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Testing a new alcohol-free hand sanitizer to combat infection.

Universal precautions require that perioperative health care personnel wash their hand before and after all patient contact. Time constraints, however, can make adhering to universal precautions, including proper hand washing, difficult. Some perioperative health care workers, therefore, routinely use rise-free hand sanitizers to supplement normal hand washing. This study evaluated immediate and persistent antimicrobial effectiveness of two alcohol--containing hand sanitizers and a novel surfactant, allantoin, benzalkonium chloride (SAB) hand sanitizer using a federally approved effectiveness protocol. Results indicate that all three products were equally effective after a single application. After repeated use, the alcohol-containing sanitizers did not meet federal performance standards, and the alcohol-free sanitizer did. These properties and others illustrated in this article indicate that the nonflammable, alcohol-free SAB hand sanitizer is the most favorable of the rise-free hand sanitizer formulas for normal hand washing.

Adolescent↗

The impact of alcohol hand sanitizer use on infection rates in an extended care facility.

BACKGROUND: Nosocomial infections are a major problem in health care facilities, resulting in extended durations of care and substantial morbidity. Since alcohol gel hand sanitizers combine high immediate antimicrobial efficacy with ease of use, this study was carried out to determine the effect of the use of alcohol gel hand sanitizer by caregivers on infection types and rates in an extended care facility. METHOD: Infection rate and type data were collected in a 275-bed extended care facility for 34 months (July 1997 to May 2000), during which an alcohol gel hand sanitizer was used by the caregivers in 2 units of the facility. RESULTS: The primary infection types found were urinary tract with Foley catheter, respiratory tract, and wound infections. Comparison of the infection types and rates for the units where hand sanitizer was used with those for the control units where the hand sanitizer was not used showed a 30.4% decrease in infection rates for the 34-month period in the units where hand sanitizer was used. CONCLUSION: This study indicates that use of an alcohol gel hand sanitizer can decrease infection rates and provide an additional tool for an effective infection control program.

Anti-Infective Agents, Local↗

Use of alcohol hand sanitizer as an infection control strategy in an acute care facility.

BACKGROUND: Nosocomial infections are a major problem in health care facilities, resulting in extended durations of care, substantial morbidity and mortality, and excess costs. Since alcohol gel hand sanitizers combine high immediate antimicrobial efficacy with ease of use, this study was carried out to determine the effect of the use of an alcohol gel hand sanitizer by caregivers on infection types and rates in an acute care facility. Patients were educated about the study through a poster on the unit, and teachable patients were given portable bottles of the alcohol hand gel for bedside use, along with an educational brochure explaining how and why to practice good hand hygiene. METHODS: Infection rate and type data were collected in 1 unit of a 498-bed acute care facility for 16 months (February 2000 to May 2001). An alcohol gel hand sanitizer was provided and used by caregivers in the orthopedic surgical unit of the facility during this period. RESULTS: The primary infection types (more than 80%) found were urinary tract (UTI) and surgical site (SSI) infections. Infection types and rates for the unit during the period the alcohol hand sanitizer (intervention) was used were compared with the infection types and rates for the same unit when the alcohol hand sanitizer was not used (baseline); the results demonstrated a 36.1% decrease in infection rates for the 10-month period that the hand sanitizer was used. CONCLUSION: This study indicates that use of an alcohol gel hand sanitizer can decrease infection rates and provide an additional tool for an effective infection control program in acute care facilities.

Analysis of Variance↗

Resistance of Listeria monocytogenes biofilms to sanitizing agents in a simulated food processing environment.

The objective of this study was to evaluate the resistance of biofilms of Listeria monocytogenes to sanitizing agents under laboratory conditions simulating a food processing environment. Biofilms were initially formed on stainless steel and Teflon coupons using a five-strain mixture of L. monocytogenes. The coupons were then subjected to repeated 24-h daily cycles. Each cycle consisted of three sequential steps: (i) a brief (60 s) exposure of the coupons to a sanitizing agent (a mixture of peroxides) or saline as a control treatment, (ii) storage of the coupons in sterile plastic tubes without any nutrients or water for 15 h, (iii) and incubation of the coupons in diluted growth medium for 8 h. This regimen was repeated daily for up to 3 weeks and was designed to represent stresses encountered by bacteria in a food processing environment. The bacteria on the coupons were reduced in number during the first week of the simulated food processing (SFP) regimen, but then adapted to the stressful conditions and increased in number. Biofilms repeatedly exposed the peroxide sanitizer in the SFP regimen developed resistance to the peroxide sanitizer as well as other sanitizers (quaternary ammonium compounds and chlorine). Interestingly, cells that were removed from the biofilms on peroxide-treated and control coupons were not significantly different in their resistance to sanitizing agents. These data suggest that the resistance of the treated biofilms to sanitizing agents may be due to attributes of extracellular polymeric substances and is not an intrinsic attribute of the cells in the biofilm.

Bacterial Adhesion↗

A randomized, controlled trial of a multifaceted intervention including alcohol-based hand sanitizer and hand-hygiene education to reduce illness transmission in the home.

OBJECTIVE: Good hand hygiene may reduce the spread of infections in families with children who are in out-of-home child care. Alcohol-based hand sanitizers rapidly kill viruses that are commonly associated with respiratory and gastrointestinal (GI) infections. The objective of this study was to determine whether a multifactorial campaign centered on increasing alcohol-based hand sanitizer use and hand-hygiene education reduces illness transmission in the home. METHODS: A cluster randomized, controlled trial was conducted of homes of 292 families with children who were enrolled in out-of-home child care in 26 child care centers. Eligible families had > or =1 child who was 6 months to 5 years of age and in child care for > or =10 hours/week. Intervention families received a supply of hand sanitizer and biweekly hand-hygiene educational materials for 5 months; control families received only materials promoting good nutrition. Primary caregivers were phoned biweekly and reported respiratory and GI illnesses in family members. Respiratory and GI-illness-transmission rates (measured as secondary illnesses per susceptible person-month) were compared between groups, adjusting for demographic variables, hand-hygiene practices, and previous experience using hand sanitizers. RESULTS: Baseline demographics were similar in the 2 groups. A total of 1802 respiratory illnesses occurred during the study; 443 (25%) were secondary illnesses. A total of 252 GI illnesses occurred during the study; 28 (11%) were secondary illnesses. The secondary GI-illness rate was significantly lower in intervention families compared with control families (incidence rate ratio [IRR]: 0.41; 95% confidence interval [CI]: 0.19-0.90). The overall rate of secondary respiratory illness was not significantly different between groups (IRR: 0.97; 95% CI: 0.72-1.30). However, families with higher sanitizer usage had a marginally lower secondary respiratory illness rate than those with less usage (IRR: 0.81; 95% CI: 0.65-1.09). CONCLUSIONS: A multifactorial intervention emphasizing alcohol-based hand sanitizer use in the home reduced transmission of GI illnesses within families with children in child care. Hand sanitizers and multifaceted educational messages may have a role in improving hand-hygiene practices within the home setting.

Anti-Infective Agents, Local↗

Evaluation of dairy and food plant sanitizers against Salmonella typhimurium and Listeria monocytogenes.

Six commonly used dairy and food plant sanitizers were evaluated against Salmonella typhimurium and Listeria monocytogenes. Of these six, two were acid anionic sanitizers, one contained a quaternary ammonium compound, one was based on active iodine, and two contained active chlorine. Of the last two, one contained hypochlorite and the other contained active chlorine in organic form. The chlorine-based sanitizers were effective at 100 ppm of available chlorine against both these organisms. The sanitizer containing iodine was effective at 12.5 and 25 ppm titratable iodine against L. monocytogenes and S. typhimurium, respectively. The acid anionic sanitizers were effective at 200 ppm of active agent against both the bacteria, and the quaternary ammonium-based sanitizer was effective at 100 and 200 ppm of active compound against L. monocytogenes and S. typhimurium, respectively. The sanitizer containing iodine at 12.5 and 25 ppm of titratable iodine showed activity equivalent to 50 and 200 ppm of available chlorine, respectively, against L. monocytogenes and 100 and 200 ppm of available chlorine, respectively, against S. typhimurium.

Dairying↗

Effect of chemical cleaning agents and commercial sanitizers on ATP bioluminescence measurements.

Nine chemical cleaning agents at three concentrations were studied to determine the effect on ATP bioluminescence measurements from pure ATP (PATP) and ATP from chicken exudate (CJATP). The nine commercial cleaning and sanitizing chemicals were concentrated foaming acid (FA), acid sanitizer (AS), iodine cleaner-disinfectant (ZI), alkaline cleaner-degreaser (PC), chlorinated alkaline cleaner (CA), chlorinated sanitizer (CS), quaternary ammonium (QA), antibiofilm agent (AB), and acidic peroxygen sanitizer (HP). Effect was reported as a percent change from the log10 relative light unit (LRLU) measurements of the control groups. All cleaners and sanitizers were tested at one-tenth of the manufacturer's recommended level (MRL), MRL, and two times MRL. FA, PC, and CA at all three concentrations significantly decreased PATP and CJATP LRLU. AS decreased PATP and CJATP LRLU at 200 and 400 ppm quaternary ammonium. ZI decreased PATP LRLU at MRL or greater, while CJATP LRLU were decreased by all concentrations of ZI tested. CS decreased PATP LRLU in a dose-dependent manner; however, for CJATP, LRLU decreased slightly at the two lower concentrations but were not affected by 1,200 ppm CS. QA at MRL or above for PATP or at all concentrations for CJATP significantly increased LRLU. AB decreased LRLU at all concentrations tested for PATP or at MRL or greater for CJATP. HPA at MRL or greater for PATP or at all concentrations for CJATP significantly reduced LRLU. These results demonstrate that commercial sanitizers and cleansers may squelch or increase LRLU measurements when the chemical comes into direct contact with the ATP bioluminescence reagents. Hence, when using ATP bioluminescence as a means of determining sanitary quality of food-processing equipment, it is essential to consider the type and concentration of chemical cleaner or sanitizer being used on the equipment prior to testing.

Adenosine Triphosphate↗

Different responses of planktonic and attached Bacillus subtilis and Pseudomonas fluorescens to sanitizer treatment.

Three commercial sanitizers containing iodophor (I), peracetic acid/ hydrogen peroxide (PAH), or chlorhexidine gluconate (CG) were evaluated in vitro against planktonic and sessile Bacillus subtilis or Pseudomonas fluorescens cells grown in Standard One Nutrient Broth. Sessile cells were attached to stainless steel or polyurethane test surfaces. Planktonic and attached cells of both bacteria were enumerated by plate counts after sanitizer treatment for 1, 3, or 5 min. Sessile cells were dislodged from test surfaces by shaking them with beads. Cell morphologies were monitored by scanning electron microscopy (SEM). Attached B. subtilis and P. fluorescens cells on both surface types were less susceptible to all three sanitizers than their planktonic counterparts. PAH, I, and CG were equally effective against planktonic P. fluorescens cells, which were reduced by 99.999% after 1, 3, and 5 min exposure. PAH was the only sanitizer effective against attached P. fluorescens cells on both surface types; it reduced counts by < or = 99.9% after 1, 3, and 5 min exposure. PAH was also the most effective sanitizer against planktonic B. subtilis cells, reducing counts by 99.9% after 1, 3, and 5 min. Sessile B. subtilis cells on both surface types were the least susceptible to all sanitizers; counts were reduced by only 99.5% or less after exposure to PAH for 5 min. SEM revealed that planktonic and attached cells of both bacteria exhibited symptoms of surface roughness, indentations, and shape distortions after treatment with any of the sanitizers.

Animals↗

Influence of extended acid stressing in fresh beef decontamination runoff fluids on sanitizer resistance of acid-adapted Escherichia coli O157:H7 in biofilms.

This study evaluated resistance to sanitizing solutions of Escherichia coli O157:H7 cells forming biofilms on stainless steel coupons exposed to inoculated meat decontamination runoff fluids (washings). A previously acid-adapted culture of a rifampicin-resistant derivative of E. coli O157:H7 strain ATCC 43895 was inoculated in unsterilized or sterilized combined hot-water (85 degrees C) and cold-water (10 degrees C) (50/50 [vol/vol]) composite water (W) washings (pH 6.29 to 6.47) and in W washings mixed with 2% acetic acid (pH 4.60 to 4.71) or in 2% lactic acid W washings (pH 4.33 to 4.48) at a ratio of 1/99 (vol/vol). Stainless steel coupons (2 by 5 by 0.08 cm) were submerged in the inoculated washings and stored for up to 14 days at 15 degrees C. Survival of E. coli O157:H7 was determined after exposure (0 to 60 s for cells in suspension and 0 to 300 s for attached cells) to two commercial sanitizers (150 ppm peroxyacetic acid and 200 ppm quaternary ammonium compound) at 2, 7, and 14 days. E. coli O157:H7 attached more rapidly to coupons submerged in washings containing the natural flora than to those without. The attached cells were more resistant to the effects of the sanitizers than were the cells in suspension, and survival was highest in the presence of the natural flora. Attached cells in the presence of dilute acid washings were more sensitive to subsequent sanitizer treatments than were cells generated in the presence of W washings. Under the conditions of this study, cells of E. coli O157:H7 in W washings were more sensitive to acidic (peroxyacetic acid) than to alkaline (quaternary ammonium) sanitizers during storage. These results suggest that meat processing plants that apply no decontamination or that use only water washings of meat should consider using acidic sanitizers to enhance biofilm removal. Plants that apply both water and acidic washings may create a sublethal acid-stressing environment in the runoff fluids, sensitizing biofilm cells to subsequent sanitizing treatments.

Acetic Acid↗

Comparison of sodium hypochlorite-based foam and peroxyacetic acid-based fog sanitizing procedures in a salmon smokehouse: survival of the general microflora and Listeria monocytogenes.

The effects of fog sanitization with peroxyacetic acid (hydrogen peroxide, peracetic acid, and acetic acid in combination) on general hygiene (aerobic plate count) and on Listeria monocytogenes were assessed in a slicing area at a salmon smokehouse and compared with the effects of foam sanitization with sodium hypochlorite (routinely performed at the smokehouse). Two hundred twenty-three environmental samples were collected with sponges and swabs after each of the sanitization procedures, and 68 samples were collected during production. The total culturable aerobic plate count was determined for each sample, and a total of 288 bacterial strains were randomly isolated and tentatively identified to genus level by physiological and biochemical tests. The microflora was dominated by Neisseriaceae, Enterobacteriaceae, and lactic acid bacteria during production. Foam sanitization caused a change in the composition of the flora, with Pseudomonas spp. and Alcaligenes spp. being the dominant gram-negative bacteria and Kurthia spp. and Bacillus spp. being the surviving gram-positive bacteria. Bacteria were very sensitive to fog sanitization, and yeasts accounted for almost half of the surviving flora. By a selective isolation method, strains of L. monocytogenes were isolated and subsequently characterized by random amplified polymorphic DNA (RAPD) typing. Following foam sanitization, 14 to 42% of the samples contained <10 CFU per site, whereas 29 to 78% of the samples collected after fog sanitization contained this level of bacteria. The prevalence of L. monocytogenes was unchanged, but L. monocytogenes was found only in poorly cleaned areas such as drains. The RAPD types for all positive samples were identical to the type that had persisted in the smokehouse since 1995, indicating the importance of drains as a niche.

Animals↗

Inactivation of escherichia coli 0157:H7 and Salmonella on mung beans, alfalfa, and other seed types destined for sprout production by using an oxychloro-based sanitizer.

The efficacy of a stabilized oxychloro-based food grade sanitizer to decontaminate seeds destined for sprout production has been evaluated. By using mung bean seeds as a model system, it was demonstrated that the sanitizer could be used to inactivate a five-strain cocktail of Escherichia coli O157:H7 or Salmonella introduced onto beans at 10(3) to 10(4) CFU/g. Salmonella was more tolerant to stabilized oxychloro than was E. coli O157:H7, with sanitizer levels of >150 and >50 ppm, respectively, being required to ensure pathogen-free sprouts. The decontamination efficacy was also found to be dependent on treatment time (>8 h optimal) and the seed-to-sanitizer ratio (>1:4 optimal). Stabilized oxychloro treatment did not exhibit phytotoxic effects, as germination and sprout yields were not significantly (P > 0.05) different as compared with untreated controls. Although human pathogens could be effectively eliminated from mung beans, the aerobic plate count of native microflora on sprouts grown from treated seed was not significantly (P > 0.05) different from the controls. The diversity of microbial populations (determined through 16S rRNA denaturing gradient gel electrophoresis analysis) associated with bean sprouts was not significantly affected by the sanitizer treatment. However, it was noted that Klebsiella and Herbasprillum (both common plant endophytes) were absent in sprouts derived from decontaminated seed but were present in control sprouts. When a further range of seed types was evaluated, it was found that alfalfa, cress, flax, and soybean could be decontaminated with the stabilized oxychloro sanitizer. However, the decontamination efficacy with other seed types was less consistent. It appears that the rate of seed germination and putative activity of sanitizer sequestering system(s), in addition to other factors, may limit the efficacy of the decontamination method.

Chlorine Compounds↗

Evaluation of chlorine, chlorine dioxide, and a peroxyacetic acid-based sanitizer for effectiveness in killing Bacillus cereus and Bacillus thuringiensis spores in suspensions, on the surface of stainless steel, and on apples.

Chlorine (10 to 200 microg/ml), chlorine dioxide (10 to 200 microg/ml), and a peroxyacetic acid-based sanitizer (40 and 80 microg/ ml) were evaluated for effectiveness in killing spores of Bacillus cereus and Bacillus thuringiensis in suspensions and on the surface of stainless steel and apples. Water and 5% horse serum were used as carriers for spore inoculum applied to the surface of stainless steel coupons, and 5% horse serum was used as a carrier for inoculum applied to apples. Inocula were dried on stainless steel for 5 h and on apples for 22 to 24 h before treating with sanitizers. At the concentrations of sanitizers tested, sensitivities of planktonic B. cereus and B. thuringiensis spores were similar. A portion of the spores surviving treatment with chlorine and, more markedly, chlorine dioxide had decreased tolerance to heat. Planktonic spores of both species were more sensitive to sanitizers than were spores on the surface of stainless steel or apples. At the same concentrations, chlorine was more effective than chlorine dioxide in killing spores in suspension and on stainless steel. The lethality of chlorine dioxide was markedly reduced when inoculum on stainless steel coupons was suspended in 5% horse serum as a carrier rather than water. Chlorine and chlorine dioxide at concentrations of 10 to 100 microg/ml were equally effective in killing spores on apples. Significant reductions of > or = 3.8 to 4.5 log CFU per apple were achieved by treatment with 100 microg/ml of either of the two sanitizers. The peroxyacetic acid sanitizer (40 and 80 microg/ml) was ineffective in killing Bacillus spores in the test systems investigated. Results provide information on the effectiveness of sanitizers commonly used in the food processing industry in killing Bacillus spores in suspension, on a food-contact surface, and on a ready-to-eat food.

Bacillus cereus↗

Effectiveness of Rack Sanitation Procedures for Elimination of Bacteria from Automatic Watering Manifolds.

An important responsibility of animal care programs is to protect research animals from exposure to potentially pathogenic microorganisms. To validate the need for steam sterilization of rodent automatic watering racks, we evaluate the post-sanitation microbial contamination of experimentally inoculated racks and of racks that had been used to house conventional mice. We tested three sanitation protocols: rack-washer sanitation without manifold flush, sanitation that included manifold flush, and sanitation that included manifold flush followed by autoclaving. Rack sanitation, with or without manifold flush, did not reliably eliminate microbial flora from the lixits or manifold drainage water. A total of 43% of all non-autoclaved racks were positive for bacterial contamination after sanitation, and racks that had been used for conventional animal housing were more frequently positive than were experimentally inoculated racks (79% vs 18%). These data indicate that steam sterilization is necessary for eliminating bacteria from automatic watering systems. These observations are particularly important in light of increasing numbers of immune-impaired rodents that may be inadvertently and unnecessarily exposed to microbial pathogens via the automatic watering system.

Journal Article↗

Economic aspects of rural sanitation in the United States of America.

Although health conditions in the rural areas of the USA are comparatively good, they are inferior to those in the urban areas. An important reason for this inferiority is the fact that rural sanitation is less a social responsibility than an individual responsibility, which many rural families cannot finance. The rural culture imposes many handicaps on the rural family's health and wealth. Such handicaps may be moderated by sanitation and related social and economic measures, if the measures selected are appropriate to the local needs and resources, which may vary greatly. Although sanitation needs are common to all rural areas, the refinement and complexity of sanitation facilities and services cannot be uniform. Allowing for variable circumstances, however, the basic elements of rural sanitation in the USA can be realized within a generation. The probable net gains in farm productivity would seem to warrant support for a rural sanitation programme on economic grounds alone, if an economic market may be assumed for the increase in agricultural production.

Agriculture↗

Natural antimicrobial agent (reuterin) produced by lactobacillus reuteri for sanitization of biological tissues inoculated with pseudomonas aeruginosa.

The study was done to evaluate the efficacy of using reuterin produced by Lactobacillus reuteri to sanitize biological tissues. The microorganism tested in the study was Pseudomonas aeruginosa, a common cause of nosocomial biomaterial-related infections. The inhibitory effect of reuterin on P. aeruginosa for an inoculated tissue was investigated at different conditions of concentration, temperature, and pH. Additionally, the cellular compatibility of the reuterin-sanitized tissue was evaluated. Glutaraldehyde was employed as a control. It was noted that the minimum inhibitory concentration (MIC, 33.0 +/- 2.9 ppm) and minimum bactericidal concentration (MBC, 50.0 +/- 0.0 ppm) values of reuterin for P. aeruginosa were significantly lower than their glutaraldehyde counterparts (MIC, 130.0 +/- 8.2 ppm and MBC, 180.0 +/- 18.3 ppm). This indicated that reuterin was more efficient than glutaraldehyde as an antimicrobial agent. The addition of reuterin on the inoculated tissue led to a reduced viability of P. aeruginosa. The reduction in the P. aeruginosa culture was more pronounced with increasing the concentration of reuterin (0-100 ppm). At increasing temperature (25-45 degrees C), there was an increasing effect of reuterin on its sanitization activity. However, it should be pointed out that the growth of P. aeruginosa in the nutrient broth was also significantly affected by temperature. The sanitization activity of reuterin was more evident with increasing the pH level (pH 6.5-8.5). The cytotoxicity of reuterin was significantly lower than that of glutaraldehyde. Additionally, the cellular compatibility of the reuterin-sanitized tissue was superior to its glutaraldehyde-sanitized counterpart.

Aldehydes↗

Creating demand for sanitation and hygiene through Community Health Clubs: a cost-effective intervention in two districts in Zimbabwe.

Unless strategies are found to galvanise rural communities and create a demand for sanitation, we cannot achieve the United Nations Millennium Development Goal of halving the 2.4 billion people without sanitation by the year 2015. This study describes an innovative methodology used in Zimbabwe--Community Health Clubs--which significantly changed hygiene behaviour and built rural demand for sanitation. In 1 year in Makoni District, 1244 health promotion sessions were held by 14 trainers, costing an average of US dollars 0.21 per beneficiary and involving 11,450 club members (68,700 beneficiaries). In Tsholotsho District, 2105 members participated in 182 sessions held by three trainers which cost US dollars 0.55 for each of the 12,630 beneficiaries. Within 2 years, 2400 latrines had been built in Makoni, and in Tsholotsho latrine coverage rose to 43% contrasted to 2% in the control area, with 1200 latrines being built in 18 months. Although Zimbabwe has historically relied on subsidies to stimulate sanitation, this intervention shows how total sanitation could be achievable. The remaining 57% of club members without latrines in Tsholotsho all practised faecal burial, a method previously unknown to them. Club members' hygiene was significantly different (p<0.0001) from a control group across 17 key hygiene practices including hand washing, showing that if a strong community structure is developed and the norms of a community are altered, sanitation and hygiene behaviour are likely to improve. This methodology could be scaled up to contribute to ambitious global targets.

Community Health Planning↗

Bacteriocidal activity of sanitizers against Enterococcus faecium attached to stainless steel as determined by plate count and impedance methods.

Enterococcus faecium attached to stainless steel chips (100 mm2) was treated with the following sanitizers: sodium hypochlorite, peracetic acid (PA), peracetic acid plus an organic acid (PAS), quaternary ammonium, organic acid, and anionic acid. The effectiveness of sanitizer solutions on planktonic cells (not attached) was evaluated by the Association of Official Analytical Chemists (AOAC) suspension test. The number of attached cells was determined by impedance measurement and plate count method after vortexing. The decimal reduction (DR) in numbers of the E. faecium population was determined for the three methods and was analyzed by analysis of variance (P < 0.05) using Statview software. The adhered cells were more resistant (P < 0.05) than nonadherent cells. The DR averages for all of the sanitizers for 30 s of exposure were 6.4, 2.2, and 2.5 for the AOAC suspension test, plate count method after vortexing, and impedance measurement, respectively. Plate count and impedance methods showed a difference (P < 0.05) after 30 s of sanitizer exposure but not after 2 min. The impedance measurement was the best method to measure adherent cells. Impedance measurement required the development of a quadratic regression. The equation developed from 82 samples is as follows: log CFU/chip = 0.2385T2-0.96T + 9.35, r2 = 0.92, P < 0.05, T = impedance detection time in hours. This method showed that the sanitizers PAS and PA were more effective against E. faecium than the other sanitizers. At 30 s, the impedance method recovered about 25 times more cells than the plate count method after vortexing. These data suggest that impedance measurement is the method of choice when evaluating the number of bacterial cells adhered to a surface.

Bacterial Adhesion↗

Evaluation of household sanitizers for reducing levels of Escherichia coli on iceberg lettuce.

Diluted solutions of various household sanitizers (apple cider vinegar, white vinegar, bleach, and a reconstituted lemon juice product) were tested for their effectiveness in reducing counts of inoculated Escherichia coli and naturally present aerobic, mesophilic bacteria on lettuce. Sanitization treatments were carried out at 4 degrees C and at room temperature (ca. 21 degrees C) with and without agitation and at different exposure times (0, 1, 5, and 10 min). Of the sanitizers tested, 35% white vinegar (1.9% acetic acid) was the most effective in reducing E. coli levels (with a 5-log10 reduction after 5 min with agitation and after 10 min without agitation) and in reducing aerobic plate counts (with a >2-log10 reduction after 10 min with agitation). Lettuce samples treated with diluted household sanitizers were analyzed for consumer acceptability by sensory evaluation using a 9-point hedonic scale. The sanitized samples did not differ in acceptability (P > 0.05), except for samples treated with white vinegar. Samples treated with the white vinegar for 10 min were noticeably sour and slightly wilted in appearance. Consumer acceptability was maintained with all sanitization treatments, including those involving 35% white vinegar.

Acetic Acid↗