Haemophilus influenzae infection

Haemophilus influenzae infection: Excerpt from Professional Guide to Diseases (Eighth Edition)

Haemophilus influenzae causes diseases in many organ systems but usually attacks the respiratory system. It's a common cause of epiglottitis, laryngotracheobronchitis, pneumonia, bronchiolitis, otitis media, and meningitis. Less commonly, it causes bacterial endocarditis, conjunctivitis, facial cellulitis, septic arthritis, and osteomyelitis.

Causes and incidence

H. influenzae, the cause of this infection, is a small, gram-negative, pleomorphic aerobic bacillus. Transmission occurs by direct contact with secretions or by respiratory droplets. It infects about half of all children before age 1 and virtually all children by age 3, although a haemophilus influenza b vaccine given at ages 2, 4, and 6 months has reduced this number.

Signs and symptoms

H. influenzae provokes a characteristic tissue response — acute suppurative inflammation. When H. influenzae infects the larynx, trachea, or bronchial tree, it leads to irritable cough, dyspnea, mucosal edema, and thick, purulent exudate. When it invades the lungs, it leads to bronchopneumonia. In the pharynx, H. influenzae usually produces no remarkable changes, except when it causes epiglottitis, which generally affects both the laryngeal and pharyngeal surfaces. The pharyngeal mucosa may be reddened, rarely with soft yellow exudate. Usually, though, it appears normal or shows only slight diffuse redness, even while severe pain makes swallowing difficult or impossible. H. influenzae infections typically cause high fever and generalized malaise. Meningitis, the most serious infection caused by H. influenzae, is indicated by fever and altered mental status. In young children, nuchal rigidity may be absent.

Diagnosis

CONFIRMING DIAGNOSIS Isolation of the organism, usually with a blood culture, confirms the diagnosis of H. influenzae infection.

Other laboratory findings include:

❑polymorphonuclear leukocytosis (15,000 to 30,000/µl)

❑leukopenia (2,000 to 3,000/µl) in young children with severe infection

❑H. influenzae bacteremia, found in many patients with meningitis.

Treatment

H. influenzae infections usually respond to a course of ampicillin, cefotaxime, gatifloxacin, moxifloxacin, or ceftriaxone as an initial treatment, although resistant strains are becoming more common. As an alternative, a combination of chloramphenicol and ampicillin is prescribed. If the strain proves susceptible to ampicillin, chloramphenicol is discontinued.

Special considerations

❑Maintain adequate respiratory function through proper positioning, humidification (croup tent) in children, and suctioning, as needed. Monitor rate and type of respirations. Watch for signs of cyanosis and dyspnea, which require intubation or a tracheotomy. Monitor the patient's level of consciousness (LOC); decreased LOC may indicate hypoxemia. For home treatment, suggest using a room humidifier or breathing moist air from a shower or bath, as necessary.

❑Check the patient's history for drug allergies before administering antibiotics. Monitor his complete blood count for signs of bone marrow depression when therapy includes ampicillin or chloramphenicol.

❑Monitor the patient's intake (including I.V. infusions) and output. Watch for signs of dehydration, such as decreased skin turgor, parched lips, concentrated urine, decreased urine output, and increased pulse rate.

❑Organize your physical care measures beforehand, and do them quickly so as not to disrupt the patient's rest.

❑Take preventive measures, such as vaccinating infants, maintaining droplet precautions, using proper hand-hygiene technique, properly disposing of respiratory secretions, placing soiled tissues in a plastic bag, and decontaminating all equipment.

Book Source Details

• Book Title: Professional Guide to Diseases (Eighth Edition)
• Author(s): Springhouse
• Year of Publication: 2005
• Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.

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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X

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