Overview.
Haemophilus influenzae pneumonia is an inflammation of the lungs caused by the bacterium Haemophilus influenzae. There are two high-incidence age groups, namely, infants and children aged 6 months to 5 years and adults with underlying disease. The peak season of incidence is fall and winter, often following an upper respiratory tract infection. Certain respiratory viruses, such as influenza virus, can contribute to the development of Hib pneumonia, especially during influenza epidemics, when the incidence and severity of Hib pneumonia increases.
Causes
Haemophilus influenzae is a small gram-negative bacillus, about 1.5 μm × 0.3 μm in size, and is polymorphic, such as rod-shaped and filamentous. In the acute infection specimens, they mostly appeared in the form of short micrococci. The bacteria in this group do not form bud cells, have no flagellum and cannot move, and some strains have polysaccharide pods. The main pathogenic substances of Haemophilus influenzae are: ① endotoxin lipo-oligosaccharides, whose pathogenic role has not been clarified; ② bacterial hairs to make the bacterial adherence; ③ pods have anti-phagocytosis, which is the main virulence factor; ④ IgA protease helps the bacteria break through the immune mechanism of the organism.
Symptoms
History of upper respiratory tract infection before the onset of disease, manifested by fever, cough, cough purulent sputum, shortness of breath, cyanosis. Similar to general pneumonia, respiratory tone is low, wet rales are heard, a few complications of pyothorax, sometimes with signs of pleural effusion.
Examination
1. Laboratory examination
Increased leukocyte count; increased serum adenosine deaminase.
2. Pathologic examination
Gram stain of sputum shows a large number of small gram-negative bacilli.
3. X-ray examination
Often show solid changes in lung segments and lobes. The image of bronchopneumonia shows patchy or multilobular infiltration, rarely forming lung abscess, and about 20% of them develop pyothorax.
Diagnosis
Be alert for Haemophilus influenzae pneumonia in all susceptible or risk factor individuals with community-acquired pneumonia and in patients on mechanical ventilation with tracheal intubation who develop early-onset ventilator-associated pneumonia. Gram staining of sputum smears and microscopic examination of short rods or small polymorphic gram-negative bacilli are suggestive of the diagnosis and are helpful in differentiating from Streptococcus pneumoniae. Sputum culture for Haemophilus influenzae may be of some significance in pediatric patients, but its significance in adult patients needs to be considered in the context of the clinical picture. Bacterial culture of samples taken directly from the lower respiratory tract is clinically significant, although a positive result does not confirm the diagnosis. Positive results of pleural fluid or blood cultures are diagnostic for Haemophilus influenzae pneumonia complicated by bacteremia or sepsis, pleurisy, etc. The above culture results can be confirmed by pod swelling test or immunofluorescence test, and bacterial typing is more valuable.
Treatment
The treatment should be benzylpenicillin intramuscularly, or by injection, or with chloramphenicol. When the bacteria are resistant to ampicillin, cephalosporin can be used instead.
Due to the widespread use of antimicrobial drugs, drug-resistant strains are emerging, some of which can produce β-lactamase and are resistant to ampicillin. Drug-resistant strains of Haemophilus influenzae isolated from pediatric patients and those with chronic obstructive pulmonary disease are particularly common. Newer macrolide antibiotics such as azithromycin, clarithromycin, amoxicillin clavulanate potassium, and ampicillin are generally used as appropriate. The 2nd generation cephalosporins such as cefaclor and cefuroxime have strong antimicrobial activity against this organism, and are advocated for use in mild to moderate infections; the 3rd generation cephalosporins ceftriaxone and cefotaxime, as well as quinolones, are more effective in moderate to severe Hib pneumonia. The 4th generation cephalosporins or carbapenems may be used in very severe cases.
Questions you may be concerned about
Haemophilus influenzae pneumonia without fever, no cough, but chest tightness what to do
Haemophilus influenzae pneumonia with chest tightness but no fever and no cough can be treated with antibiotic drugs according to the severity of the disease.
1. Mild infection: The chest tightness of Haemophilus influenzae infection may be due to the spread of infection to the large lobes of the lungs, resulting in respiratory distress, as long as the infection is controlled, the chest tightness will be relieved. Mild infection can choose oral cephalosporin, clarithromycin and other macrolide antibiotics.
2. Severe infections: need to consider whether there are other pathogenic bacteria co-infection, severe infections recommended intravenous drugs, often need to be empirical multi-drug combination, such as the use of β-lactams (eg: piperacillin sulbactam) combined with fluoroquinolones (eg: levofloxacin) to control the infection, to alleviate the symptoms of chest tightness.
It is recommended to consult a doctor in time, take sputum culture for several times and complete other laboratory tests to clarify the type of pathogen and other co-infections, and follow the doctor’s instructions for timely and reasonable standardized treatment.