Bacterial pneumonia is a common problem for many HIV-positive people, even for those who have high CD4 cell counts or are responding well to HIV treatment. In one large study, HIV-positive adults were almost eight times more likely to experience bacterial pneumonia that HIV-negative adults—though the incidence of bacterial pneumonia has declined since the introduction of more potent combination antiretroviral (ARV) therapy in recent years.
Bacterial pneumonia and less severe airway (respiratory tract) infections can be caused by one of several bacteria. Streptococcus pneumoniae is the most common, followed by Haemophilus influenzae, Pseudomonas aeruginosa, and Staphylococcus aureus. Rarely, bacterial pneumonia can be caused by Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydia pneumoniae.
Not only are HIV-positive people more likely to develop bacterial pneumonia as a result of one of these infections, they are also more likely to experience recurrent pneumonia. People with CD4 counts below 100, and those whose bacterial infection has spread beyond the lungs, are at increased risk of death from bacterial pneumonia.
HIV-positive people who smoke tobacco, use crack cocaine, are intravenous drug users, or suffer from alcoholism or liver disease, are likely at a higher risk of developing bacterial pneumonia that HIV-positive people who don't have any of these cofactors.