The paper gives an economic assessment of the present market of monochlorine-containing disinfectants. It analyzes the consumption of disinfectants in g per m2 for disinfection measures in case of avian influenza epidemic.
A capacity of microorganisms of different taxonomic groups to assimilate surface-active substances (surfactants) of Acinetobacter calcoaceticus K-4 as a single source of carbon and energy has been established. It was shown that A. calcoaceticus K-4 cannot use its own surfactants as a source of carbon nutrition. The use of biocide formalin in concentration of 0.1% permits to prolong the term of preservation of A. calcoaceticus K-4 surfactants to 3.5 months without a loss of their surfactant and emulsiying properties.
Many microorganisms (including a number of important foodborne pathogens) can be present on raw fruits and vegetables. Since these products are frequently eaten raw, any pathogens present represent a potential risk to the consumer. The objective of this study was to compare the efficacy of a commercial produce wash with that of water for reducing the total bacterial population on lettuce when used by food service employees in university dining halls. Because this study was carried out in actual food service facilities during their daily operation, we used indigenous produce microflora instead of actual pathogens. Over the course of the study, more than 40 heads of lettuce were divided into thirds, and each section was analyzed for total plate count either before washing, after washing in water, or after washing in Victory produce wash. When initial contamination levels were > or = 100 CFU/g (n = 36 samples), reductions obtained with Victory produce wash (1.8 log CFU/g) were significantly larger (P = 0.0006) than those obtained with water (0.8 log CFU/g). Our results indicate that Victory produce wash is effective in reducing indigenous flora on lettuce during food service preparation. Our results also show that care must be taken in the analysis of microbial reduction data: only a slight reduction in total plate count (ca. 0.1 log CFU/g) and no significant difference in reductions (P = 0.84) were observed when all samples (irrespective of initial contamination level) were compared.
Consumption of minimally-processed, or fresh-cut, fruit and vegetables has rapidly increased in recent years, but there have also been several reported outbreaks associated with the consumption of these products. Sodium hypochlorite is currently the most widespread disinfectant used by fresh-cut industries. Neutral electrolyzed water (NEW) is a novel disinfection system that could represent an alternative to sodium hypochlorite. The aim of the study was to determine whether NEW could replace sodium hypochlorite in the fresh-cut produce industry. The effects of NEW, applied in different concentrations, at different treatment temperatures and for different times, in the reduction of the foodborne pathogens Salmonella, Listeria monocytogenes and Escherichia coli O157:H7 and against the spoilage bacterium Erwinia carotovora were tested in lettuce. Lettuce was artificially inoculated by dipping it in a suspension of the studied pathogens at 10(8), 10(7) or 10(5) cfu ml(-1), depending on the assay. The NEW treatment was always compared with washing with deionized water and with a standard hypochlorite treatment. The effect of inoculum size was also studied. Finally, the effect of NEW on the indigenous microbiota of different packaged fresh-cut products was also determined. The bactericidal activity of diluted NEW (containing approximately 50 ppm of free chlorine, pH 8.60) against E. coli O157:H7, Salmonella, L. innocua and E. carotovora on lettuce was similar to that of chlorinated water (120 ppm of free chlorine) with reductions of 1-2 log units. There were generally no significant differences when treating lettuce with NEW for 1 and 3 min. Neither inoculation dose (10(7) or 10(5) cfu ml(-1)) influenced the bacterial reduction achieved. Treating fresh-cut lettuce, carrot, endive, corn salad and 'Four seasons' salad with NEW 1:5 (containing about 50 ppm of free chlorine) was equally effective as applying chlorinated water at 120 ppm. Microbial reduction depended on the vegetable tested: NEW and sodium hypochlorite treatments were more effective on carrot and endive than on iceberg lettuce, 'Four seasons' salad and corn salad. The reductions of indigenous microbiota were smaller than those obtained with the artificially inoculated bacteria tested (0.5-1.2 log reduction). NEW seems to be a promising disinfection method as it would allow to reduce the amount of free chlorine used for the disinfection of fresh-cut produce by the food industry, as the same microbial reduction as sodium hypochlorite is obtained. This would constitute a safer, 'in situ', and easier to handle way of ensuring food safety.
Nine chemicals and commercial disinfectants were tested for inactivation of Aleutian disease virus of mink. In the presence of distilled water, a commercial disinfectant (O-Syl), halogen derivatives (iodophor and sodium hypochlorite), and glutaraldehyde (2.0%) inactivated 4 log10 (based on 0.25 ml) of the virus within 10 minutes at 23 C. Formalin (2.0%) and O-Syl were slower to inactivate the virus, but achieved a 4 log10 reduction in titer by 30 minutes' contact time. In the presence of 10% bovine serum, formalin (1.0%), O-Syl, and sodium hydroxide (0.5%) achieved a 4 log10 reduction within 10 minutes. All agents tested had some virucidal effect.
A total of 61 strains of Staphylococcus aureus and 177 coagulase-negative staphylococcal strains were isolated from the blood of patients with bloodstream infections and from the skin of both children under cancer treatment and human immunodeficiency virus-positive patients. The MIC analyses revealed that 118 isolates (50%) were resistant to quaternary ammonium compound-based disinfectant benzalkonium chloride (BC). The frequencies of resistance to a range of antibiotics were significantly higher among BC-resistant staphylococci than among BC-sensitive staphylococci. Of 78 BC-resistant staphylococcal isolates, plasmid DNA from 65 (83%), 2 (3%), 43 (55%), and 15 (19%) isolates hybridized to qacA or -B (qacA/B), qacC, blaZ, and tetK probes, respectively. The qacA/B and blaZ probes hybridized to the same plasmid in 19 (24%) staphylococcal strains. The plasmids harboring both qacA/B and blaZ genes varied from approximately 20 to 40 kb. The Staphylococcus epidermidis Fol62 isolate, harboring multiresistance plasmid pMS62, contained qacA/B and blaZ together with tetK. Molecular and genetic studies indicated different structural arrangements of blaZ and qacA/B, including variable intergenic distances and transcriptional directions of the two genes on the same plasmid within the strains. The different organizations may be due to the presence of various genetic elements involved in cointegration, recombination, and rearrangements. These results indicate that qac resistance genes are common and that linkage between resistance to disinfectants and penicillin resistance occurs frequently in clinical isolates in Norway. Moreover, the higher frequency of antibiotic resistance among BC-resistant strains indicates that the presence of either resistance determinant selects for the other during antimicrobial therapy and disinfection in hospitals.
This objective of this study was to explore the practicality of monitoring naturally occurring organisms to predict drinking water treatment plant performance, in this case for the reduction of Cryptosporidium. Surface and ground water from seven drinking water treatment plants across North America that use chlorine dioxide were surveyed for aerobic and anaerobic bacterial spore concentrations. The concentrations of total spores were usually high enough in both raw and treated water to allow 4- to 5-log reductions to be observed across the treatment train by filtering up to 2 l of sample. These results suggested that naturally occurring treatment-resistant spores could be candidates as indicators of treatment performance. However, to be useful as indicators for Cryptosporidium reduction, the organisms would have to exhibit similar resistances to disinfection (chlorine dioxide in this case) in order to be useful. The inactivation kinetics of seven of the most common species were determined, and all were observed to be considerably more susceptible to chlorine dioxide inactivation than Cryptosporidium as reported in the literature. This study therefore did not identify an appropriate ambient microbial indicator for Cryptosporidium control.
Arcobacter spp. have in recent years received increasing interest as potential emerging enteropathogens and zoonotic agents. They are associated with various animals including poultry and can be isolated from meat products. The possibilities of persistence and cross-contamination in slaughterhouses during meat processing are not well established. We have evaluated the occurrence and persistence of Arcobacter spp. in a Danish slaughterhouse and determined the sensitivity of isolates to sodium hypochlorite, a commonly used biocide.
Arcobacter contamination was examined in a broiler slaughterhouse by selective enrichment of 235 swabs from the processing line during two production days and after sanitizing in between. In total 13.6% of samples were positive for A. butzleri with the majority (29 of 32 isolates) originating from the evisceration machine. No Arcobacter spp. was isolated after cleaning. A. butzleri isolates confirmed by PCR were typed by multilocus sequence typing (MLST) resulting in 10 new sequence types (STs). Two sequence types were isolated on both processing days. Minimum inhibitory concentration (MIC) to sodium hypochlorite was determined to 0.5% hypochlorite biocide (500 ppm chlorine) for most isolates, which allows growth of A. butzleri within the working concentration of the biocide (0.2 - 0.5%).
A. butzleri was readily isolated from a Danish broiler slaughterhouse, primarily in the evisceration machine. Typing by MLST showed high strain variability but the recurrence of two STs indicate that some persistence or cross-contamination takes place. Importantly, the isolates tolerated sodium hypochlorite, a biocide commonly employed in slaughterhouse sanitizing, at levels close to the disinfection concentration, and thus, A. butzleri may survive the disinfection process although this was not observed in our study.
The ongoing battle against multi-resistant strains: in-vitro inhibition of hospital-acquired MRSA, VRE, Pseudomonas, ESBL E. coli and Klebsiella species in the presence of plant-derived antiseptic oils.
The fight against hospital-acquired infections involving antibiotic-resistant microorganisms has become of critical concern to surgeons worldwide. In addition to the development of new effective antibiotic chemotherapy, exploration of 'forgotten' topical antibacterial agents from the pre-antibiotic era has recently gained new attention. We report the promising efficacy of plant-derived antiseptic oils used in traditional aboriginal and south-east Asian treatments such as Lemongrass, Eucalyptus and Tea Tree Oil in the inhibition of clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), multi-resistant Pseudomonas aeruginosa, ESBL-producing Escherichia coli and Klebsiella pneumoniae in the in-vitro setting. Large consistent zones of inhibition were observed for all three plant-derived oils tested in an agar diffusion test. The commonly used antibacterial agents chlorhexidine 0.1%, and ethanol (70%), and standard olive oil consistently demonstrated notably lower or no efficacy in regard to growth inhibition of strains. Notably, Lemongrass oil proved to be particularly active against gram-positive bacteria, while Tea Tree oil showed superior inhibition of gram-negative microorganisms. As proven in vitro, plant-derived antiseptic oils may represent a promising and affordable topical agent to support surgical treatment against multi-resistant and hospital-acquired infections.
Pollution by pathogenic bacteria was examined in 150 French metalworking fluid samples. Gram-negative micro-organisms such as Salmonella spp., Shigella spp., and Vibrio spp. as well as Gram-positive cocci were never isolated. Nevertheless opportunistic pathogens such as Pseudomonas aeruginosa and Klebsiella pneumoniae still contaminated these fluids with an isolation frequency of 17% of samples for each. These two micro-organisms failed to grow or even survive in vitro in sterile cutting fluids protected by biocides. Preliminary growth of other micro-organisms such as Pseudomonas putida or Pseudomonas fluorescens, which are the major part of the indigenous microflora, seemed to be a prerequisite for their growth. These former two Pseudomonas could resist three different classes of biocides and, at least in the case of formaldehyde-releasers, adaptation was followed by biocide deterioration. Resistance magnification was observed in the presence of the three different types of biocides and, in the case of formaldehyde releasers the resistance and deterioration levels were close to those recommended by the manufacturers. This is probably the reason why the preliminary growth of Pseudomonas putida allowed in vitro differed growth of Klebsiella pneumoniae and Pseudomonas aeruginosa. Due to relatively high isolation frequencies of opportunistic pathogens (17% of samples) periodical microbiological examination of cutting fluids should be carried out in order to evaluate risks for human health. Wearing masks and gloves is still recommended, at least in France.