Clinical features and outcomes of community-acquired pneumonia due to Haemophilus influenzae

Abstract number: O565

Viasus D., Garcia-Vidal C., Adamuz J., Verdaguer R., Gudiol F., Carratalà J.

Objective: We sought to determine the clinical features, outcome, and risk factors of community-acquired pneumonia (CAP) caused by Haemophilus influenzae.

Methods: Observational analysis of a prospective cohort of nonseverely immunosuppressed adults with CAP requiring hospitalization from 1995 through 2008.

Results: Of 3421 consecutive CAP episodes, 192 (5.6%) were caused by H. influenzae. The diagnosis was established with the use of one or more of the following methods: sputum Gram stain and culture (178), blood culture (23), transthoracic needle aspiration specimen culture (5) and pleural fluid culture (1). b-lactamase production was detected in 25 (13%) of H. influenzae isolates. Patients with CAP due to H. influenzae were older (69.7 vs 65.9 years; p = 0.016), more often male (75% vs 68%; p = 0.033), had more commonly chronic obstructive pulmonary disease (COPD) (52% vs 26%; p  0.001), smoking history (67% vs 56%; p = 0.001) and were more frequently classified into high-risk pneumonia severity index (PSI) classes (group IV-V) (69% vs 57%; p = 0.001) than the remaining patients. They also had received more frequently prior corticosteroid therapy (10% vs 6%; p =.039) and pneumococcal vaccine (<5 years) (24% vs 15%; p = 0.001). Previous hospitalization (<1 year) for pneumonia was more common among patients with CAP due to H. influenzae (13% vs 7%; p = 0.002). Conversely, they were less likely to had pleural effusion (12% vs 18%; p = 0.049) and empyema (1% vs 4.3%; p = 0.028). No significant differences were found regarding time to clinical stability, length of hospital stay, and ICU admission. Early (0.5% vs 2.3%; p=.1) and 30-day mortality rates (4.7% vs 7.8%; p=.11) did not differ significantly between groups. Multivariate analysis identified COPD (OR = 2.5, 95% CI 1.8–3.5) and high-risk PSI classes (OR = 1.4, 95% CI 1.02–2.17) as independent risk factors for H. influenzae pneumonia.

Conclusions: CAP caused by H. influenzae occurs mainly in patients with COPD classified into high-risk PSI classes and is associated with significant morbidity and mortality.