Презентация на тему Salmonellosis

the diseases, caused by multiply serotypes of bacteria from

the genus Salmonella.

There are well over 2000 different antigenic types of salmonella.

It is characterized by a considerable damage of the

gastrointestinal tract, and more rarely by typhus-like or septicopyemic course.

of salmonella.

They were originally classified as separate species, but

it is now generally accepted that they represent serotypes of a single species, Salmonella enterica.

Various subspecies are recognized, but most of the serotypes that infect mammals are found in a subspecies also designated enterica.

enterica subspecies enterica serotype Enteritidis, but this is usually

abbreviated to S. serotype Enteritidis, or simply S. Enteritidis.

anaerobic Gram-negative bacilli able grow on a wide range

of relatively simple media and distinguished from other members of the family by their biochemical characteristics and antigenic structure.

of antigens, which are readily demonstrable by serotyping.
Long-chain

lipopolysaccharide (LPS) comprises heat-stable polysaccharide commonly knows as the somatic or O-antigens. The long-chain LPS molecules exhibit considerable variation in sugar composition and degree of polysaccharide branching, and it is structural heterogeneity that is responsible for the large number of serotypes of S. enterica.

laboratory media, and flagellar protein subunits contain the epitopes

that form the basis of the flagella-based serotyping scheme generally known as the H-antigens.
The original Kauffmann-White scheme, which elegantly catalogued salmonellae (but named them as individual species), placed them into some 30 groups on the basis of shared O-antigenes, and further subdivided the groups into clusters with H-antigens.

within strains of S. enterica serotypes Typhimrium, Enteritidis and

Typhi.
Characterization of strains of S. enterica has also been facilitated by determining their resistance to a range of antibiotics, including ampicillin, chloramphenicol, gentamicin, streptomycin, sulphonamides, tetracycline.

are animals suffering from primary or secondary Salmonellosis, water

swimming birds and also sick-human or carriers. The mechanism of transmission of the infection is fecal-oral. The factors of transmission of the infection are food-stuffs of animal origin and other products which are contaminated by excretions of animals and human.

as outbreaks. The susceptibility of human depends on the

premorbid state of the macroorganism and on the quantity and variety (serotypes) of Salmonella.
Salmonella have been isolated from almost all animal species, including chickens and ducks, cows, pigs and other.
Poultry (chickens, ducks) and poultry products (primarily eggs) are the most important sources of human infection and are estimated to be responsible for about one-half of the epidemic spread.

are introduced into the hospital on admission, for example,

by a patient with acute enterocolitis or asymptomatic carrier with an other medical problem or by the introduction of a contaminated agent. Hospital personnel then may carry infection on hands or clothing from patient to patient; in some cases (dust, examination room, furniture), may be implicated in transmission.

of agents of adhesion of providing fix to the

cell
К-antigens provide of penetration salmonellas in a cell and reproduction in her
R-plasmids provide of resistance to the antibiotics
Different enzymes facilitating penetration in a cell (hyaluronidase, neuraminidase and other)
Ability of salmonellas to cause bacteriemia, septicemia
Ability to compete with normal microflora of intestine and cause dysbacteriosis
Ability to reprodaction in different organs and tissues, cause the polyorganic affects
Ability to make L-forms and resistance to the antibiotics
Presence of endotoxin, and at some exotoxin

of S. enterica require a range of pathogenic mechanisms

to enable them to colonize a host and cause disease.
For infections of man, the number of bacteria that must be swallowed in order to cause infection is uncertain and varies with the serotype. The development of the disease after ingestion of Salmonella depends from the number and virulence of the organisms and from the multiple host factors.

stomach. In the stomach Salmonella are exposed of the

action of gastric acid and low PH, which reduce the number of viable organisms.
Salmonella who survive the antibacterial mechanisms in the stomach and upper small bowel may multiply in the small intestine. The reproduction of Salmonella in the intestinal tract associated with clinical manifestations of either enterocolitis (acute gastroenteritis), or bacteremia.

the infection and suppuration at the almost any site.
Age

is an important factor of the disease caused by Salmonella. Salmonella enteritidis occurs with highest incidence in children less than 5 years old. Newborns and infants less one year of age are especially susceptible. The influence of age on incidence may reflect immaturity of humoral and cellular immune mechanisms, diminished antibacterial activity of the normal intestinal flora, a high frequently of fecal-oral contamination, or other factors. The patients with impaired cellular and humoral immune mechanisms are at the increased risk for development of Salmonellosis.

and endotoxins. Exotoxins are the toxic products of bacteria

who are actively secreted into environment. Endotoxins are toxic substances who are liberated only in lysis of microbial cells. The principal factor responsible for development of this disease is endotoxic complex of Salmonella.
In the majority of the cases it leads to development of the gastrointestinal forms of Salmonellosis.

course of Salmonellosis there are a lot of classifications

of this disease. The following classification is more comfortable for practice use:

Localized (gastrointestinal) forms of Salmonellosis:
Gastritic variant;
Gastroenteritic variant;
Gastroenterocolitic variant.

carriers;
Transitory carriers.

completely enough. The gastrointestinal forms of Salmonellosis are observed

in the majority cases of the disease. They occur from 80 till 85% of the cases.
The incubation period is from 4-6 hours till some days. The onset of the disease is acute. The prodromal period is not typical or is very short. It is characterized weakness, disability and slight chill it. Then the temperature increases.

illness begins in the many patients with nausea and

vomiting; these symptoms are usually resolved within a few hours. Myalgia and headache are common. The manifestation is diarrhea, which may vary from a few loose stools to fulminant diarrhea. In the majority of the losses with stool are in moderate volume, and without blood. In the exceptional cases stool is watery and of great volume (“cholera-like”).

accompanied by chills. Abdominal cramps occur in about two

– thirds of the patient. They are often localized in the periumbilical region or lower abdominal quadrants. On microscopic examination, stool show a moderate number of polymorphonuclear leukocytes and, occasionally, red blood cells. Peripheral leukocyte count is usually normal, although neutrophilia with a shift toward younger forms may be present.

2 days in the majority of cases. Diarrhea usually

persists less than 7 days, although, rarely, gastrointestinal symptoms may last for several weeks.
Clinical course of Salmonellosis is characterized by symptoms of the damage of cardiovascular system. The basis of these disturbances is water-electrolyte losses and change of rheological properties of blood.
There is toxicosis in localized forms of Salmonellosis. It is manifested by headache, pain in the muscles, mild ataxia in walking, unequal reflexes.

continue to excrete the organism in their stools for

days or weeks after complete clinical recovery, but eventual clearance of the bacteria from the body is usual. A few patients continue to excrete the salmonellae for prolonged periods. The term chronic carrier is reserved for those who excrete salmonellae for 6 months or more. But over 50 % of patients stop excreting the organisms within 5 weeks of infection, and 90 % of adults are culture-negative at 9 weeks.

basis of epidemiological, clinical and laboratory data.
Bacteriological and

serological methods are used for confirmation of salmonellosis. The main materials for bacteriological investigation are vomiting masses, water after stomach lavage, stool, blood.

the disease) reaction of agglutination (RA) and indirect hemagglutination

(RIHA) are used. It gives positive results on the 5th day of the disease.
Diagnostical titer is 1:200. Serological investigation should be done in dynamics of the disease.

from clinical from and severity of the disease course.
Most

authorities agree that antibiotics have no part to play in the management in most cases, but when a patient is clearly at increased risk of bacteriaemia and generalized invasion, an antibiotic may protect against this serious complication. Such patients include infants under 3 months of age, patients with malignancies, haemoglobinopathies, chronic gastro-intestinal disease such as ulcerative colitis, and patients who are immuno-suppressed for other reasons.

treatment depends from antibacterial therapy. The treatment of septic

variant of Salmonellosis (septicopyemia) is no different from treatment of the patients with sepsis of other etiology. Immunoglobulin, plasma, immunocorrecting therapy are prescribed.
There are two leading syndromes in clinical course of the gastrointestinal form of Salmonellosis: intoxication and dehydration.

of water and electrolytes the principal method of treatment

is its replacement with the help of intravenous or peroral introduction of salt solutions. Special salt solutions are used. The amount of introduced solutions depends on the degree of dehydration. Colloid solutions are prescribed besides polyionic solutions in predominance of symptoms of toxicosis in clinical course of the disease.