Shell egg handling and preparation practices in food service establishments in Finland.

Foodborne outbreaks are often reported to be acquired at food service establishments. As a part of a quantitative risk assessment on the consumer risk of contracting Salmonella infection via shell eggs, we studied how small, medium, and large restaurants, institutional kitchens, and staff canteens (n=171) purchase, store, and use shell eggs. In addition, we estimated the fraction of raw and undercooked risky egg dishes among all egg dishes served in food service establishments of different sizes and types. The majority of establishments used shell eggs (78%), purchased eggs once per week (39%), and stored eggs at cool temperatures (82%). The size of the food service establishment had a less significant effect on shell egg preparation and handling practices than the type of the establishment. In particular, restaurants and institutional kitchens differed from each other. Restaurants purchased shell eggs more frequently, were more likely to store them at room temperature, stored shell eggs for a shorter period, and were more likely to prepare undercooked egg dishes than institutional kitchens. It was predicted that 6 to 20% of all different egg dishes prepared in a single randomly chosen food service establishment would be risky egg dishes with a 95% Bayesian credible interval of 0 to 96%, showing uncertainty because of the variability between kitchens and uncertainty in kitchen type-specific parameters. The results indicate that although most Finnish food service establishments had safe egg handling practices, a substantial minority expressed risky behavior. Compared with the egg consumption patterns in private Finnish households, however, practices in food service establishments did not prove to be more prone to risk.

Simulation of human exposure to benzylpenicillin residues via pork originating from pigs fed with a dairy by-product.

The use of food industry by-products for feeding is restricted by European Union by-product regulation (1774/2002). However, the actual public health risks involved in the use of such products are poorly recognized. This study focuses on bovine milk rejected at the dairy because of a positive result in antimicrobial drug testing and thereafter used as feed for finisher pigs in Finland. In theory, this current practice could expose pork consumers to antimicrobial drug residues. Raw bulk milk samples originating from rejected lots were analysed with a multiresidue method detecting five beta-lactams, including benzylpenicillin. Based on the probabilistic simulation model developed, concentrations of benzylpenicillin in pork invariably remained below 1% of the maximum residue limit. Therefore, the use of this by-product as feed with the current practice was considered to pose only a negligible risk to consumers of pork products.

Salmonella risk in imported fresh beef, beef preparations, and beef products.

Additional guarantees (AGs) for Salmonella in imported defined animal-derived foods were agreed on for Finland when it was admitted to the European Community. The aim of this project was to evaluate the impact of these AGs on the prevalence of Salmonella in the Finnish beef supply and the adequacy of their scope. According to the quantitative Bayesian model, the efficacy of AGs was mainly dependent on the proportions of different beef categories imported and the true prevalence in the countries of origin. According to the model, AGs were able to reach their target in the referred year 1999 and kept the true Salmonella prevalence of beef imports below 1% with quantified uncertainty. The extension of AGs to all imported fresh beef would have reduced the Salmonella prevalence of beef imports from three- to fourfold, whereas expanding the implementation of AGs to all imports of fresh beef, beef preparations, and beef products would have resulted in a sixfold decrease. If current AGs targeting fresh beef intended to be sold as fresh or to be processed by the Finnish industry with processes not achieving 70 degrees C were not implemented, the 95% credible interval of Salmonella prevalence in the Finnish beef supply would be 0.2 to 1.3% (mean, 0.6%) instead of 0.1 to 1.2% (mean, 0.5%). However, if the prevalence in the exporting countries were to rise or the main import countries and/or magnitudes were to change, AGs would be of greater importance.

A quantitative risk assessment of the public health impact of the Finnish Salmonella control program for broilers.

In order to study the public health effects of the Finnish Salmonella control program (FSCP), a quantitative risk assessment model of Salmonella from slaughtered broiler flocks to consumers was developed. Based on the model, approximately 0.21% of domestically produced broiler meat mass was contaminated with Salmonella (95% probability interval 0.05-0.48%). This model was combined to the model on primary production of broilers. By this way, the effect of eliminating breeder flocks from production which have tested positive for Salmonella and heat-treating the meat of detected positive broiler flocks on public health could be simulated. Based on the whole model, if detected positive breeder flocks were not removed this would result in 1.0-2.5 more reported human cases compared to the expected number of cases under current FSCP (95% predictive interval). Without heat treatment of meat the increase would be 2.9-5.4-fold and without both interventions 3.8-9.0-fold. In scenarios with one grandparent or five parent flocks infected, the combined effect of these two interventions was 9.3-25.8-fold and 4.9-11.7-fold compared to the baseline level under each scenario, respectively. The scenario analyses suggest that with a higher infection level, inclusion of both interventions will be more effective than either of the interventions alone. Replacement of half of the current retail broiler meat by meat with 20-40% contamination could result in 33-93 times more human cases compared to the expected value under current situations. On the basis of the model, the interventions applied in FSCP clearly protect the public health.

Cadmium intake of moose hunters in Finland from consumption of moose meat, liver and kidney.

Although the average cadmium intake in Finland is about 10 microg day(-1), some risk groups can be identified. This study assessed cadmium intake from the consumption of moose meat, liver and kidneys by moose hunters. Consumption data from a postal questionnaire were combined with a representative database on moose cadmium concentrations. Cadmium intakes were calculated as point estimates for all respondents (n = 711), for those consuming moose meat, liver and/or kidneys, and for the highest decile of those. Probabilistic modelling using the Monte Carlo technique was used to simulate the distribution of dietary cadmium exposure. Of the respondents, 69% consumed moose liver and only 23% moose kidneys. The consumption of moose liver or kidneys significantly increased cadmium intake, whereas moose meat (median consumption 17 kg year(-1) person(-1)) contributed only slightly (0.16 microg day(-1) person(-1)) to the daily total cadmium intake. In the simulation, 10% of the moose hunters had an intake of > 8.76 microg day(-1) (14.6% of PTWI for a 60-kg person) from moose. Point estimates provided only a partial understanding of the potential exposure. Simulated distributions of intake were more useful in characterizing exposure. The study revealed that heavy users of moose organs have a relatively narrow safety margin from the levels of cadmium probably causing adverse health effects.

Exposure of Listeria monocytogenes within an epidemic caused by butter in Finland.

Data on the levels of bacteria and the amounts of food consumed in food-borne outbreaks provides an excellent opportunity to study the effects of exposure to Listeria monocytogenes. Between June 1998 and April 1999, an outbreak caused by L. monocytogenes serotype 3a in butter occurred in Finland. The majority of the cases were immunocompromised and hospitalized at the Helsinki University Central Hospital (HUCH), where 7-g butter packages produced by a dairy plant were used as the only butter brand. The butter had also been sold to 10 other central hospitals as well as to the retail market. Based on the data on hospital stay, butter consumption and the qualitative and quantitative analyses of L. monocytogenes in butter, the attack rates and exposure were estimated. Incubation studies on the naturally contaminated small butter packages showed that the levels found in the packages at the time of detection of the outbreak could reliably be used for these estimations. However, the levels of L. monocytogenes in 500-g packages increased. The attack rate among HUCH patients varied from 70 to 117 cases per 1000 patients at risk, depending on which estimate of the contamination level of butter (100-60%) was used. The highest single dose (7.7 x 10(4) CFU in one meal) could have been sufficient to cause the listeriosis cases at HUCH. However, this data also supports another hypothesis, according to which these listeriosis cases were caused by a prolonged daily consumption of contaminated butter during the hospital stay. The estimated daily dose, based on the hospital kitchen data or the highest detected level in a wholesale sample (11,000 CFU/g), would have varied from 1.4 x 10(1) to 2.2 x 10(3) CFU/day or from 2.2 x 10(4) to 3.1 x 10(5) CFU/day, respectively. The choice of the hypothesis has a crucial impact on the interpretation of this data for the dose-response estimations as well as for the discussion on Food Safety Objectives. Due to the susceptibility of hospital patients, special care must be taken in order to avoid even low levels of L. monocytogenes in food served.

An outbreak of Listeria monocytogenes serotype 3a infections from butter in Finland.

In February 1999, an outbreak of listeriosis caused by Listeria monocytogenes serotype 3a occurred in Finland. All isolates were identical. The outbreak strain was first isolated in 1997 in dairy butter. This dairy began delivery to a tertiary care hospital (TCH) in June 1998. From June 1998 to April 1999, 25 case patients were identified (20 with sepsis, 4 with meningitis, and 1 with abscess; 6 patients died). Patients with the outbreak strain were more likely to have been admitted to the TCH than were patients with other strains of L. monocytogenes (60% vs. 8%; odds ratio, 17.3; 95% confidence interval, 2.8-136.8). Case patients admitted to the TCH had been hospitalized longer before cultures tested positive than had matched controls (median, 31 vs. 10 days; P=.008). An investigation found the outbreak strain in packaged butter served at the TCH and at the source dairy. Recall of the product ended the outbreak.

The first Salmonella enteritidis phage type 1 infection of a commercial layer flock in Finland.

The first Salmonella Enteritidis phage type (PT) 1 infection in a commercial layer flock of 2700 birds in Finland occurred in 1995. All the birds were ordered to be killed, the eggs to be destroyed and access to the layer house was denied in order to prevent spread of the infection. Ninety one commercial layers, 61 replacement pullets and 1062 eggs were collected for the analyses. The total infection level of the flock was 8%, concentrated on the 2 older age groups. S. Enteritidis PT1 was isolated from livers (5%), ovaries (2%) and from caeca (3%), of which 2 positive samples were detected with pre-enrichment and 3 without pre-enrichment by cultivation Rambach agar. Eight % of 105 pooled egg samples were positive, of which 2 were detected only from contents and 3 only from shells indicating both oviductal and faecal contamination routes of eggs. The results support the use of the extended sampling procedure in poultry flocks suspected of human food-borne Salmonella outbreaks of invasive serotypes, including not only faecal but also environmental, organ, blood and/or egg samples.

Influence of processing temperature on the formation of biogenic amines in dry sausages.

Temperature is known to have a clear influence on the formation of biogenic amines in the fishing industry and in cheese fermentation In this work, the effect of processing temperature on the formation of amines in dry sausages was studied in pilot and factory trials. Sausages made from the same batch of raw materials, were divided into two groups each fermented at different processing temperatures. The influence of raw materials on amine formation was evident. When commercial preparations of starter cultures containing lactic acid bacteria and Staphylococcus carnosus were used, a lower processing temperature resulted in higher levels of amines and delayed pH decrease in comparison with the higher temperature. However, more amines were formed at the higher processing temperature when glucono-delta-lactone with S. carnosus was used. According to these results not only the selection of raw materials, but also the choice of optimal processing temperature for the amine-negative starter culture used, are important critical control points in preventing the formation of high levels of biogenic amines in dry sausages.

Contaminant lactic acid bacteria of dry sausages produce histamine and tyramine.

Exogenous biogenic amines present a food poisoning hazard in fermented foods especially with additional risk factors, e.g. amine oxidase inhibiting drugs, alcohol and gastrointestinal diseases. Forty-two lactic acid bacteria (LAB) strains were isolated from seven dry sausages during ripening (0 day, 21 day and 49 day). Their ability to produce histamine and tyramine was studied by HPLC detection from broth cultures after 2 days incubation. The tyramine and histamine concentrations in sausages increased during fermentation. 10 of 42 LAB strains produced 402-1087 ppm tyramine. Four of these 10 contaminant LABs were also histamine-positive (725-1083 ppm). Most of the amine positive strains were found in sausages at the end of ripening and with highest amine levels. On the basis of these results the contaminant LABs play an important role in tyramine and histamine formation during the ripening of dry sausages. Therefore it could be possible to decrease the levels of amines formed by limiting the initial level and growth of these contaminant bacteria.

Growth of Salmonella and competing flora in five commercial Rappaport-Vassiliadis (RV)-media.

Growth of 18 Salmonella strains belonging to 11 serotypes and the bacterial flora of deep-frozen broiler carcasses was examined in five commercial Rappaport-Vassiliadis (RV) media. Growth was measured by an automated turbidometer (Bioscreen). Significant differences in performance between the media investigated were observed. The unequal performances were ascribed to differences in the concentration of magnesium chloride (MgCl2) and the type of peptone used.