Campylobacteria

The Campylobacteriaceae family includes aerobic or microaerophilic mobile vibrioid non-spore Gram - negative bacteria of three genera: Campylobacter, Helicobacter and Arcobacter. The composition of childbirth as the new data is received is constantly being specified.

Campylobacteriosis is an infectious disease characterized by acute onset, fever, gastrointestinal tract damage. Studies conducted in recent years have shown that in some countries campylobacteria cause between 3 and 15% of all cases of acute intestinal diseases.

In the infectious pathology of humans and animals, an important role is played by the species C. Jejuni, C. Coli and S. Lari, which cause OKZ of a similar clinical course. Based on their ability to grow at a relatively high incubation temperature (42 ° C), they are combined into one group of thermophilic campylobacteria. Among other mesophilic species of campylobacteria, preferring a moderate incubation temperature (37 ° C), a prominent role in human pathology is played by C. Fetus, which is often the causative agent of arthritis, meningitis, vasculitis; The species C. Concisus and C. Sputorum are regarded as commensals of the oral cavity, possibly playing a role in the pathogenesis of periodontitis, and the species C. Fennelliae, S. Cinaedi and S. Hyointestinalis occur in the large intestine with immunodeficiencies of various genesis.

[1], [2], [3], [4], [5], [6]

Morphology of Campylobacter

Campylobacteria are gram-negative, thin, spirally bent rods 0.2-0.3 x 0.5-5.0, sometimes up to 8.0 microns. They can form one full (or slightly larger) coil turn, can be C-or S-shaped or resemble the gull's wings when connecting two cells in a short chain. In old cultures, cells can have a coccoid or hyper-spiral form. The spores and capsules do not form, they have 1 or 2 (sometimes up to 5) polar flagella, providing them with high mobility with rapid spin-like or helical translational motion. Flagellum may be 2-3 times longer than the cell. Mobility is better seen with dark-field or phase-contrast microscopy. The content of G + C in DNA is 30-38 mol%.

Biochemical properties of campylobacteria

Campylobacteria are chemo-organotrophs. Being thermophiles, they are capable of growth at a temperature of 37-44 ° C, but not at 25 ° C. The majority of campylobacteria are microaerophiles and capnophiles, the optimum atmosphere for cultivation of pathogenic species has the composition: 02-5%, CO2 = 10%, N2 = 85%. Some campylobacteria can grow as obligate anaerobes during cultivation. Energy is released from amino acids and tricarboxylic acids, but not from carbohydrates, to oxidation and fermentation which are not capable of.

For the cultivation of campylobacteria, special nutrient media are most often used, based on mediums for the isolation of brucella. However, in these media it is necessary to add substances that increase the aerotolerance of campylobacteria and reduce the redox potential of the medium (blood, sodium thioglycolate, sodium metabisulfite, sodium pyruvate, Fe2 + sulfate). Usually used meat, liver, blood, often they add antibiotics (novobiocin, cyclohexamid, bacitracin, trimethoprim) to suppress the accompanying microflora. On nutrient media, the growth of campylobacter is usually observed after 2-4 days. On liquid nutrient media, diffuse haze is observed with a hardly dissipated pronounced precipitation. In semiliquid media, they grow in the form of a diffuse turbid ring 1-4 mm thick below the surface of the medium. If campylobacteria grow in conditions of severe anaerobiosis, turbidity of the whole environment is noted.

On dense media with blood, campylobacteria form two types of colonies:

• rounded irregular shape, with even edges, 2-8 mm in diameter, colorless or light gray, transparent, homogeneous (resemble drops of water); at long cultivation can get a silvery-matte shade;
• colonies of regular rounded shape, with even edges and a diameter of 1-2 mm, with a shiny convex surface, transparent, homogeneous; in the old colonies the center is more dense than the periphery, and a yellowish pigment may form. The consistency of the colonies is inviscid, the hemolysis zone is absent.

Campylobacteria are oxidase-positive, gelatin and urea are not hydrolyzed, reactions with methyl red and Foges-Proskauer are negative. They produce cytochrome oxidase, do not grow on Russell's medium; on the ability to form catalase are divided into two groups: catalase positive (C. Fetus, S. Jejuni and catalase-negative (C. Sputorum and C. Concisus) .Some species can form hydrogen sulphide, grow in the presence of 1 and 3.5% NaCl, brilliant green , nalidixic acid, cephalothin, hydrolyse sodium hyppurate, form a yellow pigment, based on interspecific differentiation.

[7], [8], [9], [10], [11], [12], [13], [14], [15]

Antigenic structure of campylobacteria

Campylobacteria have O-, H- and K-antigens. C. Jejuni and S. Coli, the most commonly causing diseases in humans, are serologically heterogeneous. In the foreign literature, 55 serogroups differing in thermostable O-antigen are described. It has been established that strains isolated from humans give an agglutination reaction only to serum from humans, and they are not agglutinated by serum from immunized animals. It can be assumed that the formation of strains specific for humans is underway.

[16], [17], [18], [19], [20], [21], [22], [23], [24]

Pathogenic factors of campylobacteria

Campylobacteria have a variety of virulence factors, including lipopolysaccharide, enterotoxin (causes diarrhea), cytotoxin, damaging the mucous membrane of the large intestine in humans, and others.

At room temperature, and especially at low temperatures, the resistance of campylobacter to environmental factors is very high: in food, tap water and sewage, milk, urine, feces they can remain viable for 1-5 weeks. Campylobacteria are very sensitive to heating above 50 ° C, direct sunlight and ultraviolet light and air, drying, low and high pH values of the environment, are sensitive to the action of disinfectants in working concentrations.

Immunity

Campylobacteria are highly immunogenic. Antibodies appear in the blood in the early stages of the disease and in high enough titles. Titer D ° 1: 5000 is already on the 5th day of the disease; having reached a maximum, antibody titers (IgG) slowly decrease for a long time and can still be quite high in a month.

Epidemiology of Campylobacteriosis

Campylobacteria (especially thermophilic) are found in all species of wild and domestic animals and birds, many of which are their natural reservoirs (large and small cattle, chickens, starlings, sparrows, parrots, etc.). The main reservoir of campylobacteria should be considered agricultural animals, additional - sick people and domestic animals, wild city birds and rodents. The main route of transmission is food (raw milk, broken birds, beef, pork), additional water (river and sea water contaminated with faeces) and domestic (gross violations of sanitary and hygienic standards for care of sick people and animals, and when cooking meat products). Campylobacteriosis is characterized by pronounced summer seasonality with an almost complete absence of morbidity in the winter months. More often the disease is registered in the form of sporadic cases ("traveler's diarrhea"), occasionally in the form of more or less large outbreaks. After the transferred disease in people not treated with antibiotics, bacteria with feces are allocated long enough, within 2-5 weeks, and sometimes up to 10 weeks.

[25], [26], [27], [28], [29], [30], [31]

Symptoms of Campylobacteriosis

In humans, campylobacteriosis occurs mainly in the form of enteritis and enterocolitis, although diseases and other localizations are described: septicemia, endocarditis, pericarditis, meningitis; lesions of extra-intestinal localization are more often observed in older people or in patients with reduced resistance of the organism.

The incubation period is 1-10 days, usually 1-5 days. The onset of the disease is more often acute, less often subacute. Usually there is moderate intoxication and diarrhea (up to 10-20 times a day), pain in the lower abdomen. In half of the cases there is a presence of blood in the excrements, less often - dehydration. The disease occurs more often and is more severe in children aged 1 to 3 years. Pathogenesis and severity are directly dependent on the factors available for this strain of Campylobacter, as well as on the number of bacteria that enter the body.

Laboratory diagnostics of campylobacteriosis

To diagnose campylobacteriosis use microscopic, bacteriological and serological methods. The microscopic method is used as a guide. A thin smear of stool, fixed on the fire, stained with a 1% aqueous solution of basic magenta for 10-20 seconds, then washed with water. Since most other bacteria require 2 to 5 minutes to stain, only Campylobacteria usually show up in the smear in 10-20 s. In the native material, they have a characteristic shape (S-shaped short chains in the form of gull wings, rarely C-shaped with drawn ends).

The main diagnostic method is bacteriological. Material for sowing - bowel movements or rectum, sometimes blood, and also water, milk, other food products, washings from objects, etc. The crops are placed on special nutrient media, create microaerophilic conditions and incubated at 37 and 42 ° C . After obtaining typical colonies, the culture is identified by a combination of characteristics.

The serological method of research plays a very important role in large-scale epidemiological studies, but in the diagnosis of campylobacteriosis its role is small. The agglutination reaction is posed with autostams, it is possible with a living museum culture, but with the formalized culture the results are more clear. The most sensitive methods are the RIF and the IFM. RAC, latexagglutination, immunoelectrophoresis, and RPHA can also be used.

Treatment of Campylobacteriosis

Antibiotics are used to treat campylobacteriosis; the most effective are gentamicin and erythromycin, kanamycin, levomycetin and semi-synthetic penicillins are less effective.

How can I prevent Campylobacter?

Specific prophylaxis is not developed; other preventive measures include strict adherence to the norms for processing, transportation and storage of food, personal hygiene rules, protection of water bodies from pollution by sewage (especially livestock farms).