Klebsiella

The genus Klebsiella belongs to the family Enterobacteriaceae. Unlike the vast majority of genera of this family, the bacteria of the genus Klebsiella have the ability to form a capsule. Several species belong to the genus Klebsiella.

The main role in the pathology of man from them is played by the species Klebsiella pneumoniae, which is divided into three subspecies: Klebsiella pneumoniae subsp. Pneumoniae, Klebsiella pneumoniae subsp. And Klebsiella pneumoniae subsp. Rhinoscleromatis. However, in recent years, new types of Klebsiella have been identified (Klebsiella oxytoca, Klebsiella mobilis, Klebsiella planticola, Klebsiella terrigena), which have so far been little studied and their role in human pathology being specified. The name of the genus is given in honor of the German bacteriologist E. Klebs. Klebsiella constantly detect on the skin and mucous membranes of humans and animals. C. Pneumoniae is a frequent cause of nosocomial infections, including mixed infections.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14]

Morphology of Klebsiella

Klebsiella - Gram-negative ellipsoidal bacteria, have the form of thick short rods with rounded ends, 0.3-0.6 x 1.5-6.0 μm in size, the capsule form has dimensions of 3-5 x 5-8 μm. Dimensions are subject to severe fluctuations, especially in Klebsiella pneumonia. Flagellum absent, bacteria do not form spores, some cilia have cilia. Usually a thick polysaccharide capsule is visible; noncapsular forms can be obtained by exposure to bacteria of low temperature, serum, bile, phages, antibiotics and mutations. Are located in pairs or singly.

Biochemical properties of Klebsiella

Klebsiella grow well on simple nutrient media, facultative anaerobes, chemo-organotrophs. The optimum growth temperature is 35-37 ° C, pH 7.2- 7.4, but can grow at 12-41 ° C. They are able to grow on Simmons medium, ie use sodium citrate as the sole carbon source (except K. Rhinoscleromatis). Dense mucous colonies form on dense nutrient media; in young 2-4-hour colonies, bacterial ozens are scattered in concentric rows, rhinoscleromes are concentric, pneumonia is looped, which is easily determined by microscopy of the colony with a small increase and can be used for their differentiation . With growth in the MPB, the Klebsiella cause uniform turbidity, sometimes with a mucous membrane on the surface; on semi-fluid media growth is more abundant in the upper part of the medium. The content in the DNA of G + C is 52-56 mol%.

Klebsiella ferment carbohydrates to form acid or acid and gas, restore nitrates to nitrites. Gelatin is not liquefied, indole and hydrogen sulphide do not form. Have urease activity, do not always curdle milk. The least biochemical activity is expressed in the pathogen of the rhinoscleroma.

[15], [16], [17], [18], [19], [20]

Antigenic structure of Klebsiella

Klebsiella has O and K antigens. According to the O-antigen, the Klebsiella are subdivided into 11 serotypes, and by the capsular K-antigen, into 82. The serological typing of Klebsiella is based on the determination of K antigens. Group-specific antigen is found in almost all Klebsiella strains. Some K-antigens are related to K-antigens of streptococci, Escherichia and Salmonella. O-antigens related to E. Coli O-antigens were detected.

The main factors of pathogenicity of Klebsiella are K-antigen, suppressing phagocytosis, and endotoxin. In addition, K. Pneumoniae can produce a thermolabile enterotoxin - a protein, by the mechanism of action similar to the toxin of enterotoxigenic E. Coli. Klebsiella have pronounced adhesive properties.

[21], [22], [23], [24]

Epidemiology of Klebsiella

Klebsiellosis is the most common nosocomial infection. The source is a sick person and a carrier. Perhaps both exogenous and endogenous infection. The most frequent transmission routes are food, air-drop and contact-household. Transmission factors are most often food products (especially meat and dairy products), water, air. In recent years, the frequency of Klebsiella infections has increased, one of the reasons for this is an increase in the pathogenicity of the pathogen in connection with a decrease in the resistance of the human body. This is also facilitated by the widespread use of antibiotics that change the normal ratio of microorganisms in the natural biocenosis, immunosuppressants, etc. It should be noted that the klebsiella is highly resistant to various antibiotics.

Klebsiella are susceptible to the action of various disinfectants, at 65 ° C die within 1 hour. They are quite stable in the external environment: the mucous capsule protects the pathogen from drying, so Klebsiella can persist in soil, dust of wards, equipment, furniture at room temperature for weeks and even for months.

[25], [26], [27], [28], [29], [30], [31], [32], [33]

Symptoms of Klebsiella

Klebsiella pneumoniae most often cause a disease that proceeds according to the type of intestinal infection and is characterized by acute onset, nausea, vomiting, abdominal pain, diarrhea, fever and general weakness. The duration of the disease is 1-5 days. Klebsiella can cause damage to the respiratory system, joints, meninges, conjunctiva, urogenital organs, as well as sepsis and suppurative postoperative complications. The greatest severity is the generalized septic-pyemic course of the disease, often leading to a lethal outcome.

Klebsiella ozaenae affects the mucous membrane of the nose and its adnexal sinuses, causes their atrophy, inflammation is accompanied by the release of a viscous fetid secretion. C. Rhinoscleromatis affects not only the mucous membrane of the nose, but also the trachea, bronchi, pharynx, larynx, with specific granulomas developing in the affected tissue, followed by sclerosing and development of cartilaginous infiltrates. The course of the disease is chronic, death can occur against the background of obturation of the trachea or larynx.

Postinfectious immunity is fragile, mostly cellular in nature. In case of chronic disease, signs of GCHD sometimes develop.

Laboratory Diagnosis of Klebsiella

The main method of diagnosis is bacteriological. The material for sowing can be different: pus, blood, liquor, bowel movements, washings from objects, etc. It is sown to the differential diagnostic environment of K-2 (with urea, raffinose, bromotymol blue), large glossy mucous colonies with coloring grow in a day from yellow or green-yellow to blue. Further, in bacteria, the mobility is determined by inoculation into Peshkov's medium and the presence of ornithine decarboxylase. These signs are not peculiar to klebsiella. The final identification is to study the biochemical properties and determine the serogroup by the agglutination reaction of the living culture with K-sera. The isolated pure culture is tested for sensitivity to antibiotics.

Sometimes, an agglutination test or a RCC with a standard O-klebsiella antigen or with an auto-stamping can be used to diagnose klebsiella. Diagnostic value has a fourfold increase in antibody titers.

Treatment of Klebsiella

Treatment for Klebsiellosis according to clinical indications is carried out in a hospital. When lesions of the intestine antibiotics are not shown. At the phenomena of dehydration (the presence of enterotoxin in the causative agent), saline solutions are administered orally or parenterally. In generalized and slow chronic forms antibiotics are used (in accordance with the results of a test for sensitivity to them), autovaccines; carry out activities that stimulate immunity (autohemotherapy, pyrogen therapy, etc.).

How to prevent klebsiella infection?

Specific prophylaxis of Klebsiella is not developed. General prophylaxis is reduced to strict adherence to sanitary and hygienic norms for the storage of food products, strict adherence to asepsis and antiseptic in medical institutions, as well as compliance with personal hygiene rules.