclease digestion, and association with ISEcp1 was
investigated by sequencing. Conjugation experiments assessed transmissibility of plasmids carrying
blaCTX-M-14. Presence of virulence determinants was screened by PCR assay and pathogenicity potential
was determined by in vitro Galleria mellonella infection models.
84% of clinical E. coli originated from community patients. blaCTX-M-14 was found ubiquitously
downstream of ISEcp1 upon conjugative plasmids (25–150 kb). blaCTX-M-14 was also found upon the
chromosome of eight E. coli isolates. CTX-M-14-producing E. coli were found at multiple hospital sites.
Clonal commonality between patient, hospitals and livestock microbial populations was found. In vivo
model survival rates from clinical isolates (30%) and veterinary isolates (0%) were significantly different
(p < 0.05). Co-transfer of blaCTX-M-14 and virulence determinants was demonstrated.
There is evidence of clonal spread of blaCTX-M-14-positive E. coli involving community patients and farm
livestock. blaCTX-M-14 positive human clinical isolates carry a lower intrinsic pathogenic potential than
veterinary E. coli highlighting the need for greater veterinary practices in preventing dissemination of
MDR E. coli among livestock.