Inactivation of Clostridium sporogenes and Geobacillus stearothermophilus spores with the use of microwave and steam sterilizers and microwave oven

Abstract

Introduction. Equipment for sterilization used in medical laboratories must be absolutely effective in eliminating microorganisms and their spores. It often directly influences human health, even life. The aim of the study was to compare the effectiveness of sterilization using the steam sterilizer ASV E, microwave sterilizer EnbioJet ML1, microwave sterilizer for baby bottles and breast pumps AVENT and microwave oven. Results. After using the steam sterilizer, 100% inactivation of spores of both species was noted. In the case of EnbioJet ML1 sterilizer, in the test containing 10 6 CFU × cm -3 G. stearothermophilus spores, 1.63 × 10 1 CFU × cm -3 survived. The baby bottles sterilizer proved less effective. While the microwave, in the case of tests with the highest spore content, provided their inactivation only at the level of more than 70.0%. The steam sterilizer and EnbioJet ML1 sterilizer were the most effective, whereas the latter ensured a very short time of high temperature effect, which has a favorable impact on the properties of sterilized products, for example compounds decomposing in high temperature. Conclusion.Results of own, as well as other authors' studies allow to confirm the large potential in the scope of using microwave radiation for the sterilization and disinfection of materials of various sensitivity to temperature.

The Possibility of Contamination of Water-Soil Environment as a Result of the Use of Pig Slurry

“…The source of pathogenic microorganisms in pig slurry can be sick animals, individuals during an incubation period of the disease or asymptomatic carriers [59]. In slurry derived from healthy pigs there is a natural intestinal microflora characterized by moderate or negligible virulence, while the slurry from animals including sick individuals or carriers may be a significant source of zoonoses and epizootic diseases [24,62]. This is encouraged by physicochemical properties of the slurry which is inherently not subject to the process of thermal sanitizing and which, in the absence of its conditioning, can cause microbial contamination of soils, groundwater and surface waters as well as plants posing a threat to human and animal health [4].…”

“…Pathogenic microorganisms are able to survive in slurry for a relatively long time (Tables 2 and 3) and, under favorable conditions, can rapidly multiply in the early stages of storage. The activity period of bacteria, viruses, fungi and parasites in the stored pig slurry varies strongly and depends on the physicochemical properties of the slurry (reaction, dry matter content, organic matter content, nutrient content), the type and initial quantity of microorganisms and ambient temperature (the lower the temperature, the longer the viability) [4,6,24,59]. It should be mentioned that data concerning the survival of pathogens in pig slurry on-farm conditions, where urine and feces are being added on a continual basis, are limited and most of the information derives from laboratory studies [63].…”

“…There is also a risk of infecting people, especially when sprouts and vegetables intended for direct consumption (e.g. root vegetables such as radishes and carrots or leafy vegetables like lettuce) are grown on land fertilized with pig slurry as well as in the case of eating or processing (for example making unpasteurized apple cider) -without any treatment -of fruit that fell on the soil freshly sprinkled with the slurry [24,71,72].…”

“…Therefore, pig producers decide to sell and transport the slurry to distant fields, which is unprofitable, or to spill it in doses exceeding legal limits [2]. The use of excessive quantities of pig slurry poses a risk of soil contamination with biogenic elements [18,21], heavy metals [22], pharmaceuticals [4,23] and pathogenic microorganisms [4,24] that can penetrate into the groundwater and surface waters threating the health of humans and animals [21]. In addition, nutrient elements, especially phosphorus, which reach water courses and reservoirs contribute to their eutrophication and, consequently, to the ecological disequilibrium of aquatic ecosystems [18,25,26].…”

“…In addition, nutrient elements, especially phosphorus, which reach water courses and reservoirs contribute to their eutrophication and, consequently, to the ecological disequilibrium of aquatic ecosystems [18,25,26]. Improper and too heavy fertilization with slurry may also result in the deterioration of the soil properties, the decrease in crop yield [21], the contamination of edible parts of plants with pathogens [24] or the accumulation of heavy metals in their tissues [22]. It should also be noted that pig slurry must be collected and stored in tanks with a sufficiently large capacity until it is taken away to the fields [17,20,27], which generates costs and could significantly affect the environment.…”