++

Pneumonia is an infection of the pulmonary parenchyma. Despite being the cause of significant morbidity and mortality, pneumonia is often misdiagnosed, mistreated, and underestimated. In the past, pneumonia was typically classified as community-acquired (CAP), hospital-acquired (HAP), or ventilator-associated (VAP). Over the past two decades, however, some persons presenting as outpatients with onset of pneumonia have been found to be infected with the multidrug-resistant (MDR) pathogens previously associated with HAP. Factors responsible for this phenomenon include the development and widespread use of potent oral antibiotics, earlier transfer of patients out of acute-care hospitals to their homes or various lower-acuity facilities, increased use of outpatient IV antibiotic therapy, general aging of the population, and more extensive immunomodulatory therapies. The potential involvement of these MDR pathogens has led to a new category of pneumonia—termed health careassociated pneumonia (HCAP)—distinct from CAP. Conditions associated with HCAP and the likely pathogens are listed in Table 257-1.

++
Table Graphic Jump Location
Table 257-1 Clinical Conditions Associated with and Likely Pathogens in Health Care–Associated Pneumonia 
++

Although the new classification system has been helpful in designing empirical antibiotic strategies, it is not without disadvantages. Not all MDR pathogens are associated with all risk factors (Table 257-1). Moreover, HCAP is a distillation of multiple risk factors, and each patient must be considered individually. For example, the risk of infection with MDR pathogens for a nursing home resident who has dementia but can independently dress, ambulate, and eat is quite different from the risk for a patient who is in a chronic vegetative state with a tracheostomy and a percutaneous feeding tube in place. In addition, risk factors for MDR infection do not preclude the development of pneumonia caused by the usual CAP pathogens.

++

This chapter deals with pneumonia in patients who are not considered to be immunocompromised. Pneumonia in severely immunocompromised patients, some of whom overlap with the groups of patients considered in this chapter, warrants separate discussion (see Chaps. 86, 132, and 189).

++

Pneumonia results from the proliferation of microbial pathogens at the alveolar level and the host's response to those pathogens. Microorganisms gain access to the lower respiratory tract in several ways. The most common is by aspiration from the oropharynx. Small-volume aspiration occurs frequently during sleep (especially in the elderly) and in patients with decreased levels of consciousness. Many pathogens are inhaled as contaminated droplets. ...

Want access to your institution's subscription?

Sign in to your MyAccess Account while you are actively authenticated on this website via your institution (you will be able to tell by looking in the top right corner of any page – if you see your institution’s name, you are authenticated). You will then be able to access your institute’s content/subscription for 90 days from any location, after which you must repeat this process for continued access.

Ok

About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess account, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessMedicine Full Site: One-Year Subscription

Connect to the full suite of AccessMedicine content and resources including more than 250 examination and procedural videos, patient safety modules, an extensive drug database, Q&A, Case Files, and more.

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessMedicine

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.