Introduction

Pneumonia is an infection of the lower respiratory tract that can be caused by bacteria, fungi, viruses, protozoa, or parasites. Community-acquired pneumonia (CAP) occurs in patients who have gotten the infection in the community compared to nosocomial pneumonia which is acquired in a healthcare setting such as a hospital or a nursing facility. Pneumonia has considerable morbidity and mortality, especially in older adults (McCance & Heuther, 2010).

This case study will discuss community-acquired pneumonia. In CAP, it is important to understand the most common causative pathogens. CAP is usually viral or bacterial. Cap can be caused by typical or atypical pathogens. Pneumonia is often characterized by classic symptoms (SOB, wheezing, fatigue, fever); however, symptom presentation may vary slightly depending on the offending microorganism (Miskovich-Riddle & Keresztes, 2006). Common typical bacteria and atypical organisms that cause pneumonia are listed below.

"Typical" bacteria	"Atypical" pathogens
S. pneumonia (~40-70% of CAP), S. aureus (~10 of CAP), H. influenzae, M. catarrhalis, group A streptococci	M. pneumonia (~10-25% of CAP), C. pneumonia (~5-15% of CAP), Legionella pneumophila (~5-10% of CAP), viruses

(Riddle & Keresztes, 2006)

The clinician is unable to distinguish amongst causative pathogens of pneumonia based on an individual's symptoms and physical exam. Laboratory studies must be collected to determine the offending microorganism (Marrie, 2013). However, CAP is usually treated empirically for the most common causative organisms, so cultures are not always indicated.

 

http://internalmedicine.osu.edu/pulmonary/cap/10665.cfm

 

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