Efficacy Of Ultraviolet Light Research Articles

Efficacy of ultraviolet light (UV-C) and pulsed light (PL) for the microbiological decontamination of raw salmon (Salmo salar) and food contact surface materials

Abstract The decontamination effect of two light-based technologies on salmon, polyethylene (PE) and stainless steel (SS) was evaluated. Optimization of treatment conditions for ultraviolet light (UV-C) and pulsed light (PL) was carried out on raw salmon, obtaining inactivation levels of 0.9 and 1.3 log CFU/g respectively. The effects of treatments on several microbial groups present in salmon were then evaluated. For both technologies, Pseudomonas spp. were found to be the most resistant group of microorganisms tested. Three different strains from within this group were isolated and speciated, including a P. fluorescens strain which was selected for subsequent studies. PE and SS surfaces were inoculated with a suspension of the P. fluorescens suspended in a ‘salmon juice’ solution, and treated with UV-C and PL at different doses (mJ/cm2). PE surfaces were effectively decontaminated a low doses for both technologies, with a reduction of >4 log cycles observed. Decontamination of SS was also effective when treated with PL, although at higher doses than for PE. When SS was treated with UV-C, the maximum reduction of P. fluorescens achieved was 2 log cycles, even at the highest dose.

261 Efficacy of ultra-violet light on bacterial growth and biofilm production of selected strains of uropathogenic Escherichia coli and pseudomonas aeruginosa

261 Efficacy of ultra-violet light on bacterial growth and biofilm production of selected strains of uropathogenic Escherichia coli and pseudomonas aeruginosa

FACTORS AFFECTING THE ULTRAVIOLET INACTIVATION OF ESCHERICHIA COLI K12 IN APPLE JUICE AND A MODEL SYSTEM*

ABSTRACT Ultraviolet (UV) light has been used successfully for years to sterilize water and was recently approved as an acceptable irradiation treatment for the processing of juice. Although there is considerable information on the efficacy of UV processing in the treatment of water, limited data are available on its efficacy in fluid food systems. The objectives of this work were to determine the effects of apple‐juice properties on the UV inactivation of Escherichia coli K12 and the interdependence of intensity and time on the efficacy of UV light. Results showed that absorbance (A) and suspended solids (SS) affected UV inactivation, while pH and dissolved solids did not. Concerning the interdependence of intensity and time, intensity levels can only be changed without sacrificing effectiveness at a limited range of intensity and dose levels. This means that the range of the intensity level of the actual UV reactor must be considered in process‐parameter determination.

Efficacy of Ultra Violet Light for Elimination of Salmonella on Broiler Hatching Eggs

Germicidal UV light at a wavelength of 254 nm was tested as a means to eliminate inoculated Salmonella from eggshells. Eggs inoculated with 105 cells Salmonella were treated with UV light (600 μW/cm2) for 1 to 10 min. When inoculation was made by a drop of suspension on the eggshell surface, UV light treatment significantly lowered the incidence of positive eggs (P≤.05). However, UV light treatment was less effective against Salmonella when the inoculum was applied to the egg as a submersion dip. Salmonella inoculation placed on the eggshell by a drop of suspension and covered with a fecal smear was not eradicated by the UV light treatment. As few as ten cells of Salmonella in feces was sufficient to result in positive eggs following exposure to UV light (600 μW/cm2). Following a fecal smear inoculation with 100 cells, even UV light intensity as high as 1600 μW/cm2 lead to less than 25% reduction in the percentage of eggs positive for Salmonella. Continuous exposure of eggs to UV light in the incubator did not affect hatchability.

Efficacy of ultraviolet light in preventing Legionella colonization of a hospital water distribution system

We performed a controlled evaluation of ultraviolet light irradiation of hot and cold water supplies in a hospital colonized with Legionella by inserting the u.v. units near the “point-of-use”. Showers on one wing of a hospital were supplied with u.v.-irradiated water. Showers on another wing and 20 other outlets served as controls. Cultures prior to the installation of u.v. units showed all outlets to be heavily colonized with L. pneumophila. Despite disinfection of incoming water by u.v., Legionella in established niches of the plumbing system continued to survive. Superheat/flush and chlorination was then applied prior to u.v. activation. Although cultures became negative initially, recolonization occurred after I month. Scale accumulation on u.v. lamps had compromised the efficacy of u.v. irradiation. Filters were added to prevent scale accumulation on the u.v. lamps and the u.v.-supplied showers remained Legionella-free. U.V. plus prefiltration can prevent Legionella recolonization for at least 4 months after disinfection if the u.v. units are installed near the “point-of-use”. Disinfection must be directed not only at incoming water, but also at established niches within the existing plumbing system. The advantages of u.v. include easy installation, low expense, and no adverse effects on water or plumbing.

Health-care professionals' views of the effectiveness of pressure ulcer treatments. A survey among nursing-home physicians, dermatologists and nursing staff in The Netherlands.

In a survey, 237 nursing-home physicians, 113 dermatologists, and 164 supervisory nurses in nursing homes rated 30 treatments for stage III pressure ulcers by scoring their effectiveness. On average, there seems to be a fair degree of consensus between these groups of health-care workers about the effectiveness of most treatments. The most notable exceptions are ultraviolet light, ultrasound, and laser therapy and myocutaneous flap operations. Here, the dermatologists disagree with both nursing-home physicians and nurses. However, within all specialties there is disagreement about the efficacy of ultraviolet light, ultrasound, and laser therapy and the topical application of zinc oxide, betadine iodine, sodium hypochlorite and a few others.