Typing of Salmonella enterica serovar Infantis isolates from 51 outbreaks in Germany between 1974 and 2009 by a novel phage-typing scheme.

We developed a new phage-typing method and evaluated its application in combination with XbaI macrorestriction analysis by pulsed-field gel electrophoresis (PFGE) as a useful tool for the long-term epidemiology of Salmonella enterica serovar Infantis. In this study, we investigated 1008 S. Infantis isolates recovered from humans, various animal species and food products from 1973 to 2009. The typing scheme is based on 17 typing phages, defining 61 different patterns within the strain collection. The experiments showed that phage typing is a reliable method for differentiation of outbreaks and sporadic clinical cases as well as for elucidation of chains of transmission. The combined analysis of phage typing and PFGE revealed the existence of epidemic clones with a high stability over time like PT29/XB27 which was identified in nosocomial salmonellosis, community outbreaks as well as in broiler chickens from 2002 to 2009.

Tissue tropism of Toxoplasma gondii in turkeys (Meleagris gallopavo) after parenteral infection.

Turkeys are known to be natural hosts for the zoonotic protozoan parasite Toxoplasma gondii. The objective of the present study was to gain further knowledge of possible predilection sites of T. gondii infection in this species after parenteral application of tachyzoites. A total of 38 turkeys were infected with different doses of T. gondii tachyzoites. Birds were killed either 6 to 8 or 10 to 12 weeks after the experimental infection. Fourteen different tissues per bird were investigated by a nested polymerase chain reaction (PCR) for the presence of the parasites' DNA. T. gondii DNA was found in any type of tissue analysed; in 86.1 % of all infected birds, at least one sample was tested positive. Over all intravenously infected birds, 15.4 % of all analysed samples contained T. gondii DNA. Most frequently affected tissues were liver (43.3 % positive samples), breast muscle (26.7 % positive samples) and heart (20.0 % positive samples), while the brain was less frequently positive (6.7 %). The number of positive tissues varied from zero to seven tissues per animal with at least one T. gondii-positive edible tissue sample in 80 % of all intravenously infected birds. Still, the results did not indicate defined target tissues or a cyst distribution pattern. Nonetheless, edible organs were most frequently parasitised. The number of positive findings did not differ between the early and the late examination time points. Therefore, a persistence of the tissue stages until the end of the study (12 weeks after infection) is concluded.

Examinations on the prevalence of footpad lesions and breast skin lesions in B.U.T. Big 6 fattening turkeys in Germany. Part II: Prevalence of breast skin lesions (breast buttons and breast blisters).

This project involves the prevalence of breast skin alterations (breast buttons, blisters, purulent bursitis) in male and female fattened turkeys (British United Turkeys Big 6) from conventional intensive farming. In this case, 24 turkey farms across Germany and 11,860 turkeys (5,740 toms, 6,120 hens) were clinically examined, and 16,200 birds (8,400 hens, 7,800 toms) were evaluated on slaughter lines at 7 turkey abattoirs. Each turkey farm included examination of at least 3 consecutive fattening cycles. Especially in the meat examinations, breast skin alterations were a frequent discovery, particularly in the form of breast buttons. The turkey toms exhibited a prevalence of 27.15%, and the toms were affected significantly more frequently (P < 0.001) by these variations than the turkey hens (7.77%). It is possible that the higher BW of the male specimens leads to increased lying times and is therefore connected with more severe strain on the breast region. The increased fattening period of the turkey toms (slaughtering at wk 21 to 22 of life) vs. the female specimens (slaughtering at wk 15 to 17 of life) must be discussed as a cause. Breast blisters and bursitis sternalis were discovered with a prevalence of 7.36 and 1.24% in toms and more seldom in hens, at 0.30% and 0.15%. Large differences in prevalence were partially recognizable between individual farms as well as between the 3 fattening cycles on a farm. Breast buttons and breast blisters are pathological skin variations for which the etiology is multifactorial. Clear correlations between the prevalence of breast skin alterations and the manner of rearing the birds were not able to be determined. An improvement in this situation, which is considered very problematic from the perspective of bird protection and economics, may be achieved only via cooperation to achieve optimized rearing methods, management, and breeding practices.

Examinations on the prevalence of footpad lesions and breast skin lesions in British United Turkeys Big 6 fattening turkeys in Germany. Part I: prevalence of footpad lesions.

The present study demonstrates the prevalence of footpad lesions in turkeys and their level of expression in both live birds and in carcasses. In clinical investigations of 11,860 turkeys (5,740 males, 6,120 females) of the strain British United Turkeys Big 6, individuals of all the observed flocks showed alterations to the plantar skin. In general, the degree and severity of skin alterations were higher in the 16th week of life than in the 6th or 11th week of life. Epithelial necrosis, however, was already apparent in about 45% of individuals in the 6th week of life. At this point, deep lesions on the footpad surface were still rare findings. In the 11th week of life, such skin changes were apparent in 14.7% of males and 25.7% of hens. In general, the feet of male turkeys were less affected by footpad damage than those of females in the subsequent fattening period. In hens, the prevalence of lesions of the footpads at wk 16 of age was 60.0%, almost twice as high as in males of the same age group (33.8%). A comparison of the findings from the right and left feet showed that the state of the 2 extremities was correlated (Spearman correlation: r = 0.830). During the visual inspection of 16,200 slaughtered turkeys (7,800 males, 8,400 hens), almost all carcasses studied showed alterations to the footpad skin. Only 2.1% of males and 0.6% of females were without lesions. The most frequently observed lesions measured up to 2 cm in diameter (males: 59.2%; hens: 57.7%). Pronounced skin lesions of the footpad (males: 21.1%; females: 29.5%) and necrosis of the superficial epithelium (males: 17.5%; females: 12.1%) were less common. Foot abscesses were diagnosed only sporadically (males: 0.1%; females: 0.1%).

Migration of Salmonella enteritidis from the albumen into the egg yolk.

Migration of Salmonella enteritidis from the albumen into the egg yolk was investigated in 860 eggs. After artificial contamination of the albumen with different doses of S. enteritidis phage-type 4 the migration and the effect of temperature on the migration process during a storage period of up to 4 weeks were studied. The experiments showed that the first cells can be detected in the yolk within a few days. The process will be relatively rare during chilled storage if the albumen is only slightly contaminated. The migration rate was positively correlated with the level of contamination, the storage temperatures and the age of the eggs.

[Microbial risks--from animal farming to the food]. / Mikrobiologische Risiken--von der Tierhaltung zum Lebensmittel.

Microorganisms by far are representing the most important cause for food safety risks. Sources of food contamination are given along the whole food chain. The most frequent causative agents of food infections, Salmonella and Campylobacter, mostly can be found in the animals herds. A real improvement of the situation can only be reached by a strong inclusion of the agricultural area in the programs for repressing the pathogens. Problems in animal health and premortal stress of the slaughter animals cause considerable bacterial translocation processes and increase the consumer risks. Only few publications exist on the influence of the animal farming systems on the development of microbial food risks. The consumer accepts only animal management systems, which meet the demands for animal welfare, economical efficiency and especially the demand for product safety.

[Quantitative occurrence of lipolytic and proteolytic enzymes in food of animal origin]. / Quantitatives Vorkommen von Lipolyten und Proteolyten in Lebensmitteln tierischer Herkunft.

Proteolytic and lipolytic enzymatic activities of microorganisms are the most important cause for food spoilage and a limited shelf life. Until now the determination of the total aerobic count is the base of shelf life evaluations. Our investigations show the proportion of proteolytes and lipolytes to the total germ count in different kinds of food (milk and milk products, meat products and fish) which is in part surprisingly high. Results were observed on different media--proteolytic germs were counted on protein containing agar (casein, meat protein, fish protein) and lipolytic organisms on fat containing agar (tributyrin, olive oil, butterfat). Using the predictive microbiology and the knowledge about the activity of microbial enzymes under different milieu conditions in food the results give an important tool for a better shelf life evaluation.

Antiviral Potential of Selected Starter Cultures, Bacteriocins and D,L-Lactic Acid.

The antiviral potential of selected bacteria species [lactic acid bacteria (LAB) and micrococcaceae] was examined. By this, the effect of their cell-free supernatants as well as of certain species-related metabolites (sakacin A, nisin, and lactic acid) was investigated on different viruses after exposure at 24 °C for 3 days. Viruses were incubated with supernatants and metabolites in a dilution ratio of 1:10. Data for antiviral effects towards murine norovirus S99 (MNV), influenza A virus A/WSN/33 (H1N1), Newcastle disease virus Montana (NDV) and feline herpesvirus KS 285 (FHV) were generated in vitro simulating pH and temperature conditions according to raw sausage fermentations. Investigations showed no antiviral effect of sakacin A and nisin on MNV, H1N1, FHV and NDV. Furthermore, the antiviral potential of D,L-lactic acid was determined for MNV and H1N1. At raw sausage-related pH values (5.0-6.2) it could be shown that the virus titre for MNV and H1N1 was reduced by a maximum of 3.25 log and 2.5 log units, respectively. In addition, 29 culture supernatants of different bacteria species, mainly LAB and staphylococci, were tested for their antiviral activity against MNV. Only the cell-free supernatant of a Lb. curvatus strain showed a higher virus titre reduction of MNV by 1.25 log units compared to the control. Further studies on the characterisation of this cell-free supernatant were carried out, however, the antiviral substance could not be identified so far.

Effects of pH, sodium chloride, and curing salt on the infectivity of Toxoplasma gondii tissue cysts.

Toxoplasma gondii is one of the most common zoonotic parasites in the world. The parasite causes no or mild symptoms in immunocompetent humans. However, a high potential hazard exists for seronegative pregnant women and immunocompromised patients. The consumption of meat containing tissue cysts or oocyst-contaminated vegetables and fruits or the handling of cat feces poses a high risk of infection with T. gondii. It is known that raw minced meat, raw fresh sausages, and locally produced raw meat products are possible causes of T. gondii infection. The infectivity of T. gondii tissue cysts in meat products depends, among other factors, on the pH and the salt concentration. Therefore, the impact of these two factors on the tissue cysts was examined. For this purpose, dissected musculature and brain from experimentally infected mice (donor mice) were placed in a cell culture medium (RPMI 1640). The medium was adjusted to different pH values (pH 5, 6, and 7) with lactic acid and to different salt concentrations (2.0, 2.5, and 3.0%) with sodium chloride (NaCl) or nitrite-enriched curing salt (NCS) for the various tests. After storage at 4°C for different time periods, the materials were fed to bioassay mice. Later, the brains were examined for presence of T. gondii to assess the infectivity. The data show that T. gondii tissue cysts have a high pH tolerance. Cysts were infectious in the muscle for up to 26 days (pH 5). In contrast to their tolerance to pH, cysts were very sensitive to salt. Muscle cysts survived at an NaCl concentration of up to 2.0% only, and for no longer than 8 days. At NaCl concentrations of 2.5 and 3.0%, the cysts lost their infectivity after 1 day. When NCS instead of NaCl was used under the same conditions, T. gondii muscle cysts retained infectivity for only 4 days at 2.0%. Consequently, NCS (NaCl plus 0.5% nitrite) has a stronger effect on T. gondii cysts than does common table salt. Sausages produced with low NaCl concentration and short contact times pose a potential risk for susceptible individuals.

Experimental Toxoplasma gondii oocyst infections in turkeys (Meleagris gallopavo).

Toxoplasma (T.) gondii is a protozoan parasite with a broad range of intermediate hosts. Humans are often infected by ingestion of tissue cysts in raw or undercooked meat or meat products. Turkeys as food-producing animals can also serve as intermediate hosts. The aim of the present study was to investigate occurrence and predilection sites of T. gondii infection in turkeys after oral infection with oocysts. Experimental infections with different doses of T. gondii oocysts were performed in 36 turkeys to mimic natural infection. Systemic distribution of parasitic stages was investigated by screening 14 different tissues including the edible tissues heart, liver, thigh, breast and drumstick muscle. Parasite detection was based on a conventional nested polymerase chain reaction (PCR). Animals were sacrificed 6-12 weeks after infection. Results demonstrated parasite spreading over the whole organism after oral infection by oocysts. Most frequently affected tissues were brain (47.2% of all brains were positive for T. gondii) and thigh muscle (25.0% positive samples). Other muscles were regularly T. gondii-positive, all other sampled tissues were positive at least once. Thus, edible tissues are one of the predilection sites of T. gondii in turkeys which renders raw or undercooked turkey meat a potential risk for parasite transmission to humans. Data were compared to results from previous parenteral turkey infections with tachyzoites. With the exception of brain, liver and breast muscle affection, no significant differences were observed between both infection routes. Both infection models could be used for research purposes with certain advantages and disadvantages.

In vitro influence of D/L-lactic acid, sodium chloride and sodium nitrite on the infectivity of feline calicivirus and of ECHO virus as potential surrogates for foodborne viruses.

The importance of foodborne viruses is increasingly recognized. Thus, the effect of commonly used food preservation methods on the infectivity of viruses is questioned. In this context, we investigated the antiviral properties of D,L-lactic acid, sodium chloride and sodium nitrite by in vitro studies. Two model viruses, Feline Calicivirus (FCV) and Enteric Cytophatic Human Orphan (ECHO) virus, were chosen for this study simulating important foodborne viruses (human noroviruses (NoV) and human enteroviruses, resp.). The model viruses were exposed to different solutions of D,L-lactic acid (0.1-0.4% w/w, pH 6.0-3.2), of sodium chloride (2-20%, w/v) and of sodium nitrite (100, 150 and 200 ppm) at 4 and 20 °C for a maximum of 7 days. Different results were obtained for the two viruses. ECHO virus was highly stable against D,L-lactic acid and sodium chloride when tested under all conditions. On the contrary, FCV showed less stability but was not effectively inactivated when exposed to low acid and high salt conditions at refrigeration temperatures (4 °C). FCV titers decreased more markedly at 20 °C than 4 °C in all experiments. Sodium nitrite did not show any effect on the inactivation of both viruses. The results indicate that acidification, salting or curing maybe insufficient for effective inactivation of foodborne viruses such as NoV or human enteroviruses during food processing. Thus, application of higher temperature during fermentation and ripening processes maybe more effective toward the inactivation kinetics of less stable viruses. Nevertheless, more studies are needed to examine the antiviral properties of these preserving agents on virus survival and inactivation kinetics in the complex food matrix.

The importance of Campylobacter coli in human campylobacteriosis: prevalence and genetic characterization.

The primary aim of this study was to detect and genotype Campylobacter coli strains from humans over a period of one year from November 2002 to October 2003. Campylobacter spp. were isolated from patients with symptoms of enteric infection. Amplified fragment length polymorphism (AFLP) analysis was used to identify the genetic diversity of C. coli strains by cluster analysis. A total of 18.6% of all Campylobacter isolates were identified as C. coli. These data show, that C. coli is indeed of importance to human campylobacter infections. Heterogeneous patterns were detectable among the human C. coli pool by AFLP analysis suggesting different sources of infection. A continuous seasonal shift of genotypes was detectable.

[Significance for food hygiene of salmonellae--ecology and risks]. / Zur lebensmittelhygienischen Bedeutung der Salmonellen--Okologie und Risiken.

Foodstuffs are the main source of Salmonellae. Infection risks for the consumer are caused by the occurrence of the bacteria in animals and by consumption of raw food of animal origin. Specially risks arise, when bacteremia in animals caused by stress in the time before slaughtering is not diagnosed. Slaughtered poultry contains more frequently Salmonellae than hens eggs, but the eggs represent the higher infectious risk. Other risks for salmonellosis in man are caused by imperfect decontamination during production of foods and by incorrect handling of foods.

[The secondary microbial colonization of organ samples for bacterial meat examination]. / Untersuchungen über die Sekundärkeimbesiedlung von Organ-proben für die bakteriologische Fleischuntersuchung.

The capability of bacteria to penetrate liver, spleen, and kidney samples was investigated, using one strain each of Salmonella typhimurium. Serratia marcescens, and Micrococcus luteus. The intact organ capsule was found to be an effective barrier to bacterial invasion, even at room temperature and with high contamination doses. Injuries to or absence of the organ capsule led to massive secondary germ colonisation of samples within 5 hours, even under conditions of cool storage. Germ colonisation of the sample interior will inevitably start from cut surfaces and cannot be prevented, if samples have to be stored several hours or transported, since sterile sampling is not possible under slaughterhouse conditions. Hence, new approaches have to be found to bacteriological carcass inspection.

[Model studies on incubated hen's eggs for the detection of synthetic gestagens within the framework of residue determination]. / Modelluntersuchungen an bebrüteten Hühnereiern zum Nachweis synthetischer Gestagene im Rahmen von Rückstandsbestimmungen.

Reported in this paper are model experiments with the incubated hen's egg, since an easily practicable and sufficiently accurate biological testing procedure has long been necessary for the detection of gestagen residues, in the context of food hygiene testing. The gestagens chloromadinone acetate and megestrol acetate were identified as pure substance in concentrations as low as 1 microgram/egg. These gestagens had caused in hatched chickens significant reduction in body weight as well as conspicuous loss of feathers or growth of stubble feathers. However, the same effects were not obtainable from normethisterone acetate or norgestrel.

[Effect of premortal stress on the endogenous microbial contamination of broiler carcasses]. / Untersuchungen zum Einfluss prämortaler Belastungen auf die endogene mikrobielle Kontamination bei Schlachthähnchen.

A study was undertaken to determine the interrelation between premortal stress and endogenic contamination. In 370 broilers the influence of transport, of a 48-h rest period and of an additional heat stress on the bacterial translocation was investigated. Even the normal transportation caused a contamination rate of nearly 50 per cent. 10 per cent of the transported animals suffered from a bacteriaemia induced by stress. The control group showed a significantly lower contamination rate. The rest time reduced the frequency of contamination. Heat stress did not have an influence on the contamination rate. The conclusion is that stress is aggravating the microbial risk for the consumer of poultry meat. Further research is necessary for characterizing the process of endogenic contamination.

The study of Salmonella enteritidis growth kinetics using Rapid Automated Bacterial Impedance Technique.

In order to study strain-specific differences in their growth behaviour at different, and particularly lower, temperatures, generation times for 45 strains of Salmonella enteritidis isolated from food were determined impedimetrically over a temperature range from 7 to 42 degrees C. In practical terms, 7 degrees C is the minimum requirement for Salm. enteritidis growth, and generation time variability increases markedly as this temperature is reached. Reports in the literature describing psychrotrophic behaviour and multiplication at lower temperatures cannot be confirmed. Generation time variability increased as temperature moved away from the optimal range with variation coefficients tending to rise as temperature fell. The great variability of multiplication parameters near the growth limit found in Salm. enteritidis may also be a characteristic of other bacterial species. It is therefore imperative to commence studies on larger numbers of strains to allow prediction of their behaviour at lower temperatures.

[Influence of spiced feed additives on taste of hen's eggs]. / Einfluss von würzenden Futterzusätzen auf den Geschmack von Hühnereiern.

The effect of the spices garlic (Allium sativum), extract from garlic, sage (Salvia officinalis), caraway (Carum carvi), peppermint (Mentha piperita), fennel (Foeniculum vulgare), thyme (Thymus vulgaris), paprika (Capsicum annuum), marjoram (Majorana hortensis), cardamom (Elettaria cardamomum) and sausage-mix fed to white hybrides on the quality of eggs (n = 705) was tested by 10 qualified persons. Changes in smell or taste were partly significant; a direct improvement is hard to induce. A well seasoned taste was obtained by feeding of garlic, fennel, peppermint and marjoram. They produce an aromatic flavor. A practical application is possible but limited by higher production prices. Further, it is uncertain if there is a need for "taste-manipulated" eggs.

[Not Available]. / Toxoplasmose: Eine lebensmittelübertragene Parasitose.

Toxoplasmosis is one of the more common parasitic zoonoses world-wide. The organism causing the disease, Toxoplasma gondii, may infect a broad spectrum of hosts and it has developed several potential routes for transmission within and between different host species. Food-borne toxoplasmosis in humans may result from exposure to different stages of the parasite, in particular from the ingestion of tissue cysts or tachyzoites which are contained in meat or primary offal (viscera) of many different animals, or from the ingestion of sporulated oocysts which are contained in the environment and may contaminate fruits and vegetables. Although the potential transmission of the parasite to humans via food has been known for several decades, the route which is the most important from an epidemiological point of view is still unknown. On one hand, the seroprevalence of human infections is higher in countries with high meat consumption compared to those with low meat consumption, but on the other hand up to 47% of strict vegetarians have been shown to possess antibodies against the parasite. It is likely that the transmission of the parasite to humans is not only influenced by the contamination of various food sources, but also by the consumers' behaviour, as preventive measures may significantly reduce the risk of contracting T. gondii infection.

[Endogenous contamination in slaughtered animals (literature review)]. / Endogene Kontamination bei Schlachttieren (Literaturübersicht).

The tissues and organs of animals slaughtered under normal conditions may be affected by primary or secondary bacterial contamination. Endogenic contamination creates hazards for the consumer in cases where the animals for slaughter are subject to latent infection with pathogens which penetrate other organs and tissues as a result of bacteraemia. The bacteraemic propagation of microorganisms may have various reasons, and premortal stress is apparently a major contributing factor under normal conditions of slaughter. This problem deserves greater attention if hygienic meat is to be produced. Questions where there is a need for research relate to the numbers of animals for slaughter with latent infections, the role of premortal stress in causing endogenic contamination/asymptomatic bacteraemia, and the role of isolated organ changes in animals for slaughter in causing microbes to settle on organs and muscular tissue.