Small gram-negative bacterium, immobile, asporigenous, facultative aerobic, not resistant to acid, coconut-shaped but with pleomorphism, therefore the ability to modify its morphology if necessary, Haemophilus influenzae it owes its name to the error of having been initially recognized as the microorganism responsible for the flu, which we now know has a viral origin.
Compared to the flu, infections from Haemophilus influenzae they are much more feared, because they are potentially very serious, especially in children.
of the upper airways of many adults, especially in the winter months, without causing particular diseases.
Although it is found in 80% of healthy adults, as a rule the infection is limited by the immune system and proceeds asymptomatically.
However, when the lines of defense of the organism are compromised by particular conditions (immunosuppression, intercurrent illnesses, bad environmental conditions), Haemophilus influenzae it becomes pathogenic, causing mainly local infections (upper and lower airways) and in more serious cases systemic.
The frequency of pathological infection with Haemophilus influenzae is inversely proportional to age; this means that the bacterium attacks above all children, so much so that in the absence of vaccination at least 50% of the pediatric population suffers an "infection by Haemophilus influenzae in the first year of life and almost all children have already been infected by the age of three.
The elderly are also less resistant to infection.
).Currently, 6 antigenic types of Haemophilus influenzae equipped with LPS; these bacteria are identified with the first six letters of the alphabet, from A to F.
Among the 6 different antigenic types of Haemophilus influenzae equipped with a capsule, the most widespread in human pathology is Haemophilus influenzae type B.
It has an invasive tendency, is often associated with bacteremia and mainly affects infants and children under the age of two.
The danger of this bacterium in children has stimulated the search for a specific vaccine, available for some years now, to be administered for the first time at the age of two months.
Bacteria lacking a polysaccharide capsule are defined Haemophilus influenzae not typable.
from two months to five years of age.Inflammation of the meninges caused by Haemophilus influenzae it is the most serious clinical form of the infection, since it can cause quite serious damage with severe localized handicaps especially at the level of the nervous system:
- Deafness and blindness;
- Problems of learning and development;
- Brain damage in general.
Meningitis from Haemophilus influenzae Type B is rare in adults over 27 years of age.
The symptomatic onset of purulent meningitis from Haemophilus influenzae it is abrupt, even if the onset of meningitis is often preceded by symptoms localized to the airways (nasopharyngitis, bronchitis, bronchopneumonia) or to the ear (otitis), foci which - especially in the absence of adequate treatment - represent the entrance doors of the pathogen for blood diffusion (septicemia) and from there to the meninges.
Fever, difficulty breathing, sore throat, pain when swallowing, overproduction of saliva are the initial symptoms of meningitis.
The evolution can be dramatic, with diffusion of the bacterium through the blood (septicemia) and multi-organ involvement with the death of the patient.
The bacterium Haemophilus influenzaeIt can also cause a severe throat infection in the laryngeal (vocal fold) area. This infection is called acute epiglottitis.
Due to its explosive symptomatological course, if not promptly recognized and treated, acute epiglottitis can be fatal, because it prevents the child from normal breathing. Acute epiglottitis manifests itself with sore throat, fever, and shortness of breath, more and more asphyxiating up to respiratory obstruction; not surprisingly, acute epiglottitis is also known as acute suffocating laryngitis.
, hemodialysis) and in those with chronic obstructive bronchitis (COPD) or other chronic lung diseases.
These untypable strains of Haemophilus influenzaemoreover, they are frequently found in the lower respiratory tract of patients with cystic fibrosis during episodes of exacerbation of the disease.
Infection due to strains of Haemophilus influenzae untypable can be localized to various levels of the airways and ear, directly causing otitis media, tonsillitis, acute sinusitis, pharyngitis (sore throat), tracheitis, tracheobronchitis, chronic bronchitis, pleurisy and / or pneumonia, or exacerbating the same when caused by other etiological agents (viruses and bacteria).
Infections from Haemophilus influenzae they generally have a purulent character, so they are associated with the production of pus.
Rarely, strains of Haemophilus influenzae not typeable, they give invasive forms, spreading by blood to other parts of the organism.
However, when this occurs, they are potentially responsible for: septic arthritis, pericarditis, endocarditis, cholecystitis, purulent arthritis, urinary infections, empyema and epiglottitis in adults, puerperal sepsis and septicemia in the newborn.
third generation, such as ceftriaxone (2g / day in adults) and cefotaxime (2g three times / day), elective drugs in severe cases (such as purulent bacterial meningitis).
Therapy should be continued for 7-14 days and completed even in the presence of a marked improvement in symptoms.
For less severe cases, a different combination of antibiotics is preferred: ampicillin and sulbactam, second generation cephalosporins (cefaclor, cefamandone and cefuroxime) and third generation, or fluoroquinolones.
capsular of Haemophilus influenzae type B, usually combined with other components that ensure immunity against other diseases, such as diphtheria, tetanus, pertussis, poliomyelitis and hepatitis B (see the pharmaceutical product Infanri Hexa).
The vaccine is usually inoculated for the first time at the age of two months. Three more vaccinations are then required: at four months, at six months and at 12-18 months.
By completing the full course of vaccinations, the serum protects approximately 95% of children against severe infections Haemophilus influenzae type B: on the other hand, it is totally ineffective in preventing meningitis caused by other bacteria.
In case of contact with infected subjects, in children and adults who have not yet manifested the symptoms of the infection, a chemoprophylaxis with rifampicin is feasible.
For further information: Hexavalent vaccine: what it protects against and when to do itAnti Haemophilus influenzae vaccine: Mandatory
With the decree law on vaccination prevention for minors from zero to 16 years, approved on 19/05/2017, the vaccine against the "Haemophilus influenzae has become mandatory for those born after 2001.
Furthermore, always in terms of protection from meningitis:
- Those born between 2012 and 2016 are obliged to vaccinate against meningococcus C.
- Those born from 2017 are obliged to carry out the vaccination also against meningococcus C and meningococcus B.
For more information on mandatory vaccines in children see this article.
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