Contamination of hands and work surfaces with Salmonella enteritidis PT4 during the preparation of egg dishes

Isolation and identification of microorganisms associated with automated teller machines on Federal Polytechnic Ede campus

Automated Teller Machines (ATM) are visited everyday by millions of people. This machine is accessible to the general public irrespective of class, age or race. The contact point of all ATM machines is the hand which on their own are ‘vaults’ of microorganisms. An elaborate survey was taken for complete assessment of possible microbial contamination in the Federal Polytechnic Ede campus. Selected ATM machines on campus were used as case study to characterize, identify and determine the degree of bacterial contamination of microorganisms and their potential as reservoir of microbes. Swabs were collected from each ATM screen, buttons, floor, user’s hand, and exposure of plates. After collection of the samples, they were plated in nutrient agar. The results showed the presence of increased bacterial count subsequently, most pathogens on characterization revealed the genus of the particular organisms E. coli, Pseudomonas, Staphylococcus aureus, Klebsiella, Micrococcus, Salmonella and Serratia. The study showed the potential hazard inherent in ATM machine usage and draws attention to our level of hand hygiene compliance.

Multistate outbreak of Salmonella Poona infections associated with imported cucumbers, 2015-2016

We investigated a large multistate outbreak that occurred in the United States in 2015-2016. Epidemiologic, laboratory, and traceback studies were conducted to determine the source of the infections. We identified 907 case-patients from 40 states with illness onset dates ranging from July 3, 2015 to March 2, 2016. Sixty-three percent of case-patients reported consuming cucumbers in the week before illness onset. Ten illness sub-clusters linked to events or purchase locations were identified. All sub-clusters investigated received cucumbers from a single distributor which were sourced from a single grower in Mexico. Seventy-five cucumber samples were collected, 19 of which yielded the outbreak strain. Whole genome sequencing performed on 154 clinical isolates and 19 cucumber samples indicated that the sequenced isolates were closely related genetically to one another. This was the largest US foodborne disease outbreak in the last ten years and the third largest in the past 20 years. This was at least the fifth multistate outbreak caused by contaminated cucumbers since 2010. The outbreak is noteworthy because a recall was issued only 17 days after the outbreak was identified, which allowed for the removal of the contaminated cucumbers still available in commerce, unlike previous cucumber associated outbreaks. The rapid identification and response of multiple public health agencies resulted in preventing this from becoming an even larger outbreak.

The Effects of Dry, Humid and Wear Conditions on the Antimicrobial Efficiency of Triclosan-Containing Surfaces

This study evaluated the effects of triclosan-containing polyester surfaces under various conditions at concentrations of between 400 ppm and 850 ppm. Staphylococcus aureus was chosen for the tests because it rapidly develops resistance to many antimicrobial agents. The results show that dry and humid conditions have bacteriostatic activity that inhibits the growth of S. aureus, with a greater effect under dryness (p < 0.05). Further, concentrations as low as 400 ppm showed activities of 0.99 log10 and 0.19 log10 for dry and humid conditions, respectively. The study of the association between triclosan concentrations and bacterial inhibition showed a high correlation for dry (R2 = 0.968) and humid conditions (R2 = 0.986). Under wear conditions, triclosan showed a gradual reduction in its bacteriostatic activity due to successive washing/drying treatments (p < 0.05). Thus, the use of triclosan in low concentrations is suggested as achieving bacteriostatic activity. Moreover, its use can be considered as complementary to the cleaning and disinfection procedures carried out in the food industry. However, it must not replace them. Manufacturing processes must be improved to preserve the triclosan properties in the antimicrobial materials to control microorganisms involved in cross-contamination between surfaces and food.

Preventing infection in the home

F undamental to controlling infection transmission in the home is the need to recognise it as an environment where all human activities occur, including food hygiene, hand hygiene and hygiene related to care of vulnerable groups. In recent years the concept of a risk assessment/risk reduction approach to hygiene has successfully controlled microbial risks in food and other manufacturing environments.

To deliver hygiene policy with real health benefits it is now accepted that a risk-based approach must also be developed for the home. The first step, hazard characterisation, involves identifying sites and surfaces where pathogens most frequently occur, and whether they are likely to be present in numbers that represent an infectious dose. A risk assessment is then made by considering this information together with an assessment of the probability of human exposure to the hazard. Risk reduction is achieved by application of a suitable hygiene procedure at the appropriate time.

Consumer Shell Egg Consumption and Handling Practices: Results from a National Survey

Numerous cases and outbreaks of Salmonella infection are attributable to shell eggs each year in the United States. Safe handling and consumption of shell eggs at home can help reduce foodborne illness attributable to shell eggs. A nationally representative Web survey of 1,504 U.S. adult grocery shoppers was conducted to describe consumer handling practices and consumption of shell eggs at home. Based on self-reported survey data, most respondents purchase shell eggs from a grocery store (89.5%), and these eggs were kept refrigerated (not at room temperature; 98.5%). As recommended, most consumers stored shell eggs in the refrigerator (99%) for no more than 3 to 5 weeks (97.6%). After cracking eggs, 48.1% of respondents washed their hands with soap and water. More than half of respondents who fry and/or poach eggs cooked them so that the whites and/or the yolks were still soft or runny, a potentially unsafe practice. Among respondents who owned a food thermometer (62.0%), only 5.2% used it to check the doneness of baked egg dishes when they prepared such a dish. Consumers generally followed two of the four core "Safe Food Families" food safety messages ("separate" and "chill") when handling shell eggs at home. To prevent Salmonella infection associated with shell eggs, consumers should improve their practices related to the messages "clean" (i.e., wash hands after cracking eggs) and "cook" (i.e., cook until yolks and whites are firm and use a food thermometer to check doneness of baked egg dishes) when preparing shell eggs at home. These findings will be used to inform the development of science-based consumer education materials that can help reduce foodborne illness from Salmonella infection.

Impact of disinfectant wipes on the risk of Campylobacter jejuni infection during raw chicken preparation in domestic kitchens

AIMS

In the present study, we conducted a quantitative microbial risk assessment forecasting the exposure to Campylobacter jejuni contaminated surfaces during preparation of chicken fillets and how using a disinfectant-wipe intervention to clean a contaminated work area decreases the risk of infection following the preparation of raw chicken fillet in a domestic kitchen.

METHODS AND RESULTS

Using a Monte Carlo simulation of the risk of transferring Camp. jejuni strain A3249, from various surfaces to hands and subsequently transferring it to the mouth was forecasted. The use of a disinfectant-wipe intervention to disinfect contaminated surface area was also assessed. Several assumptions were used as input parameters in the classical Beta-Poisson model to determine the risk of infection. The disinfectant-wipe intervention reduced the risk of Camp. jejuni infection by 2-3 orders on all fomites.

CONCLUSIONS

The use of disinfectant wipes after the preparation of raw chicken meat reduces the risk of Camp. jejuni infections.

SIGNIFICANCE AND IMPACT OF THE STUDY

This risk assessment shows that the use of disinfectant wipes to decontaminate surface areas after chicken preparation reduces the annual risk of Camp. jejuni infections up to 99·2%, reducing the risk from 2 : 10 to 2 : 1000.

Salmonella and eggs: from production to plate

Salmonella contamination of eggs and egg shells has been identified as a public health concern worldwide. A recent shift in consumer preferences has impacted on the egg industry, with a push for cage-free egg production methods. There has also been an increased desire from consumers for raw and unprocessed foods, potentially increasing the risk of salmonellosis. In response to these changes, this review explores the current literature regarding Salmonella contamination of eggs during the production processing through to food handling protocols. The contamination of eggs with Salmonella during the production process is a complex issue, influenced by many variables including flock size, flock age, stress, feed, vaccination, and cleaning routines. Currently there is no consensus regarding the impact of caged, barn and free range egg production has on Salmonella contamination of eggs. The literature regarding the management and control strategies post-collection, during storage, transport and food handling is also reviewed. Pasteurisation and irradiation were identified as the only certain methods for controlling Salmonella and are essential for the protection of high risk groups, whereas control of temperature and pH were identified as potential control methods to minimise the risk for foods containing raw eggs; however, further research is required to provide more detailed control protocols and education programs to reduce the risk of salmonellosis from egg consumption.

Comparative phenotypic and genotypic virulence of Salmonella strains isolated from Australian layer farms

There are over 2500 Salmonella enterica serovars that circulate globally. Of these, serovars those classified into subspecies I are the most common cause of human salmonellosis. Many subspecies I Salmonella serovars are routinely isolated from egg farm environments but are not frequently associated with causing disease in humans. In this study, virulence profiles were generated for 10 strains of Salmonella enterica isolated directly from egg farm environments to investigate their potential public health risk. Three virulence parameters were assessed including in vitro invasion, in vivo pathogenicity and characterization of genomic variation within five specific pathogenicity islands. These 10 Salmonella strains exhibited significant differences in invasion into the human intestinal epithelial cell line, Caco2. Low, moderate, and high invasion patterns were observed and the degree of invasion was dependent on bacterial growth in a nutritive environment. Interestingly, two Salmonella strains, S. Adelaide and S. Bredeney had consistently low invasion. The S. Typhimurium definitive types and S. Virchow exhibited the greatest cell invasion following growth in Luria Bertani broth. Only the S. Typhimurium strains caused disease in BALB/c mice, yet the majority of serovars were consistently detected in feces over the 21 day experiment. Genomic comparison of the five specific pathogenicity islands has shown that variation in virulence is likely multifactorial. Sequence variability was observed primarily in strains with low virulence. In particular, genes involved in forming the structures of the SPI-1 and SPI-2 type 3 secretion systems as well as multiple effector proteins were among the most variable. This variability suggest that serovars with low virulence are likely to have both invasion and within host replication defects that ultimately limit their pathogenicity.

Consumer-reported handling of raw poultry products at home: results from a national survey

Salmonella and Campylobacter cause an estimated combined total of 1.8 million foodborne infections each year in the United States. Most cases of salmonellosis and campylobacteriosis are associated with eating raw or undercooked poultry or with cross-contamination. Between 1998 and 2008, 20% of Salmonella and 16% of Campylobacter foodborne disease outbreaks were associated with food prepared inside the home. A nationally representative Web survey of U.S. adult grocery shoppers (n = 1,504) was conducted to estimate the percentage of consumers who follow recommended food safety practices when handling raw poultry at home. The survey results identified areas of low adherence to current recommended food safety practices: not washing raw poultry before cooking, proper refrigerator storage of raw poultry, use of a food thermometer to determine doneness, and proper thawing of raw poultry in cold water. Nearly 70% of consumers reported washing or rinsing raw poultry before cooking it, a potentially unsafe practice because "splashing" of contaminated water may lead to the transfer of pathogens to other foods and other kitchen surfaces. Only 17.5% of consumers reported correctly storing raw poultry in the refrigerator. Sixty-two percent of consumers own a food thermometer, and of these, 26% or fewer reported using one to check the internal temperature of smaller cuts of poultry and ground poultry. Only 11% of consumers who thaw raw poultry in cold water reported doing so correctly. The study results, coupled with other research findings, will inform the development of science-based consumer education materials that can help reduce foodborne illness from Salmonella and Campylobacter.

Epidemiological investigation of an outbreak of salmonellosis in Gyeongju, Korea

Objectives

A salmonellosis outbreak occurred within a community of Gyeongju residents who ingested catered food from a wedding in June 2009. We aimed to epidemiologically investigate the probable vehicle of the infection.

Methods

We conducted a retrospective cohort study on 34 local residents who ingested the wedding food.

Results

Among the 34 residents, 31 (91.2%) reported symptoms of infection after eating the food. Among all of the wedding foods, pan-fried foods were highly associated with the diarrheal attack rate. On bacteriological examination, Salmonella species were detected in the pan-fried foods among the leftover foods and in 17 of the 31 stool specimens from the cases. There were five different types of pan-fried foods, but the onset of symptoms was independent of the ingredients used. We found that the pan-fried food was prepared at a food store in Seoul and that eggs were a common ingredient.

Conclusions

The major cause of the salmonellosis in this population was presumed to be the pan-fried food prepared with contaminated eggs. These food items might have been partially undercooked because of their irregular shape, which allowed the Salmonella species to survive and multiply before ingestion.

An outbreak of gastroenteritis caused by Salmonella enterica serotype Enteritidis traced to cream cakes

INTRODUCTION

This paper describes the epidemiological, microbiological and environmental investigations conducted during an outbreak of Salmonella gastroenteritis in Singapore.

METHODS

A case-control study was undertaken to identify the vehicle of transmission. Microbiological testing was performed on faecal, food and environmental samples. Isolates of Salmonella were further characterized by phage typing and ribotyping.

RESULTS

There were 216 gastroenteritis cases reported from 20 November to 4 December 2007. The causative agent was identified as Salmonella enterica subspecies enterica serotype Enteritidis for 14 out of 20 cases tested. The vehicle of transmission was traced to cream cakes produced by a bakery and sold at its retail outlets (P < 0.001, OR = 143.00, 95% Cl = 27.23-759.10). More than two-thirds of the 40 Salmonella strains isolated from hospitalized cases, food samples and asymptomatic food handlers were of phage type 1; the others reacted but did not conform to any phage type. The phage types correlated well with their unique antibiograms. The ribotype patterns of 22 selected isolates tested were highly similar, indicating genetic relatedness. The dendrogram of the strains from the outbreak showed distinct clustering and correlation compared to the non-outbreak strains, confirming a common source of infection.

DISCUSSION

The cream cakes were likely contaminated by one of the ingredients used in the icing. Cross-contamination down the production line and subsequent storage of cakes at ambient temperatures for a prolonged period before consumption could have contributed to the outbreak.

Potential zoonotic pathways of Salmonella enteritidis in laying farms

Salmonella Enteritidis is a communicable zoonotic bacterium. The present investigation was done to evaluate the potential occurrence of Salmonella Enteritidis in laying hen farms and its contamination pathways. Samples were collected from 10 laying hen farms located in the Delta of Egypt. Cloacal swabs (n=300), eggshell swabs (n=400), and hand swabs from egg packagers (n=38) were collected. Pools of ovary and oviduct were obtained from 150 hens; all samples were examined for the presence of Salmonella Enteritidis. Results indicated that Salmonella Enteritidis may initially occupy in ovary, oviduct, and cloaca. The risk for eggshell contamination is highly impending from laying hen flocks infected with Salmonella Enteritidis with percentage of >30%. Farms having eggshell contamination percentage of >60% with Salmonella Enteritidis provided a high risk for packagers' hand contamination. Questionnaire of egg packagers specified that seven out of the eight smoker packagers suffered from repeated Salmonellosis. Thus, smoking during egg packing process could be considered as an exposure factor to contract the infection via hand-cigarette-mouth route.

The importance of hygiene in the domestic kitchen: Implications for preparation and storage of food and infant formula

Aims: Public concerns relating to food safety remain high with most attention focused on manufactured foods and those served in catering operations. However, previous data have suggested that the home may be the main location for cases of food-borne disease. The aim of this paper is to review the microbiological risks associated with hygiene in the domestic kitchen related to food and infant formula safety.

Methods: Compared to other food sectors, research on consumer food hygiene, domestic food-handling and preparation of infant formula is relatively understudied. Behavioural and microbiological studies of consumer hygiene and the domestic kitchen have been reviewed to incorporate research relating to the safety of infant formula.

Results: Incidence data identify the home as an important location for acquiring food-borne disease. The domestic kitchen can be used for a variety of purposes and is often contaminated with potentially harmful micro-organisms such as Campylobacter and Salmonella. Consumer hygiene habits have frequently been found to be inadequate and relate both to microbial growth, survival and cross-contamination. Due to the reduced immune response of infants, the activities associated with the preparation of infant formula and associated bottles and equipment are of particular concern.

Conclusions: Cumulatively, the data suggest that more effort should be made to educate the consumer in food hygiene, especially when the kitchen is used to reconstitute infant formula. This information needs to be provided in a form appropriate for use by consumers.

Outbreaks where food workers have been implicated in the spread of foodborne disease. Part 6. Transmission and survival of pathogens in the food processing and preparation environment

This article, the sixth in a series reviewing the role of food workers in foodborne outbreaks, describes the source and means of pathogen transfer. The transmission and survival of enteric pathogens in the food processing and preparation environment through human and raw food sources is reviewed, with the main objective of providing information critical to the reduction of illness due to foodborne outbreaks. Pathogens in the food preparation area can originate from infected food workers, raw foods, or other environmental sources. These pathogens can then spread within food preparation or processing facilities through sometimes complex pathways and may infect one or more workers or the consumer of foods processed or prepared by these infected workers. The most frequent means of worker contamination is the fecal-oral route, and study results have indicated that toilet paper may not stop transmission of pathogens to hands. However, contact with raw foods of animal origin, worker aerosols (from sneezes), vomitus, and exposed hand lesions also have been associated with outbreaks. Transfer of pathogens has been documented through contaminated fabrics and carpets, rings, currency, skin surfaces, dust, and aerosols and though person-to-person transmission. Results of experiments on pathogen survival have indicated that transmission depends on the species, the inoculum delivery route, the contact surface type, the duration and temperature of exposure, and the relative humidity. Generally, viruses and encysted parasites are more resistant than enteric bacteria to adverse environmental conditions, but all pathogens can survive long enough for transfer from a contaminated worker to food, food contact surfaces, or fellow workers.

Populations of Salmonella enteritidis in artificially inoculated chicken eggs as influenced by the temperatures under which eggs might be held from the day of lay until the day of processing

This study was undertaken to determine the levels of Salmonella Enteritidis in artificially inoculated eggs as affected by the temperatures under which eggs might be held from the day of lay until the day of processing. Unprocessed chicken eggs of different sizes (n=1920, with 480 being laid in each season) were inoculated in the albumen with a five-strain mixture of Salmonella at 102 CFU per egg. The eggs were stored at 4, 10, and 22 degrees C for 3 weeks and sampled twice a week to determine the populations of Salmonella and total aerobic bacteria. The season in which eggs were laid did not significantly impact the growth of the pathogen (P > 0.05). The mean populations of the inoculated Salmonella were not significantly different in eggs stored at 4 versus 10 degrees C (P > 0.05). Eggs stored at 22 degrees C had a mean Salmonella population that was 3.71 or 3.37 log higher than the Salmonella population of eggs stored at 4 or 10 degrees C (P > 0.05). The mean Salmonella population at 22 degrees C increased from the initial 2.12 log CFU/ml to 3.36 log CFU/ml after 2 weeks of storage and to 7.84 log CFU/ml after 3 weeks of storage. A sharp increase in the population of Salmonella occurred after 2 to 2.5 weeks of storage at 22 degree C. This study provided a scientific basis for the current egg handling and transporting temperature requirements and reinforced the importance of maintaining low temperatures in controlling and preventing the growth of Salmonella Enteritidis in eggs from the day of lay until the day of processing.

Survey of Salmonella contamination of raw shell eggs used in food service premises in the United Kingdom, 2005 through 2006

This survey was launched after an unusual number of Salmonella Enteritidis outbreaks associated with the use of eggs in food service premises in England and Wales. Between November 2005 and December 2006, 9,528 eggs (1,588 pooled samples of 6 eggs) were collected from 1,567 food service premises in the United Kingdom, most of which (89%) were produced in the United Kingdom. Salmonella was isolated from 6 (0.38%) pools of eggs. Of these, 5 (0.31%) were Salmonella Enteritidis, which were further characterized to phage types (PTs): PT 4 (0.19%), PT 8 (0.06%), and PT 12 (0.06%). Salmonella Mbandaka was also isolated (0.06%). Salmonella was detected from five and one of pooled eggs samples that were produced in the United Kingdom and Germany, respectively; these were from different producers. The study showed evidence of poor egg storage and handling practices in food service premises, in that 55% did not store eggs under refrigerated conditions; 20.7% of eggs had expired "best before" dates or were in use after 3 weeks of lay, indicating poor stock rotation; and 37.1% pooled eggs not intended for immediate service. Eggs are a commonly consumed food that may occasionally be contaminated with Salmonella at different rates, according to their country of origin. The food service sector needs to be aware of this continuing hazard, receive appropriate food safety and hygiene training on storage and usage of raw shell eggs, adopt appropriate control measures, and follow advice provided by national food agencies in order to reduce the risk of infection.

Effect of hand wash agents on controlling the transmission of pathogenic bacteria from hands to food

The goals of this study were to evaluate the effectiveness of two hand wash regimens in reducing transient bacteria on the skin following a single hand wash and the subsequent transfer of the bacteria to a ready-to-eat food item, freshly cut cantaloupe melon. The number of bacteria recovered from hands and the quantity transferred to the melon were significantly less following the use of an antibacterial soap compared with plain soap. The antimicrobial soap achieved > 3-log reductions versus Escherichia coli and 3.31- and 2.83-log reductions versus Shigella flexneri. The plain soap failed to achieve a 2-log reduction against either organism. The bacteria recovered from the melon handled by hands treated with antimicrobial hand soap averaged 2 log. Melon handled following hand washing with plain soap had > 3 log bacteria in the experiments. Based on previously published feeding studies, an infection rate in the range of approximately 15 to 25% would be expected after ingesting melon containing 2 log CFU compared with ingesting greater than the 3 log transferred from hands washed with plain soap, which would result in a higher infection attack rate of 50 to 80%. The data thus demonstrate there is a greater potential to reduce the transmission and acquisition of disease through the use of an antimicrobial hand wash than through the use of plain soap.

Residence time and food contact time effects on transfer of Salmonella Typhimurium from tile, wood and carpet: testing the five-second rule

AIMS

Three experiments were conducted to determine the survival and transfer of Salmonella Typhimurium from wood, tile or carpet to bologna (sausage) and bread.

METHODS AND RESULTS

Experiment 1. After 28 days, 1.5 to 2.5 log(10) CFU cm(-2) remained on tile from and the more concentrated media facilitated the survival of S. Typhimurium compared with the more dilute solutions. Experiments 2 and 3. The bacterial transfer rate to food decreased as the bacterial residence time on the surface increased from 2, 4, 8 to 24 h with transfers of 6.5, 4.8, 4.6 and 3.9 log CFU ml(-1) in the rinse solutions, respectively. Over 99% of bacterial cells were transferred from the tile to the bologna after 5 s of bologna exposure to tile. Transfer from carpet to bologna was very low (<0.5%) when compared with the transfer from wood and tile (5-68%).

CONCLUSIONS

(i) Salmonella Typhimurium can survive for up to 4 weeks on dry surfaces in high-enough populations to be transferred to foods and (ii) S. Typhimurium can be transferred to the foods tested almost immediately on contact.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrated the ability of bacteria to survive and cross-contaminate other foods even after long periods of time on dry surfaces, thus reinforcing the importance of sanitation on food contact to minimize the risk of foodborne illness.

Food safety in the domestic environment: an interdisciplinary investigation of microbial hazards during food preparation

It has been established that, to a considerable extent, the domestic hygiene practices adopted by consumers can result in a greater or lesser microbial load in prepared meals. In the research presented here, an interdisciplinary study is reported in which interviews, observations of consumers preparing a recipe, and microbial contamination of the finished meals were compared. The results suggest that, while most consumers are knowledgeable about the importance of cross-contamination and heating in preventing the occurrence of foodborne illness, this knowledge is not necessarily translated into behavior. The adoption of habitual cooking practices may also be important. Potentially risky behaviors were, indeed, observed in the domestic food preparation environment. Eighteen of the participants made errors in food preparation that could potentially result in cross-contamination, and seven participants allowed raw meat juices to come in contact with the final meal. Using a tracer microorganism the log reduction as a result of consumer preparation was estimated at an average of log 4.1 cfu/salad. When combining these findings, it was found that cross-contamination errors were a good predictor for log reduction. Procedural food safety knowledge (i.e., knowledge proffered after general open questions) was a better predictor of efficacious bacterial reduction than declarative food safety knowledge (i.e., knowledge proffered after formal questioning). This suggests that motivation to prepare safe food was a better indicator of actual behavior than knowledge about food safety per se.

Does microbiological testing of foods and the food environment have a role in the control of foodborne disease in England and Wales?

This review looks at the contribution of microbiological sampling to the safety of retail foods in England and Wales. It compares sampling methods available and assesses the value of testing as part of outbreaks of foodborne disease, as part of routine management by local authorities, as part of work done or commissioned by the food industry, and as part of research. It confirms that microbiological testing has a role during outbreaks as it makes a significant contribution to help identify foods and other areas of greatest risk for future study. The review suggests that routine testing by local authorities is often of limited use and could be improved by more targeted surveillance. Testing could be better used to validate primary control methods, such as Hazard Analysis and Critical Control Point (HACCP) system. Any public health benefit from testing in the food industry is often restricted by client confidentiality. Microbial research on foods is important as it can lead to significant improvements in safety. Current microbiological methods are slow and, in future, rapid molecular methods may make an even bigger contribution to the control of foodborne disease.

[Bacterial contamination in an egg-breaking factory and its control]

From January to November, 2003, bacterial contamination was surveyed in a small egg-breaking factory that produced non pasteurized liquid egg. Test egg samples were taken at various stages of the egg processing operation. Salmonella Enteritidis was isolated from liquid egg yolk and liquid egg white on October, but was not found in any other samples (50 liquid egg samples, 21 containers and 94 attached production facilities and gloves). The data suggest that the contamination rate (3.8%) is lower than those reported previously. Levels of bacterial standard plate counts, gram-positive bacterial counts and gram-negative bacterial counts were in the ranges of 2 to 5 log CFU/g, 2 to 3 log CFU/g, 2 to 5 log CFU/g, respectively. Liquid egg containers returned from customers was contaminated with bacteria at the level of 8 log CFU per container. However, washing and application of a sanitizer containing sodium hypochlorite reduced the bacterial counts.

Too clean, or not too clean: the hygiene hypothesis and home hygiene

The 'hygiene hypothesis' as originally formulated by Strachan, proposes that a cause of the recent rapid rise in atopic disorders could be a lower incidence of infection in early childhood, transmitted by unhygienic contact with older siblings. Use of the term 'hygiene hypothesis' has led to several interpretations, some of which are not supported by a broader survey of the evidence. The increase in allergic disorders does not correlate with the decrease in infection with pathogenic organisms, nor can it be explained by changes in domestic hygiene. A consensus is beginning to develop round the view that more fundamental changes in lifestyle have led to decreased exposure to certain microbial or other species, such as helminths, that are important for the development of immunoregulatory mechanisms. Although this review concludes that the relationship of the hypothesis to hygiene practice is not proven, it lends strong support to initiatives seeking to improve hygiene practice. It would however be helpful if the hypothesis were renamed, e.g. as the 'microbial exposure' hypothesis, or 'microbial deprivation' hypothesis, as proposed for instance by Bjorksten. Avoiding the term 'hygiene' would help focus attention on determining the true impact of microbes on atopic diseases, while minimizing risks of discouraging good hygiene practice.

Risk factors for contamination of ready-to-eat street-vended poultry dishes in Dakar, Senegal

Our objective was to investigate the Salmonella and Campylobacter contamination of traditional ready-to-eat street-vended poultry dishes and to assess the association of some restaurant characteristics and cooking practices with the contamination of these meals. One hundred and forty-eight street-restaurants were studied from January 2003 to April 2004 in Dakar. A questionnaire was submitted to the managers, and samples of ready-to-eat poultry dishes were taken. Salmonella spp. was isolated in 20.1% of the 148 street-restaurants studied and in 10.1% samples of poultry dishes. The most prevalent serovars isolated were Salmonella hadar, Salmonella enteritidis and Salmonella brancaster. Campylobacter jejuni was detected in only 3 restaurants and 3 poultry dishes. Not peeling and not cleaning vegetables and other ingredients during meal preparation (OR=3.58), dirty clothing for restaurant employees (OR=4.65), reheating previously cooked foods (OR=5.2), and no kitchen and utensils disinfection (OR=3.47) were associated with an increasing risk of Salmonella contamination. Adequate cooking procedures decreased the risk of Salmonella contamination (OR=0.15).

Salmonella and raw shell eggs: results of a cross-sectional study of contamination rates and egg safety practices in the United Kingdom catering sector in 2003

This study was prompted by epidemiological investigations of the unusual number of Salmonella Enteritidis outbreaks associated with the use of eggs in catering premises in England and Wales during 2002. The aims of the study, performed between April and May 2003, were to establish the rate of Salmonella contamination in raw shell eggs from catering premises, investigate any correlation between the origin and type of eggs and the presence of particular serotypes or phage types (PTs) of Salmonella, and examine the use of raw shell eggs in catering premises in the United Kingdom. A total of 34,116 eggs (5,686 pooled samples of six eggs) were collected from 2,104 catering premises, most of which were eggs produced in the United Kingdom (88%). Salmonella was isolated from 17 pools (0.3%) of eggs. Of these, 15 were Salmonella Enteritidis, which were further characterized to PTs as follows: PT6 (0.1%), PT4 (0.07%), PT12 (0.04%), PT1 (0.04%), and PT14b (0.02%). Salmonella Livingstone and Salmonella Typhimurium definitive type 7 resistant to ampicillin, streptomycin, sulfonamides, and tetracycline were also isolated. The Salmonella contamination rate of eggs produced in the United Kingdom appears to have decreased significantly since 1995 and 1996. This trend is reflected in the decrease of Salmonella Enteritidis and, in particular, Salmonella Enteritidis PT4. The impact of the United Kingdom Food Standards Agency's advice on the use of eggs, issued in January 2003, is discussed.

Descriptive Study of California Egg Layer Premises and Analysis of Risk Factors for Salmonella enterica serotype enteritidis as Characterized by Manure Drag Swabs

This cross-sectional, double-blind study reports the prevalence of Salmonella enterica serotype enteritidis (SE) on California egg layer premises using single vs. pooled manure drag swabs and presents a description of egg production and management systems in the state and an initial analysis of risk factors for SE. The study included 91% of all known eligible egg premises in California, representing the majority of eggs produced in the state. The overall prevalence of SE on California egg layer premises was 10.5%, while 1.1% of all rows sampled were positive for SE. The percentage of positive rows for SE on any premises never exceeded 25% of the 16 swabs collected per premises. A description of egg production and management on California egg layer premises is presented. Statistically significant associations for SE were not evident and were limited because of sample size and the low prevalence of SE on California egg layer premises. Several biological and management factors, such as flock health, stage of production, manure management, ventilation, and watering systems, show trend associations with premises positive for SE and require further investigation. Manure drag swabs serve as a useful tool to validate the core components of an egg quality assurance program for SE based on process control principles.

Prevalence of high-risk egg-preparation practices in restaurants that prepare breakfast egg entrées: an EHS-Net study

Salmonella enterica serotype Enteritidis (SE) is a common cause of foodborne illness in the United States. Foods prepared with raw shell eggs have often been associated with SE outbreaks. The federal government published the Egg Safety Action Plan in December 1999 that called for reduction of egg-preparation practices that may contribute to the survival and proliferation of SE. In seven states, an interview and brief site evaluation of 153 restaurants that prepare eggs during all hours of operation was conducted by the Environmental Health Specialists Network to determine the prevalence of such practices. Fifty-four percent (83 of 153) of restaurants pooled raw shell eggs not intended for immediate service. These pooled eggs were held a median of 4 h for scrambled eggs, 5.5 h for omelets, and 6 h for pancakes and French toast. Nearly 26% (39 of 152) of restaurants reported storing eggs at room temperature, and 5% (7 of 152) stored eggs on ice or in cold-water baths before cooking. Generally, eggs were cooked to 72 to 83 degrees C, which is above the recommended final cook temperature of 63 to 68 degrees C. Employees reported sanitizing utensils used to prepare eggs less than once every 4 h in 42% (57 of 136) of restaurants. Several areas were identified in which further emphasis might reduce egg-associated SE infections in accordance with Healthy People 2010 goals.

Ribotyping and a study of transmission of Staphylococcus aureus collected from food preparation facilities

Food poisoning from Staphylococcus aureus is sometimes caused by improper handling of food items in food preparation facilities. Prevention of contamination by employees is particularly important in facilities where a significant amount of food preparation is performed by hand. Some experiments have been performed to describe bacterial cross-contamination in the food preparation process, but there have been few studies of cross-contamination in actual food preparation facilities. Aiming to shed light on the transmission of S. aureus in food preparation facilities, this study collected samples of 66 strains of this bacterium from the fingers of food preparation staff, foodstuffs, prepared foods, cooking utensils, and cooking equipment and typed them with the ribotyping method. S. aureus from the same ribogroup was detected on the hands of a study participant, a faucet, knife, frying pan, and a salad, indicating that bacteria found on the hands of the study participant was transmitted to cooking utensils and prepared foods. Transmission (from a faucet to a frying pan handle) of bacteria by another person, a third party, was also detected.

Shelf Life and Safety Concerns of Bakery Products—A Review

Bakery products are an important part of a balanced diet and, today, a wide variety of such products can be found on supermarket shelves. This includes unsweetened goods (bread, rolls, buns, crumpets, muffins and bagels), sweet goods (pancakes, doughnuts, waffles and cookies) and filled goods (fruit and meat pies, sausage rolls, pastries, sandwiches, cream cakes, pizza and quiche). However, bakery products, like many processed foods, are subject to physical, chemical and microbiological spoilage. While physical and chemical spoilage limits the shelf life of low and intermediate moisture bakery products, microbiological spoilage by bacteria, yeast and molds is the concern in high moisture products i.e., products with a water activity (a(w)) > 0.85. Furthermore, several bakery products also have been implicated infoodborne illnesses involving Salmonella spp., Listeria monoctyogenes and Bacillus cereus, while Clostridium botulinum is a concern in high moisture bakery products packaged under modified atmospheres. This extensive review is divided into two parts. Part I focuses on the spoilage concerns of low, intermediate and high moisture bakery products while Part II focuses on the safety concerns of high moisture bakery products only. In both parts, traditional and novel methods of food preservation that can be used by the bakery industry to extend the shelf life and enhance the safety of products are discussed in detail.

Hygiene in the home: relating bugs and behaviour

Much infectious intestinal disease (IID) arises in the home environment. If programmes to prevent infection are to be effective it is essential to both identify the particular practices that risk disease transmission, and to understand the reasons for these practices. An in-depth, multidisciplinary study of carer and child hygiene in the domestic environment in the Wirral, UK, employed structured observation, surface swabbing for polio vaccine virus and enteric marker organisms, semi-structured interviews, projective interviews and focus group discussions. Observations revealed that child carers washed hands with soap after changing a dirty nappy on 42% of occasions, and that one in five toilet users did not wash hands with soap afterwards. Microbiological samples were taken from household surfaces at sites thought likely to be involved in the transfer of faecal material. 15% of bathroom samples showed contamination with polio vaccine virus. Nappy changing took place mainly in living rooms. Contact with living room surfaces and objects during nappy changing was frequent and evidence of faecal contamination was found in 12% of living room samples. Evidence of faecal contamination was also found in kitchens, again on surfaces thought likely to be involved in the transmission of faeces (taps and soap dispensers). Key factors motivating hygiene were the desire to give a good impression to others, protection of the child and aesthetics. In this setting, the particular risk practices to be addressed included washing hands with soap after stool and nappy contact and preventing the transfer of pathogenic organisms to the kitchen. The occasion of the birth of a child may be a privileged moment for the promotion of safer home hygiene practices. Using polio vaccine virus as an indicator of faecal contamination produces results that could be used in large-scale studies of household disease transmission. A better understanding of the household transmission of the agents of IID using multidisciplinary methods is needed if effective hygiene promotion programmes are to be designed.

Disinfection and the prevention of infectious disease

This article reviews published literature to determine the role environmental disinfection plays in the prevention of infectious disease. Health benefits from disinfection have been established through studies of applications such as critical instrument sterilization, water treatment, and food production. Guidelines by the Centers for Disease Control and Prevention, the Food and Drug Administration, the Environmental Protection Agency, and the International Scientific Forum on Home Hygiene acknowledge the incidence of disease due to insufficient disinfection and that one of the means for prevention of disease is through proper disinfection. Studies conducted in day care centers, long-term care facilities, and laboratories show that disinfectants containing a variety of active ingredients demonstrated efficacy against a broad spectrum of pathogens and interrupted microbial transmission and that the use of disinfectants results in public health benefits.

The infection potential in the home and the role of hygiene: historical and current perspectives

The control of infection through hygiene has a long erratic history. Personal hygiene and handwashing was less appreciated in the past, since it was not known that invisible organisms could spread from apparently clean hands and surfaces. The role of a hygienic home environment received little attention until the 19th century. Since then, the modern tradition of hygiene has served us well, with improved water and drainage developing alongside vaccination, antibiotics, water purification, improved food production and hygienic food preparation and storage. Two major epidemiological trends are relevant to hygiene perspectives: the decline in the morbidity and mortality from infection, and the transition towards higher levels of chronic or debilitating disease. While mortality from some infections has decreased, communicable disease is no less prevalent. Infectious intestinal disease is still unacceptably high in both developed and developing countries. The control of infection within the home needs to take account of changing epidemiological trends, emphasis on evidence-based approaches and loss of public awareness of the role of hygiene. In earlier eras lack of research on the home environment prevented sufficient attention to infection transmission in the domestic setting. Recent research has demonstrated how microbial contamination can be transmitted by activities in the home. Application of this knowledge could significantly reduce the continuing impact of infectious diseases in our communities.

Home hygiene: a risk approach

The need to place "prevention through hygiene" at the core of strategies for infection prevention has been emphasised by recent events. Indications are that re-evaluation of current practice and the promotion of improved hygiene in the domestic setting could have a significant impact in reducing infectious disease. If the public are to play a part however they must be properly informed. Encouraging the concept of the home as a setting in which the whole range of activities occur, including food hygiene, personal hygiene and hygiene related to medical care, provides the opportunity for a rational approach to home hygiene based on risk assessment. In the home surfaces (including hand surfaces) and other sites play an important part in the transmission of infection, especially food-borne infections. From an assessment of the frequency of occurrence of pathogens and potential pathogens at reservoirs, disseminators and hand and food contact sites together with the potential for transfer within the home, the risks of exposure can be assessed. This can be used to develop a rational approach in which effective hygiene procedures involving cleaning and disinfection as appropriate are targeted at these sites to reduce risks of cross contamination. This approach is consistent with the view that good home hygiene is not about "getting rid of household germs" but about targeting hygiene measures appropriately to reduce exposure to germs and thereby prevent cross infection. In motivating change, education programmes must take account of concerns related to antimicrobial resistance, the environment and the "health" of the immune system.

An assessment of cleaning regimes and standards in butchers' shops

Cleaning regimes and standards in retail butchers taking part in the Accelerated HACCP project initiative, were assessed by means of visual inspection, examination of cleaning schedules and ATP bioluminescence assays of selected food and hand contact sites. There was a wide variation in surface ATP results, both within and between butchers' shops, but overall they indicated that food and hand contact surfaces were heavily soiled during food production and service. Although separate preparation equipment/utensils were provided, staff undertook raw and cooked product handling throughout the day, with the concomitant danger of contaminating hand and food contact surfaces. The extent of soiling was generally underestimated when assessed visually, the technique used most commonly by the food retail trade and inspection authorities. Periodic or interim cleaning practices produced a significant improvement in cleanliness assessed visually and with ATP assay; however, these results were generally less satisfactory than those obtained by the use of best practice protocols. A lack of written cleaning schedules and records, training in the correct use of cleaning products and awareness of the importance of cleaning hand contact sites were identified as common defects. The results are discussed in relation to the establishment of an effective HACCP system and recommendations for improving cleaning standards are given.

Enteric and foodborne disease in children: A review of the influence of food- and environment-related risk factors

Canadian statistics show that children from birth to four years of age are more likely to be reported with an infection from Campylobacter, Giardia, Salmonella and Shigella species, and verotoxigenic Escherichia coli than any other age group. A review of the Canadian and international literature, and an analysis of case and outbreak data suggest that the risk factors for infection in young children (ages birth to four years) are different from the risk factors for older children and adults. In children from birth to four years of age, infant formula, fast foods, snacks and candies have caused major outbreaks of enteric and foodborne diseases; however, the contamination of a child's environment or the presence of ill individuals in a household may be highly significant to disease expression. Contact with animals (including family pets) and contaminated surfaces, together with experimental touching and testing behaviours, are important routes of infection for infants and preschool children. Risk factors for enteric infections in children appear to be related, occasionally, to specific foods that are particularly attractive to all children (all age groups from infants up to and including elementary school-aged childen), to an infected person or pet in the same household, or to the contamination of a child's environment. Nonfood-related risk factors may be of particular significance in infection in infants and very young children. Contact with animals, particularly exotic pets and farm animals, or their environments should be considered to be a potential source of infection in children in situations in which there is an absence of other risk factors. The evidence presented in the current paper emphasizes the importance of personal and home hygiene practices in limiting children's exposure to enteric pathogens. Strict hand washing practices and restrictions on touching birds, reptiles and other animals at petting zoos or in nursery and primary school facilities are recommended to avoid widespread infection. Public health authorities should consider the development of guidelines on the provision of hand washing facilities and instruction notices in settings where the public may come into contact with farm or other animals in jurisdictions where such guidelines do not already exist.