Molecular analysis of OXA-48-carrying conjugative IncL/M-like plasmids in clinical isolates of Klebsiella pneumoniae in Ireland.

This study characterized an IncL/M-like plasmid containing a bla(OXA-48)-encoding gene from a clinical isolate of Klebsiella pneumoniae, denoted as E71T. Investigation of this plasmid sequence identified unique regions of interest along with conserved regions detected in eight other clinical carbapenem-resistant isolates. A 63-kb plasmid (pE71T) from K. pneumoniae E71T was sequenced and found to be highly similar to the recently published K. pneumoniae pOXA-48a (JN626286). Two copies of the insertion sequence element IS1R were identified, one of which was located adjacent to the bla(OXA-48)-encoding gene forming part of a composite transposon Tn1999.2 and the second located 16-kb downstream. Plasmid profiling and PCR assays confirmed that the pE71T backbone was conserved among the eight other clinical bla(OXA-48)-positive isolates, and in all cases, the OXA-48 genes were part of the Tn1999.2 composite transposon. This is the first report of a bla(OXA-48) and IS1R arrangement-containing plasmid in Ireland.

Further characterization of three Yersinia enterocolitica strains with a nalidixic acid-resistant phenotype isolated from humans with diarrhea.

Antimicrobial-resistant bacteria pose a threat to public health. Three Yersinia enterocolitica strains cultured from patients presenting with diarrhea and resistant to nalidixic acid were studied. Target gene mutations in gyrA alone were identified as part of the genetic basis for this phenotype. Efflux activity was also noted, since the presence of the efflux pump inhibitor, phenylalanine-arginine-ß-naphthylamide, increased susceptibility to nalidixic acid.

Susceptibility of Campylobacter to high intensity near ultraviolet/visible 395±5nm light and its effectiveness for the decontamination of raw chicken and contact surfaces.

Campylobacter is an important cause of human gastroenteritis worldwide. Chicken meat is frequently contaminated with this organism and is considered to be a significant source of infection. It has been predicted that lowering the numbers of Campylobacter on chicken meat can reduce the risk to public health. The aims of the current study were to investigate the susceptibility of Campylobacter to high intensity near ultraviolet/visible (NUV-vis) 395±5nm light and to examine its potential for the microbiological decontamination of raw chicken and contact surfaces. Exposure of Campylobacter jejuni and Campylobacter coli to NUV-vis light of irradiances was assessed at three distances (3, 12 and 23 cm) from the light source for up to 10 min, corresponding to doses of 0.06 to 18J/cm(2). Overall, levels of inactivation in liquid and on raw chicken improved with longer exposure times and shorter distances from the light source. Reductions of more than 7log(10)CFU/mL were achieved for Campylobacter isolates in liquid following 2 min exposure at 3 cm. Exposure of skinless chicken fillet to NUV-vis light for 1 or 5 min at 3 cm distance reduced C. jejuni by 2.21 and 2.62 log(10)CFU/g, respectively. Increasing the treatment time to 10 min did not significantly increase the level of inactivation. In general, NUV-vis light treatment did not affect the colour of raw chicken. Excluding treatments which resulted in excessive heating (>50°C) of chicken skin, a maximum reduction of 0.95 log(10)CFU/g was achieved for C. jejuni following 10 min exposure to NUV-vis light at 12 cm (P<0.05). For Enterobacteriaceae and total viable counts, significant reductions were achieved only on chicken fillet samples. Light treatments were significantly effective for decontaminating contact surfaces as there were no C. jejuni recovered from stainless steel or cutting board surfaces after NUV-vis light treatments from an initial inoculum of 2-4 log(10)CFU/cm(2) (P<0.05). The current study demonstrates potential for the use of NUV-vis light for the inactivation of Campylobacter spp. in liquids, on raw chicken and contact surfaces. The incorporation of this technology could be implemented in a commercial processing plant at various stages, for example to decontaminate carcasses during air chilling. It could also be applied at critical stages within the plant to control microbial contamination on equipment surfaces.

Effect of crust freezing applied alone and in combination with ultraviolet light on the survival of Campylobacter on raw chicken.

The application of crust freezing (CF) applied as a stand-alone treatment or in combination with ultraviolet (UV) light for reducing the level of artificially inoculated Campylobacter jejuni on raw chicken was investigated. CF air temperatures of -5, -15 and -27 °C (±3 °C) with freezing times of 70, 15 and 6 min, respectively, were used. The level of C. jejuni on chicken was also examined following subsequent refrigerated (0-4 °C) storage at 3 and 7 days. All CF treatments resulted in significant reductions compared to untreated controls (P < 0.05). Although combining CF with UV also resulted in significant reductions for C. jejuni, the combined treatments were generally no more effective than treatment by CF alone. Overall, the color of chicken drumsticks was not affected by CF treatments (P ≥ 0.05). In general, CF resulted in increased drip loss (P < 0.05), which increased over storage time and was greater at higher CF temperatures. The current study indicates that CF has potential for reducing the levels of C. jejuni by between 0.5 and 1.5 log(10) CFU/g and impacts minimally on the color of treated skin.

Efficacy of high-intensity pulsed light for the microbiological decontamination of chicken, associated packaging, and contact surfaces.

The efficacy of high-intensity light pulse (HILP) technology (3 Hz, maximum of 505 J/pulse, and a pulse duration of 360 µs) for the decontamination of raw chicken and associated packaging and surface materials was investigated. Its ability to reduce microbial counts on raw chicken through plastic films was also examined. Complete inactivation of Campylobacter spp., Escherichia coli, and Salmonella Enteritidis in liquid was achieved after 30 sec HILP treatment. Reductions of 3.56, 4.69, and 4.60 log10 cfu/cm²) were observed after 5 sec HILP treatment of Campylobacter jejuni, E. coli, and Salmonella Enteritidis inoculated onto packaging materials and contact surfaces, respectively. The greatest reductions on inoculated chicken skin were 1.22, 1.69, and 1.27 log10 cfu/g for C. jejuni, E. coli, and Salmonella Enteritidis, respectively. Corresponding reductions on inoculated skinless breast meat were 0.96, 1.13, and 1.35 log10 cfu/g. The effectiveness of HILP treatment for reducing microbial levels on chicken increased as the film thickness decreased. HILP treatments of 2 sec did not significantly affect the color of raw chicken although treatments of 30 sec impacted color. This study has shown HILP to be an effective method for the decontamination of packaging and surface materials. Additionally, it has demonstrated the potential of HILP to be used as a decontamination method for packaged chicken.