Prophylaxis and treatment of bacterial infections: do we need new strategies?

Bacterial infections in patients with hematologic malignancies still represent a severe and life-treating problem. Several observational studies during the last decade have revealed that neutropenic patients with fever are a heterogeneous population with various differences regarding response to initial therapy, development of serious complications and mortality. The role of neutropenia as main risk factor for infections in hematologic patients and the definition of different level of risk related to neutrophils count and duration of neutropenia have been extensively studied and different categories of patients based on the risk of infection, mostly the condition of neutropenia, have been clearly defined. The strategies on antimicrobial therapy and supportive care in hematologic patients need to be continuously assessed, in fact new conditions favouring the occurrence of infectious complications in patients with hematologic malignancies have progressively emerged. The use of oral prophylactic antibiotics in neutropenic cancer patients is still a matter of debate. Before 2005, several trials showed how the prevention of infection can be extremely important in this setting of patients but none was conclusive. In 2005 two meta-analysis and two large randomized clinical trials gave new evidence that antibacterial prophylaxis can reduce in neutropenic patients several important outcomes including mortality. The use of the empiric antibacterial therapy represents the cornerstone of the antimicrobial strategies in the febrile neutropenic patients leading, over the span of 20 years, to a dramatic decrease of deaths: Actually beta-lactam monotherapy is commonly used for the empiric treatment of febrile neutropenia. Recently, large randomized clinical trials and meta-analysis showed that the addition of an aminoglycoside and/or a glycopeptides results in a more favourable outcome only in selected severe infections. The use of antibiotics should be prudent and safe also in neutropenic hematologic patients to prevent emergence of microbial resistance, to save costs, to reduce toxicity. For this reasons, according to the evidence, antibacterial prophylaxis should be restricted to high risk hematologic patients and empiric parenteral antibiotic monotherapy should be recommended in case of febrile neutropenia limiting the use of amynoglicosides and glycopeptides. In the next future, a major effort should be made to state in hematologic patients new risk factors which could more accurately define subgroups for targeted anti-infective strategies.