Bacterial infections represent a major cause of morbidity in solid organ transplant recipients (OTRs). Soft-tissue infections from bacteria generally occur in the first month after transplantation when the skin is disrupted by the surgery itself or by indwelling catheters and lines. The incidence of wound infections in solid organ transplant patients ranges from 2 to 56% depending on surgical technique, host characteristics, and antibiotic prophylaxis.

The skin flora may also be a source of infection when introduced into normally sterile tissue, such as the transplanted organ itself. Surgical contamination of allografts can lead to pyelonephritis and cystitis in renal transplant recipients, cholangitis and intra-abdominal abscesses in liver transplants, and bronchitis and pneumonia in the lung transplant recipient. If infection is not promptly addressed, bacteremia may ensue and manifest itself to a dermatologist as subcutaneous abscesses from hematogenous spread.

In this chapter, we will discuss bacterial infections in solid organ transplant patients. In the setting of immunosuppression, it is helpful to characterize pathogens by their pathophysiology: (1) true pathogens – infection originating in skin and being typical of that which occurs in immunocompetent persons, albeit with the potential for more serious illness in immunosuppressed transplant patients; (2) sometime pathogens – extensive cutaneous involvement with pathogens that normally produce trivial or localized disease in immunocompetent patients; (3) opportunistic pathogens – infection originating from a cutaneous source and caused by opportunistic pathogens that rarely cause disease in immunocompetent patients but that may cause either localized or widespread disease in immunosuppressed transplant patients; (4) indicator of visceral pathogens – cutaneous or subcutaneous infection that represents hematogenous spread from a noncutaneous site. With this framework, we will explore the common cutaneous bacterial pathogens (Table 11.1).