Explore the vast range of titles available.

The high prevalence of methicillin-resistant Staphylococcus aureus (MRSA) ST398 among pigs in certain European countries and North America and its occurrence in other animal species raises a question concerning the molecular mechanisms mediating the success of this lineage. In this study a panel of S. aureus strains belonging to sequence type (ST) 5 (n = 4), ST8 (n = 5), ST15 (n = 5), ST22 (n = 8), clonal complex (CC) 30 (n = 8), CC97 (n = 8), CC130 (n = 4), CC151 (n = 4) and ST398 (n = 18) were screened by DNA microarray and PCR for the carriage of virulence and antimicrobial resistance genes. Isolates belonging to the same sequence type/clonal complex (ST/CC) were found to share similar virulence gene profiles. The ST398 lineage displayed the lowest content of virulence genes, which consisted mainly of genes detected among the majority or all of the analysed lineages. All MRSA ST398 isolates lacked accessory virulence genes that were detected in other ST/CC. In contrast to virulence genotype, the antimicrobial resistance genes profiles varied between isolates belonging to the same ST/CC and profile similarities could be observed for isolates from different lineages. MRSA ST398 isolates in particular displayed significant diversity and high content of antimicrobial resistance genes. This was comparable with certain MRSA belonging to other sequence types particularly the equine MRSA ST8. The apparent lack of significant virulence genes among MRSA ST398 strains, demonstrates that the lineage features a unique genetic background but no ST398-specific virulence markers could be identified.

The bacterial cell wall presents a barrier to the uptake of unmodified synthetic antisense oligonucleotides, such as peptide nucleic acids, and so is one of the greatest obstacles to the development of their use as therapeutic anti-bacterial agents. Cell-penetrating peptides have been covalently attached to antisense agents, to facilitate penetration of the bacterial cell wall and deliver their cargo into the cytoplasm. Although they are an effective vector for antisense oligonucleotides, they are not specific for bacterial cells and can exhibit growth inhibitory properties at higher doses. Using a bacterial cell growth assay in the presence of cefotaxime (CTX 16 mg/L), we have developed and evaluated a self-assembling non-toxic DNA tetrahedron nanoparticle vector incorporating a targeted anti- bla CTX-M-group 1 antisense peptide nucleic acid (PNA4) in its structure for penetration of the bacterial cell wall. A dose-dependent CTX potentiating effect was observed when PNA4 (0–40 μM) was incorporated into the structure of a DNA tetrahedron vector. The minimum inhibitory concentration (to CTX) of an Escherichia coli field isolate harboring a plasmid carrying bla CTX-M-3 was reduced from 35 to 16 mg/L in the presence of PNA4 carried by the DNA tetrahedron vector (40 μM), contrasting with no reduction in MIC in the presence of PNA4 alone. No growth inhibitory effects of the DNA tetrahedron vector alone were observed.

The putative virulence and antimicrobial resistance gene contents of extended spectrum β-lactamase (ESBL)-positive E. coli (n=629) isolated between 2005 and 2009 from humans, animals and animal food products in Germany, The Netherlands and the UK were compared using a microarray approach to test the suitability of this approach with regard to determining their similarities. A selection of isolates (n=313) were also analysed by multilocus sequence typing (MLST). Isolates harbouring bla(CTX-M-group-1) dominated (66%, n=418) and originated from both animals and cases of human infections in all three countries; 23% (n=144) of all isolates contained both bla(CTX-M-group-1) and bla(OXA-1-like) genes, predominantly from humans (n=127) and UK cattle (n=15). The antimicrobial resistance and virulence gene profiles of this collection of isolates were highly diverse. A substantial number of human isolates (32%, n=87) did not share more than 40% similarity (based on the Jaccard coefficient) with animal isolates. A further 43% of human isolates from the three countries (n=117) were at least 40% similar to each other and to five isolates from UK cattle and one each from Dutch chicken meat and a German dog; the members of this group usually harboured genes such as mph(A), mrx, aac(6')-Ib, catB3, bla(OXA-1-like) and bla(CTX-M-group-1). forty-four per cent of the MLST-typed isolates in this group belonged to ST131 (n=18) and 22% to ST405 (n=9), all from humans. Among animal isolates subjected to MLST (n=258), only 1.2% (n=3) were more than 70% similar to human isolates in gene profiles and shared the same MLST clonal complex with the corresponding human isolates. The results suggest that minimising human-to-human transmission is essential to control the spread of ESBL-positive E. coli in humans.

Sulforaphane is a naturally occurring isothiocyanate with promising chemopreventive activity. An analytical method, utilising liquid chromatography-MS/MS, which allows the determination of sulforaphane in small volumes of rat plasma following exposure to low dietary doses, was developed and validated, and employed to determine its absolute bioavailability and pharmacokinetic characteristics. Rats were treated with either a single intravenous dose of sulforaphane (2·8 μmol/kg) or single oral doses of 2·8, 5·6 and 28 μmol/kg. Sulforaphane plasma concentrations were determined in blood samples withdrawn from the rat tail at regular time intervals. Following intravenous administration, the plasma profile of sulforaphane was best described by a two-compartment pharmacokinetic model, with a prolonged terminal phase. Sulforaphane was very well and rapidly absorbed and displayed an absolute bioavailability of 82 %, which, however, decreased at the higher doses, indicating a dose-dependent pharmacokinetic behaviour; similarly, Cmax values did not rise proportionately to the dose. At the highest dose used, the rate of absorption constant kab, biological half-life t½ and apparent volume of distribution decreased significantly. It is concluded that in the rat orally administered sulforaphane is rapidly absorbed, achieving high absolute bioavailability at low dietary doses, but dose-dependent pharmacokinetics was evident, with bioavailability decreasing with increasing dose.

A wide range of chemicals with diverse structures derived from plant and environmental origins are reported to have hormonal activity. The potential for appreciable exposure of humans to such substances prompts the need to develop sensitive screening methods to quantiate and evaluate the risk to the public. Yeast cells transformed with plasmids encoding the human estrogen receptor and an estrogen responsive promoter linked to a reporter gene were evaluated for screening compounds for estrogenic activity. Relative sensitivity to estrogens was evaluated by reference to 17β-estradiol ( E2) calibration curves derived using the recombinant yeast cells, MCF-7 human breast cancer cells, and a prepubertal mouse uterotrophic bioassay. The recombinant yeast cell bioassay (RCBA) was approximately two and five orders of magnitude more sensitive to E2 than MCF-7 cells and the uterotrophic assay, respectively. The estrogenic potency of 53 chemicals, including steroid hormones, synthetic estrogens, environmental pollutants, and phytoestrogens, was measured using the RCBA. Potency values produced with the RCBA relative to E2 (100) included estrone (9.6), diethylstilbestrol (74.3), tamoxifen (0.0047), α-zearalanol (1.3), equol (0.085), 4-nonylphenol (0.005), and butylbenzyl phthalate (0.0004), which were similar to literature values but generally higher than those produced by the uterotrophic assay. Exquisite sensitivity, absence of test compound biotransformation, ease of use, and the possibility of measuring antiestrogenic activity are important attributes that argue for the suitability of the RCBA in screening for potential xenoestrogens to evaluate risk to humans, wildlife, and the environment.