Haemophilus Influenzae Infection
Although Haemophilus influenzae can affect many organ systems, it most commonly attacks the respiratory system. It’s a common cause of epiglottiditis, laryngotracheobronchitis, pneumonia, bronchiolitis, otitis media, and meningitis. Less commonly, it causes bacterial endocarditis, conjunctivitis, facial cellulitis, septic arthritis, and osteomyelitis.
H. influenzae infection predominantly affects children, although it’s becoming more common in adults, especially if they have a history of alcoholism and are older than age 50. It infects about half of all children before age 1 and virtually all children by age 3, although a vaccine has reduced this number. The vaccine is administered at ages 2, 4, 6, and 15 months.
Causes
A small, gram-negative, pleomorphic aerobic bacillus, H. influenzae appears predominantly in coccobacillary exudates. It’s usually found in the pharynx and less commonly in the conjunctiva and genitourinary tract. Transmission occurs by direct contact with secretions or by airborne droplets. The organism enters the body through the nasopharynx.
Complications
Many organ systems can be affected by H. influenzae. The microorganism can cause subdural effusions and permanent neurologic sequelae from meningitis; complete upper airway obstruction from epiglottiditis; and pericarditis, pleural effusion, and respiratory failure from pneumonia. Arthritis and cellulitis also commonly occur.
Assessment
The patient may report a recent viral infection. He frequently complains of generalized malaise and is likely to have a high fever. Other symptoms vary. For example, with acute epiglottiditis, the patient may complain of a sore throat, severe dysphagia, and dyspnea. With pneumonia, he may report a productive cough, dyspnea, and pleuritic chest pain. With meningitis, he may experience headache, vomiting, photophobia, and diplopia.
Your inspection findings will vary with the site of infection. For example, a child with acute epiglottiditis appears restless and irritable and may exhibit the use of accessory muscles to breathe. Typically, he attempts to relieve severe respiratory distress by hyperextending his neck, sitting up, and leaning forward with his mouth open, tongue protruding, and nostrils flaring.
AlertIf a child develops symptoms of acute epiglottiditis, don’t attempt to examine his throat or obtain a throat culture—either could lead to a fatal respiratory obstruction. Any examination or diagnostic procedure involving the child’s throat should be performed by an anesthesiologist.
You may also observe stridor and inspiratory retractions. The trachea appears normal. The pharyngeal mucosa may look red (rarely with soft yellow exudate) but usually appears normal or shows only slight, diffuse redness. The epiglottis appears red with considerable edema. Severe
pain makes swallowing difficult or impossible.
pain makes swallowing difficult or impossible.
Your inspection of a patient with pneumonia may reveal shaking chills, tachypnea, a productive cough, and impaired or asymmetrical chest movement caused by pleuritic pain.
With meningitis, you may note an altered level of consciousness (LOC) progressing to seizures and coma as the disease advances. You may also observe positive Brudzinski’s and Kernig’s signs and exaggerated and symmetrical deep tendon reflexes.
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