Project description:Bacterial resistance to the third-generation cephalosporin antibiotics has become a major concern for public health. This study was aimed to determine the characteristics and distribution of bla CTX-M-14, which encodes an extended-spectrum β-lactamase, in Escherichia coli isolated from Guangdong Province, China. A total of 979 E. coli isolates isolated from healthy or diseased food-producing animals including swine and avian were examined for bla CTX-M-14 and then the bla CTX-M-14 -positive isolates were detected by other resistance determinants [extended-spectrum β-lactamase genes, plasmid-mediated quinolone resistance, rmtB, and floR] and analyzed by phylogenetic grouping analysis, PCR-based plasmid replicon typing, multilocus sequence typing, and plasmid analysis. The genetic environments of bla CTX-M-14 were also determined by PCR. The results showed that fourteen CTX-M-14-producing E. coli were identified, belonging to groups A (7/14), B1 (4/14), and D (3/14). The most predominant resistance gene was bla TEM (n = 8), followed by floR (n = 7), oqxA (n = 3), aac(6')-1b-cr (n = 2), and rmtB (n = 1). Plasmids carrying bla CTX-M-14 were classified to IncK, IncHI2, IncHI1, IncN, IncFIB, IncF or IncI1, ranged from about 30 to 200 kb, and with insertion sequence of ISEcp1, IS26, or ORF513 located upstream and IS903 downstream of bla CTX-M-14. The result of multilocus sequence typing showed that 14 isolates had 11 STs, and the 11 STs belonged to five groups. Many of the identified sequence types are reported to be common in E. coli isolates associated with extraintestinal infections in humans, suggesting possible transmission of bla CTX-M-14 between animals and humans. The difference in the flanking sequences of bla CTX-M-14 between the 2009 isolates and the early ones suggests that the resistance gene context continues to evolve in E. coli of food producing animals.
Project description:The purpose of this study is to determine whether the presence of pathogenic Escherichia coli in colon is associated with psychiatric disorders.
Project description:Investigation of whole genome gene expression level changes in a Escherichia coli MG1655 K-12 ∆fnr mutant, compared to the wild-type strain. The mutations engineered into this strain produce a strain lacking the FNR protein.
Project description:To investigate the regulatory targets of the RegR virulence regulon of rabbit specific enteropathogenic Escherichia coli strain E22
Project description:In order to understand the impact of genetic variants on transcription and ultimately in changes in observed phenotypes we have measured transcript levels in an Escherichia coli strains collection, for which genetic and phenotypic data has also been measured.
Project description:Responses of Escherichia coli W3110gyrb234 as they are upshifted to 42C Escherichia coli W3110gyrb234 cells sampled at several time points (2,5, 10, 40 min) as they are shifted to 42 C in LB, vs 0 min before upshift in LB
Project description:Despite the characterization of many aetiologic genetic changes. The specific causative factors in the development of sporadic colorectal cancer remain unclear. This study was performed to detect the possible role of Enteropathogenic Escherichia coli (EPEC) in developing colorectal carcinoma.
Project description:Eleven multidrug-resistant Escherichia coli isolates (comprising 6 porcine and 5 bovine field isolates) displaying fluoroquinolone (FQ) resistance were selected from a collection obtained from the University Veterinary Hospital (Dublin, Ireland). MICs of nalidixic acid and ciprofloxacin were determined by Etest. All showed MICs of nalidixic acid of >256 ?g/ml and MICs of ciprofloxacin ranging from 4 to >32 ?g/ml. DNA sequencing was used to identify mutations within the quinolone resistance-determining regions of target genes, and quantitative real-time PCR (qRT-PCR) was used to evaluate the expression of the major porin, OmpF, and component genes of the AcrAB-TolC efflux pump and its associated regulatory loci. Decreased MIC values to nalidixic acid and/or ciprofloxacin were observed in the presence of the efflux pump inhibitor phenylalanine-arginine-?-naphthylamide (PA?N) in some but not all isolates. Several mutations were identified in genes coding for quinolone target enzymes (3 to 5 mutations per strain). All isolates harbored GyrA amino acid substitutions at positions 83 and 87. Novel GyrA (Asp87 ? Ala), ParC (Ser80 ? Trp), and ParE (Glu460 ? Val) substitutions were observed. The efflux activity of these isolates was evaluated using a semiautomated ethidium bromide (EB) uptake assay. Compared to wild-type E. coli K-12 AG100, isolates accumulated less EB, and in the presence of PA?N the accumulation of EB increased. Upregulation of the acrB gene, encoding the pump component of the AcrAB-TolC efflux pump, was observed in 5 of 11 isolates, while 10 isolates showed decreased expression of OmpF. This study identified multiple mechanisms that likely contribute to resistance to quinolone-based drugs in the field isolates studied.