Haemophilus influenzae is a group of bacterial infections caused by influenza bacillus (Pfeiffer). The respiratory organs, the brain, the musculoskeletal system are most often affected; sepsis occurs during generalization. About a third of those who have been ill remain permanently disabled or have persistent disorders of the central nervous system, joints, ENT organs. Diagnosis is based on the detection of the pathogen (molecular genetic, bacteriological study), the growing titer of antibodies to the pathogen (ELISA). Treatment: etiotropic antibiotic therapy, pathogenetic measures, symptomatic therapy.
A41.3 B96.3 J14 A49.2
Haemophilus influenzae (Hib infection) is a pathological process caused by conditionally pathogenic microorganisms. The pathogen was discovered in 1892 by the German immunologist R. Pfeiffer (the wand bears his surname). The infection is widespread everywhere, the incidence increases in the winter-spring period. Up to a third of all childhood meningitis is caused by hemophilic bacillus. Children under 5 years of age suffer mainly, there are no gender differences. According to some reports, up to 40-70% of children attending preschool institutions are carriers of the bacterium.
The causative agent of infection is a bacterium of the genus Haemophilus (species H. influenzae), the most common lesion in humans is caused by H. influenzae type b. The microorganism is a conditionally pathogenic representative of the normal microflora of the mucous membranes of the human respiratory tract. The source of infection can be healthy carriers, as well as sick people. The transmission path is airborne, in children it is often combined with contact (through common toys, cutlery).
The high-risk group consists of people living in nursing homes, boarding schools, people after splenectomy, newborns on artificial feeding, HIV-infected, patients receiving systemic glucocorticosteroids for a long time, cancer patients. Main risk factors:
- age: under 2 years and over 60;
- harmful addictions: alcoholism, drug addiction;
- heart defects;
- unsatisfactory sanitary and hygienic conditions.
The pathogenesis of infection has not been definitively studied. When ingested into the human body, the bacterium persists for a long time in the entrance gate, being outside and intracellularly. Colonization can occur by typed and untyped strains with a dynamic change of the microbial landscape. Serotype b has proteases capable of inactivating secretory mucosal immunoglobulins. Proteins of the hemophilic bacillus capsule can block phagocytosis.
With a decrease in the resistant properties of the body (concomitant viral damage, stress, hypothermia), activation of the reproduction of the pathogen and local inflammation occurs. Hemophilic bacillus can penetrate the mucosa, enter the systemic bloodstream, spread through target organs (brain, lungs, soft tissues). The bacterium is able to multiply in the blood, forming bacteremia with secondary foci, and then a septic state.
Haemophilus influenzae is more often a disease associated with the transition of latent pathology to manifest after asymptomatic colonization of the upper respiratory tract by microorganisms. Hib infection can be classified according to clinical manifestations:
- Invasive. It includes epiglottitis, meningitis, pneumonia, lesions of bones, joints, subcutaneous fat. More than 85% of cases are detected in children under 4 years of age.
- Non-invasive. It is often caused by untyped strains, occurs as recurrent sinusitis, otitis, conjunctivitis. Both children and adults are affected.
- Sepsis. Characterized by rapid flow, high mortality, absence of secondary foci. Usually infants aged 6-12 months, women in labor get sick. Patients die from septic shock.
Hib infection has a short incubation period – 2-4 days. Symptoms vary depending on the affected organ, but in typical cases they begin acutely with an increase in body temperature of more than 38.5 ° C, chills, weakness. With inflammation of the epiglottis, the ability to speak, swallow suffers, salivation occurs, lack of air when inhaling. Breathing becomes noisy, the skin acquires a bluish hue. Patients sit with their chin outstretched and leaning forward.
The onset of meningitis is characterized by manifestations similar to ARVI: cough, runny nose, fever over 38 ° C. Then there is lethargy, severe headaches with vomiting at the height of the pain peak, rigidity of the occipital muscles, photophobia. Delirium, hallucinations, drowsiness appear. The addition of sepsis manifests itself as a hemorrhagic rash on various parts of the body. Painful red seals (cellulite, phlegmon) appear on the face and neck.
Symptoms of pneumonia – runny nose, dry cough, sore throat. After a few days, there is an increase in cough tremors, the appearance of scanty sputum, chest pain when inhaling, fever more than 39 ° C. Patients note an increasing lack of air, pallor, and then cyanosis of the skin, profuse sweating. Shortness of breath is initially noticeable only with physical exertion, eventually appears at rest. Weakness is growing, a forced position is required.
In children up to the first year of life, symptoms of meningitis caused by hemophilic bacillus can manifest as persistent fever over 39 ° C, not stopped by antipyretics, regurgitation (equivalent to vomiting), constant piercing “brain scream”. Often there are convulsions, twitching of facial muscles, swelling and pulsation of the large fontanel. Children may refuse to eat, become sluggish, sleepy, or, conversely, be in psychomotor agitation.
Haemophilus influenzae has a number of complications, the main of which is acute respiratory failure. It develops due to asphyxia or due to edema of the respiratory tissue. Up to 70% of cases of pneumonia caused by hemophilic bacteria in children are complicated by pleurisy. Epiglottis abscesses often occur. A dangerous complication of meningitis is cerebral edema.
Sepsis causes symptoms of multiple organ failure in 20% of patients. Long-term consequences of a haemophilus influenzae: chronic pathologies of the ENT organs (otitis, sinusitis, deafness), blindness after meningitis and endophthalmitis, osteomyelitis. Up to 50% of children who have had hemophilic meningitis receive a disability group. Rare complications are chronic pericarditis, arthritis.
Diagnosis of haemophilus influenzae is carried out by doctors of various specialties, more often pediatricians, infectious diseases specialists. It is important to carefully collect an epidemiological history, especially the vaccination history of a child or an adult. The main laboratory-instrumental and clinical signs of the disease:
- Physical data. Symptoms of DN are objectively revealed: shortness of breath, change in skin tone, retraction of intercostal spaces, forced position. Hemorrhagic rash is detected on the skin of the trunk and extremities with sepsis. Neurological manifestations include rigidity of the muscles of the occiput, a positive symptom of Laseg, Kernig, Brudzinsky. Purulent skin lesions look hyperemic, fluctuating, swollen, sharply painful.
- Laryngoscopy. Symptoms of epiglottitis require examination by an ENT doctor with a visual assessment of the condition of the respiratory tract. Indirect laryngoscopy reveals hyperemia of the pharynx, a large amount of saliva, mucus. The epiglottis is enlarged in size, of a purplish-bluish hue, the entrance to the larynx is narrowed due to swelling of the walls.
- Laboratory tests. Leukocytosis is determined with a sharp shift of the formula to the left, acceleration of ESR. With sepsis, anemia, thrombocytopenia occurs, an increase in the activity of hepatic transaminases, urea, creatinine, as well as bilirubin, D-dimer, hypoalbuminemia is recorded. In blood test – increased density, proteinuria, erythrocyturia. The cerebrospinal fluid is characterized by neutrophil pleocytosis.
- Identification of infectious agents. The detection of the bacterium is carried out by microscopy and inoculation on nutrient media of flushes from the nasopharynx, pharynx, sputum, liquor, blood or purulent discharge. The fastest method of detecting an infectious bacillus is PCR. Serological diagnostics (ELISA) is carried out in paired sera with an interval of at least 14 days, serves for retrospective confirmation of the diagnosis.
- Instrumental methods. It is necessary to conduct an X-ray of the chest organs or a low-dose CT scan of the lungs. Radiography of the neck in a lateral projection is used when epiglottitis is suspected. In severe cases, it is possible to perform optical fiber laryngobronchoscopy. Ultrasound of soft tissues, abdominal cavity is recommended. With symptoms of meningitis, a lumbar puncture is mandatory.
Differential diagnosis is carried out with purulent meningitis and pneumonia of a different etiology (often the differences are only laboratory, determined when the pathogen is isolated). Epiglottitis is clinically similar to paratonsillar, pharyngeal abscesses. A similar clinic has foreign bodies of the larynx, burns with acids, alkalis, however, in these cases, the details of the anamnesis are usually known. It may be necessary to exclude acute stenosing laryngitis, true diphtheria croup.
Indications for hospitalization
Hib infection in the form of epiglottitis, phlegmon, lesions of fatty tissue on the face or meningitis is an indication for emergency hospitalization, often in the intensive care unit. Inpatient treatment is recommended based on the severity of the condition. So, pneumonia without respiratory failure can be stopped on an outpatient basis. There are epidemic indications for hospital therapy.
Up to 5-7 days of normal body temperature with meningitis and inflammation of the epiglottis, strict bed rest is prescribed, bedsores and hypostatic pneumonia are prevented. A high-protein, fortified diet is recommended, an increase in water load (in the absence of contraindications).
Patients with haemophilus influenzae must receive antibacterial agents, which must be administered from the first hours of confirmation of the diagnosis. It is better to start treatment with infusion of drugs. It is important to sanitize contact persons, since pathogenic hemophilic bacilli are detected in 70% of caregivers. Therapeutic tactics include:
- Etiotropic treatment. Broad-spectrum antibiotics are prescribed, taking into account the growing antibiotic resistance. Drugs of choice: protected penicillins, cephalosporins, macrolides, carbapenems and fluoroquinolones can be used.
- Pathogenetic agents. Massive infusion detoxification with hydroxyethyl starches, crystalloids, the introduction of albumin solutions, freshly frozen plasma is carried out. It is possible to prescribe NSAIDs, less often glucocorticosteroids.
- Symptomatic therapy. It includes antipyretics, painkillers, sedatives and other drugs – mucolytics, antitussives. Diuretics, oxygen therapy, anticonvulsants are used. Correction of acid-base balance, compensation of chronic pathologies is carried out.
It is carried out in case of phlegmon and abscesses, especially on the face. In half of patients with purulent arthritis of the shoulder and hip joints, there is a need for therapeutic arthroscopy. Local treatment after a wide excision of a purulent focus consists in washing, the use of antiseptics for dressings in soluble, less often ointment forms. Tracheostomy is often performed to improve the patency of the respiratory tract.
Prognosis and prevention
The prognosis is always serious and depends on the form of haemophilus influenzae. The mortality rate reaches 10-20%. Specific prevention has been developed. Vaccines are allowed to be administered from 3 months of life, according to the scheme of 3-4,5-6 months, revaccination is carried out in 1.5 years. They are used both in the form of multicomponent (Pentaxime, Infanrix Hexa) and monopreparations (ActHIB, Hiberix). After 5 years, vaccination is not carried out for healthy children.
Non-specific measures are sanitary and educational work with the population, sanitation of bacterial carriers in foci, improvement of living conditions. An important element of prevention is isolation of patients and contact persons at home or in a hospital, quarantine measures in children’s institutions (up to 10 days). Emergency antibiotic prophylaxis is indicated for people from risk groups.