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Human herpesvirus 6, 7, and 8

Over the past several decades, three novel human herpesviruses (HHVs) have been identified and designated HHV-6, HHV-7, and HHV-8. HHV-6 has since been designated as two distinct species, HHV-6A and HHV-6B. HHV-6 was first isolated from the white blood cells of patients with human immunodeficiency syndrome and lymphoproliferative disease in the 1980s. The virus was initially designated as human B-lymphotropic virus, but the name was changed…

Herpes simplex and varicella-zoster viruses

Herpes simplex virus (HSV) types 1 and 2 (HSV-1 and -2) and varicella-zoster virus (VZV) comprise the human α-herpesviruses, a subfamily of enveloped, double-stranded DNA viruses defined in part by the ability to be transmitted and replicate in mucoepithelial surfaces and to establish latent infection in sensory ganglia of the nervous system. Infection with HSV is common, with serologic evidence of HSV-1 infection in about 48%…

Epstein-Barr virus and posttransplant lymphoproliferative disorder

Epstein-Barr virus (EBV) is a human γ-herpesvirus that is associated with important syndromes in both the immunocompetent and immunocompromised host. It is a ubiquitous virus, as it is found worldwide. In community settings, EBV is primarily transmitted by exposure to human saliva since humans are the only known host of the virus. Peaks of primary infection occur in early childhood and young adulthood, with the highest…

Cytomegalovirus

Viral infections represent a significant cause of morbidity and mortality among children who have undergone either solid organ (SOT) or hematopoietic stem cell transplantation (HSCT), as well as in children undergoing therapy for malignancies. Herpesviruses, which possess a unique ability in their life cycle to establish latent infection, are especially significant within these patient populations because of their capacity to reactivate in the setting of immunosuppression.…

Nontuberculous and tuberculous Mycobacterium

Mycobacterium tuberculosis infection Epidemiology, risk factors, and pathogenesis Mycobacterium tuberculosis ( MTB) is among the most successful respiratory pathogens worldwide as the majority of those infected are asymptomatic and will live their lifetime without clinical manifestations. Latent infection is defined as having asymptomatic MTB infection, as the immune system can control but not eradicate the pathogen. In low-incidence areas, latent infection is treated to reduce the…

Bartonella, Legionella, Mycoplasma, and Ureaplasma

Bartonella Epidemiology and risk factors Bartonella species are fastidious, slow-growing, gram-negative bacilli. There are 45 different species that can cause disease in zoonotic hosts, with Bartonella henselae and Bartonella quintana causing most Bartonella -related disease in human hosts in the United States. B. henselae has been reported to cause infection in pediatric and adult heart, liver, and renal transplant recipients and in adult lung transplant recipients.…

Multidrug-resistant gram-negative infections in transplant and oncology patients

Common mechanisms of gram-negative resistance Gram-negative organisms are divided into the Enterobacteriaceae (e.g., Escherichia coli, Klebsiella species, Enterobacter cloacae ) and the glucose nonfermenting gram-negative organisms ( Pseudomonas aeruginosa , Acinetobacter baumannii , Stenotrophomonas maltophilia ). Drug resistance in Enterobacteriaceae is often due to the production of β-lactamases. Common β-lactamases include extended-spectrum β-lactamases (ESBLs), AmpC β-lactamases, and carbapenemases. ESBLs and carbapenemases are generally plasmid mediated, whereas…

Safe living after transplantation or chemotherapy

Prevention of infections by direct contact Children are particularly prone to infections acquired by direct contact. Frequently, children engage in behaviors that place them at risk, such as placing their hands in their nose or mouth and then touching surfaces, playing in close proximity to others, and coughing or sneezing without observing adequate etiquette. Studies have shown that hand hygiene rates among children and adolescents in…

Hospital infection prevention for pediatric transplant recipients and oncology patients

General principles Children with deficient immune mechanisms, immunologic disorders, or those receiving immunosuppressive therapy (e.g., radiation, cytotoxic chemotherapy, antirejection medication, and steroids) are identified as high-risk patients with the greatest risk of acquiring healthcare-associated infections. Patients in this subset include those who are severely neutropenic for prolonged periods of time (i.e., an absolute neutrophil count ≤500 cells/mL), allogeneic hematopoietic stem cell transplantation (HSCT) patients, and those…

Antimicrobial stewardship in immunocompromised hosts

Antimicrobial stewardship refers to the appropriate selection, dosing, route, and duration of antimicrobial therapy to optimize patient outcomes and minimize toxicity and the development of resistant pathogens. Over the past decade, the number of pediatric antimicrobial stewardship programs (ASPs) has increased. Pediatric ASPs, which typically include dedicated pediatric infectious diseases–trained physicians and pharmacists, have expanded from freestanding children’s hospitals to pediatric units within larger hospitals to…

Microbiome implications in transplantation and oncology

At birth, infants become colonized with trillions of commensal microbes that play important roles in health and disease. The majority of these microbes reside in the gastrointestinal tract, reaching densities of 10 12 bacteria per gram of intestinal content in the colon. Complex microbial communities are also found on all human surfaces, including the skin, oropharynx, vagina, and lung. These microbiomes are highly abundant—bacteria represent an…

Vaccination issues for transplantation and chemotherapy

Vaccination has repeatedly been acknowledged as one of the most important tools for reduction of mortality worldwide and one of the most cost-effective ways to decrease health care–related costs. Immunocompromised children are at higher risk of complications caused by vaccine-preventable pathogens; however, it has been recurrently demonstrated that they are undervaccinated. , This can be linked to several factors, such as an overlooked priority in an…

Management principles for patients with neutropenia

Chemotherapy agents have been the cornerstone of cancer treatments since the 1960s when the first concerted attempts were made to treat cancer. Although these agents are effective at destroying cancer cells, they often indiscriminately destroy other healthy cells, such as epithelial cells and leukocytes, with rapid turnover. Not long after chemotherapy agents were initially used in cancer treatment, clinicians and researchers recognized the negative consequences of…

Prevention of infections in the solid organ transplantation recipient

Solid organ transplantation (SOT) has transformed the prognosis of many children with organ failure. An estimated 135,860 SOTs were performed worldwide in 2016. A total of 33,610 SOTs were performed in the United States, with children, the majority of whom were younger than 10 years, receiving 1878 of these transplants. , Despite advances in the field of transplantation, infections remain an important cause of morbidity and…

Prevention of infections in the hematopoietic stem cell transplant recipient

Patients who undergo hematopoietic stem cell transplantation (HSCT) are at risk for developing bacterial, fungal, viral, and/or parasitic infections, particularly those who receive allogeneic transplants. Infections in these patients are associated with high rates of morbidity and mortality; therefore preventative strategies are of outmost importance. For the purpose of this chapter, the term HSCT includes receipt of blood- or marrow-derived hematopoietic stem cells, regardless of transplant…

Donor screening and donor-derived infections

Donors of cells or organs are important potential sources of infection in children undergoing hematopoietic stem cell (HSCT) or solid organ transplantation (SOT). In both settings, the donor may be a source of anticipated or unanticipated transmission of pathogens to the recipient. Parents and patients are often appropriately focused on the transplant itself as a lifesaving procedure and therefore do not always appreciate that there may…

Infectious disease evaluation of infants and children awaiting solid organ or hematopoietic stem cell transplant

Basic principles of the infectious disease pretransplant evaluation The pretransplant infectious disease evaluation represents the first step in a long continuum of infection prevention that extends into the posttransplant period. This evaluation is a critical element in the pretransplant process and should be performed as early as possible, ideally as soon as a child is considered for transplant. The overall objectives of infectious disease evaluation are…

Cancer and antineoplastic therapies and the risk of infection in the pediatric cancer patient

Invasive infections are a common source of morbidity and mortality in children with cancer. The risk for infectious complications during therapy for cancer is inversely related to age: children with cancer are more commonly affected by infection compared with adult oncology patients, and infants are more vulnerable to infection than older children. This is due to both environmental exposures that occur in childhood and the chemotherapy…

Immunologic recovery and basis for infections in the pediatric hematopoietic stem cell transplant recipient

Infections are one of the most frequent serious complications of hematopoietic stem cell transplantation (HSCT). The risk of infections corresponds to the complex interplay between organ dysfunction or tissue damage, exposure to pathogens, virulence of those pathogens, and the net state of immunosuppression. Although all of these factors are interrelated and each contributes to infection risk in some way, the time to recovery of the immune…

The surgical and immunosuppressive basis for infections in the pediatric solid organ transplant recipient

Balanced immunosuppression is essential to ensure acceptance of a solid organ transplant and an overall successful patient outcome. The fundamental purpose of immunosuppression is to modulate the immune system’s ability to recognize the transplanted organ. However, an overly suppressed immune system increases the risk of certain infections in pediatric solid organ transplant recipients. The goal of balanced immunosuppression is to carefully walk the fine line between…