Adenoviruses (AdVs) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or meningoencephalitis. AdV infections are more common in young children, due to lack of humoral immunity. Epidemics of AdV infection may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The disease is more severe and dissemination is more likely in patients with impaired immunity (e.g., organ transplant recipients, human immunodeficiency virus infection). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 50 serotypes of AdV have been identified. Different serotypes display different tissue tropisms that correlate with clinical manifestations of infection. The predominant serotypes circulating at a given time differ among countries or regions, and change over time. Transmission of novel strains between countries or across continents and replacement of dominant viruses by new strains may occur. Treatment of AdV infections is controversial, as prospective, randomized therapeutic trials have not been conducted. Cidofovir is the drug of choice for severe AdV infections, but not all patients require treatment. Live oral vaccines are highly efficacious in reducing the risk of respiratory AdV infection and are in routine use in the military in the United States, but currently are not available to civilians.

Adenoviruses (AdV) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal (GI) tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or encephalitis. Adenovirus infections are more common in young children, owing to lack of humoral immunity. Epidemics of AdV infections may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The disease is more severe, and dissemination is more likely in patients with impaired immunity (eg, organ transplant recipients, human immunodeficiency virus infection, congenital immunodeficiency syndromes). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 50 serotypes of AdV have been identified. Different serotypes display different tissue trophisms and correlate with clinical manifestations of infection. The predominant serotypes differ among countries or regions and change over time. Transmission of novel strains between countries or across continents and replacement of dominant serotypes by new strains may occur. Treatment of AdV infections is controversial because prospective, randomized therapeutic trials have not been done. Cidofovir is considered the drug of choice for severe AdV infections, but not all patients require treatment. Vaccines have been shown to be highly efficacious in reducing the risk of respiratory AdV infection but are currently not available.

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia, meningitis, and bacteremia in children and adults. Invasive pneumococcal disease (IPD) primarily affects young children, older adults (> 65 years of age), and individuals with comorbidities or impaired immune systems. Case fatality rates range from 10 to 30% in adults with IPD but are much lower (< 3%) in children. In this article, we describe the epidemiology of IPD, risk factors, and the influence of host- and organism-specific factors on outcomes. Most cases of IPD are caused by a limited number of serotypes that vary in infectivity and virulence. Vaccinating adults and high-risk patients with the pneumococcal polysaccharide vaccine reduces the incidence of IPD in populations at risk but does not affect nasopharyngeal colonization and has had limited benefit in the population at large. Use of the heptavalent pneumococcal conjugate vaccine (PCV7) in children in the United States since 2000 has resulted in a substantial decline of IPD in both children and adults (by herd immunity), but has facilitated the emergence of serotypes not encompassed in the PCV7 vaccine. Recent reports of “replacement” serotypes that have heightened virulence are worrisome. In this chapter, we discuss the role of vaccines (both polysaccharide and conjugate) and other preventive strategies to limit this important and potentially lethal disease.

Mucormycosis is an infection caused by a group of filamentous molds within the order Mucorales. Infections may result from ingestion of contaminated food, inhalation of spores into the nares or lungs, or inoculation into disrupted skin or wounds. In developed countries, mucormycosis occurs primarily in severely immunocompromised hosts (e.g., those with hematological malignancies, organ transplantation, neutropenia, autoimmune disorders, or other impairments in immunity). Only 6 to 10% of cases occur in subjects with no underlying disease. In contrast, in developing countries, most cases of mucormycosis occur in persons with poorly controlled diabetes mellitus or in immunocompetent subjects following trauma. Mucormycosis exhibits a marked propensity to invade blood vessels, leading to thrombosis, necrosis, and infarction of tissue. Mortality associated with invasive mucormycosis is high (> 30–50%), with 90% mortality associated with disseminated disease. Mortality rates are much lower, though still significant (10–30%), among patients with localized cutaneous disease.The diagnosis of mucormycosis relies upon histopathology and culture. Blood tests are of limited diagnostic value. Even with disseminated disease, blood cultures are usually negative. Mucorales have a distinct histological appearance, with irregular, nonseptate hyphae that branch at right angles. Cultures and/or polymerase chain reaction (PCR) are important to identify the genera.Based on anatomic localization, mucormycosis can be classified as one of six forms: (1) rhino-orbital-cerebral mucormycosis (ROCM), (2) pulmonary, (3) cutaneous, (4) gastrointestinal (GI), (5) disseminated, and (6) mucormycosis of uncommon sites. Among diabetics, ROCM is the most common clinical presentation, whereas lung involvement is uncommon. In contrast, among organ transplant recipients or patients with hematological malignancies (HemeM), pulmonary and disseminated diseases are most common. Mucormycosis can progress rapidly, and delay in initiation of treatment by even a few days markedly worsens outcomes.Due to the rarity of mucormycosis, randomized controlled therapeutic trials have not been performed. Lipid formulations of amphotericin B (LFAB) are the mainstay of therapy, but the newer triazoles, posaconazole (POSA) and isavuconazole (ISAV) (the active component of the prodrug isavuconazonium sulfate), may be effective in patients refractory to or intolerant of LFAB. Early surgical debridement or excision plays an important adjunctive role. Additional studies are required to assess the optimal duration of therapy as well as the specific roles of LFAB and the triazoles in the treatment of mucormycosis.