Endothelial hyperpolarizing factor increases acetylcholine-induced vasodilatation in pulmonary hypertensive broilers arterial rings

Salmonellosis is an important disease of cattle caused predominantly by Salmonella enterica serotypes Typhimurium (S. typhimurium) and Dublin (S. dublin). S. typhimurium causes acute enteritis and exudative diarrhea in calves. In addition to enteric disease, S. dublin can cause systemic infections, and may cause abortion in pregnant cows. Calves are considered a relevant model for non-typhoidal salmonellosis in humans. Experimental oral infections or inoculation of ligated ileal loops in calves have been extensively studied recently. This article reviews relevant published results regarding bovine salmonellosis as a natural disease or as an animal model.     

Prevalence and epizootiology of equine salmonellosis.

Feces from 1,451 horses entering a veterinary hospital over a 13-month period were cultured for salmonella. A total of 46 horses (3.2%) yielded 1 or more salmonella-positive fecal cultures. Twenty horses were found to be excreting salmonella in the feces on admission, and 5 of these later had severe diarrhea associated with enteric salmonellosis. Abdominal surgery and other severe stresses were associated with all cases of severe enteric salmonellosis. Serotypes of salmonella isolated included Salmonella agona (15), S anatum (14), S typhimurium (7), S typhimurium var copenhagen (4), S infantis (2), S montevideo (1), S meleagridis (1), S drypool (1), and an unnamed Salmonella serotype (1). Seven deaths were attributed to 4 serotypes (S typhimurium, 3; S anatum, 2; S typhimurium var copenhagen, 1; and S montevideo, 1). A marked seasonal incidence is isolations was found with isolations highest in later summer to early fall and lowest in the spring. It was also found that horses can shed salmonella intermittently, and a minimal of 5 consecutive negative fecal cultures is recommended before considering a horse not to be infected with salmonella.     

OBSERVATIONS ON SALMONELLA INFECTIONS OF BIRDS

During the period 1961 to 1976, 29 species of Salmonella other than Salmonella pullorum were isolated from 180 accessions of birds examined at the Animal Research Institute, Yeerongpilly. These birds were submitted to the laboratory from flocks with disease or production problems. S. typhimurium was the most frequently isolated serotype being obtained from 63% of accessions. Outbreaks of systemic salmonellosis occurred most frequently in young birds and although pathological changes were most commonly observed in visceral organs they were also seen in eyes, joints and the brain. Diseases other than salmonellosis were identified in many accessions of birds with systemic or enteric salmonella infections.     

Some aspects of the epidemiology of equine salmonellosis

A survey of 2 horse populations was done to detect the number of asymptomatic faecal excretors of Salmonella sp. 1201 faecal samples from 250 horses hospitalised at the University of Sydney were cultured. Three serotypes, S. typhimurium (4 horses), S. anatum (2) and S. tennessee (1) were isolated from 7 horses (2.8%). None was detected in 75 mares similarly examined at a thoroughbred stud farm. In retrospect, S. typhimurium was also the most common (70%) of the 19 serotypes recovered from 171 horses with clinical salmonellosis seen at Camden, 1969 to 1986. Forty cases occurring since 1983 were reviewed in detail; the mortality rate was high (60%) and an increased proportion was due to S. bovis-morbificans. Five horses developed salmonellosis while hospitalised and it was usually impossible to be certain whether these cases developed from the carrier state into overt disease or resulted from infections acquired in hospital.     

Porcine salmonellosis. 3. Production of fibrinous colitis by intravenous injections of a mixture of viable cells of salmonella cholerae-suis and disintegrated cells of the same agent, or hemolytic Escherichia coli

Hemorrhagic necrosis of the gastric and colonic mucosa with capillary thrombosis were induced in pigs experimentally infected with Salmonella cholerae-suis when an additional intravenous supply of disintegrated cells of Salmonella cholerae suis or hemolytic Escherichia coli was administered. Except for the gastrointestinal lesions, the necropsy findings were almost identical with the picture found in acute septicemic salmonellosis. The gastrointestinal changes were interpreted as a special gastroenteric effect of endotoxins of Gramnegative bacteria during the development of septicemic salmonellosis.     

Salmonellosis in hospitalized horses: seasonality and case fatality rates

Salmonellosis was studied during an 11-year period (July 1971 through June 1982) in 245 hospitalized horses. Ten years' data (207 cases) were analyzed in a time series study. Peak seasonality of the disease was from June through September. The cycle curve revealed 3 major outbreaks, with no apparent periodicity. Eighteen Salmonella serotypes caused clinical salmonellosis in horses, but 84% of the cases and 90% of the deaths were caused by 5 serotypes: Salmonella typhimurium, S typhimurium var copenhagen, S anatum, S kottbus, and S saint-paul. Overall, the case fatality rate was 44.9%. Excluding mixed infections, horses infected with S typhimurium and S typhimurium var copenhagen, had a significantly higher (P less than 0.001) case fatality rate (60.4%) than those infected with other Salmonella serotypes (32.3%).     

Salmonellosis in calves

Despite the efforts of both physicians and veterinarians, the number of cases of salmonellosis per year has held steady or risen. The ability of the organism to live in many different animal species and under inhospitable environmental conditions is likely responsible for Salmonella's prevalence today. Diverse clinical signs occur in salmonellosis; they range from unthriftiness to explosive, necrotizing diarrheas with high mortality. Secondary complications of pneumonia, bone and joint infections, and meningoencephalitis can result from calfhood infections. Treatment of enteric salmonellosis is chiefly aimed at maintaining fluid, acid-base, and electrolyte balance. Bacteremic or septicemic calves also require systemic antibiotics. The control measures for salmonellosis are based on sanitation and management. Individual calf hutches or pens provide adequate isolation if sufficient spacing and good sanitation are maintained. The Salmonella vaccines presently available provide limited protection; however, live vaccines made from auxotrophic strains of Salmonella appear to be more efficacious.     

Investigation and control of an outbreak of salmonellosis caused by multidrug-resistant Salmonella typhimurium in a population of hospitalized horses

An outbreak of salmonellosis in a population of hospitalized horses resulted in the closure of a teaching hospital for a period of 10 weeks. Fecal samples were collected from suspected cases and cultured for Salmonella. Salmonella isolates were characterized using antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE) and phage typing. Thirty-three cases of infection by a multidrug-resistant strain of S. typhimurium were detected. The index case was admitted on 26 August 1999. Fifteen (45%) cases occurred between April and June 2000. PFGE results suggested that this strain of S. typhimurium might have been introduced into the hospital environment by a foal presenting with diarrhea. The hospital was closed on June 13, and intensive environmental cleaning and disinfection were completed. Enforcement of infectious disease control protocols in hospitals and environmental and patient surveillance is needed to prevent outbreaks of salmonellosis.     

Proteomic analysis of intestinal mucosa responses to Salmonella enterica serovar typhimurium in naturally infected pig

Salmonella enterica serovar typhimurium (S. typhimurium) is one of the most frequent Salmonella serotypes isolated from European pigs. Despite the advances in understanding the mechanisms involved in host–pathogen interactions and host cell responses to S. typhimurium, the global change that occurs in naturally exposed populations has been poorly characterized. Here, we present a proteomics study on intestinal mucosa of pigs naturally infected with S. typhimurium, in order to better understand the pathogenesis of salmonellosis and the pathways which might be affected after infection. Samples were analyzed by 2D-DIGE and 44 different proteins exhibited statistically significant differences. The data set was analyzed by employing the Ingenuity Pathway Analysis and the physiological function most significantly perturbed were immunological and infectious disease, cellular assembly and organization and metabolism. The pathways implicated in the porcine immune response to S. typhimurium were gluconeogenesis and Rho GDI/RhoA signaling, and our results suggest that keratins and the intermediate filaments could play an important role in the damage of the mucosa and in the success of infection. The role of these findings in salmonellosis has been discussed, as well as the importance of analyzing naturally infected animals to have a complete picture of the infection. Also, we compared the results found in this work with those obtained in a similar study using experimentally infected animals.     

Comparative plasmid profile analysis of Salmonella typhimurium var. Copenhagen strains from a Salmonella outbreak in hospitalized horses]

From April 1990 through June 1991 clinical salmonellosis and asymptomatic faecal excretion of Salmonella spp. were seen in hospitalized horses at two veterinary hospitals. 76 Salmonella strains from hospitalized horses and 18 strains from horses without any clinical contact were characterized by serotyping and plasmid profile analysis. From April 1990 through January 1991 97.8% of the hospitalized horses were infected with strains of S. typhimurium var. Copenhagen, which were closely related according to their similar plasmid patterns. Other strains of S. typhimurium var. Copenhagen and serotype S. enteritidis were isolated not before February 1991. In the same period various plasmid profile types of S. typhimurium var. Copenhagen and strains of S. typhimurium, S. enteritidis and S. lexington were isolated from horses of the control group. Our results suggest that the high incidence of salmonellosis and latent salmonella infection in hospitalized horses was mainly due to the spread of one particular strain of S. typhimurium var. Copenhagen and that this strain was obviously acquired during hospitalisation.     

Virulence of Salmonella enteritidis phagetypes 4, 8 and 13 and other Salmonella spp. for day-old chicks, hens and mice.

Virulence of three Canadian poultry strains of Salmonella enteritidis, namely phagetypes (PT) 4, 8 and 13, and one Salmonella heidelberg strain was assessed in orally and intraperitoneally inoculated one-day old chickens and compared to the virulence of a human S. enteritidis PT 4 strain from the United Kingdom (UK). The two PT 4 strains were also compared in orally inoculated adult laying hens. In addition, orally inoculated Balb/c mice were used to evaluate virulence of the above strains and two strains of Salmonella typhimurium containing different plasmids. In orally inoculated one-day old chickens, the UK S. enteritidis PT 4 strain was more virulent than the Canadian PT 4 strain. The UK PT 4 strain was also more virulent and invasive in adult laying hens than the Canadian PT 4 strain. The S. enteritidis PT 8 strain and one S. typhimurium strain isolated from a chicken hatchery were the most virulent for orally inoculated Balb/c mice. This strain of S. typhimurium contained the 60 megadalton plasmid associated with virulence for Balb/c mice which was not present in the S. typhimurium strain isolated from a pig with septicemic disease.     

仔猪沙门菌病的诊断与防治

仔猪副伤寒是由猪霍乱沙门菌、鼠伤寒沙门菌和肠炎沙门菌引起危害仔猪健康的传染病,主要临床症状表现为腹泻,急性出现败血症.论文对发病猪场疑似病料的分离菌株进行鉴定,结果分离菌株符合沙门菌检验标准,采用纸片法进行药敏试验,筛选敏感药物进行治疗,取得很好的效果,降低了养殖户的经济损失.     

Alteration of neutrophil function in BCG-treated and non-treated swine after exposure to Salmonella typhimurium.

Salmonella typhimurium infection in swine causes an enterocolitis followed by a persistent carrier state, but little is known about the mechanisms that allow this organism to colonize and persist in host tissues. Neutrophils provide a first line of defense against invading pathogens such as Salmonella typhimurium. The purpose of this study was to evaluate porcine neutrophil function after in vivo exposure to Salmonella and to determine if the immunomodulator, bacillus Calmette Guerin (BCG), exerts any effect on neutrophil function or on the colonization and persistence of S. typhimurium in the pig. Compared to negative controls, neutrophils from pigs exposed to S. typhimurium exhibited significantly decreased iodination, cytochrome-C reduction, antibody-dependent cell-mediated cytotoxicity, random migration, and chemotaxis (P less than or equal to 0.05). Neutrophil bactericidal activity against S. typhimurium was significantly enhanced. Most of the significant differences were noted in the first two days after exposure to Salmonella. Often the functional alterations were biphasic, peaking again 7-10 days after exposure. BCG alone significantly depressed random migration and cytochrome-C reduction in unstimulated neutrophils. The clinical course, colonization pattern, and persistence of Salmonella were similar between pigs receiving BCG and untreated pigs. These data suggest that S. typhimurium infection causes a depression in oxidative metabolism and motility, yet an increase in overall bactericidal activity against S. typhimurium in circulating porcine neutrophils. It also appears that BCG treatment, as reported here, does not enhance resistance of pigs to S. typhimurium colonization or reduce the number of persistent organisms in the porcine ileum.     

Seroprevalence of antibodies to Salmonella spp in semidomesticated reindeer in Norway,determined by enzyme-linked immunosorbent assay

An indirect ELISA was developed as a possible tool to detect the seroprevalence of antibodies to Salmonella spp in semidomesticated reindeer. To cover a broad spectrum of serogroups a lipopolysaccharide mix of S. typhimurium and S. choleraesuis was used as antigen in this pilot study. Sera from 31 culture-negative reindeer with no clinical or historical evidence of salmonellosis were used as negative serum control. After immunisation with an inactivated S. typhimurium vaccine, pooled sera from 6 reindeer were used as positive serum control as no serum from naturally infected animals was available. A seroprevalence of 0.6% in 2000 clinically healthy, slaughter-reindeer from Norway was determined by using this ELISA. No more information on Salmonella in reindeer in Norway is known to the authors. This is the first ELISA established for indirect detection of Salmonella in reindeer.     

Use of a Salmonella typhimurium-derived virulence probe in the detection of Salmonella sp. and in the characterization of S. cholerae-suis virulence plasmids

A genetic probe encoding a virulence gene from Salmonella typhimurium was useful in the detection of Salmonella from feces during an outbreak of salmonellosis at a local dairy. A 3.2-kb BamHI restriction endonuclease fragment of the S. typhimurium virulence plasmid, pStSR100, has been useful as a DNA probe for both detection of Salmonella sp. and characterization of virulence plasmids from numerous field isolates. This virA probe hybridizes to a highly conserved gene carried on the large virulence plasmids of invasive Salmonella isolates. Colony blots prepared from feces directly plated onto MaConkey's agar failed to detect low numbers of Salmonella sp. However, hybridization of the VirA probe to vacuum blots or colony blots prepared from feces in tetrathionate enrichment broth incubated for 16 hours at 37 C was effective for detecting Salmonella sp. and resulted in an 85.9% correlation with culture results. The probe also demonstrated the highly conserved nature (96%) of the virulence gene among S. cholerae-suis isolate plasmids detected using Southern blot analysis.     

Evaluation of protection against experimental salmonellosis in sheep immunised with 1 or 2 doses of live aromatic-dependent Salmonella typhimurium

The minimum number of doses of a live aromatic dependent (aro-) Salmonella typhimurium vaccine strain (SL1479), given by the intramuscular, oral or subcutaneous route required to protect sheep from experimentally-induced clinical salmonellosis, was determined. A significant reduction in mortalities and diarrhoea occurred in those sheep immunised with one or 2 intramuscular doses or 2 subcutaneous doses. On the other hand, sheep immunised with one subcutaneous dose were not protected. Immunisation with one or 2 oral doses also resulted in a significant reduction in mortality, although reduction in the prevalence of severe diarrhoea was less consistent. Sheep immunised with a single intramuscular dose of aro- S. typhimurium developed high levels of serum antibodies and significant delayed-type cutaneous hypersensitivity response to homologous Salmonella lipopolysaccharide and flagellin, whereas those with a single oral dose did not. It was concluded that immunisation of sheep with a single oral or intramuscular dose of live aro- S. typhimurium reduced mortalities and the prevalence of diarrhoea in sheep due to infection with virulent S. typhimurium.     

Humoral responses and salmonellosis protection in chickens given a vitamin-dependent Salmonella typhimurium mutant

Humoral responses in chickens inoculated with an aromatic vitamin dependent (Aro-) Salmonella typhimurium mutant (STM) were studied to ascertain the efficacy of the organism as a vaccine for salmonellosis and possibly as a delivery system for antigens from enteric pathogens of chickens. Serum antibody responses in chickens that were given oral or subcutaneous inoculations of the bacterium followed the classic order of antibody production, with IgM being detected first, followed by IgG and IgA. Antibody responses in the gut of orally inoculated chickens were restricted to IgG and IgA. Weight gain measured in chickens given high doses of STM (up to 5 x 10(9)) orally, revealed that the bacterium did not adversely affect the chickens; in fact, inoculated chickens had significantly higher body weights than controls at the same age. Salmonellosis protection of chickens by oral vaccination with STM was examined in a vaccination/challenge experiment. The experiment revealed that oral vaccination reduced excretion of a virulent S. typhimurium used as the challenge organism.     

Expression of inflammatory cytokines (TNF-alpha, IL-1, IL-6 and IL-8) in colon of pigs naturally infected with Salmonella typhimurium and S. choleraesuis

The expression of mRNA encoding tumour necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), IL-6 and IL-8 was studied, by in situ hybridization with a non-radioactive digoxigenin-labelled probe, in formalin-fixed, paraffin wax-embedded colonic tissue from pigs naturally infected with Salmonella typhimurium and S. choleraesuis. By in situ hybridization, a distinct positive signal for TNF-alpha, IL-1, IL-6 and IL-8 was detected in colon from all 12 infected pigs. Hybridization signals for all four inflammatory cytokines were detected primarily inflammatory cells infiltrating the lamina propria and submucosa. In comparison, expression of all four inflammatory cytokines was minimal in non-lesional colon of infected pigs and in normal colon from control pigs. The results suggest that these cytokines play an important role in the pathophysiological processes in porcine salmonellosis.     

Characterization of Salmonella Dublin and Salmonella Typhimurium (Copenhagen) Isolates from Cattle

Brackelsberg, C.A., Nolan, L.K. and Brown, J., 1997. Characterization of Salmonella dublin and Salmonella typhimurium (Copenhagen) isolates from cattle. Veterinary Research Communications, 21 (6), 409-420Eight Salmonella typhimurium (Copenhagen) and eight Salmonella dublin isolates from cattle were compared by their antibiotic resistance patterns, by their production of colicin, aerobactin, haemolysin and capsule, by their possession of transmissible R plasmids and the spvC gene, and by their ability to invade and replicate within cultured epithelial cells. The two groups differed in their antibiotic resistance profiles, with more of the host-adapted S. dublin isolates resistant to tetracycline than were the non-host-adapted S. typhimurium (Copenhagen) group, but more of the S. typhimurium (Copenhagen) isolates resistant to the other antibiotics tested. None of the isolates produced colicin, but all produced aerobactin. One isolate in each group was encapsulated. All of the S. typhimurium (Copenhagen) and S. dublin isolates contained plasmids, and all of them contained the spvC-homologous sequences. Four of the S. typhimurium (Copenhagen) isolates were able to transfer an R plasmid to a recipient organism by conjugation. One of the five S. dublin isolates, which showed resistance to some of the antibiotics tested, was able to transfer an R plasmid by conjugation. Both groups of isolates invaded cultured epithelial cells to a similar degree after 1 h, but the S. dublin isolates reached significantly higher levels within the cells than did S. typhimurium (Copenhagen) after 9 h. This ability may, in part, explain the association of S. dublin with more severe forms of salmonellosis and prolonged carrier states. Further study of the intracellular growth of these isolates seems warranted.     

Salmonella typhimurium DT104: a virulent and drug-resistant pathogen.

Salmonella typhimurium phage type (PT) or definitive type (DT) 104 is a virulent pathogen for humans and animals, particularly cattle. It has been isolated increasingly from humans and animals in the United Kingdom and several other European countries and, more recently, in the United States and Canada. Humans may acquire the infection from foods of animal origin contaminated with the infective organism. Farm families are particularly at risk of acquiring the infection by contact with infected animals or by drinking unpasteurized milk. The symptoms in cattle are watery to bloody diarrhea, a drop in milk production, pyrexia, anorexia, dehydration and depression. Infection may result in septicemic salmonellosis and, upon necropsy, a fibrinonecrotic enterocolitis may be observed. The infection occurs more commonly in the calving season than at other times. Feedlot cattle and pigs may also be affected. Prolonged carriage and shedding of the pathogen may occur. Symptoms in humans consist of diarrhea, fever, headache, nausea, abdominal pain, vomiting, and, less frequently, blood in the stool. Salmonella typhimurium DT104 strains are commonly resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline.