[Prevention and treatment of opportunistic infections].

An opportunist infection (OI) is understood to be an infection produced by microorganisms that invade a host with impaired immune capacity, such as children with HIV infection. The adequate treatment and chemoprophylaxis of these infections has improved the prognosis of their evolution, although they still present a high morbidity and mortality when they occur. In this sense, the introduction of triple therapy (new antiretroviral inhibitors and protease inhibitors) is likely to produce a prompt decrease in the incidence of OI because of the regression in the degree of immunosuppression that it induces. The degree of immunosuppression is determined by the number of CD4 lymphocytes, the most reliable marker for assessment. Normal CD4 lymphocytes values are different for each age group and have important connotations for the prophylactic measures to be used at each moment depending on the CD4 lymphocyte count. Opportunist infections influence the quality of life of patients. More than 100 microorganisms, including bacteria, viruses, fungi and protozoa, cause OI. This paper describes primary and secondary prophylaxis as well as the treatment of the most frequent opportunist infections (Pneumocystis carinii pneumonia, bacterial infections, Cryptococcus neoformans, Cytomegalovirus, Herpes simple, Varicella-zoster virus. Toxoplasmosis, Mycobacterium tuberculosis, M. avium-intracellulare, M. kansasii).