Pneumonia and Host Defense in the Elderly

Abstract

The population worldwide continues to age, with those over the age of 80 years constituting the fastest-growing sector of the population. As one ages, infectious complications become more frequent, leading to higher rates of hospitalization. This is also true for the lung, where pneumonia is one of the most frequent causes for hospitalization in the elderly and is the number 3 cause of death in the United States. Several unique changes occur with aging, both in the structure and the function of the respiratory system itself and in the immune system, which increase the predisposition and the potential severity of pneumonia as one ages. In this review, we will highlight the risk factors that are associated with the increased incidence of pneumonia in the elderly and will explore the changes that occur with aging, with focus on the innate and the adaptive immune systems that increase their predisposition to infections. (Clin Pulm Med 2015;22:271-278) T he United States' (US) population is aging, with those over the age of 80 years constituting the fastest-growing sector in the US. 1,2 As the lifespan is extending and the absolute number of patients who are identified as elderly (typically stated as those older than 60 to 65 y old) is increasing, a greater focus has been placed on meeting the health care needs of this population. Similar to the opposite end of the age spectrum, that of infancy and childhood, it has been increasingly understood that unique changes occur with aging, both at the structural and the cellular levels, which alter the physiological response both in health and with disease. These age-specific changes in the physiology will require unique approaches and treatments for medical conditions that arise in the elderly. In addition to age-related alterations in the physiology, social changes occur, leading to changes in the living situation/residence, wealth, and the socioeconomic status (SES). These changes increase the susceptibility to infections as one ages. 3 Although these differences have been recognized in the outpatient setting with the specialty of Geriatrics, hospitalized elderly patients are typically cared for by those without specific training in caring for the elderly. This is particularly true for Pulmonary and Critical Care physicians. Overall, differences in the management of elderly patients in the inpatient setting, and particularly in the intensive care unit, are just beginning to be recognized. As more knowledge is gained, it is likely that aging-specific therapies and guidelines will be in place to manage these patients optimally. Furthermore, aging should be considered as a continuous spectrum and not something that ends once the age of 60 to 65 years is reached. Structural and cellular functions continue to change in those termed elderly (older than 60 to 65 y) and in those very elderly (older than 80 y). As the population continues to age, more differences will likely be identified. In this review, we will explore the unique features of aging as it relates to the most com...

Insights Into the Effects of Mucosal Epithelial and Innate Immune Dysfunction in Older People on Host Interactions With Streptococcus pneumoniae

“…Why older people are so vulnerable to disease caused by S. pneumoniae is likely to be multifactorial including co-morbidities, relative immunodeficiency, malnutrition and defective swallowing ( Janssens and Krause, 2004 ; Zalacain, 2004 ; Arndt, 2015 ). Disease follows pneumococcal carriage and reported nasopharyngeal and oropharyngeal carriage rates in older people vary between 0–39% ( Krone et al., 2015 ; Adler et al., 2020 ; Almeida et al., 2020 ; Smith et al., 2020 ; Yasuda et al., 2020 ).…”