[Occurrence of verotoxin-producing Escherichia coli (VTEC) in fecal swabs from slaughter cattle and sheep--an observation from a meat hygiene view]. / Vorkommen verotoxinbildender Escherichia coli (VTEC) in Kottupfern von Schlachtrindern und Schlachtschafen--eine Betrachtung aus fleischhygienischer Sicht.

Fecal samples from 544 beef cattle and 140 sheep were investigated by PCR for verotoxin (VT)-producing Escherichia coli (VTEC) without and with an enrichment step. 6.1% (after enrichment 14%) of cattle samples and 10% (after enrichment 29.2%) of sheep samples were VT-PCR-positive. Moreover, a noticeable age-depending prevalence in cattle was found. Eleven VTEC strains isolated from fecal samples of 5 cattle and 6 sheep were taken for further characterization. None of the strains belonged to serogroup O157. But, as reported previously, we also found in this study strains with virulence genes that are associated with increased pathogenicity. The importance of slaughter hygiene and of bacteriological monitoring of carcass contamination has to be pointed out.

Prevalence and characteristics of verotoxin-producing Escherichia coli (VTEC) in stool samples from asymptomatic human carriers working in the meat processing industry in Switzerland.

A total of 5590 stool samples from healthy employees in the meat industry were screened by PCR for verotoxin-producing Escherichia coli (VTEC). The PCR product of VT-encoding genes was detected in 3. 5% of the samples. Phenotypic and genotypic traits of 47 VTEC strains isolated from asymptomatic carriers were characterized. A variety of serotypes was found; one strain belonged to the serotype O157:H7. The majority of the isolates proved to be VT2-positive. Fifty-seven percent of the verotoxin-producing strains harboured the genes for one or several additional virulence associated factors, including intimin (eae, 8.5%), the 60 MDa plasmid (42.5%), enterohaemolysin (EHEC-hlyA, 38.3%), the heat-stable enterotoxin (astA, 6.4%), a serin protease (espP, 6.4%), colicin production (col D157, 12.8%) and a secretion system II (etpD, 10.6%). None of the strains was positive for a specific enzyme with catalase-peroxidase activity (katP).

Pulsed-field gel electrophoresis (PFGE) typing of Listeria strains isolated from a meat processing plant over a 2-year period.

As part of a hygiene monitoring program in a meat processing plant a total of 131 Listeria isolates were detected by sampling different processing areas and meat products within a 2-year period. The isolates were differentiated by means of phenotypic characteristics. Furthermore, the genomic ApaI and SmaI fragment patterns of all isolates were examined by pulsed-field gel electrophoresis (PFGE). PFGE using SmaI and ApaI yielded 15 (Listeria monocytogenes), 20 (Listeria innocua) and six (Listeria welshimeri) pulsotypes. Of the environmental Listeria monocytogenes isolates the predominating PFGE-type B was clearly associated with processing area A whereas PFGE-type E predominated in the meat products. Moreover, the study showed the persistence of closely related Listeria strains over a 2-year period in the environment of this meat processing plant.

[Resistance situation and enterotoxin production capacity of Staphylococcus aureus strains from bovine mastitis milk samples]. / Resistenzsituation und Enterotoxinbildungsfähigkeit von Staphylococcus aureus Stämmen aus bovinen Mastitismilchproben.

In total, 63 S. aureus strains from mastitis milk samples of different animals in 57 farms were isolated. In 14 (22%) of the S. aureus strains resistancies against one or several of the examined antibiotics could be observed whereby six resistance patterns were found. 14.3% of the strains were penicillin resistant. 34 (54%) of the 63 S. aureus produced enterotoxins (SE). Three strains formed SEA, 21 SEC, three SED and seven strains 2 SE, SEAC, SEAD or SEBD.

Virulence factors and phenotypical traits of verotoxin-producing Escherichia coli strains isolated from asymptomatic human carriers.

Fourteen verotoxin-producing Escherichia coli strains isolated from stool samples of 14 different asymptomatic human carriers were further characterized. A variety of serotypes was found, but none of the strains belonged to serogroup O157. Only one isolate carried most of the virulence genes that are associated with increased pathogenicity.

Reliability and practicability of bacteriological monitoring of beef carcass contamination and their rating within a hygiene quality control programme of abattoirs.

A total of 9600 swab samples from 900 carcasses originating from ten different abattoirs were subjected to bacteriological examination. Two sampling sites, brisket and forearm, consistently showed the highest contamination rates. The following sites are recommended for sampling: on the lateral side of the carcass neck, forearm, shoulder, brisket and abdomen. The neck is recommended for the medial side. Compared to the large variance of contamination either on individual carcasses or between different carcasses, the differences in the variance of results between double swab and incision sampling techniques should be of minor importance. Considering this big variance of colony counts, it is suggested to take five to six swab samples from each of at least ten to 15 carcasses once a month. With a view to a more differentiated and evident evaluation the results should be recorded in a 'box plots' and not in the form of mean values and standard deviations. The data confirms bacteriological monitoring of beef carcasses as a useful tool for the verification of slaughter hygiene.

Chemical attributes characterizing sticky post-mortem ageing in beef.

Reports in literature on post-mortem sticky ageing are rare and data about chemical metabolites that occur particularly during sticky ageing are partly contradictory. In the present study different chemicals (pH, NH(3), TVB-N, H(2)S, R value, IMP, pyruvate and various volatile acids such as lactic acid, acetic acid, butyric acid, uric acid and pyroglutamic acid) were tested for their suitability to serve as parameters to characterize sticky post-mortem ageing in beef muscle samples. Results show that a high butyric acid concentration (0.46 µMol g(-1)) seems to be typical for sticky post-mortem ageing in beef. A distinction from onset of spoilage is possible due to the high butyric acid concentration, a low ammonia content (10.5 mg 100 g(-1)) and a low pH value. From meat with normal ageing it can be differentiated by sensory, colour, smell, consistency, a high butyric and pyroglutamic acid content and a low IMP concentration (0.04 µMol g(-1)).

[Risk assessment and risk management according to the HACCP (Hazard Analysis and Critical Control Point) concept: a concept for safe foods]. / Risiko-Bewertung und Risikomanagement nach dem HACCP-Konzept: Ein Weg zu sicheren Lebensmitteln.

The volume of official hygiene regulations for food processing establishments has been growing continuously over the past 20 to 30 years. This led to a decrease in hygiene risk awareness in food processing establishments which was partly replaced by a strong reliance on legislative measures in food hygiene. After experiences in industrialized nations had shown that even numerous and detailed hygiene regulations could not prevent the increase of infections and intoxications of consumers by food products, new solutions had to be found. On the one hand, the implementation of intensified control measures by the producers themselves is required. Such a control much then be "controlled" by the state authorities. On the other hand, the so-called HACCP (Hazard Analysis and Critical Control Point) system has been introduced as a new quality assurance principle for the avoidance of health hazards. This concept was developed in the 1960s in the United States of America in order to produce safe foods for the space programme. For the production of a particular food according to the HACCP system informations on hazards and situations leading to their presence are collected and evaluated in order to decide which are significant for food safety and therefore should be addressed in the HACCP plan. According to this analysis the necessary preventive measures which lead to the prevention, elimination or reduction to an acceptable level of identified health hazards have to be defined. All steps of food processing have to be included in the HACCP system. Raw materials, storage of foods, types of distribution and the intended usage of the final product by the consumer have to be considered in this system. However, the introduction of the HACCP system into European hygiene regulations does not constitute an entirely new development. It can rather be regarded as a renaissance of traditional scientific concepts. This is demonstrated by the example of drinking milk processing as it was practised sixty years ago.

[Case report: tyrosine deposits]. / Fallbericht: Tyrosinablagerungen.

Whitish precipitations in three samples of raw cured ham, which appeared in the stereomicroscope as piles of crystals, were confirmed as tyrosine crystals. Tyrosine is readily soluble in nitric acid (yellowish discoloration) and, after addition of potash lye, it precipitates as yellow-orange picrate. Factors that influence the formation of tyrosine crystals are largely unknown. In raw cured ham of Parma experience has shown that tyrosine crystals are found in ham stored for a very long time.

[Risk assessment of microorganisms relevant to food hygiene]. / Risikobewertung von lebensmittelhygienisch relevanten Mikroorganismen.

In the public's view, chemical residues still dominate in the ranking of foodborne hazards. This perception is changing slowly as a result of public discussions on the dangers to human beings from various microorganisms in foodstuff. Statistics on foodborne infections and intoxications comprising acute diseases have shown that chemical substances (including fungal toxins) play a less significant role than bacteria. A sentinel and a populations study from Holland provides information on the incidence of cases of acute gastroenteritis caused by microorganisms in foods. The results of this study show that 100 to 150 cases are to be expected annually per 1000 inhabitants. An economic cost of about $1000 per case of disease is calculated in Canada and the USA. On the basis of these figures and the Dutch study, the estimated annual economic impact is more than 10 billion DM for the Federal Republic of Germany. The difficulties in quantification of microbiological hazards from foodstuffs on the base of dose-response relation and exposure assessment such as are usual in the risk assessment of chemical hazards are discussed. A safety concept of the food industry (the HACCP concept) is then described. This comprises hazard identification. risk assessment as well as risk management. This concept is also applicable in other food areas such as communal catering. In the meantime, it has also been taken into consideration in European food legislation.

Characterization of Bacillus licheniformis with the RAPD technique (randomly amplified polymorphic DNA).

RAPD technique (randomly amplified polymorphic DNA) was used for epidemiological subtyping of Bacillus licheniformis and other Bacillus spp. Within 46 isolates of B. licheniformis, up to 10 strain types could be determined when two 10-mer primers were used. RAPD patterns, which were found in eight further strains of Bacillus spp., clearly differed from those of B. licheniformis. Thus RAPD technique proved to be a promising tool for characterization of Bacillus spp.

[Problems of food hygiene with carriers of microorganisms and permanent excretors]. / Probleme der Lebensmittelhygiene mit Keimträgern und Dauerausscheidern.

To appraise the significance of chronic excretors and carriers for the development of "food poisoning", the analysis must also include the food. First of all, the question arises as to whether foods only have a vector function or whether an increase in the bacterial count is an important prerequisite for the elicitation of human disease. When pure intoxication pathogens are not involved, this question arises in connection with the minimum infectious dose. A classification of the most important causative organisms of bacterial foodborne infections and intoxications is presented in the light of these considerations. If foods only have a vector function, hygiene measures are automatically concentrated on excretors in order to prevent the bacteria from passing into foods. When this is not the case (as in the vast majority of human foodborne infections and intoxications of bacterial origin), two strategies can be successfully applied. First of all, precautions must be taken to rule out bacterial contamination. On the other hand, an increase in the bacterial count, i.e. proliferation of the pathogens in the food must be prevented by appropriate measures. The interacting factors are described. The example of salmonellae is cited to illustrate the routes of contamination from excretors (humans and animals) to foods ready for consumption and possible hygiene measures.

[Quality assurance in food production: a challenge for veterinary food hygiene?]. / Qualitätssicherung in der Lebensmittel-produktion: Eine Herausforderung für die tierärztliche Lebensmittelhygiene?

Production liability, safety regulations as well as marketing strategies are important motivations for companies to establish in-house quality control measures which can be certified by an independent control body. Companies that advertise quality control measures place pressure on opposition companies to follow suite. It follows that certification in foodstuff production will lead to a chain reaction and spread quickly to other companies. In the establishment of a quality assurance system it is just as important to distinguish between quality control and quality assurance as it is to consider the guidelines laid down in the ISO-Standards 9000-9004. After certification according to the ISO-Standards, which dictates certain forms of quality assurance, there is no guarantee that all important risks, such as hygiene risks introduced with technology, can be excluded. In terms of public health monitoring an important responsibility awaits veterinary public health. Strategies and consequences for official monitoring of foodstuffs are presented and discussed.

Influence of aw value and storage temperature on the multiplication and enterotoxin formation of staphylococci in dry-cured raw hams.

Growth and enterotoxin A production in dry-cured raw ham, with different aw and pH values, was investigated for Staphylococcus aureus strain FRJ-100 over a temperature range of 20-35 degrees C when stored for up to 7 days. Enterotoxin production took place at all temperatures tested in the meat of ham that was cured, but not dried (aw 0.95). In dry-cured raw ham with an aw-value of about 0.92, and stored at 20 degrees C, no enterotoxin production was detectable within the 7-day storage period, whereas enterotoxin was produced at the higher temperatures. In ham with an aw of about 0.89, enterotoxin was produced only when stored for 7 days at 35 degrees C. Critical points for S. aureus multiplication and enterotoxin-formation during production and storage of dry-cured raw ham are discussed.

Contamination of pig hindquarters with Staphylococcus aureus.

Swab specimens from 4357 pig hindquarters provided for production of cured raw ham were contaminated with Staphylococcus aureus in 22.7%. The bacterial counts for S. aureus on the rind surface of the raw, uncured ham were between 10(1) and 10(3) cfu/cm2 in 89% of the positive samples. In the remaining 11% of contaminated ham counts of 10(3) to 10(6) cfu/cm2 were determined. There were major differences in the rate of contamination between pork from different suppliers. Questioning the suppliers revealed that pork highly contaminated with S. aureus could be traced back to certain abattoirs. This suggests that the technique of slaughter, concomitant hygiene precautions and the subsequent refrigeration of the carcasses affect the contamination of the meat with staphylococci.

The presence of enterotoxigenic Clostridium perfringens strains in faeces of various animals.

The presence of Clostridium perfringens in faeces of horses, cattle, poultry and pigs was determined. C. perfringens was detected in 24%, 36%, 80% and 2% of the faecal samples, respectively. Faecal samples containing enterotoxigenic strains as assessed by colony hybridization amounted to 14%, 22%, 10% and 0% respectively.

Growth of pathogenic Yersinia enterocolitica strains in minced meat with and without protective gas with consideration of the competitive background flora.

The growth of two pathogenic Yersinia enterocolitica strains (O:3, O:9 at 1 degree C, 4 degrees C, 10 degrees C and 15 degrees C) in minced meat produced under sterile conditions and in minced meat with a normal background flora was investigated. In addition, the influence of treatment with a protective gas (20% CO2, 80% O2) was tested. In minced meat produced under sterile conditions and incubated under normal atmospheric conditions, Y. enterocolitica increased in numbers by only 1 log at 1 degree C and 3.5 logs at 4 degrees C within 14 days. At 10 and 15 degrees C, there was about a 5-log increase in cell numbers within 5 days. There was a marked inhibition of growth by the background flora on Y. enterocolitica. This effect was so marked that only a slight additional inhibition on the growth of Y. enterocolitica at 1, 4 and 10 degrees C was observed under the CO2:O2 modified atmosphere. This is in contrast to the situation where minced meat with a low total bacterial count was used, and the growth of Y. enterocolitica was adversely affected by the CO2:O2 environment. The significance of raw minced meat in the development of human Y. enterocolitica infections is also discussed.