Haemophilus influenzae infection in children

Haemophilus influenzae infection manifests itself as purulent meningitis, otitis media, various respiratory diseases (pneumonia, bronchitis, epiglottitis), conjunctivitis, endocarditis, osteomyelitis, etc.

ICD-10 code

A49.2 Infection due to Haemophilus influenzae, unspecified.

Epidemiology

Although H. influenzae is an opportunistic pathogen, it can cause epidemic outbreaks in young children. In these cases, the diseases are caused by so-called epidemic clones of the pathogen with increased pathogenic and invasive properties. Outbreaks of infection have been described in maternity hospitals, departments for patients with chronic diseases, and among those treated with glucocorticoid and cytostatic drugs.

The source of infection is patients with obvious or latent forms of the disease, as well as healthy carriers. The pathogen is transmitted most often by airborne droplets. Transmission factors can also be infected linen, toys, and household items. Children become infected through contact with parents, medical personnel, and from each other.

The contagious index depends on age. In children of the first year of life it can reach 3-5%, at the age of up to 5 years - no more than 1-2%. Premature children with signs of primary or secondary immunodeficiency are most susceptible.

Classification of Haemophilus influenzae infection

Depending on the localization of the process, pneumonia, meningitis, otitis media, osteomyelitis, acute epiglottitis, cellulitis are possible. In newborns, frequent clinical forms are septicemia, conjunctivitis, mastoiditis, purulent arthritis, etc.

Causes of Haemophilus influenzae infection

H. influenzae are gram-negative pleomorphic rod-shaped or coccoid cells measuring (0.2-0.3) x (0.5-2) µm. They are located in smears singly or in pairs, and sometimes in the form of short chains and groups. On dense media they form small (up to 1 mm in diameter) round colorless colonies. Microorganisms are immobile, do not form spores, but it is possible to form capsular forms, which are associated with pathogenic properties. The pathogen produces endotoxin, the carrier of which is considered to be capsular polysaccharides. According to the antigen structure, 6 serotypes are distinguished (a, b, c, d, e, f). Type b is of leading importance in the development of various pathological conditions. The microorganism is pathogenic only for humans,

Causes and pathogenesis of hemophilic infection

Symptoms of Haemophilus influenzae infection

Pneumonia associated with H. influenzae accounts for about 5% of all patients with pneumonia; even more often, this pathogen is isolated from pleural exudate in patients with pleurisy. As a rule, children in the first 2 years of life are ill.

The disease begins acutely with a rise in body temperature to 39-40 °C, catarrhal symptoms and severe toxicosis. The symptoms are no different from other bacterial pneumonias. Percussion and auscultation reveal a focus of inflammation in the projection of one or more segments of the lungs. The process is most often localized in the root zones, but the lower and upper lobes of one or both lungs can be affected. Abscessing is possible. Radiographic changes are also not specific. In accordance with the clinical picture, foci of homogeneous darkening or dense focal-confluent shadows are detected in the case of exudative pleurisy.

Symptoms of Haemophilus influenzae infection

Diagnosis of Haemophilus influenzae infection

Laboratory test results are of decisive importance for diagnosing hemophilic infection. Material from the patient (sputum, pus, aspirate from the site of the lesion, cerebrospinal fluid, etc.) is examined under a microscope (Gram staining) and inoculated onto blood agar. The isolated pure culture is differentiated from the whooping cough bacillus, with which H. influenzae has a great deal of similarity. Modern methods include PCR, latex agglutination reaction, and ELISA.

Differential diagnostics

Purulent meningitis caused by H. influenzae is differentiated from meningococcal, streptococcal, pneumococcal, staphylococcal and other bacterial meningitis. The same can be said about other forms of infection: pneumonia, arthritis, pericarditis, etc. Although diseases caused by H. influenzae do not have specific symptoms, such manifestations of the disease as panniculitis (cellulitis) and acute epiglottitis are more common with infection caused by H. influenzae. Laboratory research methods are of decisive importance in differential diagnostics.

Treatment of Haemophilus influenzae infection

Antibiotics are of primary importance in the complex therapy of diseases caused by H. influenzae. The drugs of choice are cephalosporins of the third and fourth generations. The pathogen is also highly sensitive to chloramphenicol, gentamicin, rifampicin, but is resistant to oxacillin, lincomycin, etc. In severe cases, it is recommended to prescribe two antibiotics.

Treatment and prevention of hemophilic infection

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