Cause:Haemophilus influenzae, unencapsulated or encapsulated (type B)
Airborne from respiratory tract of infected person. Worldwide distribution. Infections with unencapsulated types occur in all age groups and are common in people with COPD. Infections with more invasive and malignant encapsulated type now becoming rare with advent of vaccine in children; most now in adults (Ann IM 1992;116:806). Before Hib vaccine, incidence was 100/100 000 and meningitis in 60/100 000 under age 5 yr.
Si:Otitis media, bronchitis, sinusitis. Encapsulated type can also cause epiglottitis (Acute Epiglottitis (Bacterial Supraglottitis)), sore throat with dysphagia, meningitis, pneumonia, but only rarely otitis media (10% of all H. flu otitis media)
Encapsulated type causes:
Lab: Bact: Gram-negative coccobacilli; capsule may be visible in encapsulated type
Xray:Lateral neck soft tissue view to look for epiglottis involvement
Rx:
Active immunization: Hib vaccine conjugated with diphtheria protein to give better immune response in infants (Nejm 1987;317:717); give MSD Pedvax Hib at 2 and 4 mo with DTP and boost at 12 mo, perhaps a 6-mo shot if using one of the other vaccines; all appear interchangeable (Jama 1995;273:849). Vaccinating mother in 3rd trimester may help where risk is high (Jama 1996;275:1182)
of active disease: ampicillin, but 8-20% of all US isolates now resistant; in life-threatening illness, ceftriaxone or rarely used chloramphenicol. Tm/S if mild infection and may be or is resistant to ampicillin
of cmplc's: steroids and tracheotomy for acute airway obstruction; steroids for meningitis, like dexamethasone 0.15 mg/kg iv 20 min before antibiotic, then q 6 h × 4; decreases cmplc's, esp deafness (Nejm 1990;319:968)