Haemophilus influenzae
Haemophilus influenzae - the acute infectious diseases caused by a Pfeiffer's bacillus, it is characterised by a primary lesion of a respiratory organs, the central excitatory system and development of suppurative focuses in various organs. Children are ill more often.
Aetiology. The originator - Haemophilus influenzae (Pfeiffer's bacillus) concerns a sort haemophilus (which 16 kinds of bacteria include) and has the greatest value in a pathology of the human. It represents a fine coccobacillus (0,3-1 microns in diameter), for the growth demands presence containing in erythrocytes of thermolabile factor Y and the thermostable factor X. On cultural properties (indole production, activity of an urease, etc.) is parted on 7 biotypes (from 1 to VII). The part of the Pfeiffer's bacilli secured from mucosas has capsules. It is known antigenically differing 6 capsular types designated from A to F. The greatest value in a pathology of the human has Haemophilus influenzae type b. The Pfeiffer's bacillus is sensitive to ampicillin, Levomycetinum, antibiotics of tetracycline bunch, however for last years increase of resistance of the originator to ampicillin and other antibiotics becomes perceptible.
Epidemiology. A source and the infection contamination reservoir is only the human. The originator is localised on a mucosa of the top parts of respiratory tracts. It is possible to secure it from a nasopharynx at 90 % of healthy humans, and on more virulent type b it is necessary about 5 % of all discharged strains. The healthy carriage can proceed from several days about several months. The carriage remains even at high titer of specific antibodies and even at appointment of high doses of antibiotics. Children at the age of 6-48 months most often are ill, is rarer - newborns, children more advanced age and adults. Indicators of a case rate a hemophilic infection contamination of a type b in thousand times above at children of acquisitive age and at persons with some kinds of a pathology (a sickemia, an agammaglobulinemia, persons with the remote lien, sick of a lymphogranulomatosis, receiving chemotherapy). The big danger to these persons is represented by contact with sick of a hemophilic infection contamination. The case rate raises in the end of winter and in the spring. For last years the case rate of adults was considerably enlarged. The infection contamination is transferred air-drop by.
Pathogenesis. Infection atriums is the nasopharynx mucosa. The originator can long time persistate in the field of infection atriums in the form of a latent (asymptomatic) infection contamination. In some cases, basically at persons with the relaxed protective forces, the latent form passes in the demonstrative. The infection contamination extends on surrounding tissues, causing development of sinusitises, otites, a bronchitis, a pneumonia, an inflammation of a hypodermic fat, or by a hematogenous dissimination amazes joints and other organs, proceeding as a sepsis. The strains of a hemophilic rod which do not have capsules, amaze only mucosas. General diseases cause only the originators possessing a capsule, in 95 % it is a hemophilic rod of a type b. More expressed pathogenicity of these strains is bound by that the capsule is capable to depress a phagocytosis. The action synergy between a hemophilic rod and some respiratory viruses is taped. At tolerated disease enough durable immunity educes.
Symptoms and flow. Duration of an incubation interval to establish difficultly as disease quite often is a consequence of latent infection transition in the demonstrative. Aboriginal inflammatory process of a mucosa of respiratory tracts can educe or hematogenically caused diseases educe. The hemophilic rod of a type b is one of the frequent causes of a generalised infection contamination (bacteriemia) at children, at half from them the purulent meningitis educes, is frequent enough (15-20 %) a pneumonia and is rarer other focal lesions. As a rule, the hemophilic infection contamination proceeds acutely, but some clinical forms can accept fixing flow. The hemophilic infection contamination can proceed in following clinical forms:
- a purulent meningitis
- an acute pneumonia
- a hematosepsis
- an inflammation of a hypodermic fat
- an epiglottiditis
- a purulent arthritis
- other diseases (a pericarditis, sinusitises, an otitis, diseases of respiratory tracts, etc.)
The purulent meningitis is observed mainly at children from 9 months till 4 years (for the given age-grade it is the most frequent cause of a meningitis). Disease begins acutely, sometimes from symptoms the ARD, then quickly educes clinical semiology, characteristic for a bacteriemic meningitis. Sometimes the meningeal syndrome is combined with other implications of a hemophilic infection contamination (a purulent arthritis, an epiglottis inflammation, cellulites). Disease proceeds hardly and quite often comes to an end is lethal (about 10 %). The hemophilic pneumonia can show both in the form of focal, and in the form of share (croupous), is very frequent (to 70 %) is accompanied by a purulent pleuritis (at children), can become complicated a purulent pericarditis, a middle ear inflammation. Can accept fixing flow. At adults, especially at elderly persons, the hemophilic infection contamination can accumulate on other diseases of lungs.
The hemophilic sepsis educes at children of 6-12 months predisposed to this disease is more often. Proceeds roughly, it is frequent as lightning, with a septic shock and fast destruction of the patient. The secondary locuses at this form it is not observed. The inflammation hypodermic fats (cellulitis) also educes at children till 12 months, is more often localised on the person. The ARD (nasopharyngitis) begins quite often with a picture, then there is a tumescence in the field of a cheek or round an orbit, the skin over a tumescence is hyperemic with a cyanochroic shade, sometimes disease is accompanied by a middle ear inflammation. A body temperature subfebrile, symptoms of the general intoxication are expressed weakly. At more senior children the inflammation of a hypodermic fat can be localised on extremities.
The inflammation of an epiglottis (epiglottiditis) is very serious form of a hemophilic infection contamination, in most cases (about 90 %) is accompanied by a bacteriemia. Begins acutely, it is characterised by fast lifting of the body temperature expressed by the general intoxication and a picture of quickly progressing croup which can lead to death of the child from an asphyxia (full impassability of respiratory tracts or an apnoea).
Purulent arthritises are a consequence of hematogenous drift of a hemophilic rod, are quite often accompanied by an osteomyelitis. Other implications of a hemophilic infection contamination meet was rarely.
The diagnosis and the differential diagnosis. At recognition it is necessary to consider age of the patient, presence of the factors promoting a becoming infected by a hemophilic rod, characteristic clinical implications (cellulites, an epiglottiditis, etc.). As diagnosis acknowledgement abjection of a hemophilic rod (pus, a sputum, cerebrospinal fluid, a stuff taken from mucosas) serves. In cerebrospinal fluid (and sometimes and in urine) it is possible to find a capsular antigen of a hemophilic rod by means of counter immunoelectrophoresis or immunoenzyme method reaction.
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