Staphylococcus, Streptococcus, and Enterococcus

Abstract

Gram-positive bacteria (GPB) are an important cause of systemic disease in immunocompromised patients, especially those undergoing transplantation. A rise in infections due to GPB in the last two decades has been attributed to a variety of reasons that prominently include antimicrobial prophylaxis with a focus on prevention of Gram-negative bacterial infections. The near-universal use of indwelling intravascular access devices that are usually retained for an extended duration also contributes toward this trend. In solid organ transplant recipients, postsurgical wound and deep tissue infections resulting from tissue ischemia, prolonged and complicated surgical procedures, allograft rejection, and severity of iatrogenic, drug-induced immune suppression are important factors contributing toward bacterial infections, and GPB are conspicuous among such infections, whereas in stem cell transplant population, presence of mucositis involving the orointestinal tract , severe and prolonged pre-engraftment neutropenia, and graft-versus-host disease involving the skin and orointestinal tract are considered important risk factors for GPB infections. Emergence and widespread distribution of community-acquired methicillin-resistant Staphylococcus aureus has led to the trend for invasive GPB disease among a wide spectrum of population, which also includes transplant recipients. Early diagnosis, prompt institution of appropriate therapy, assessment for outcome prognosticators, and recognizing the potential for early and late infection- and treatment-related complications form the bases for optimum management for such infections. In this chapter, medically important GPB pathogens are discussed, with an emphasis on epidemiology, disease pathogenesis, risk factors, clinical presentation, and management for patients undergoing solid organ and hematopoietic stem cell transplantation.