Background: The incidence and significance of Haemophilus spp. in plural fluid were retrospectively studied over a period of 11 years.
Methods: Gram staining and culture in aerobic and anaerobic media was performed in 7517 pleural fluids. Haemophilus spp. was identified with the AMS-Vitek and/or conventional systems. The presence of beta-lactamase was assessed by this method or by the acidometric method.
Results: Haemophilus spp. was identified in 72 samples (0.9%) corresponding to 37 patients. The medical records of 22 were reviewed. The most common species isolated was H. influenzae. Gram stain exam was positive on 28 occasions (38.8%), with gram-negative bacilli being observed in 78.5%. A pure culture was obtained in 43 samples with anaerobic bacteria associated in 18% of the cases. Only 10 strains (16.4%) produced beta-lactamase. No predominance of any determined biotype was observed. Most of the patients were male with a mean age of 59.2 years (range: 2-82). Seventeen patients presented with community-acquired pneumonia, as well as tuberculous sequelae, pneumonectomy and pulmonary and/or upper GI truct neoplasms. All were treated with antibiotics, beta-lactam drugs alone or with aminoglycosides. Half of them also required surgical drainage. Four patients died in relation with the underlying disease.
Conclusions: Haemophilus spp. was isolated in 7.7% of 7517 samples of pleural fluid. This finding may indicate the coexistence of an underlying thoracic disease of neoplastic origin.