Haemophilus species bacteremia in adults - The importance of the human immunodeficiency virus epidemic

Background: Until the late 1970s, invasive infections caused by Haemophilus species were thought to occur mainly in children and only infrequently in adults. Objective: To report the largest series to date of Haemophilus species bacteremia (HE) from a single center. Design: Retrospective. Setting: large, tertiary care, general teaching hospital. Methods: We reviewed the charts of adult patients with HE detected from January 1, 1986, to December 31, 1994. Haemophilus strains were serotyped, and the antimicrobial resistance pattern was analyzed. Results: One hundred sixteen patients had HE (0.26 cases per 1000 admissions). Thirty-eight children and 16 adults were excluded. Human immunodeficiency virus (HIV) infection was the most common underlying condition (n=18 [29%]), followed by malignant neoplasms (n=12 [19%]) and chronic obstructive pulmonary disease (n=12 [19%]). Prevalence in HIV-positive patients was 5 cases per 1000 admissions vs 0.2 cases per 1000 admissions in HIV-negative patients. Infection was nosocomial in 16 patients (26%). Focal diseases were pneumonia in 41 patients (66%), cholangitis in 5 patients (8%), endocarditis in 3 patients (5%), meningitis and septic arthritis each in 1 patient (2%), and primary bacteremia in 9 patients (14%). The HIV-positive patients were significantly younger and presented more frequently with pneumonia (P<.05). Overall, 14 patients died (22%). Bacteremia was polymicrobial in 11 patients (18%). Haemophilus influenzae was isolated in 53 patients (85%). Rates of antimicrobial resistance were 11% to chloramphenicol sodium succinate, 48% to ampicillin sodium, 78% to erythromycin stearate, 76% to combined sulfamethoxazole and trimethoprim, 15% to rifampin, and 57% to clarithromycin. Conclusions: Infection with HIV has become the most common underlying disease in adults with HE in our hospital. Therapeutic approaches must take into account the high rate of antimicrobial resistance.