Array based detection of antibiotic resistance genes in Gram negative bacteria isolated from retail poultry meat in the UK and Ireland.

The use of antibiotics in birds and animals intended for human consumption within the European Union (EU) and elsewhere has been subject to regulation prohibiting the use of antimicrobials as growth promoters and the use of last resort antibiotics in an attempt to reduce the spread of multi-resistant Gram negative bacteria. Given the inexorable spread of antibiotic resistance there is an increasing need for improved monitoring of our food. Using selective media, Gram negative bacteria were isolated from retail chicken of UK-Intensively reared (n=27), Irish-Intensively reared (n=19) and UK-Free range (n=30) origin and subjected to an oligonucleotide based array system for the detection of 47 clinically relevant antibiotic resistance genes (ARGs) and two integrase genes. High incidences of ß-lactamase genes were noted in all sample types, acc (67%), cmy (80%), fox (55%) and tem (40%) while chloramphenicol resistant determinants were detected in bacteria from the UK poultry portions and were absent in bacteria from the Irish samples. Denaturing Gradient Gel Electrophoresis (DGGE) was used to qualitatively analyse the Gram negative population in the samples and showed the expected diversity based on band stabbing and DNA sequencing. The array system proved to be a quick method for the detection of antibiotic resistance gene (ARG) burden within a mixed Gram negative bacterial population.

Elimination of electrically induced iontophoretic artefacts: implications for non-invasive assessment of peripheral microvascular function.

Iontophoretic assessment of skin microvascular function is complicated by the occurrence of electrically induced hyperaemia, especially at the cathode. Studies were performed to identify means of reducing such effects. Skin vasodilator responses were measured using a laser Doppler imager that controlled iontophoretic current delivery. A novel feature involved monitoring voltage across the iontophoresis chambers. Comparison between responses to vehicle (distilled H(2)O), acetylcholine (ACh) and sodium nitroprusside (SNP) showed electrically induced hyperaemia at the cathode associated with the vehicle, whose time course overlapped with that of the SNP response. Voltage across the chambers containing drugs dissolved in H(2)O was significantly (p = 0.018, n = 7) lower than the voltage profile of H(2)O alone. H(2)O iontophoresis was associated with cathodal hyperaemic responses in most subjects, whereas a 0.5% NaCl vehicle produced lower voltages and eliminated this artefact. Voltage.time integral rather than charge was the prime determinant of electrically induced hyperaemic responses. No significant correlation was found between skin fold thickness and either calculated skin resistance (r(2) = 0.0002) or vascular response to ACh (r(2) = 0.13). Smaller chamber size led to higher voltages and greater electrically induced hyperaemic responses. These appear to be prostaglandin dependent as they were ablated by cyclooxygenase inhibition. Use of a low-resistance vehicle combined with larger chamber sizes and lower currents can prevent such artefacts, thereby increasing the robustness of this methodology for clinical assessment of endothelial function.