Efficacy of Common Laboratory Disinfectants on the Infectivity of Cryptosporidium parvum Oocysts in Cell Culture

Nine liquid disinfectants were tested for their ability to reduce infectivity of Cryptosporidium parvum oocysts in cell culture. A 4-min exposure to 6% hydrogen peroxide and a 13-min exposure to ammonium hydroxide-amended windshield washer fluid reduced infectivity 1,000-fold. Other disinfectants tested (70% ethanol, 37% methanol, 6% sodium hypochlorite, 70% isopropanol, and three commercial disinfectants) did not reduce the infectivity after a 33-min exposure. The results indicate that hydrogen peroxide and windshield washer fluid or ammonium hydroxide disinfectant may be suitable laboratory disinfectants against C. parvum oocysts.     

Efficacy of some commerical disinfectants against the bacterial isolates from a poultry slaughterhouse in Turkey

In this study, efficacy of seven different commercial disinfectant preparations was investigated against characteristic bacteria of a poultry slaughterhouse in Ankara (Turkey) by using paper disc-agar diffusion method and surface effectiveness test. According to paper disc-agar diffusion method, some disinfectants had wide efficacy against the test bacteria. The disinfectant effectiveness generally increased by the increasing of disinfectant concentration. However, some disinfectants were ineffective even though at their highest concentrations. The most effective disinfectant was B which contains QAC as active agent.Staphylococcus spp.,Staphyloccus aureus andEscherichia coli were the most sensitive bacteria to the disinfectants. Some pathogenic isolates, especiallySalmonella spp. andCampylobacter spp., were the most resistant ones to many of the disinfectants tested. The results of paper disc-agar diffusion method indicated the importance of characteristic bacterial strains of food plants as the test bacteria for disinfectant efficacy tests. Conversely of paper disc-agar diffusion method, all disinfectants were effective against the isolates by surface effectiveness test depending on exposure time. The disinfectants, except A and F, produced at least 3 log unit reduction during 5 min of exposure. However, all disinfectants at their lowest concentrations were effective against all tested bacteria during 15 and 30 min by this test.     

The fungicidal efficacy of various commercial disinfectants used in the food industry

The antifungal effects of eight commercial disinfectants namely alcohol, peracetic acid, iodophors, aldehydes, quaternary amine compounds (QAC, a, b and c), and a chlorine-based agent were assessed at different concentrations. The time taken for these disinfectants to kill different microorganisms was used to assess their efficacy. The microorganisms tested were six yeasts,Saccharomyces cerevisiae, Saccharomyces uvarum, Kloeckera apiculata, Candida oleophila, Metschnikowia fructicola, Schizosaccharomyces pombe, and two moulds,Aspergillus niger (5 strains) andPenicillium roqueforti (5 strains). The disinfectants QAC (a) and QAC (c) were the most effective against all the microorganisms tested. The chlorine-based disinfectant worked most efficiently against the moulds at all concentrations used (0.5, 1.0, 1.5 and 2.0%). Peracetic acid and alcohol based disinfectants were most effective against the yeasts than mould. Tested yeasts were more resistant to the aldehyde and iodophors base disinfectants than the others.     

Efficacy of common laboratory disinfectants on the infectivity of Cryptosporidium parvum oocysts in cell culture

Nine liquid disinfectants were tested for their ability to reduce infectivity of Cryptosporidium parvum oocysts in cell culture. A 4-min exposure to 6% hydrogen peroxide and a 13-min exposure to ammonium hydroxide-amended windshield washer fluid reduced infectivity 1,000-fold. Other disinfectants tested (70% ethanol, 37% methanol, 6% sodium hypochlorite, 70% isopropanol, and three commercial disinfectants) did not reduce the infectivity after a 33-min exposure. The results indicate that hydrogen peroxide and windshield washer fluid or ammonium hydroxide disinfectant may be suitable laboratory disinfectants against C. parvum oocysts.     

The effect of new male sterilants: Exo-3,4-methano-L-proline and cis-α-(carboxycyclopropyl)glycine on the IAA- and ACC-induced ethylene formation ia wheat coleoptile segments

The male sterilants exo-3,4-methano-L-proline (MP) and cis-α-(carboxycyclopropyl)glycine (CCPG) were not converted to ethylene, eitherin vitro or in wheat coleoptile segments. Neither of these substances was able to affect IAA- and ACC-induced ethylene biosynthesis in wheat coleoptile segments to such an extent that it could explain their effect ay male sterilants.     

Effects of Disinfectants on Larval Development of Ascaris suum Eggs

The objective of this study was to evaluate the effects of several different commercial disinfectants on the embryogenic development of Ascaris suum eggs. A 1-ml aliquot of each disinfectant was mixed with approximately 40,000 decorticated or intact A. suum eggs in sterile tubes. After each treatment time (at 0.5, 1, 5, 10, 30, and 60 min), disinfectants were washed away, and egg suspensions were incubated at 25˚C in distilled water for development of larvae inside. At 3 weeks of incubation after exposure, ethanol, methanol, and chlorohexidin treatments did not affect the larval development of A. suum eggs, regardless of their concentration and treatment time. Among disinfectants tested in this study, 3% cresol, 0.2% sodium hypochlorite and 0.02% sodium hypochlorite delayed but not inactivated the embryonation of decorticated eggs at 3 weeks of incubation, because at 6 weeks of incubation, undeveloped eggs completed embryonation regardless of exposure time, except for 10% povidone iodine. When the albumin layer of A. suum eggs remained intact, however, even the 10% povidone iodine solution took at least 5 min to reasonably inactivate most eggs, but never completely kill them with even 60 min of exposure. This study demonstrated that the treatment of A. suum eggs with many commercially available disinfectants does not affect the embryonation. Although some disinfectants may delay or stop the embryonation of A. suum eggs, they can hardly kill them completely.     

Preliminary glasshouse and field tests of soil partial sterilants for clubroot control

Experiments were made on field plots and in individually dosed pots to investigate the effects of ten soil partial sterilants on percentage infection of cabbage with clubroot. Additionally, cores of naturally-infested soil or samples of artificially infested and buried soil removed from some treated plots were also sown with cabbage in a glasshouse and the seedlings then assayed for the presence of clubroot. There was evidence that the partial sterilants were optimally effective at different depths. Dowfume M.C.2 and Basamid having the unique properties of effectiveness at deep and shallow horizons of the soil respectively. Chloropicrin at 60 ml/m² and Dowfume M.C.2 at 98 g/m² were the most effective partial sterilants in controlling clubroot while Basamid and Telone were also considered to merit further testing. All other partial sterilants reduced percentage infection in pot experiments and field crops to varying extents although formaldehyde was least effective.     

Efficacy of Two Peroxygen-Based Disinfectants for Inactivation of Cryptosporidium parvum Oocysts

Two commercial peroxygen-based disinfectants containing hydrogen peroxide plus either peracetic acid (Ox-Virin) or silver nitrate (Ox-Agua) were tested for their ability to inactivate Cryptosporidium parvum oocysts. Oocysts were obtained from naturally infected goat kids and exposed to concentrations of 2, 5, and 10% Ox-Virin or 1, 3, and 5% Ox-Agua for 30, 60, and 120 min. In vitro excystation, vital dyes (4′,6′-diamidino-2-phenylindole and propidium iodide), and infectivity in neonatal BALB/c mice were used to assess the viability and infectivity of control and disinfectant-treated oocysts. Both disinfectants had a deleterious effect on the survival of C. parvum oocysts, since disinfection significantly reduced and in some cases eliminated their viability and infectivity. When in vitro assays were compared with an infectivity assay as indicators of oocyst inactivation, the excystation assay showed 98.6% inactivation after treatment with 10% Ox-Virin for 60 min, while the vital-dye assay showed 95.2% inactivation and the infectivity assay revealed 100% inactivation. Treatment with 3% Ox-Agua for 30 min completely eliminated oocyst infectivity for mice, although we were able to observe only 74.7% inactivation as measured by excystation assays and 24.3% with vital dyes (which proved to be the least reliable method for predicting C. parvum oocyst viability). These findings indicate the potential efficacy of both disinfectants for C. parvum oocysts in agricultural settings where soil, housing, or tools might be contaminated and support the argument that in comparison to the animal infectivity assay, vital-dye and excystation methods overestimate the viability of oocysts following chemical disinfection.     

Impact of biocides on biofilm formation by methicillin-resistant Staphylococcus aureus (ST239-SCCmecIII) isolates

Procedures of sterilization and disinfection are essential to ensure that medical and surgical instruments will not transmit infectious pathogens to patients. In the present paper, we tested the residual effect of these compounds on biofilm formation and its efficiency in disrupting preformed biofilms using methicillin-resistant Staphylococcus aureus (MRSA) isolates of the lineage ST239-SCCmecIII. All compounds examined, except 70% alcohol, caused a significant impairment in biofilm formation with concomitant inhibition of cell growth. Among the compounds examined, 10% povidone-iodine (PVP-I) was the only antiseptic that exhibited more than 90% reduction of both biofilm formation and dispersion. In the group of sterilants and disinfectants, a formulation containing 7% hydrogen peroxide and 0.2% peracetic acid (HP-PA), and sodium hypochlorite with 1% active chlorine (NaOCl) were equally effective.     

Bacterial spore structures and their protective role in biocide resistance

The structure and chemical composition of bacterial spores differ considerably from those of vegetative cells. These differences largely account for the unique resistance properties of the spore to environmental stresses, including disinfectants and sterilants, resulting in the emergence of spore-forming bacteria such as Clostridium difficile as major hospital pathogens. Although there has been considerable work investigating the mechanisms of action of many sporicidal biocides against Bacillus subtilis spores, there is far less information available for other species and particularly for various Clostridia. This paucity of information represents a major gap in our knowledge given the importance of Clostridia as human pathogens. This review considers the main spore structures, highlighting their relevance to spore resistance properties and detailing their chemical composition, with a particular emphasis on the differences between various spore formers. Such information will be vital for the rational design and development of novel sporicidal chemistries with enhanced activity in the future.     

Effectiveness of Disinfectants in Killing Enterobacter sakazakii in Suspension, Dried on the Surface of Stainless Steel, and in a Biofilm

The effectiveness of 13 disinfectants used in hospitals, day-care centers, and food service kitchens in killing Enterobacter sakazakii in suspension, dried on the surface of stainless steel, and in biofilm was determined. E. sakazakii exhibited various levels of resistance to the disinfectants, depending on the composition of the disinfectants, amount and type of organic matrix surrounding cells, and exposure time. Populations of planktonic cells suspended in water (7.22 to 7.40 log CFU/ml) decreased to undetectable levels (<0.30 log CFU/ml) within 1 to 5 min upon treatment with disinfectants, while numbers of cells in reconstituted infant formula were reduced by only 0.02 to 3.69 log CFU/ml after the treatment for 10 min. The presence of infant formula also enhanced the resistance to the disinfectants of cells dried on the surface of stainless steel. The resistance of cells to disinfectants in 6-day-old and 12-day-old biofilms on the surface of stainless steel was not significantly different. The overall order of efficacy of disinfectants in killing E. sakazakii was planktonic cells > cells inoculated and dried on stainless steel > cells in biofilms on stainless steel. Findings show that disinfectants routinely used in hospital, day-care, and food service kitchen settings are ineffective in killing some cells of E. sakazakii embedded in organic matrices.     

Methicillin-Resistant Staphylococcus aureus in Commercial Swine Herds Is Associated with Disinfectant and Zinc Usage

Methicillin-resistant Staphylococcus aureus (MRSA) originating from swine is concerning for public health, but an understanding of the emergence and persistence of MRSA in nursery herds is lacking. The aim of this study was to determine whether MRSA in nursery pigs is associated with particular herd-level parameters, including the use of antimicrobials, disinfectants, and heavy metals, which may be driving the selection and persistence of antimicrobial resistance. Nasal cultures for MRSA were completed for 390 pigs from 26 farms at the end of the suckling phase and again at 3 weeks postweaning. Herd-level information was collected, and a random subset of MRSA isolates was screened for resistance to zinc and quaternary ammonium compounds (QACs). Multivariate analysis revealed that in-feed concentrations of zinc (P < 0.001) and frequent disinfection of nursery pens (P < 0.001) are associated with MRSA shedding in nursery pigs. Furthermore, 62.5% (25/40) of MRSA isolates carried the zinc resistance gene czrC and demonstrated decreased susceptibility to zinc. All MRSA isolates carried at least 1 QAC resistance gene. The most common genotype was qacG qacH smr, which occurred in 32.5% (13/40) of isolates. Seven isolates (17.5%) demonstrated a significant tolerance to benzalkonium chloride, indicating a potential to survive commercial QAC exposure in the presence of organic matter. Overall, these findings indicate that high levels of in-feed zinc and QAC-based disinfectants are important drivers in the selection and persistence of MRSA in commercial swine herds, and these agents may be coselecting for other antimicrobial resistance genes.     

Monoxenic liquid culture with Escherichia coli of the free-living nematode Panagrolaimus sp. (strain NFS 24-5), a potential live food candidate for marine fish and shrimp larvae

The free-living, bacterial-feeding nematode Panagrolaimus sp. (strain NFS 24-5) has potential for use as live food for marine shrimp and fish larvae. Mass production in liquid culture is a prerequisite for its commercial exploitation. Panagrolaimus sp. was propagated in monoxenic liquid culture on Escherichia coli and parameters, like nematode density, population dynamics and biomass were recorded and compared with life history table data. A mean maximum nematode density of 174,278 mL^?1 and a maximum of 251,000 mL^?1 were recorded on day 17 after inoculation. Highest average biomass was 40 g L^?1 at day 13. The comparison with life history table data indicated that the hypothetical potential of liquid culture is much higher than documented during this investigation. Nematode development is delayed in liquid culture and egg production per female is more than five times lower than reported from life history trait analysis. The latter assessed a nematode generation time of 7.1 days, whereas the process time at maximum nematode density in liquid culture was 16 days indicating that a reduction of the process time can be achieved by further investigating the influence of nematode inoculum density on population development. The results challenge future research to reduce process time and variability and improve population dynamics also during scale-up of the liquid culture process.     

常用消毒剂对布鲁氏菌疫苗株的灭菌效果评估

[背景]布鲁氏菌是一种重要的人畜共患胞内寄生菌,是引起动物和人发生布鲁氏菌病(布病)的病原体.高效消毒剂杀灭环境中的布鲁氏菌是防控布病的关键措施.[目的]评价市面上常用消毒剂对布鲁氏菌的灭菌效果及差异.[方法]选用市面上9种不同类型的常用消毒剂,以高、中、低3种不同使用浓度分别研究其对牛种、羊种和猪种布鲁氏菌的杀灭效果...     

Evaluation of chemical seed coat sterilants

Summary Three seed coat sterilants were evaluated for effectiveness as surface sterilants and for effects on seed germination. Several exposure times in sodium hypochlorite, hydrogen peroxide and peracetic acid were evaluated. Seeds of the following crop plants were used: wheat (Triticum aestivum L.); sorghum [Sorghum bicolor (L.) Moench]; soybean [Glycine max (L.) Merrill]. All treatments reduced germination of wheat and soybean seed, but only the most severe peracetic acid treatments substantially reduced germination of sorghum seed. Considering both sterilization effectiveness and seed germination, a treatment with 5% sodium hypochlorite for 45 min appeared to be the most satisfactory of the treatments used.     

Development and Testing of a Microbiological Assay To Detect Residual Effects of Disinfectant on Hard Surfaces

We describe a glucuronidase bioassay for detecting residual bactericidal activity from the use of disinfectants on hard surfaces; in this assay we used formaldehyde, ethanol, isopropanol, chlorine, and a commercial preparation containing 2-bromo-2-nitro-1,3-propanediol. Chlorine and the commercial preparation showed bactericidal activity (53.5% and 98.2%, respectively) for a week after disinfection.     

Isolation and selection of native microorganisms for the aerobic treatment of simulated dairy wastewaters

Milk fat/protein degrading microorganisms were isolated from different locations of a dairy wastewater treatment system with the goal of developing an inoculum for bioaugmentation strategies. Eight isolates, identified by 16S rRNA gene sequence analysis as belonging to the genera Bacillus, Pseudomonas, and Acinetobacter, were tested for their ability to remove COD and protein from a milk-based medium (3000 mg/L COD) and compared to a commercial bioaugmentation inoculum. The Acinetobacter isolate exhibited a pellet-type growth in liquid culture, a property that could potentially aid in the separation of microbes and liquid phase following treatment. Based on the individual degradation capacity and growth behavior of the isolates, three microorganisms were further selected and tested together. This consortium exhibited a COD removal similar to the commercial inoculum (57% and 63%, respectively), but higher protein (consortium: 93%; commercial inoculum: 54%), and fat removals (consortium: 75%; commercial inoculum: 38%).     

Modeling the inactivation kinetics of bacillus spores by glutaraldehyde

Aims: Our goal was to develop a mathematical kinetic model to predict the sporicidal activity of glutaraldehyde, which is an active ingredient frequently used in commercial products employed for liquid disinfection and decontamination. Methods and Results: We used our previously published data on spore inactivation by glutaraldehyde to develop a predictive model obtained by calculating multiple independent modifying functions. The model was then validated by comparing model predicted values to new experimental data. For model validation, quality‐controlled spores of Bacillus athrophaeus (previously and generally known as Bacillus subtilis globigii) were exposed under conditions where several physicochemical variables were modified simultaneously, and the spore surviving fractions were measured by titration. Conclusions: The model predicted within one order of magnitude variations in sporicidal effectiveness due to changes in main parameters (glutaraldehyde concentration, temperature or time‐duration of the treatment). Other parameters such pH, salinity and the effect of serum concentration were also addressed, albeit with less accuracy. Significance and Impact of the study: The model should be useful to quantitatively estimate the effectiveness of glutaraldehyde‐based disinfectants, decontaminants, and germicides under the described conditions, particularly when limited data are available or when spore virulence (like that of Bacillus anthracis) precludes extensive experimentation. A similar approach could predict the effectiveness of a variety of decontaminant and disinfecting agents.     

Effects of quinestrol and levonorgestrel on prolactin serum concentration in lactating Mongolian gerbils (Meriones unguiculatus) and reproductive parameters of their offspring

The effects of the two sterilants, quinestrol (QE) and levonorgestrel (LNG) on serum prolactin (PRL) level in lactating Mongolian gerbils and reproductive parameters of their offspring were examined in the study. Both sterilants increased the serum PRL level in lactating gerbils. The body weight as well as weights of the ovary, testis, epididymides, and seminal vesicles were lower, whereas that of the uterus was higher in the pups originating from QE-treated mothers in comparison to controls. Histological ovarian sections of the offspring from QE-treated mothers contained only growing follicles, whereas their uterine sections showed a thinner endometrium, thicker myometrium, and greater epithelial-cell height than in controls. The histometrical testis characteristics as well as sperm concentration and motility of male pups from QE-treated mothers were lower compared to those of the control group. The serum gonadotropin levels of female pups from mothers treated with QE were lower, whereas the serum estradiol (E₂) and progesterone (P₄) levels were higher than in control gerbils. In contrast, serum gonadotropin and testosterone (T) levels of male pups from QE-treated mothers were lower compared to controls. LNG did not affect the examined parameters of the offspring. The offspring from QE-treated mothers was infertile, whereas the offspring from LNG-treated mothers was fertile. In summary, QE and LNG have a stimulatory effect on PRL level in lactating gerbils. It also appears that QE administered via milk to mothers affects reproductive processes of their offspring.     

Development and testing of a microbiological assay to detect residual effects of disinfectant on hard surfaces.

We describe a glucuronidase bioassay for detecting residual bactericidal activity from the use of disinfectants on hard surfaces; in this assay we used formaldehyde, ethanol, isopropanol, chlorine, and a commercial preparation containing 2-bromo-2-nitro-1, 3-propanediol. Chlorine and the commercial preparation showed bactericidal activity (53.5% and 98.2%, respectively) for a week after disinfection.