Effectiveness of UV light as a means to reduce Salmonella contamination on tomatoes and food contact surfaces

The effectiveness of ultraviolet light at a wavelength of 254 nm to reduce Salmonella contamination on tomatoes and food contact surfaces was evaluated. Inoculated tomatoes were exposed to UV-C light at doses ranging from 0 to 223.1 mJ/cm². All UV treatments significantly reduced Salmonella populations (p < 0.05). The effectiveness of UV-C light in reducing Salmonella contamination on different locations on tomato surfaces under various UV doses (0–117.2 mJ/cm²) was also explored. Results indicated that regardless of the locations, UV treatment was shown to be effective in decreasing Salmonella populations. Subsequent studies evaluated possible photoreactivation or dark repair of injured Salmonella post-UV treatment. Following UV light exposure at doses of 0, 22.3, 44.6, and 89.2 mJ/cm², tomatoes were either exposed to visible light for 0, 3, and 5 h or stored in the dark for the same amount of time. Photoreactivation was not detected, nor was dark repair. UV light was also evaluated for its effectiveness to reduce Salmonella contamination on food contact surfaces (stainless steel, HDPE, waxed cardboard and PVC). Contaminated coupons were exposed to UV-C light at 0, 3.3, and 19.7 mJ/cm². Significant differences were observed between coupons treated with UV light and the controls (p < 0.05). Coupons exposed for longer time had greater Salmonella population reductions, except for waxed cardboard coupons. Application of UV-C light to reduce Salmonella contamination in tomato handling facilities is feasible.     

Effects of UV-C treatment on inactivation of Salmonella enterica and Escherichia coli O157:H7 on grape tomato surface and stem scars,microbial loads,and quality

The purpose of this study was to investigate the effectiveness of ultraviolet-C (UV-C) light inactivation as affected by the location of pathogens on the surface and at stem scars of whole grape tomatoes. A mixed bacterial cocktail containing a three strain mixture of Escherichia coli O157:H7 (C9490, E02128 and F00475) and a three serotype mixture of Salmonella enterica (S. Montevideo G4639, S. Newport H1275, and S. Stanley H0558) were used. Tomatoes were spot inoculated using approximately 100 μL of inocula to achieve a population of about 10^7±1 CFU/tomato. Additionally, the effects of treatment on color, texture, lycopene content, and background microbial loads during post UV-C storage at 4 °C for 21 days were determined. Results showed that UV-C doses of 0.60–6.0 kJ/m² resulted in 2.3–3.5 log CFU per fruit reduction of E. coli O157:H7 compared to 2.15–3.1 log CFU per fruit reduction for Salmonella on the surfaces. Under the same conditions, log reductions achieved at stem scar were 1.7–3.2 logs CFU for E. coli O157:H7 and 1.9–2.8 logs CFU for Salmonella. The treatment was effective in controlling native microbial loads during storage at 4 °C as the total aerobic mesophilic organisms (PCA) and anaerobic lactic acid bacteria (LAB) counts of treated tomatoes were significantly (p < 0.05) lower during storage compared to the control group and the yeast and mold populations were reduced significantly below the detection limit. Furthermore, the firmness of tomato and its color was not affected by the UV-C doses during storage. UV-C radiation could potentially be used for sanitizing fresh tomatoes and extending shelf-life. The results of this study indicate that the specific location of pathogens on the produce influences the effectiveness of UV-C treatment, which should be taken into consideration for the design of UV-C systems for produce sanitization.     

Inactivation of Salmonella Typhimurium and quality preservation of cherry tomatoes by in-package aerosolization of antimicrobials

The purpose of the present study was to investigate the efficacy of in-package aerosolized aqueous sanitizers in reducing populations of Salmonella enterica serovar Typhimurium on tomato fruit and in maintaining fruit quality. Cherry tomatoes were inoculated with a cocktail of attenuated S. Typhimurium ATCC 53647 and 53648 strains on the smooth skin surface and stem scar area. Next, 200 ppm free chlorine, and peroxyacetic acid (PAA) and aqueous ClO₂ at different concentrations, 2% lactic acid + 2% acetic acid + 2% levulinic acid, and 3% acetic acid + 3% lactic acid were aerosolized into a clamshell container containing cherry tomatoes. Results showed that S. Typhimurium populations on smooth tomato surfaces were reduced by more than 5 log CFU/fruit with 400 ppm PAA, 2% lactic acid + 2% acetic acid + 2% levulinic acid, 3% acetic acid + 3% lactic acid, and aqueous ClO₂ (100 and 400 ppm). On the stem scar area, 400 ppm aqueous ClO₂ was more effective in reducing S. Typhimurium populations than other treatments, achieving 4.89 log CFU/fruit reduction, followed by 400 ppm PAA (2.62 log CFU/fruit). The efficacy of ClO₂ and acid combination treatments increased during 3-week storage at 10 °C, achieving >3 log CFU/fruit inactivation with the acid combination and ca. 6 log with for 400 ppm with ClO₂. None of the treatments significantly (p > 0.05) affected color, appearance, firmness, vitamin C, lycopene or antioxidant values of tomatoes during 3 weeks of storage; although, an acidic odor was detected for samples treated with the organic acids in the earlier period of the storage. These results suggest that in-package aerosolized sanitizers can be used as a novel method for the inactivation of Salmonella on tomato fruit.     

Effects of integrated treatment of nonthermal UV-C light and different antimicrobial wash on Salmonella enterica on plum tomatoes

The aim of this study was to evaluate inactivation of inoculated Salmonella enterica on whole tomato surface exploiting integration of nonthermal ultraviolet light (UV-C) treatment with antimicrobial wash. The effect of combined treatment on background microflora (aerobic mesophilic, and yeast and mold), during storage at ambient temperature (22 °C) for 21 days was also determined. A bacterial cocktail containing three serotypes of S. enterica (S. Newport H1275, S. Stanley H0558, and S. Montevideo G4639) was used based on their association with produce-related outbreaks. Tomatoes were spot inoculated using approximately 100 μL of inocula to achieve cell population of about 10⁷ CFU/tomato. An inoculated tomato was initially treated with a low (0.6 kJ/m²) dose of UV-C light (253.7 nm) followed by immersion in selected sanitizing solution (700 ml) to wash under mild agitation (ca. 250 rpm) for 2 min at room temperature (22 °C). Inactivation efficacy of combined treatments varied widely depending on the sanitizer property. Combined UV-C plus aqueous ozone (1 ppm) provided 3.13 ± 0.47 log CFU/fruit Salmonella reduction which was significantly lower (p < 0.05) compared to the rest of the combination treatments; whereas the treatment of UV-C followed by immersion in a novel antimicrobial preparation ‘HEN’, formulated mixing hydrogen peroxide, EDTA and nisin provided the best log reduction (4.71 ± 0.25 log CFU/fruit). Organic acids (1%) or their binary mixtures, hydrogen peroxide (3%), and HEN provided greater than 4.0 log reductions for UV-C treated tomatoes. Treatments were effective in controlling native microbial loads as the total aerobic mesophilic organisms and the population of yeast and mold remained significantly (p < 0.05) low during storage compared to control. Findings from this study provide safe and effective post harvest intervention strategies for produce industry as an alternative to current chlorine based wash. These results may also help researchers design future decontamination studies.     

Survival of Salmonella spp. on surface-inoculated forced-air cooled and hydrocooled intact strawberries,and in strawberry puree

Fresh-market strawberries are cooled to 1–3 °C before commercial storage and distribution; typically by forced-air cooling. Hydrocooling ensures a faster and more uniform cooling of strawberries, although its effect on reducing microbial contamination on the fruit has not been evaluated. Salmonella has been reported to survive on damaged strawberries, but is unable to multiply, potentially due to the low pH or other intrinsic factors associated with strawberries. This study evaluated Salmonella survival a) on the surface of intact hydrocooled or forced-air cooled strawberries; b) as affected by agitation and density of packing during hydrocooling and c) as affected by pH, temperature and food matrix (strawberry or tomato puree). Intact strawberries inoculated with Salmonella were subjected to forced-air cooling or hydrocooling in water containing 100 or 200 ppm HOCl. Salmonella population was enumerated 0, 7 and 8 days post-treatment. Strawberry and tomato puree (pH 3.7 and 4.6) spiked with Salmonella and incubated at 4, 10 or 25 °C, were evaluated at 0, 1 and 3 days post-inoculation (n = 9). Compared to forced-air cooling, hydrocooling significantly reduced Salmonella survival on inoculated intact strawberries, with levels below the enumerable limit (1.5 log CFU/berry) by day 8. Hydrocooling reduced the initial Salmonella levels by 1.9 log CFU/berry, while the addition of 100 or 200 ppm HOCl reduced levels by 3.5 and 4.4 log CFU/berry, respectively. Initial Salmonella populations (day 0) were significantly lower when the berries were agitated or loosely packed during hydrocooling. Salmonella survival was significantly higher at a higher pH (4.7) compared to lower intrinsic pH (3.6) of strawberry puree. Higher temperature (25 °C) was conducive for Salmonella survival on strawberry puree compared to lower temperatures (4 and 10 °C). The data shows that a lower pH of 3.6 or refrigeration below 10 °C are effective in controlling the survival of Salmonella on damaged strawberries.     

A risk assessment of salmonellosis linked to chicken meals prepared in households of China

A quantitative microbiological risk assessment model was used to quantify the risk of salmonellosis caused by bacterial growth and cross-contamination of chicken meals prepared in households of China. Chinese data on initial loads of Salmonella in chicken carcasses sold at retail, storage time and handling of raw chicken meat in household kitchens and confirmatory transfer rates of Salmonella among different kitchen objects were collected. Only one third of Chinese families in our sample separated the cutting board between raw and ready-to-eat foods. The cross-contamination of ready-to-eat foods from chicken meals via the cutting board, the knife and cooks’ hands increased the frequency of pathogen ingestion and the risk of salmonellosis. A significant decrease in the risk of salmonellosis could be achieved by reducing the cross-contamination when handling raw chicken meat and ready-to-eat foods. Decreasing the prevalence of Salmonella contamination to 8.8% or removing chicken carcasses with contamination densities higher than 100 MPN/100 g at retail was less effective. Using transfer rates of Salmonella from raw chicken meat to the wooden cutting board instead of that from references, a statistically higher risk of salmonellosis per serve due to the cross-contamination in households was observed. The present study validated values of hygiene practices in China to reduce the risk of salmonellosis from contaminated raw chicken meat at retail. Deliberate surveys for cooking behaviors and transfer rates of Salmonella from and to different objects including wooden cutting boards were needed.     

Assessment of microbiological quality of raw fruit juice vended in Dar es Salaam city,Tanzania

Fresh fruit juices are highly nutritious food for human but the hygiene involved during preparation, packaging and storage make fresh juices prone to microbial contamination. This study was conducted to assess bacterial quality and establish the risk factors for contamination of raw fruit juices vended in Dar es Salaam city, Tanzania. Ninety fruit juice vendors were assessed for possible factors of microbial contamination in fruit juices. One juice sample per vendor was collected for microbial analysis using standard laboratory protocols of International Standards Organisation (ISO), Tanzania Bureau of Standards and Codex specifications. The results showed that the total plate counts (TPC) ranged between 2.32 and 8.54 (Log cfu/ml). About 72.2% of juice samples had TPC above Codex recommended maximum levels (3.7–4.7 Log cfu/ml). The prevalence of Escherichia coli in the juices was 80% with a range between 0.0 and 5.0 (Log MPN/ml) suggesting of direct faecal contamination or contamination from the environment. All samples were negative for Salmonella species. Risk factors for high TPC and E. coli counts which were statistically significant (P < 0.05) included type of juice, extraction methods, vending sites, storage containers and sex of the vendors. Generally, 78.9% of preparation and vending premises were unhygienic and encouraged contamination of the juices. It is concluded that, the overall handling, preparation practices and bacterial quality of unpasteurized fruit juices vended in Dare es Salaam city are poor. The government should educate the vendors on food safety and hygiene as well as enforcing regular monitoring of the quality of street fruit juices.     

Effect of dominant specie of lactic acid bacteria from tomato on natural microflora development in tomato purée

The dominant lactic acid bacteria specie from tomatoes surface and its effect, as competitive microflora, on tomato purée during storage at 30 °C was investigated. Four genera were found Leuconostoc mesenteroides ssp. mesenteroides being the dominant group. Leuc. mesenteroides ssp. mesenteroides Tsc when inoculated on tomato purée, pH 4.1, grew approximately 2 log cycles in 48 h, inhibiting natural bacterial development and delaying the growth of yeasts. The faster organic acids production by inoculated microorganism contributed to the diminution in the natural microflora cells number. This microorganism could be considered to help to control the contaminates proliferation on tomato purée during storage at abusive temperature.     

Prevalence and serovar diversity of Salmonella spp. in primary horticultural fruit production environments

Increases in foodborne disease outbreaks associated with fresh produce have necessitated the need to identify potential sources of microbial contamination in produce and agricultural environments. The present study evaluated Salmonella prevalence and serovar diversity in fruit (225), water (140) and surface (126) samples, from three commercial farms and associated packhouses, located in different farming regions in South Africa. Fruit and water samples were collected from both orchards and packhouses, while surface samples were collected from conveyer belts and hands of packhouse employees. Salmonella was detected in 26 of the 491 (5.3%) samples. Environmental samples (water and surfaces) recorded a slightly higher proportion (3.1%; 15/491) of positive samples compared to fruit samples (2.2%; 11/491). Salmonella was not detected on employee hands and river water samples. A total of 263 Salmonella isolates were obtained from the 26 positive samples by standard culture methods, preliminarily identified through matrix-assisted laser desorption ionisation-time of flight mass spectroscopy (MALDI-TOF MS) and API 20E, and confirmed by invA gene. Of the 39 representative isolates serotyped the serovars Muenchen (33.3%), Typhimurium (30.8%), Heidelberg (20.5%), Bsilla (7.7%), Salmonella subspecies IIb: 17: r: z (5.1%) and one untypable strain were identified. Most samples had multiple serovars with orchard water form one site recording the highest serovar diversity (4 serovars). Our findings show the potential of agricultural fruit production environments to act as reservoirs of clinically important Salmonella serovars.     

Temporal patterns in the occurrence of Salmonella in raw meat and poultry products and their relationship to human illnesses in the United States

The prevalence and level of microbial pathogens on various commodities often exhibit seasonal patterns. As a consequence, the incidence of foodborne illness tends to follow these trends. Of the various product classes, the occurrence of microbial contamination can be high on raw meat and poultry products, with Salmonella potentially occurring in all meat and poultry product classes. Since 1999, the Food Safety and Inspection Service in the United States has collected samples of meat and poultry products and analyzed them for the presence of Salmonella. This study uses a common modeling approach to estimate the seasonal change in the proportion of test-positive samples for seven classes of raw meat and poultry products. The results generally support the hypothesis of a seasonal increase of Salmonella during the summer months. The proportions of test-positive samples decrease rapidly in the late fall for all product classes except chicken and ground turkey, which remain somewhat elevated through late winter. A comparison of the pathogens' seasonal pattern in meat and poultry with human cases reveals that the seasonal increase in human cases precedes the seasonal increase in meat and poultry by between one and three months. These results suggest that while contaminated meat and poultry products may be responsible for a substantial number of human cases, they are not necessarily the primary driver of the seasonal pattern in human salmonellosis.     

Growth or penetration of Salmonella into citrus fruit is not facilitated by natural-light labels

In natural-light labeling of fruits and vegetables, the desired information is etched onto the produce surface using a low-energy carbon dioxide laser beam (10,600 nm). Etched characters are formed by surface depressions in the epidermis that may facilitate entrance of decay and pathogenic organisms. The objective of this study was to determine the effects of natural-light labeling and different postharvest treatments on Salmonella populations' ability to survive/grow and penetrate into citrus fruit. A five-strain cocktail of Salmonella was spot inoculated onto Valencia orange in different application sequences with wax and natural-light etching. Samples were stored at 10, 26 °C, or combinations of both, for up to 42 days. Etched peels and corresponding juices were extracted from whole oranges following storage and enumerated for Salmonella. No set of conditions involving natural-light labeling promoted the growth of Salmonella on the fruit surface or resulted in the detection of Salmonella from the juice of sound fruit. Survival of Salmonella populations on the peel surface did not differ between any of the treatment and control samples. In all cases, Salmonella declined between 1.5 and 3.0 log CFU/orange after 30 days, with faster decline noted at 10 °C. Based on the data obtained from all treatments and under conditions extremely unfavorable and unrealistic in terms of fruit storage, natural-light labeling citrus fruit peels and subsequent waxing in any order did not allow for the growth or influence the natural decline of Salmonella populations on citrus fruit surfaces, or movement into juices, as compared to controls.     

The prevalence and serovar diversity of Salmonella in various food products in Estonia

In this work the prevalence and serovar diversity of Salmonella in various food products including non-thermally processed food and ready-to-eat (RTE) food in Estonia in 2008–2012 are summarized. The findings demonstrate that the overall prevalence of Salmonella in these food categories was low. A total of 260 (0.54%) of 47,927 food samples were found to be positive for Salmonella, the overall prevalence in non-thermally processed food was 0.81% (256/31,576) and in RTE products only 0.02% (4/16,351). Salmonella was most often isolated from raw eggs and products thereof (2.17%, 5/230), followed by raw meat products (0.95%, 207/21,723), RTE mayonnaises (0.90%, 2/221) and raw meat (0.89%, 38/4252). In the raw meat category, Salmonella was most frequently isolated from turkey meat (6.96%, 11 positive samples out of 158), broiler chicken meat (4.00%, 7/175) and from layer hen meat (2.22%, 11/496). Salmonella was isolated in lesser extent from meat preparations (1.91%, 82/4292), minced meat and mechanically separated meat products (0.97%, 100/10,344) and from raw sausages (0.35%, 25/7087).Altogether 24 different serovars were identified among the 260 Salmonella positive samples. Salmonella Typhimurium was the most frequent serovar (26.90% of the positive samples) and it was isolated most commonly in raw food products. The next most frequent serovars were Salmonella Derby (17.50%), Salmonella Enteritidis (8.37%) and Salmonella Newport (7.57%). The only serovars isolated from the Salmonella positive RTE food samples were Salmonella Infantis (two isolates) and S. Enteritidis (two isolates).     

Enteropathogens in cocoa pre-processing

The European community lists cocoa among the products associated with major salmonellosis outbreaks in humans. Though cocoa products are not the only ingredients that may introduce Salmonella into chocolate, they have been implicated as the most prominent potential source of some outbreaks. The objective of this study was to investigate the presence of Salmonella, Escherichia coli and the level of total coliforms throughout the four different steps of cocoa pre-processing. The presence of Salmonella was detected in only one of the 119 samples analyzed – a sample of stored beans. Contamination by total coliforms and E. coli was highest during drying and storage, with percentages of up to 100% and 89% of positive samples. The environment, including the presence of vectors, intense handling and storage conditions appear to be the main critical points during pre-processing of cocoa contributing to contamination by these enteropathogens.     

Review of Salmonella detection and identification methods: Aspects of rapid emergency response and food safety

Salmonella has been recognized as a major and important foodborne pathogen for humans and animals over more than a century, causing human foodborne illness as well as high medical and economical cost. Accordingly, the effort to develop efficient and reliable Salmonella detection methods continues. This paper reviews and describes the development and application of commercially available Salmonella detection methods. These are categorized into several groups based on the principle applied: conventional culture methods, immunology-based assays, nucleic acid-based assays, miniaturized biochemical assays, and biosensors. Conventional culture methods serve as the basis in food testing laboratories despite rather laborious and time-consuming protocols. Considerable progress in rapid methods using emerging technologies yield faster answers and higher throughput of samples. This paper also shows and analyzes Salmonella test results and summarizes the features and limitations of the studies involving Salmonella detection methods developed for emergency response, mainly by food emergency response laboratories participating during recent fiscal years. The emergency response laboratories utilize Salmonella detection methods possessing properties that include simplicity, versatility, high sensitivity, good specificity, and cost efficiency. Collaboration of the food emergency response laboratories in the development of these technologies is important essentially to compare for the purpose of continually improving Salmonella detection methods.     

Validation of real-time PCR for detection of six major pathogens in seafood products

Seafood can pose a public health concern to consumers. It is often consumed raw and may be contaminated with several foodborne pathogens. In order to guarantee the safety of seafood, real-time polymerase chain reaction (PCR) protocols may be used as these enable results to be provided within 24 h.The first goal of our work was to develop real-time PCR protocols enabling the detection of six foodborne pathogens that may be present in seafood products (Campylobacter jejuni, Campylobacter coli, enterohemorrhagic Escherichia coli, Salmonella spp., Vibrio parahaemolyticus, and Vibrio vulnificus). The corresponding gene targets were: 50S/VS1, rfbE, ttr, tlh, and vvp. A multiplex PCR was also developed to detect the virulence genes of V. parahaemolyticus: tdh and trh. A total of 420 bacterial strains belonging to four different genera/strains were used in this study. Sensitivity and specificity were always 100%, except in the case of Salmonella spp., where three strains were not detected by our PCR protocols.The second objective of our work was to assess the detection limit of our real-time PCR protocols on artificially contaminated seafood products (raw shrimps, cooked shrimps, and raw mussels), purchased in public stores. Six different levels of contamination were assayed in four replicates for each matrix. The real-time PCR protocols enabled a better level of detection than the ISO methods, except for Salmonella in raw shrimps and for V. vulnificus in shrimps (raw and cooked). The estimated level of detection was between 1 and 47 cfu/25 g sample for the ISO norms and between 1 and 315 cfu/25 g sample for the real-time PCR protocols tailored in our work.The real-time PCRs developed in our work allowed for good selectivity, sensitivity, and specificity. The sensitivity on seafood products was estimated at a level of 100%, except for Salmonella (97%). In the spiking assays, the levels of detection were lower with the real-time PCR protocol than those obtained with the ISO method. This was not the case for V. vulnificus in raw and cooked shrimps and for Salmonella in raw shrimps.These real-time PCR protocols appear to be good alternative methods for surveillance of seafood products to ensure the absence of foodborne pathogens.One additional conclusion is that laboratories have to use enrichment media that are compatible with those recommended by ISO standards. This may facilitate the isolation of the pathogen if the real-time PCR protocol gives a suspect positive signal during the first step of the seafood analysis.     

Simulation of decontamination and transmission of Escherichia coli O157:H7, Salmonella Enteritidis,and Listeria monocytogenes during handling of raw vegetables in domestic kitchens

Epidemiological data indicates that a large number of foodborne illnesses are attributed to cross-contamination during food preparation in the domestic kitchen. The objectives of this study were to evaluate the efficiency of household washing practices in removing Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Enteritidis on artificially contaminated lettuce and to determine the transfer rate of these three foodborne pathogens from contaminated lettuce to wash water, tomato, cabbage, and cutting boards during washing and cutting processes. Washing under the running tap water with scrubbing for 60 s was the most effective method in reducing pathogen populations by 1.86–2.60 log₁₀ CFU/g. Also, final rinsing and scrubbing practices were found to enhance the efficiency of washing treatment. In this study, the transfer rates of S. Enteritidis, E. coli O157:H7, and L. monocytogenes from cutting board to cabbage and tomato via cutting process (17.5–31.7%) were higher (P < 0.05) than from wash water to cabbage and tomato (0.8–23.0%) during washing treatment. Overall, our findings suggest that wash water and cutting board can be potential vehicles in the dissemination of foodborne pathogens. Therefore, there is a need to promote consumer awareness for proper handling practices in the kitchen to minimise the risk of foodborne infection.     

Development of a quantitative real-time PCR assay for viable Salmonella spp. without enrichment

Propidium monoazide (PMA) combined with molecular quantitative real-time PCR (qPCR) has been widely used for only detection of viable bacteria. However, recent studies indicated PMA did not fully inhibit the detection of dead Salmonella. In this study, we developed a more effective PMA Taqman-based qPCR than previous studies to quantify viable Salmonella spp. in raw shrimp. This method has high specificity by using 60 strains belonging to 23 species. The optimization of the PMA concentration showed that 100 μM was considered optimal to effectively inhibit 10⁶ CFU/mL dead cells, while only 10³–10⁴ CFU/mL dead cells could be inhibited in previous reports. This assay could detect viable Salmonella spp. at as low as 36 CFU/mL in pure culture and 100 CFU/g in raw shrimp. By comparing with PMA-qPCR, qPCR and plate counting for quantifying Salmonella in samples, this PMA-qPCR was obviously superior to qPCR and had good agreement with plate counting. In conclusion, this effective method can be used as an available tool to quantify viable Salmonella spp. in raw shrimp.     

Hygienic conditions and microbiological status of chilled Ready-To-Eat products served in Southern Spanish hospitals

Chilled Ready-To-Eat (RTE) foods are of concern in hospital foodservices because they can support microbial growth when subjecting to time/temperature abuses during processing and distribution together with poor handling practices. This study was conducted in five different hospitals (A–E) of Southern Spain during 2008–2009 to perform an evaluation of their sanitary conditions and microbiological quality of two RTE meals: lettuce salads and cooked ham. A checklist based on hygiene principles embedded in Food European legislation was developed and applied in each hospital. In parallel, microbiological analysis of food contact surfaces, air quality and time/temperature measurements along the distribution chain were carried out. RTE samples (n = 150) were examined for mesophilic aerobic bacteria (MAB), total coliforms, coagulase-positive Staphylococci (CPS), Escherichia coli, Listeria spp. and Salmonella spp. Differences were found between hospitals regarding handling practices and cleanliness of working surfaces. Cooked ham samples presented lower counts of MAB and total coliforms (<10³ and <10 cfu/g respectively) than lettuce salads (10⁴ to 10⁵ and 10 to 10⁴ cfu/g respectively), although concentration of CPS was higher in cooked ham samples reaching maximum levels close to 10³ cfu/g. Neither Listeria spp. nor Salmonella spp. were detected in any food sample. Prevalence of E. coli was low (3%). Surface counts and air quality presented high variability among the different hospitals evaluated. It was concluded that good manufacturing practices and HACCP principles should be followed together with special training of food handlers. This study can help risk managers to better define the control measures to be adopted in healthcare settings in order to prevent foodborne infections.     

Occurrence and characterization of nontyphoidal Salmonella in retail table eggs in Kandy district of Sri Lanka

Salmonellosis in humans is typically a foodborne bacterial zoonotic disease. In this regard, eggs and egg products contaminated with nontyphoidal Salmonella represent a serious threat to consumers. Eggs are one of the most common sources of animal protein for Sri Lankans but minimum attention is paid to their quality assurance. Except for a few packaged eggs sold under brand names for higher prices, in general, grading, cleaning or cooling is not practised before sale posing a microbiological health hazard to the general public. Hence, the objective of this study was to identify the presence of Salmonella in raw table eggs available at retail outlets in one selected district of Sri Lanka. Eggs were purchased from 100 retail outlets situated in highly populated areas of the district. Samples were tested for the presence of Salmonella in eggshell washings and egg contents, separately. Isolation and identification of Salmonella was performed according to standard methods. The isolates were serotyped and their antimicrobial sensitivity was determined. Salmonella was isolated from the eggs purchased from 15 retail outlets, of which 12 yielded Salmonella from shell washings and three from egg contents. The serovars identified were S. Mbandaka, S. Braenderup, S. Corvallis, and S. Emek. Except one isolate showing resistance to nalidixic acid and another to a third generation cephalosporin, other isolates were sensitive for the tested antimicrobials. According to the results of this study, retail raw table eggs can be considered as an important source of nontyphoidal Salmonella to egg consumers in Sri Lanka.     

Prevention of travel-related foodborne diseases: Microbiological risk assessment of food handlers and ready-to-eat foods in northern Italy airport restaurants

The focus of this study was to assess the hygienic standards of 44 foodservice facilities located in three Italian International Airports (with an output ranging from 100 to 800 meals a day), by monitoring the microbiological quality and safety of foods ready for consumption (n = 773), food contact surfaces (n = 302), and food handlers (n = 287). The hygienic standard of surfaces was sufficiently high. Only 7.9% of surfaces did not conform with advisory standards in terms of total coliforms, and 2.6% were found to be contaminated with Enterococcus spp. at ≥1.0 log₁₀ CFU/cm². The hygienic standard of washed and disinfected hands of food workers was not adequately high: the total bacterial count and coagulase positive Staphylococci exceeded the satisfactory limit in 8.4% and 3.5% of cases, respectively. The microbial analysis of foods examined showed an absence of Listeria monocytogenes and Salmonella spp. Food sample analyses highlighted a percentage of samples that did not conform to microbial reference standards: Staphylococcus aureus non-conforming percentages ranged from 2.3% for “fully cooked food” to 9.2% for “raw fruit and vegetables”; Escherichia coli, from 0.0% for “raw fruit and vegetables” to 6.1% for “cooked and uncooked foods”; total coliforms from 14.3% for “fully cooked food” to 79.8% for “cooked and uncooked food”. In conclusion, the results suggest that more effort is needed in the application of HACCP principles. In order to prevent travel-related foodborne infections, various changes in the timing of food preparation and holding temperatures are needed, together with further training of food handlers.