The Effects of 405-nm Visible Light on the Survival of Campylobacter on Chicken Skin and Stainless Steel.

Campylobacter spp. are foodborne pathogens responsible for a significant portion of human cases of bacterial-mediated gastrointestinal disease. A primary method for the introduction of Campylobacter into the food supply is through poultry products. Reducing the number of Campylobacter on poultry products may reduce the incidence of human disease. Research has been conducted on the use of light to inactivate Campylobacter on poultry products and processing environments. More recently, the use of high intensity visible 405-nm light has been proposed for the elimination of pathogenic bacteria. This study investigated the ability of 405-nm light to reduce Campylobacter jejuni and Campylobacter coli in poultry products. Campylobacter in chicken exudate were placed onto chicken skin or food-grade stainless steel before treatment with 405-nm light. A range of 405-nm light doses were applied to cocktails of six C. jejuni or six C. coli strains in exudate at 10°C to minimize thermal effects. Little difference was observed between inactivation of C. jejuni and C. coli on poultry skin with only minor average reductions of 1.7 logs and 2.1 logs, respectively, at the maximal dose of 184-186 J/cm(2). More noticeable differences were observed when the samples were placed on stainless steel and treated with a dose of 89 J/cm(2), producing an average reduction of 3.0 logs for C. coli but only 1.1 logs for C. jejuni. The maximal dose (181-183 J/cm(2)) applied to Campylobacter on stainless steel produced significant (p ≤ 0.05) reductions for C. jejuni and C. coli of 4.9 logs and 5.1 logs, respectively. However, significant 405-nm-mediated reductions in Campylobacter numbers required exposure times to achieve necessary dose levels that might be impractical under processing conditions. In addition, the most potent exposure times likely produced secondary thermal effects by raising sample surface temperatures above 48°C.

Impact of antibiotic use in the swine industry.

Antibiotic resistance in bacteria associated with pigs not only affects pig production but also has an impact on human health through the transfer of resistant organisms and associated genes via the food chain. This can compromise treatment of human infections. In the past most attention was paid to glycopeptide and streptogramin resistance in enterococci, fluoroquinolone resistance in campylobacter and multi-drug resistance in Escherichia coli and salmonella. While these are still important the focus has shifted to ESBL producing organisms selected by the use of ceftiofur and cefquinome in pigs. In addition Livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) suddenly emerged in 2007. We also need to consider multi-resistant strains of Streptococcus suis. Environmental contamination arising from piggery wastewater and spreading of manure slurry on pastures is also a growing problem.

Combined steam and ultrasound treatment of broilers at slaughter: a promising intervention to significantly reduce numbers of naturally occurring campylobacters on carcasses.

Steam or hot water decontamination treatment of broiler carcasses is hampered by process limitations due to prolonged treatment times and adverse changes to the epidermis. In this study, a combination of steam with ultrasound (SonoSteam®) was investigated on naturally contaminated broilers that were processed at conventional slaughter speeds of 8,500 birds per hour in a Danish broiler plant. Industrial-scale SonoSteam equipment was installed in the evisceration room, before the inside/outside carcass washer. The SonoSteam treatment was evaluated in two separate trials performed on two different dates. Numbers of naturally occurring Campylobacter spp. and TVC were determined from paired samples of skin excised from opposite sides of the breast of the same carcass, before and after treatments. Sampling was performed at two different points on the line: i) before and after the SonoSteam treatment and ii) before the SonoSteam treatment and after 80 min of air chilling. A total of 44 carcasses were examined in the two trials. Results from the first trial showed that the mean initial Campylobacter contamination level of 2.35 log10 CFU was significantly reduced (n=12, p<0.001) to 1.40 log10 CFU after treatment. A significant reduction (n=11, p<0.001) was also observed with samples analyzed before SonoSteam treatment (2.64 log10 CFU) and after air chilling (1.44 log10 CFU). In the second trial, significant reductions (n=10, p<0.05) were obtained for carcasses analyzed before (mean level of 2.23 log10 CFU) and after the treatment (mean level of 1.36 log10 CFU). Significant reductions (n=11, p<0.01) were also found for Campylobacter numbers analyzed before the SonoSteam treatment (2.02 log10 CFU) and after the air chilling treatment (1.37 log10 CFU). The effect of air chilling without SonoSteam treatment was determined using 12 carcasses pre- and postchill. Results showed insignificant reductions of 0.09 log10 from a mean initial level of 2.19 log10 CFU. Numbers of TVC before treatments ranged between 3.47 and 4.79 log10 CFU. In all cases, TVC was significantly (p<0.001, n=45 in each trial) reduced by approximately 0.7 log10 CFU. An authorized sensory panel at the Danish Veterinary and Food Administration concluded that broiler carcasses treated with SonoSteam were acceptable for purchase. These conclusions were based on organoleptic differences (smell, skin/meat consistency, texture and color) of treated vs. untreated carcasses. Results obtained from this study suggest that steam-ultrasound treatment of carcasses at broiler processing plants can significantly reduce numbers of Campylobacter on naturally contaminated broilers.

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.

Occurrence of thermotolerant Campylobacter spp. on eggshells: a missing link for food-borne infections?

We analyzed the prevalence of thermotolerant Campylobacter spp. compared that of to Salmonella spp. in raw yolk and on eggshells. A total of 2,710 eggs were investigated for each bacterium. Viable bacteria were found in 4.1% (Campylobacter spp.) and 1.1% (Salmonella spp.) of the eggshell samples, whereas the egg yolk samples were negative for both bacteria.

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.

Survival rate of thermotolerant Campylobacter on poultry meat during microwave heating.

Survival rates of Campylobacterjejuni ATCC 33 291, Campylobacter jejuni PZH 38 and Campylobacter coli ATCC 43 478 in leg quarters (ca 330 g) of chicken broilers after microwave heating (480 and 760 Watt) for 2, 4, 6, 8 and 10 minutes were determined. Heating the meat in a microwave oven (Moulinex, type Dialog cook) at 480 Watts caused a gradual decrease in the number of cells of the studied bacterial strains to total inactivation after 8-10 minutes of heating. Increasing the heating power to 760 Watts led to a decreased microwave heating time of 6-8 minutes for inactivation of all the cells of the studied C. jejuni/coli strains. These findings clearly indicate the dependence of effectiveness of inactivation of the bacteria studied on microwave heating power, heating duration and bacterial strain.

Salmonella, Campylobacter and Escherichia coli O157:H7 decontamination techniques for the future.

Raw meat, particularly poultry meat, remains an important, and probably the major source of human infection with campylobacters and salmonellas. In spite of decades of effort it has so far proved extremely difficult to raise food animals free of these pathogens. For the foreseeable future, therefore, the most effective approach must be to decontaminate the final raw product. In this way numbers of these pathogens entering kitchens and commercial food processing premises will be reduced substantially, and hence opportunities for cross-contamination onto ready-to-eat foods or for survival during cooking or other processes will be much lower. The ideal method of decontamination will have the following attributes: it will not change appearance, smell, taste or nutritional properties; it will leave no residues; it will pose no threat to the environment; it will encounter no objections from consumers or legislators; it will be cheap and convenient to apply; it will improve the shelf life by inactivating spoilage organisms as well as pathogens. Various techniques will be listed and their potential assessed (see Table 1).

Sensitivity of Campylobacter spp. to irradiation in poultry meat.

The sensitivity of Campylobacter jejuni (three strains), Camp. coli (three strains), Camp. fetus (one strain) and Camp. lari (one strain) to irradiation in poultry meat was investigated. There was no significant difference in the counts obtained on Blood or Skirrows agar. Preston agar gave a significantly lower recovery of the pathogens after irradiation so these results were not included in calculations of D10 values. The D10 values ranged from 0.12 to 0.25 kGy and there was a significant difference in the radiation sensitivity between different Campylobacter spp. and within strains of the same species. These values indicate that Campylobacter spp. are more radiation-sensitive than Salmonella and Listeria monocytogenes irradiated under similar conditions. Therefore irradiation treatments suggested to eliminate the latter from poultry carcasses would also be sufficient to remove Campylobacter.

Thermophilic campylobacters in surface waters around Lancaster, UK: negative correlation with Campylobacter infections in the community.

The incidence of campylobacter enteritis in Lancaster City Health Authority is three times the UK average for similar sizes of population and has marked seasonal peaks in May and June. Environmental monitoring of surface waters around Lancaster showed that thermophilic campylobacters were absent from drinking water from the fells and from the clean upper reaches of the River Conder but were present in the main rivers entering Morecambe Bay, the lower reaches of the River Conder, the Lancaster canal, and seawater from the Lune estuary and Morecambe Bay. All the surface waters tested showed the same seasonality, namely, higher numbers in the winter months and low numbers or none in May, June and July. The absence of thermophilic campylobacters in the summer months may be due to high sunshine levels because experiments on the effects of light showed that campylobacters in sewage effluent and seawater were eliminated within 60 and 30 min of daylight respectively but survived for 24 h in darkness. As the concentrations of campylobacters in surface waters were at their lowest precisely at the time of peak infections in the community it is unlikely that surface waters form Lancaster's reservoir of campylobacter infection for the community.

Effect of free-radical and oxygen scavengers on photochemically generated oxygen toxicity and on the aerotolerance of Campylobacter jejuni.

Exposure of a nutrient agar medium to the combined action of fluorescent light and air produced toxic factors in the medium which affected the growth of Campylobacter jejuni. Sodium dithionite (5-10 mM), a powerful reducing agent, and catalase were effective in counteracting the injurious action of light and air. Among the quenchers of singlet oxygen tested, only histidine had a beneficial effect on the recovery of C. jejuni in the photo-oxidized medium, while the addition of superoxide dismutase, a hydroxyl radical scavenger such as cysteamine, or the free radical antioxidants tocopherol and butylated hydroxy toluene, did not increase the recovery rate of photochemically injured cells. Histidine (40 mM) and dithionite (5-10 mM) also assisted recovery of C. jejuni inoculated on nutrient agar stored in air in the dark. Cysteamine and dithionite were toxic to Campylobacter when added at concentrations of greater than or equal to 10 mM and greater than or equal to 20 mM, respectively. A high inoculum of C. jejuni could not be recovered in unsupplemented nutrient agar incubated in air but was recovered in atmospheres containing 17 or 21% oxygen plus 10% carbon dioxide. The addition of dithionite, catalase or histidine resulted some colony formation on nutrient agar incubated in air. Among the scavengers tested, only dithionite was consistently able to maintain the viability of C. jejuni on nutrient agar stored in air for longer than 4 weeks. In view of the ability of catalase, dithionite and histidine to enhance the aerotolerance of C. jejuni, it is concluded that various oxygen species might be involved in the toxicity of high levels of oxygen.