Patients with neoplastic disease and suspected infection require the following main factors to be considered in their evaluation: (1) geographic predisposition for exposure to and to acquire infection including prior colonization with drug-resistant organisms and alteration in hosts’ microbiota; (2) known and unrecognized immune defect or defects due to underlying malignancy or antineoplastic therapy, or both (Table 86.1); (3) breakthrough infections due to drug-resistant pathogens in patients receiving antimicrobial chemoprophylaxis, and (4) familial/genetic predisposition to certain infections in the immunocompromised host. The febrile cancer patient may also have fever from noninfectious conditions such as tumor fever or drug fever. After evaluation, the next question is whether to treat empirically.

EPIDEMIOLOGY

People may be exposed to a variety of organisms through travel, work, habits, or hobbies; in the home; or in other hospitals, outpatient clinics, and infusion centers. A person with children at home is likely to be exposed to a number of infectious agents such as influenza, parainfluenza, respiratory syncytial virus, varicella-zoster virus (VZV), human herpesvirus 6 (HHV-6), and cytomegalovirus (CMV). Hospitals are a rich source of antibiotic-resistant microorganisms, including multidrug-resistant Staphylococcus aureus (MRSA), vancomycin-resistant and/or vancomycin-tolerant Enterococcus species, multidrug-resistant Pseudomonas and Stenotrophomonas, and extended-spectrum β-lactamase producing Enterobacteriaceae such as Escherichia coli and Klebsiella species. The recent global spread of carbapenem-resistant Enterobacteriaceae (CRE) has underscored the limitations of antibiotic regimens.