Infections in patients with acute leukemia

Patients with acute leukemia are at increased risk of developing infections both as a result of the leukemia and its treatment. Neutropenia is the primary risk factor associated with the development of infection, with the severity and frequency of infection increasing as the absolute neutrophil count drops below 500 cells/mm³, as initially described by Bodey and colleagues. Other risk factors may be present including impaired cellular or humoral immunity, breakdown of normal barriers such as the skin and mucosal surfaces, and vascular access catheters and other foreign medical devices. Multiple risk factors are often present in the same patient. Additionally, the frequent use of antimicrobial agents for various indications (prophylaxis, empiric therapy, pre-emptive administration, specific or targeted therapy, and occasionally maintenance or suppressive therapy) has an impact on the nature and spectrum of infections, with the emergence/selection of multidrug-resistant (MDR) organisms being of particular concern. Bacterial infections tend to occur early on in a neutropenic episode, with fungal infections being uncommon at this stage. If neutropenia persists, the risk for fungal infections increases. There are periodic changes in the epidemiology/spectrum of infection in patients with leukemia. It is important to conduct periodic epidemiologic and susceptibility/resistance surveys, especially at institutions dealing with large numbers of such patients, in order to detect these shifts and changes in susceptibility/resistance patterns, since empiric therapy is largely based on this information. Such surveys are conducted every 3–5 years at our institution.