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Viral Respiratory Infections

Abstract Viruses are an important but underrecognized cause of pneumonias. The exact percentage of all pneumonias caused by viral infection is unknown, but viruses are probably responsible for at least 25% of cases. This figure will likely change as a result of utilization of molecular diagnostic panels. The most common respiratory viruses are influenza, rhinovirus, coronavirus, respiratory syncytial virus (RSV), parainfluenza virus, human metapneumovirus, and adenovirus.…

Aspiration Pneumonia

Abstract While microaspiration of oropharyngeal secretions is usually the cause of most cases of community- and hospital-acquired pneumonias, macroaspiration of oropharyngeal or upper gastrointestinal contents is the cause of aspiration pneumonia (AP). Chemical pneumonitis (CP) is triggered by aspiration of acidic gastric material. A variety of different microbial communities exist in the lung. It is postulated that a macroaspiration event may trigger an inflammatory response resulting…

Atypical Pneumonia

Abstract The term atypical pneumonia was first used more than 50 years ago to describe cases of pneumonia caused by an unknown agent(s) and that appeared clinically different from pneumococcal pneumonia. Although the original distinction between atypical and typical pneumonia arose from the perception that the clinical presentation of patients was different, recent studies have shown that there is excessive overlap with clinical manifestations from specific…

Hospital-Acquired Pneumonia

Abstract Hospital-acquired pneumonia (HAP) is a new infection of the lung parenchyma that develops more than 48 hours after hospital admission. Epidemiologic data suggest that HAP occurs in up to 1.6% of patients, prolongs hospital stay by 2 to 3 days, and represents the most common hospital-acquired infection leading to death in critically ill patients. The morbidity and mortality attributed to HAP are significantly increased if…

Community-Acquired Pneumonia, Bacterial

Abstract There have been several new developments concerning community-acquired pneumonia (CAP) since the prior version of Netter’s Infectious Diseases ; these include: advances in molecular diagnostic methods to identify the causative pathogen; increasing awareness of viral etiology; decreasing rate of Streptococcus pneumoniae (although still the most common bacterial cause); increase of macrolide-resistant S. pneumoniae ; awareness of the role of the lung microbiome; and elimination of…

Nontuberculous Mycobacterial Skin and Soft-Tissue Infections

Abstract Nontuberculous mycobacteria (NTM) are a group of acid-fast bacteria that are ubiquitous in the environment. They have been isolated from water and soil, and, when it is possible to identify the etiology, related infections are almost always associated with environmental sources. NTM skin and soft-tissue infections (SSTIs) have been reported with slowly growing NTM species (e.g., avium complex, kansasii, marinum, haemophilum), but rapidly growing NTM…

Herpes Simplex Virus Infection

Abstract Herpes simplex viruses (HSVs) are double-stranded deoxyribonucleic acid (DNA) viruses that cause lifelong infection and frequent reinfections or reactivations. There are two types of HSV: HSV-1, the cause of human cold sores, and HSV-2, the usual cause of genital herpes. Each virus type has different clinical manifestations, modes of transmission, and epidemiologies. The development of type-specific serologic assays has allowed for differentiation between the two…

Superficial Dermatophyte Infections of the Skin

Acknowledgments The authors wish to acknowledge the work of previous edition authors Gregory Raugi and Thao U. Nguyen. Abstract Fungal infections of the skin can be divided into superficial and deep infections. The vast majority are superficial and are caused by dermatophytes, which invade only fully keratinized tissues (stratum corneum, hair, and nails). They are classified into three genera: Epidermophyton, Microsporum, and Trichophyton . Less frequent…

Life-Threatening Skin and Soft-Tissue Infections

Abstract This chapter discusses those soft-tissue infections that are truly life threatening. As such, early clinical recognition is the most important aspect of their clinical management. Staphylococcal and streptococcal toxic shock syndromes (referred to here as StaphTSS and StrepTSS, respectively) have similar clinical features once established, yet their prognosis and management are quite different. Necrotizing soft-tissue infections occur in three distinct settings. The first, necrotizing fasciitis…

Folliculitis, Furuncles, and Carbuncles

Abstract Localized purulent infections of the skin are extremely common in all parts to the world, in all age groups, and in both sexes. Staphylococcus aureus is the single most common cause of these infections; most are minor, requiring only local treatment such as drainage, unless systemic effects are evident, in which case surgical incision and drainage as well as appropriate antibiotics are necessary. In the…

Erysipelas and Cellulitis

Abstract Pathologically, cellulitis is defined as a diffuse area of soft tissue infection characterized by leukocytic infiltration of the dermis, capillary dilatation, and proliferation of bacteria. Clinically, cellulitis is recognized as an acute infection of the skin characterized by localized pain, pinkish erythema, swelling, heat, and a diffuse, indistinct border. Erysipelas is similar to cellulitis but characteristically has fiery red erythema and a distinct border. Cellulitis…

Human Papillomavirus Infections and Prevention

Abstract Human papillomavirus (HPV) is the most common sexually transmitted infection (STI) worldwide and is the etiologic agent of cervical cancer, the majority of anogenital and oropharyngeal cancers, and genital warts. In the United States, vaccination to prevent HPV infection was first introduced in 2006 and is now routinely recommended for adolescent males and females aged 11 to 12 years to prevent morbidity and mortality from…

Hepatitis B Infection

Abstract Hepatitis B infection is one of the most common global health problems. Persons with acute hepatitis B infection can be asymptomatic or present with hepatitis with or without jaundice. Most acute infections resolve without sequelae; however, progression to chronic infection may occur and the risk is inversely related to age at the time of acquisition of infection. This progression to chronic hepatitis B infection may…

Hepatitis A Infection and Prevention

Abstract Hepatitis A infection is the most common cause of viral hepatitis worldwide and a commonly reported vaccine-preventable disease in the United States. Clinical illness—characterized by fever, malaise, jaundice, and nausea—caused by hepatitis A virus (HAV) is similar to hepatitis caused by other viral pathogens. Although most cases of hepatitis A are self-limited, fulminant hepatitis resulting in death may occur. Widespread routine childhood vaccination against hepatitis…

Varicella-Zoster Virus Infections

Abstract Varicella-zoster virus (VZV) causes primary varicella, a common childhood illness called chickenpox. This virus establishes latency and may reactivate later in life, causing herpes zoster, which is commonly called shingles or simply zoster. Although both chickenpox and zoster usually resolve without event, significant complications may develop, even in healthy individuals. In the United States, widespread use of a VZV vaccine in children has diminished the…

Rubella

Acknowledgment The authors acknowledge Alison Margaret Kesson for her contributions as author of a prior version of this chapter. Abstract Rubella (German measles), a leading cause of vaccine-preventable birth defects, is an acute viral infection that can affect people of all ages. When acquired postnatally, rubella is most often characterized by a generalized maculopapular rash, fever, and lymphadenopathy resembling a mild case of measles (rubeola). Many…

Mumps

Acknowledgment The authors acknowledge the work of Alison Margaret Kesson on the previous edition chapter. Abstract Mumps is an acute, highly contagious systemic viral infection and the leading cause of parotitis worldwide. The most common clinical manifestation is nonsuppurative inflammation of the salivary glands, most notably the parotid glands. In most prepubertal children and adults, the illness is benign and self-limited, with one third of infections…