The incidence of bacterial pneumonia is increased about 100-fold by HIV infection. The severity, likelihood of bacteraemia, risk of recurrent pneumonia, and mortality are all increased compared with HIV-uninfected patients. The aetiology is similar to that of communityacquired pneumonia in HIV-uninfected patients with co-morbidity: S. pneumoniae is the commonest, followed by Haemophilus influenzae, enterobacteriaceae (e.g. Klebsiella pneumoniae) and Staphylococcus aureus. The prevalence of atypical bacteria in HIV-infected patients with pneumonia is probably similar to that in the general population, but the data are limited. Treatment is with a broad-spectrum β-lactam (e.g. ceftriaxone, amoxicillin– clavulanate), with the addition of a macrolide if the pneumonia is severe.
Uncommon bacteria causing pneumonia include Pseudomonas aeruginosa, Nocardia (which mimics tuberculosis) and Rhodococcus equi (which can cause pulmonary cavity).
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