No abstract

Aims: The transfer of tetO gene conferring resistance to tetracycline was studied between Campylobacter jejuni strains, in the digestive tract of chickens. Methods and Results: In vitro conjugation experiments were first performed in order to select donor/recipient couples for further in vivo assay. Then, chickens were inoculated with a donor/recipient couple of C. jejuni strains displaying spontaneous in vitro tetracycline resistance gene transfer. The donor was a tetracycline-resistant ampicillin-susceptible strain, and the recipient was a tetracycline-susceptible ampicillin-resistant strain. Chicken droppings were streaked on antimicrobial selective media and bi-resistant Campylobacter isolates were further characterized according to their donor or recipient flaA gene RFLP profile. The acquisition of tetracyclineresistance gene by the recipient C. jejuni strain from the donor C. jejuni strain was confirmed by tetO PCR. Conclusions: The study showed that transfer of tetO gene occurs rapidly and without antimicrobial selection pressure between C. jejuni strains in the digestive tract of chickens. Significance and Impact of the Study: The rapid and spontaneous transfer of tetO gene may explain the high prevalence of tetracycline resistance in chicken Campylobacter strains.

The data plead for combining phenotypic and genotypic approaches in the diagnosis of efflux-mediated resistance in P. aeruginosa.

No abstract

Pseudomonas aeruginosa causes severe nosocomial pneumonia in IntensiveCare Unit (ICU) patients, with an increased prevalence of multiresistant strains. We examined the impact of the use of antipseudomonal antibiotic(s) on the susceptibility of P. aeruginosa isolated from ICU patients with clinically suspected hospital-acquired pneumonia collected in five teaching hospitals

Capillary-driven microfluidics are simple to use and provide the opportunity to perform fast biological assays with nanogram quantities of reagents and microliters of sample. Here we describe capillary soft valves (CSVs) as a simple-to-implement and -actuate approach for stopping liquids in capillary-driven microfluidics. CSVs are inserted between wettable microstructures and work to block liquids owing to a capillary pressure barrier of a few kPa. This barrier is suppressed by pressing down the soft cover of the CSV using, for example, the tip of a pen. CSVs comprise a hard layer (in silicon or polymer) with wettable microstructures and a soft cover made of poly(dimethylsiloxane) (PDMS) here. CSVs have a footprint as small as 0.6 mm(2). We illustrate how these valves work in the context of detecting DNA analytes. Specifically, a dsDNA target (997 bp PCR product, non-purified) was detected at concentrations of 20 and 200 nM in a sample volume of 0.7 μL and within 10 min. The assay includes melting of the dsDNA at 95 °C, annealing of a 30-base biotinylated probe at 50 °C, and intercalation of a fluorescent dye into the re-hybridized dsDNA at 25 °C. Actuation of the CSV allows the DNA target-probe-dye complexes to flow over 100 μm wide, streptavidin receptor lines. This work suggests that CSVs can fulfil the requirements set by complex assays, in which elevated temperatures and reaction with probes, dyes and capture species are needed. CSVs therefore greatly complement capillary-driven microfluidics without adding significant design, fabrication and actuation issues.

Exposure of Streptococcus pneumoniae to subinhibitory MICs of ciprofloxacin, a substrate for efflux pumps, results in patA/B-mediated efflux whatever the initial level of expression of pmrA of the strain. Quinolones that are poorly (levofloxacin) or not affected (moxifloxacin, garenoxacin) in their activity by efflux transporters preferentially select for target site mutants.

There was an increase in the incidence of antibiotic resistance of C. coli between 1992-1996 and 2001-2002.