Infections in immunocompromised patients. II. Established therapy and its limitations.

Diseases affecting host defense mechanisms include neutropenia, aplastic anemia, leukemia, lymphocytopenia (B- and T-lymphocyte abnormalities), deficiencies of complement, splenectomy, diabetes mellitus, renal failure, and autoimmune diseases. Immunocompromised patients face frequent life-threatening complications of infections, particularly when they are hospitalized and receiving cytotoxic myelosuppressive drugs. Oral antimicrobial agents affect the flora of the host's alimentary tract, enhancing colonization by resistant, potentially pathogenic, strains and species, especially in a hospital environment. Nalidixic acid, oxolinic acid, pipemidic acid, polymyxins, co-trimoxazole, polyene antibiotics, and framycetin, which preserve anaerobic colon flora, do not affect the host's colonization resistance and can be given in oral doses high enough to suppress and clear susceptible potential pathogens from the intestinal tract. Such prophylactic treatment permits patients to stay hospitalized in ward conditions. In the compromised host who has fever and suspected septicemia, a decision concerning treatment should be made within an hour of notification of the patient's condition. In acute stages of life-threatening infection, the principal aim of antimicrobial chemotherapy is to provide the most potent treatment; at this stage, the accompanying side effects are less important. An essential component of therapy should be an aminoglycoside paired with a beta-lactam antibiotic. Because the incidence of staphylococcal resistance to antibiotics is high, preliminary sensitivity-testing is essential when staphylococcal sepsis threatens the life of a compromised host. Despite aggressive antibiotic therapy, more than half of immunocompromised patients and patients with severe underlying diseases die when gram-negative bacteria invade their blood. In these patients, medical or surgical removal of the septic focus is a major part of management, but plasma or plasma fractions should be given to correct hypovolemia, and an agent such as dopamine should be administered if volume replacement fails to restore adequate blood pressure. A high dose of corticosteroids should have a beneficial effect, and, for neutropenic patients with gram-negative bacteremia or fever, transfusion with functional neutrophils improves survival.