[Cytomegalovirus coinfection]

The rapid advancement of modern pharmacological and surgical therapeutic interventions is often accompanied by potential disruptions to the immune system, both permanent and transient. Consequently, life-threatening infectious complications may emerge, which were either absent or exceedingly rare in the past. Observational studies have identified pneumocystis and cytomegalovirus pneumonia as one of the most prevalent coinfections. These diseases carry a high risk of a fatal course, making rapid and precise diagnosis and treatment absolutely crucial. Diagnostic and therapeutic procedures for coinfection with pneumocystis and cytomegalovirus pneumonia are based on empirical knowledge obtained from certain categories of patients and subsequently extrapolated to other categories. In cases where the immune system is dysfunctional, a significantly longer time interval is required before the effect of treatment becomes evident. Therefore, the treatment must be sufficiently prolonged compared to immunocompetent patients and administered with relatively high drug doses. The text highlights the fundamental epidemiological, clinical, diagnostic, and therapeutic aspects. We have attempted to address the questions that arose when confronted with similar situations, often facing ambiguous answers due to the lack of precisely documented data. With the increasing number of immunocompromised patients, particularly in countries with advanced healthcare systems, it becomes evident that the future will require the widespread availability of modern diagnostic methods and the development of drugs with significantly improved safety profiles. These advancements would enable extensive prophylaxis for at-risk patients.