Acute infections in intravenous drug users.

pneumonia (CAP), including aspiration pneumonia, and a greater incidence of pulmonary tuberculosis compared with the general population. This relates to smoking, alcohol abuse, poor nutrition and homelessness. Organisms commonly causing CAP in this group include Streptococcus pneumoniae, S aureus, Haemophilus influenzae and Klebsiella pneumoniae.11,12 Septic pulmonary emboli can seed from injection-site infections and tricuspid valve endocarditis and usually present with high fever and symptoms suggestive of pulmonary emboli.11 Lung abscesses result typically from aspiration, frequently due to K pneumoniae13 or septic emboli. Although chest X-ray is sufficient to demonstrate the pulmonary infection in most cases, CT can be useful to confirm cavitation and the distribution of infection and to exclude pulmonary embolus. Choice of antibiotic therapy is dependent on the organism isolated from blood or sputum and may need to be given for a prolonged period – 4 weeks or more depending on clinical progress. Empirical treatment for lung abscesses should cover S aureus, Gram-negative bacteria and anaerobes.