Chien-Chun Wang¹, Han-Yueh Kuo¹, Dung-Hung Chiang¹, Chen-Chi Tsai², Mei-Lin Lin¹, Yu-Jiun Chan^1,3, Su-Pen Yang¹, Cheng-Yi Liu^1
1Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, and National Yang-Ming University, Taipei; ²Division of Infectious Diseases, Department of Medicine, Buddhist Tzu-Chi General Hospital, Hualien; and ³Division of Clinical Virology, Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan

Received: April 12, 2007      Revised: June 20, 2007       Accepted: July 31, 2007

Corresponding author: Dr. Su-Pen Yang, Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan. E-mail: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

Background and Purpose: Haemophilus influenzae is an important cause of invasive infection in infants and children, but it has been considered an uncommon cause of invasive disease in adults. We conducted a retrospective survey of invasive H. influenzae disease in adults in order to better understand the characteristics of clinical presentation and microbiology.

Methods: Patients older than 18 years with H. influenzae isolated from normally sterile sites, between July 1999 and June 2002 in a teaching hospital for adult patients were retrospectively analyzed. Data on demographics, clinical presentation, serotype, antibiotic susceptibility, and beta-lactamase production of H. influenzae isolates were analyzed.

Results: Fifteen patients were enrolled. The infectious diagnosis of invasive diseases comprised: pneumonia (5 patients), empyema (2), pelvic inflammatory disease (2), peritonitis (2), periorbital cellulitis with abscess formation (2), endophthalmitis (1) and primary bacteremia (1). Most patients were elderly with underlying illness. Of ten H. influenzae isolates available for analysis, two were serotype b and eight were nontypeable. Beta-lactamase production and ampicillin resistance were found in 6 H. influenzae isolates (5 nontypeable, and 1 type b).

Conclusion: These data show H. influenzae disease in adults to be rare in Taiwan. Our limited number of cases suggest that nontypeable strains predominate in patients with invasive infection due to H. influenzae. Most patients had respiratory tract infections. Ampicillin resistance was found in more than one-half of H. influenzae isolates, and should be taken into consideration when antibiotics are prescribed on an empirical basis.

Key words: Bacteremia; Drug resistance, bacterial; Haemophilus influenzae; Morbidity; Treatment outcome

J Microbiol Immunol Infect. 2008;41:209-214.