[Detection and prevalence of verotoxin-producing Escherichia coli (VTEC) in raw sausage]. / Untersuchungen zum Nachweis und Vorkommen von Verotoxin-bildenden Escherichia coli (VTEC) in Rohwurst.

We investigated 158 samples of shortly ripened raw sausages bought in supermarkets of Dessau within 4 month. In 14 (8.8%) samples Verotoxin-producing E. coli were detected. 13 VT-positive samples were found in the group of easily spread raw sausages. The 14 isolates belonged to 6 different O-serotypes. 4 VT1-, 8 VT2- and 2 VT1/VT2-producers were found. 4 isolates belonged to serogroups which were already described in WHO tables and associated with EHEC infections in human beings. One strain of serogroup O22: H8, isolated from a "Teewurst", possessed the complete virulence gene combination of EHEC (eae, hlyA, stx). The detection procedure, already successfully used for detection and isolation of VTEC from raw milk, soft cheese and raw minced beef showed a sensitivity of approximately 10 CfU/25 g of raw sausages. It has to be considered that VTEC are frequently (8.8%) present in shortly ripened raw sausages. The group of easily spread raw sausages has a higher VTEC-contamination rate than firm raw sausages. Raw sausages, especially easy to spread types, belong to the risk foods for EHEC-infections in human beings.

[Detection and occurrence of verotoxin-forming and/or shigatoxin producing Escherichia coli (VTEC and/or STEC) in milk]. / Nachweis und Vorkommen von Verotoxin- bzw. Shigatoxin-bildenden Escherichia coli (VTEC bzw. STEC) in Milch.

Raw milk contaminated with VTEC was described as a source of human EHEC infection. Diagnosis of VTEC from milk is complicated by the low number of VT-positive cells in the total bacterial count, the great variety of serovars with different combinations of virulence markers and the lack of characteristic biochemical properties for the cultural detection of all VTEC. The graduated procedure presented and used for the examination of milk samples is based on VT detection in suitable enrichment cultures and the selective isolation of VTEC by means of VT-specific monoclonal antibodies using the VT-colony immunoblot. This method was used to examine 127 samples of raw milk and 146 samples of certified raw milk (Vorzugsmilch) from 5 different regions in Germany. 3.9% of the raw milk samples and 2.1% of the certified raw milk samples were VTEC-positive. Except for one O157:H- isolate from a raw milk sample, the VTEC found belonged to the group of non-O157 VTEC. They were assigned to 5 different serovars with different combinations of virulence markers. Therefore, raw milk and certified raw milk will continue to present a potential source of EHEC infection. It is recommended to use the procedure presented for the elucidation of the route of infection and for the improvement of detection of VTEC and EHEC-strains in milk in order to obtain comparable data for diagnosis in the official food control laboratories of the federal lands.

Detection of STEC and epidemiological investigations in surrounding of a HUS patient.

After occurrence of a case of HUS infection in a 2-year-old infant from a dairy farmer's family living near Oldenburg, investigations were performed in the infant's surrounding in order to elucidate the route of infection. Since hospitalization took place at a late stage, it was not possible to isolate EHEC from the patient's stool samples. However, E. coli O157 antibody determinations in serum were positive. Since STEC of serogroup O157 were found in faeces from the 34 dairy cows of the farm, stool samples were taken from 6 members of the child's family and examined. Non-O157 STEC could be isolated from the stools of 2 family members. Determination of other virulence factors and other characteristics such as serotype, biotype and phage type showed identity of the agent for 3 isolates (2 from animals, 1 from humans). By means of pulsed-field gel electrophoresis of the restricted DNA of the isolates and by means of RAPD-PCR it was not possible to establish any differences in the band patterns. It can be assumed, therefore, that the organisms had been transmitted from animals to humans.

[Present problems in detection of sources of infection and chains of infection with enterohemorrhagic E. coli (EHEC)]. / Uber die derzeitigen Probleme zum Auffinden von Infektionsquellen und Infektionsketten beim enterohämorrhagischen E. coli (EHEC).

In the context of the detection of the haemolyticuraemic syndrome (HUS) and of enterohaemorrhagic E. coli (EHEC) in 13 persons, 372 faeces samples from 13 herds of cattle in northern Bavaria were examined for the presence of EHEC. 128 (34.4%) of the faeces samples were found to be VT-positive. From 78 of these samples (61%), verotoxin-producing E. coli strains (VTEC) could be isolated. During these examinations, E. coli strains with combinations of markers (VT, eae A, EHEC haemolysin) being typical of EHEC were found in 3 samples from animals belonging to the same herd. In 2 cases, these could be assigned to O157:H-, in one, to O118:H16. It has not been possible to detect possible sources of infection and chains of infection assumed to exist in association with the detection of HUS and EHEC infections in humans because most cases had been diagnosed on the basis of verotoxin detection in stool specimens. Moreover, corresponding isolates for a comparative onward differentiation from verotoxin-producing E. coli isolates from animals were not or could not be made available.

[Verotoxin-producing E. coli (VTEC) in feces from cattle slaughtered in Germany]. / Verotoxin-bildende E. coli (VTEC) im Kot von Schlachtrindern aus Deutschland.

In man, EHEC infections may result in severe disease. Cattle and foods derived from this animal species are considered as a source of infection. The presence of VTEC being potential EHEC was studied. For analysis, feces samples were examined which had been taken from 204 heads of cattle slaughtered in various regions of Germany. VTEC could be isolated from 97 animals (47.6%). This indicates a presence of VTEC in slaughtered cattle being 5 times higher than known for Germany so far. The aeaA gene could be demonstrated in a mere 23 out of 667 VTEC isolates. The CVD 419 sequence was present in 55.3% of the VTEC isolates. Ehly was found in 61% of them. Consequently, both markers were unsuitable for the detection of VTEC in faeces samples from cattle and in foods with faecal contamination. The VTEC isolates belonged to 54 different serotypes of E. coli, VTEC 0157 have not been found so far. Some of the VTEC serovars found in this study have already been described as associated with human disease following EHEC infection. The presently available laboratory methods do not permit to exclude a risk for humans from bovine VTEC reliably. For this reason, bovine VTEC should be further on considered as potential EHEC and an infection of humans by such agents be avoided.

[Utilization of nylon membranes for specific isolation and characterization of verotoxin-producing Escherichia coli using DNA probes]. / Einsatz von Nylon Membranen zur gezielten Isolierung und Charakterisierung Verotoxin-bildender Escherichia coli mittels DNA-Sonden.

A method for specific isolation of VT(+)-strains in raw milk is given. DNA-hybridization technique with DIG-labeled PCR-amplificates as probes are the basis. No background is seen by using "DIG Easy Hyb" solution and nylon membranes for colony- and plaque-hybridization (Boehringer Mannheim GmbH). Marked colonies are visible on the membranes after detection. So it is possible to select these colonies from a masterplate. The results are available within one day (without enrichment and membrane preparation). After stripping the membranes can be used for a new hybridisation to detect another factor of virulence.

[A method for specific isolation of verotoxin-producing Escherichia coli colonies]. / Eine Methode zur gezielten Isolierung Verotoxin-bildender Escherichia coli-Kolonien.

The described colony immunoblot is a special double membrane-agar technology, which permits the specific isolation of VTEC in biological materials decided VT-positive by EIA or PCR. The produced Verotoxin (VT) is detected on the surface of the lower membrane by help of monoclonal antibodies. A direct allocation of the corresponding VT-expressing E. coli-colonies on the upper membrane is possible. So the isolation and further characterisation of potential VTEC is practicable in materials with a high microbial contamination too. This isolation method is available for the examination of VT-positive faeces and foods. In the case of foods it is necessary to work with an enrichment culture.

Prevalence of the fimbrial antigens F18 and K88 and of enterotoxins and verotoxins among Escherichia coli isolated from weaned pigs.

Until recently, the fimbrial F18 antigen has been provisionally designated F107, 2134P, or 8813. Using the slide agglutination test, this antigen was shown to be present on 139 of 160 Escherichia coli strains of type O139:K82 and on all of the 146 K88-negative strains of the other pathogenic porcine serotypes. These strains were isolated from weaned pigs which in most cases had died from postweaning colibacillosis. All strains were haemolytic. With only three exceptions, they produced verotoxin and/or enterotoxin. The F18ab variant strongly predominated on the O139:K82 strains and was found on about half of the O138:K81 strains and a few O157 strains, whereas the other strains carried the F18ac variant. In serotypes which can carry either F18 or K88 fimbriae, closer clonal relationships between the strains associated with F18 and those associated with K88 were missing.

[Detection of verotoxin-producing E. coli in field isolates from domestic and agricultural animals in Sachsen-Anhalt]. / Nachweis verotoxinbildender E. coli in Feldisolaten von Haus- und landwirtschaftlichen Nutztieren in Sachsen-Anhalt.

A report is given on the detection of verotoxin-producing E. coli (VTEC) strains from field isolates of healthy or ill cattle (n = 141), pigs (n = 306), sheep (n = 15), cats (n = 29) and dogs (n = 25) in the region of the new federal land Sachsen-Anhalt. 5% of the strains isolated from cattle, 32% from pigs, 20% from sheep, 4% from dogs and 0% from cats have shown VTEC. The E. coli-strains were checked for the presence of other factors of virulence, too. A good correlation (82%) was found between the colonization factor F107 and SLT 2/2v-containing strains from pigs in the region of Sachsen-Anhalt, too. Enterohemolysin was not found in SLT 2/2v-positive strains. 91% of the VTEC, isolated from pigs, produced alpha-Hemolysin. The correlation of SLT-containing strains and the production of enterohemolysin was confirmed for ruminants, only. Plasmidprofilings of VTEC from pigs showed mainly a 60 MDa or a 68 MDa plasmid or both, too. The occurrence of heat labile (LT) and in some cases of heat stable (ST) toxin was also checked, to differentiate the VTEC-strains from the enterotoxigenic E. coli strains (ETEC). These investigations showed, that VTEC produce SLT almost without exception. Correlations and conclusions on the pathogenicity for humans are discussed.

[Escherichia coli R live vaccine Suicolplex "Dessau"]. / Escherichia-coli-R-Lebendimpfstoff Suicolplex "Dessau".

Immunisation of pregnant sows prior to parturition has long proved to be a good method to forestall coli dysentery in piglets before weaning. Inactivated vaccines of the pathogenetically important E. coli serogroups with and without adjuvant so far were primarily used at international level. A vaccine of that kind has become available in the GDR more than eight years ago. Its name is Coliporc "Dessau". A live vaccine has been developed from two R-mutants at the authors' institute. The effectiveness of that live vaccine on laboratory animals and in field experiments is reported in this paper together with possibilities of differential diagnosis to distinguish wild strains from the mutants. The live vaccine was commercially registered under the name of Suicolpex "Dessau", in spring 1976.