Hemophils, Influe Wand
Last reviewed: 23.04.2024
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Stick Influenza - Haemophilus influenzae - often present on the mucous membrane of the upper respiratory tract of a healthy person. When the resistance of the body is weakened, it can cause meningitis (especially in weakened children), bronchitis, pneumonia, purulent pleurisy, tracheitis, laryngitis, conjunctivitis, otitis and other diseases.
The causative agent of hemophilia infection was discovered by MI Afanasiev (1891) and described by R. Pfeiffer and S. Kitaçato in 1892 during the pandemic influenza, the cause of which the Influenza rod was mistaken for more than 40 years.
The genus Haemophilus is a member of the Pasteurellaceae family and consists of 16 species. Two kinds of pathogen are pathogens: Y. Influenzae - the causative agent of the inflammatory processes of the respiratory tract, and I ducreyi - the causative agent of soft chancre; this disease has not been found in Russia since 1961.
Hemophils are short sticks of coccoid form 0.3-0.4 x 1.0-1.5 microns in size. Sometimes located in short chains, more often - singly. They are very polymorphic, they can form threads, which depends on the conditions of cultivation; immovable, do not have a dispute. A rod of influenza in the body and in the first generations on nutrient media can have a capsule. Bacteria are slowly stained with aniline dyes: Pfeiffer's fuchsin stains for 5-15 minutes.
Bacteria of the genus Haemophilus belong to the hemophilic group. They require for the cultivation of rich nutrient media, usually containing blood or its products. For their growth requires the presence of hemin or some other porphyrins (X-factor) and (or) nicotinamide adenine dinucleotide (V-factor) in the medium. It was found that of the 16 known representatives of the genus Haemophilus, two species (I influenzae and J. Haemolyticus) require simultaneous X-factor and V-factor, 4 species require only X-factor and 10 species-only V-factor. X-factor is thermostable, and its sources are the blood of various animals or an aqueous solution of hematin chloride. V-factor is thermolabile and contained in the tissues of plants, animals, produced by many bacteria.
Influenza rod is an optional anaerobic, the optimum temperature for its growth is 37 ° C. The content of G + C in DNA is 39-42 mol%. On the "chocolate" agar (agar with warm blood) colony sticks, the influenza grows in 36-48 hours and reaches a diameter of 1 mm. On the blood agar with the addition of the cardiovascular extract in a day, small, rounded, convex colonies with iridescent overflows grow. Hemolysis is absent. In colonies without capsular variants iridescent coloring is absent. On liquid media with the addition of blood, diffuse growth is observed, whitish flakes and sediment on the bottom are sometimes formed.
A specific feature of the influenza rod is the ability of their colonies to grow much faster and be larger near the colonies of staphylococci or other bacteria ("satellite", or satellite, growth). Pneumococci are the inhibitors of the growth of the rod of influenza.
Saccharolytic properties are weak and unstable. Usually ferments with the formation of acid ribose, galactose and glucose, has urease activity, has alkaline phosphatase, restores nitrates to nitrites. By the ability to form urease, indole and ornithine decarboxylase, H. Influenzae is divided into six biotypes (I-VI).
Capsular influenza strains of influenza by the specificity of the polysaccharide antigen are divided into 6 serovariants: a, b, c, d, e, f. This antigen sometimes gives a cross-reaction with capsular pneumococcal antigens. The capsular polysaccharide antigen is detected by the swelling reaction of the capsule, RIF, the precipitation reaction in agar. From the sick people the serovar b is more often isolated. In addition to the capsular antigen, the causative agent of influenza has a somatic antigen, in which thermally stable and thermolabile proteins are found.
Exogenous influenza rod does not produce influenza, its pathogenicity is related to the thermostable endotoxin released during the destruction of bacterial cells. Invasiveness and suppression of phagocytosis are associated with the presence of a capsule.
In the external environment, the pathogen is unstable, quickly dies under the action of direct sunlight and ultraviolet rays and disinfectants at normal working concentrations. At a temperature of 60 ° C, it dies within 5-10 minutes.
[Immunity
Children of the first three months of life are less susceptible to the causative agent of influenza, since they have antibodies in the serum transmitted through the placenta from the mother. Subsequently, they disappear, and the child becomes susceptible to the pathogen. Infection can occur asymptomatically or with a respiratory tract infection. Meningitis most often develop in children aged 6 months. Up to 3 years. By 3-5 years in many children complement-binding and bactericidal antibodies to capsular polysaccharide antigen (polyribose phosphate) appear.
Epidemiology of Haemophilus Infections
The source of infection in diseases caused by a stick of influenza is sick people; Capsular strains in this case are transmitted from person to person by airborne droplets. Often the disease develops as a manifestation of autoinfection with a decrease in the reactivity of the organism against the background of some other disease, such as influenza. Influenza rod in healthy people is found not only on the mucous membrane of the upper respiratory tract, but also in the mouth, middle ear, sometimes on the mucous membrane of the vagina.
Symptoms of Hemophilus Infection
Associated primarily with the characteristics of the pathogen (there is a capsule or not), as well as with the underlying disease, against which the resistance of the macroorganism decreases. A rod of influenza can multiply on the mucous membranes both out-and intracellularly, sometimes penetrating the blood. In this case, the causative agent can further penetrate the blood-brain barrier and cause meningitis. Influenza rod, along with meningococci and pneumococci, is one of the most frequent pathogens of meningitis. The lethality with such an untreated meningitis can reach 90%. The clinic is determined by symptoms dominant in each specific case, depending on the degree of involvement of one or another organ.
Laboratory diagnosis of hemophilia infection
To diagnose diseases caused by a rod of influenza, use the RIF, bacteriological method and serological reactions. With sufficient concentration of the pathogen in the material under investigation (pus, mucus, liquor), it can be detected easily and quickly by the swelling reaction of the capsule and RIF; The cerebrospinal fluid can also be studied by the method of oncoming immunoelectrophoresis. A pure culture is isolated by sowing the material on special nutrient media ("chocolate" agar, Levantal's medium, cardiac brain agar); typical colonies are identified by the swelling reaction of the capsule, the need for growth factors and other tests (biochemical properties, precipitation reactions in agar, etc.). Agglutination and precipitation reactions can be used for serological diagnosis.
Specific prevention and treatment of hemophilia infection
For prophylaxis, a vaccination against hemophilic infection from the capsular polysaccharide (polyribose phosphate) is used. Currently, diseases caused by Haemophilus influenzae type b are considered as candidates for eradication. For treatment, aminoglycosides, levomycetin, sulfonamides are most effective, however, in selected pathogens, the sensitivity to antibiotics should be determined.