[Infections in immunosuppressed patients].

Molecular biology techniques represent a major advance in the microbiologic diagnosis of infectious diseases, since these methods are able to detect etiological microorganisms with high sensitivity. Moreover, these procedures can also establish prognostic and therapeutic efficacy markers with a sufficiently short turnaround time for the results to have a real impact on the clinical management of immunosuppressed patients. However, these techniques still have substantial limitations that should be solved in the near future: lack of standardization, inter- and intra-assay variability, the difficulty of comparing results among different laboratories and low positive predictive value, due to their high sensitivity, leading to problems in the interpretation of results. The present article reviews the usefulness of molecular biology techniques in the diagnosis and clinical management of infectious diseases caused by human cytomegalovirus, Epstein-Barr virus, human herpes viruses 6 and 7, JC and BK viruses, Toxoplasma gondii and Pneumocystis jiroveci in immunosuppressed patients.