Prospective epidemiological study of invasive Haemophilus influenzae disease in adults.

The incidence and characteristics of invasive Haemophilus influenzae disease were studied in 43 adult patients admitted to the acute care hospitals in El Vallés County (Barcelona, Spain) between January 1987 and June 1992. The annual incidence of Haemophilus influenzae disease was 1.2 per 100,000 inhabitants. Pneumonia occurred in 24 patients, meningitis in five, intraabdominal infections in three, obstetric infections in two, epiglottitis in two and cellulitis in one. In six patients the source of infection was unknown. Ten (23%) of the infections were hospital acquired. Underlying conditions were diagnosed in 30 (70%) patients. Nontypeable Haemophilus influenzae strains predominated in all adult age groups. Sixty-one percent of type b and 34% of nontypeable strains were ampicillin resistant (p = 0.08). Multiple antibiotic resistance was also high among type b (53%) and nontypeable (18%) strains. The mortality rate was significantly higher in patients with pneumonia, bacteremia from an unidentified focus or shock at presentation.