The serology of experimental Salmonella dublin infections of cattle.

Agglutinating antibodies to somatic "O" and flagellar "H" antigens of S. dublin were measured in the serum of 43 pregnant heifers before intravenous or oral infection with S. dublin and in the serum of 21 uninfected control animals. The data from these animals were analysed statistically and a titre of 1/80, to both antigens, has been interpreted as of doubtful significance and a titre of 1/160 to both antigens, has been interpreted as significantly raised. Animals in which fetal infection occurred after challenge by either the intravenous or oral route developed significant increases in "H" and "O" titres indicating the value of measure "H" titres in the diagnosis of S. dublin abortion. In animals which were infected orally and in which infection appeared to be confined to the alimentary tract the "H" titre did not become significantly raised. Lack of correlation between antibody titres and faecal excretion of S. dublin and persistence of infection in carcasses confirms that the serum agglutination test is of no value in detecting latent carriers.     

Salmonellosis in wild mammals.

One thousand two hundred and sixty-nine freeliving, wild mammals, representative of 16 species from estates in Berkshire, Oxfordshire and Surrey, were examined for the presence of salmonellas. Salmonella typhimurium was isolated from 1 and S. dublin from 7 house mice (Mus musculus). There were no isolations from the other species examined. It was concluded that the house-mice infected with S. dublin acquired the organism from experimentally infected cattle. The wild mammal population does not at present appear to constitute a reservior for infection of domestic animals.     

Salmonellosis in two dairy herds associated with a sewage farm and water reclamation plant.

Two dairy herds, situated on a sewage farm, were monitored for the presence of salmonellas following outbreaks of Salmonella dublin infection. In addition an S. dublin control scheme, which involved examination of adult animals and calf vaccination, was instigated. During the period 1975-84, 12 salmonella serotypes and 10 phage types of S. typhimurium were isolated from the cattle and their environment although their presence was seldom associated with disease. Two adult S. dublin excreters were detected but it was concluded that none of the tests employed to examine the adult animals was sensitive enough. The prevalence of disease in the calves was low and although vaccination may have been beneficial it did not eradicate S. dublin infection. Thus S. dublin persisted in adults and calves during the 8-year period but its presence was seldom associated with disease. The results are discussed with regards the disease risk to animals from the agricultural use of sewage sludge and the public health aspects.     

The in vitro drug resistance of Salmonella dublin isolated from cattle.

The resistance of Salmonella dublin to eight antibacterial drugs was assessed under diagnostic laboratory conditions. Two techniques were used consecutively and the differences in the results are described. Strains of S. dublin isolated from either calves, adult cattle or abortion material showed no differences in resistance for either of the techniques, though differences between the two techniques were found.     

The effect of storage in slurry on the virulence of Salmonella dublin.

The mouse was used as a model to determine whether storage of Salmonella dublin in slurry and in broth reduces the virulence of the organism. No reduction in virulence of S. dublin stored in slurry for 36 days or in maintenance broth for 70 days was observed. The disease hazard involved in pasture-spreading of slurry contaminated with salmonellas is related to factors other than virulence.     

Salmonella dublin infection of calves: use of small doses to simulate natural infection on the farm.

Small numbers of Salmonella dublin were used to infect calves in an attempt to simulate natural infection on the farm. Twenty calves were exposed to S. dublin by one or more of the following methods: Sucking cows which were excreting S. dublin in their faeces (less than 10(2)-10(5) organisms/g). Housing on S. dublin contaminated bedding. Drinking S. dublin contaminated water (10(2)-10(4) organisms/ml). During this experiment some calves were given therapeutic does of oxytetracycline. After exposure the calves were examined for faecal excretion of S. dublin (in some instances mouth swabs and blood samples were also examined) and for clinical signs of illness. Most of the calves became infected with S. dublin but excretion was usually sporadic and the numbers of salmonellas excreted were small. No clinical signs of salmonellosis were observed by S. dublin was isolated from one calf at post-mortem. Another six calves, dosed orally with either 10(6) or 10(8) S. dublin, showed signs of mild illness and although three calves had diarrhoea excretion of salmonellas was intermittent. S. dublin was isolated from one of these calves at post-mortem.     

Salmonellosis in two dairy herds associated with a sewage farm and water reclamation plant

Two dairy herds, situated on a sewage farm, were monitored for the presence of salmonellas following outbreaks of Salmonella dublin infection. In addition an S. dublin control scheme, which involved examination of adult animals and calf vaccination, was instigated. During the period 1975-84, 12 salmonella serotypes and 10 phage types of S. typhimurium were isolated from the cattle and their environment although their presence was seldom associated with disease. Two adult S. dublin excreters were detected but it was concluded that none of the tests employed to examine the adult animals was sensitive enough. The prevalence of disease in the calves was low and although vaccination may have been beneficial it did not eradicate S. dublin infection. Thus S. dublin persisted in adults and calves during the 8-year period but its presence was seldom associated with disease. The results are discussed with regards the disease risk to animals from the agricultural use of sewage sludge and the public health aspects.     

Assessment of the excess risk of Salmonella dublin infection associated with the use of certified raw milk

The risk of serious illness attributable to infection with Salmonella dublin associated with the consumption of certified raw milk in California was evaluated. Data were derived from case reports of S. dublin isolations from persons in the State of California during the period 1980-83 and from production figures for raw milk from the major supplier. It is estimated that more than one-third of reported S. dublin infections in California in the first 4 years of this decade were attributable to raw milk consumption. Among raw milk consumers, it is estimated that more than 95 percent of reported S. dublin infections were acquired from raw milk; this proportion corresponds to a rate of reported S. dublin infections acquired from raw milk in the range of 8 to 35 cases per 100,000 users per year. It appears that immunocompromised persons are at exceptionally high risk of becoming seriously ill or dying from S. dublin exposure, and therefore raw milk is a particular health hazard for such persons.     

Outbreaks of bovine salmonellosis caused by serotypes other than S. dublin and S. typhimurium.

Outbreaks of salmonellosis caused by serotypes other than S. dublin and S. typhimurium were investigated on 41 farms in north-west England. Of these, 37 (90 per cent) were in dairy cows. There was strong circumstantial evidence that contaminated dairy cake was the source of infection in at least four herds and probably many more. Twenty-six serotypes were encountered with S. newport, the commonest, causing the most severe disease. Most cattle seemed to rid themselves of infection during the following months whether or not they were at pasture, housed in cubicles or in byres. Some cows excreted salmonellas for up to 11 months after the disease outbreak. Associated human salmonellosis was confirmed on 3/41 (7 per cent) of the farms.     

A men with a Salmonella dublin-infected aneurysm of the abdominal aorta

A 71-year-old male was diagnosed with a Salmonella dublin infection. He presented with abdominal pain with no diarrhoea, and sepsis, and was found to have an infected aneurysm of the infrarenal abdominal aorta. He was treated surgically with resection of the aneurysm and implantation of an extra-anatomic axillobifemoral bypass, followed by long-term antibiotic treatment. Nine months after the primary treatment, the patient died as a result of rupture of the aortic stump. S. dublin-infected aneurysm of the abdominal aorta is a rare condition with high mortality. Human S. dublin infections are associated with the consumption of unpasteurised dairy products from infected animals.     

Salmonella dublin abortion in cattle: II. Observations on the whey agglutination test and the milk ring test

The serum and whey agglutination test were compared on paired samples from thirty-five cases of bovine abortion associated with Salmonella dublin infection. The whey test proved nearly as useful as the serum test for confirming an active infection though it was only practicable to examine the whey for flagellar antibodies. S. dublin was isolated from nearly half of the milk samples obtained within the first week of abortion but none of those collected after the fourth week. The whey test proved of no value in retrospective identification of abortion cases. The trial using the milk ring test was disappointing.     

The role of home-made ice cream as a vehicle of Salmonella enteritidis phage type 4 infection from fresh shell eggs.

A family outbreak of Salmonella enteritidis PT4 infection is described in which home-made ice cream was identified as the vehicle of infection. The ice cream contained approximately 10(5) S. enteritidis PT4 organisms per gm and was probably contaminated by an infected shell egg containing between 10(5)-10(8) organisms. The continued relevance of the Chief Medical Officer''s warning on the use of raw shell eggs is highlighted. Home-made ice cream using the same recipe as ice cream that had been incriminated as the cause of the family outbreak of S. enteritidis PT4 infection was used to study the growth of the organism that might have occurred in the 3-4 h it took to prepare the product. When the inoculum was in the stationary phase, as it would be from shell or other cross contamination, there was a lag phase of 3 h before growth occurred at room temperature. Even when actively multiplying organisms were introduced, as may be found in an infected egg, there was less than 3 log(10) increase in the salmonella count in 4 h at room temperature. It was, therefore, given the high S. enteritidis count, unlikely that the ice cream was cross-contaminated. By contrast, raspberry sorbet at pH 3.73 proved to be lethal to a large inoculum of S. enteritidis and may be a relatively safe raw egg containing product.     

Salmonella dublin infection in adult cattle: a slaughter house and knackery survey in South West Wales.

A survey was carried out between June 1970 and December 1971 in which gall bladders from cattle either slaughtered for food consumption or disposed of through knackeries were cultured for salmonellas. Salmonella dublin was isolated from 28 of 1917 gall-bladders of adult cattle killed in the slaughterhouse at Carmarthen, and from 23 of 197 gall-bladders obtained from adult cattle sent to a knackery at Abergwili, near Carmarthen. The results are compared with a similar survey carried out in 1947 and 1948. Between June and November 1971 gall-bladders and uteri were also obtained from a slaughterhouse in Newcastle Emlyn, North Carmarthenshire, and a knackery in Tanygroes, South Cardiganshire. S. dublin was cultured from two gall-bladders but from none of the uteri of the 161 slaughterhouse cases. Seven of the 46 cows from the knackery yielded S. dublin on culture: 2 in the gall-bladder only, 3 in the uterus only and 2 in both gall bladder and uterus.     

Genotype analysis of faecal and blood isolates of Salmonella dublin from humans in England and Wales.

An analysis of genotype was made for representative strains of Salmonella dublin. The collection consisted primarily of strains isolated from humans in England and Wales, and were of both intestinal and extra-intestinal origin. Three genetic elements were characterized by DNA hybridization. They were the spvBC genes, extrachromosomal virulence determinants, the salmonella-specific insertion sequence IS200, and the 16S ribosomal RNA genes, a phylogenetic marker. Two clones of S. dublin (SdRI and SdRII) which shared an identical IS200 profile, were identified on the basis of restriction fragment length polymorphism at the 16S rRNA locus. With one exception, all strains harboured a 52 MDa plasmid which contained a conserved 3.7 kbp Hind III fragment homologous to the spvBC mouse-virulence genes of S. typhimurium. However, a single plasmid-free strain of SdRI, isolated from a patient with septicaemia exhibited no spc homology. In SdRI there was no observable genotype distinction between strains causing gastroenteritis or bacteraemia. In contrast, none of the strains of SdRII were from cases of bacteraemia, and all human isolates of this clone were from cases of gastroenteritis.     

Synthetic recombinant vaccine expressing influenza haemagglutinin epitope in Salmonella flagellin leads to partial protection in mice.

The influenza virus haemagglutinin epitope 91-108, which is a conserved amino acid sequence in all type A H3 strains, was expressed in Salmonella flagellin, to evaluate its potential as a vaccine. For that purpose, a synthetic oligonucleotide comprising 54 bases coding for the corresponding sequence was inserted into the plasmid pLS408 and transformed into Escherichia coli JM101. Colonies containing the recombinant plasmid were used to transform Salmonella typhimurium LB5000 and were then transduced to a flagellin negative 'live vaccine' aroA mutant of Salmonella dublin. Rabbits immunized either with the live recombinant S. dublin or with the flagellin isolated from it, showed significant levels of IgG response against the synthetic peptide 91-108 as well as against the intact A/Texas/77 influenza virus. Mice immunized with the same preparations developed influenza-specific IgG antibodies in the blood and secreted IgA antibodies in their lungs. Furthermore, these mice showed about 50% protection against challenge infection with the virus. The most successful results were achieved by intranasal immunization with the isolated recombinant flagellin, when employed without the aid of adjuvant.     

An outbreak of Salmonella dublin infection in England and Wales associated with a soft unpasteurized cows' milk cheese.

An outbreak of Salmonella dublin infection occurred in England and Wales in October to December 1989. Forty-two people were affected, mainly adults, and most lived in south-east England. Microbiological and epidemiological investigations implicated an imported Irish soft unpasteurized cows' milk cheese as the vehicle of infection. A case-control study showed a statistically significant association between infection and consumption of the suspect cheese (p = 0.001). Salmonella dublin was subsequently isolated from cheeses obtained from the manufacturer's premises. Initial control measures included the withdrawal of the cheese from retail sale and a Food Hazard Warning to Environmental Health Departments, as well as a press release, from the Department of Health. Subsequently, a decision was taken by the manufacturer to pasteurize milk used in the production of cheese for the UK market and importation of the cheese resumed in June 1990.     

Salmonella dublin abortion in cattle: I. Observations on the serum agglutination test

The somatic and flagellar serum agglutinin titre were determined in paired samples obtained from seventy-seven cases of bovine abortion associated with Salmonella dublin infection. The cases could be divided into four serological groups with an active infection being demonstrated in most cases. The serum agglutination test was shown to be a relatively specific diagnostic test but was of more limited value in the retrospective identification of convalescent cases.     

孕妇外周血sIL-2R水平与绒毛CMV感染的相关性

目的: 探讨巨细胞病毒 (CMV) 活动性感染孕妇的外周血可溶性白细胞介素-2受体 (sIL-2R) 水平与孕早期绒毛感染及生长发育状况的相关性。方法: 从自愿人工流产或过期流产行清宫手术的孕早期妇女中, 筛查CMVIgM和晚期mRNA均阳性者, 再检测其绒毛组织CMVDNA。然后, 随机选择绒毛CMVDNA阳性和阴性各 50例为观察对象, 检测其孕妇外周血sIL-2R水平。结果: 绒毛组织CMVDNA阳性和阴性的孕妇外周血sIL-2R平均水平分别为 286 66±16 84u/ml和 122 67±23 37u/ml(t=2 65, P=0 01 ), 19例过期流产和 81例自愿人工流产孕妇的外周血sIL-2R平均水平分别为 234 41±11 48u/ml和 158 41±14 48u/ml(t=2 73, P=0 01)。结论 : CMV活动性感染早孕妇女的外周血sIL-2R水平可能与绒毛感染发病机制相关。     

Clostridium difficile infection in patients with haematological malignant disease. Risk factors, faecal toxins and pathogenic strains

Two hundred and forty-eight patients from shared oncology and general medical wards were prospectively studied over a 6-month period for carriage of Clostridium difficile during an outbreak of clinical disease with an epidemic strain of the organism. Risk factors for infection were assessed. Acute leukaemia and/or its treatment were identified as significantly increasing the risk of infection. The relationship between the type of C. difficile isolated (as defined by a typing system based on the incorporation of [35S]methionine into bacterial proteins followed by gel electrophoresis), the presence of faecal toxins A and B and clinical symptoms were analysed. Carriage of the epidemic strain, type X, had a significant association with symptoms amongst oncology patients, with two thirds of these patients having detectable faecal toxin A and one third detectable faecal toxin B. During an outbreak of C. difficile-associated disease, typing the organism and assaying for both faecal toxins in symptomatic patients may be of benefit in determining which patients require specific, urgent treatment.