Considerations in Immune Deficiency

Immune dysfunction increases risk of SSTIs for patients, including the elderly and patients with renal failure, diabetes, Hodgkin's disease, lymphoma, HIV infection, cancer chemotherapy, transplantation (especially bone marrow), and patients who receive long-term immunosuppressive therapies. In the neutropenic or cellular immunity compromised patient SSTIs can be common and caused by a variety of organisms. A systemic infection can transfer to soft tissue in such cases. Unfortunately, typical signs and symptoms can be masked in patients with immune dysfunction. This makes it especially difficult and crucial to carefully diagnose and treat SSTIs.

Initial infections that occur within seven days of the development of neutropenia are most commonly gram-negative or gram-positive bacteria. Subsequent infections more typically include antibiotic-resistant bacteria and fungus or yeast infections. The latter two implicated as the primary cause of infection-associated death in neutropenic patients.

Broad-spectrum agents such as vancomycin, linezolid, and daptomycin can be used to treat even resistant gram-positive infections, while cephalosporins with carbapenems or other combinations may be required to treat Pseudomonas spp. and other infections. Immunocompromised patients with cellulitis in patients with immune deficits is sometimes associated with less common infections such as Cryptococcus neoformans. Repeated infections and antibiotic use can increase the risk for the development of resistant strains. Vancomycin or other antibiotics that cover such resistance may be used empirically in the immunocompromised patient. In some cases, vancomycin resistance may emerge requiring the use of alternate choices of linezolid or daptomycin (though no randomized studies have been reported).

Subsequent infections that occur more than seven days after the onset of neutropenia may include Candida spp., Aspergillis spp., and Fusarium spp.  Careful monitoring should include looking for signs of therapy failure due to incorrect diagnosis of the pathogen(s), severity of infection, and a higher potential for antibiotic resistance. Early treatment for any complicated SSTI will be a key factor in its success.

Patients with cellular-mediated immune dysfunction may experience less-common infections, including Mycobacterium spp. and Norcardia spp. along with a variety of viruses and fungi. Antibacterial medication combinations and antifungal or antiviral medications may be necessary to assure the full suppression of these infections.