Oral health has increasingly become a priority issue for healthcare agencies in North America and worldwide. This review article attempts to (1) inform various healthcare providers of the risk factors that can arise from poor oral hygiene, specifically aspiration pneumonia; (2) report the mechanisms of bacterial colonization that are responsible for the development of aspiration pneumonia and the factors that can influence these mechanisms; and (3) propose an interdisciplinary approach to enhance oral care delivery that is imperative to limiting the risks of developing systemic diseases such as aspiration pneumonia. Key words: aged, aspiration, dysphagia, health promotion, long-term care, oral hygiene, pneumonia, risk factors
THE links between oral health, general health, and systemic disease in institutionalized elderly populations have been established in the literature.1,2 As a result, major health organizations, both within North America and worldwide, have increasingly mandated oral health as a priority.3–5 As a result of dramatic improvements in general dental health in the western world during the latter half of the 20th century, people are increasingly reaching old age with intact dentition.6 Although this trend indicates improvements in the delivery of dental services, it brings with it an imperative to promote proper oral care delivery to seniors and persons with disability to limit the oralhealth–related risk of systemic diseases such as pneumonia. Pneumonia is the leading cause of acute care hospitalization and the primary cause of death in many diseases found among longterm care (LTC) residents.
7 The reported in-cidence of pneumonia in LTC ranges from 0.1 to 2.4 per 1000 patient days.8 Bacterial pneumonia (as opposed to viral pneumonia) is directly precipitated by aspiration (defined as the inhalation of oropharyngeal secretions into the larynx and down to the lower respiratory tract9 ). Aspiration is a common feature of dysphagia (swallowing difficulty), particularly in the elderly population.10–12 Poor oral hygiene has been linked with the elevated presence of respiratory pathogen (RP) in oropharyngeal secretions.
13,14 When RPs are aspirated, they can overburden host defense mechanisms and lead to infection.9 For this reason, the promotion of high-quality oral care should be a priority strategy for limiting the occurrence of bacterial pneumonia, particularly in individuals with an increased risk of aspiration secondary to dysphagia. SIGNS, SYMPTOMS, AND DIAGNOSIS OF PNEUMONIA The typical signs and symptoms of bacterial pneumonia are cough, fever, tachypnea, chills, and pleuritic chest pain.15,16 A differential diagnosis of aspiration pneumonia is made if predisposing risk factors coexist with typical signs and symptoms of bacterial pneumonia17 ; these predisposing risk factors include a history of aspiration
From the Department of Speech-Language Pathology, University of Toronto (Ms Yoon and Dr Steele), and the Toronto Rehabilitation Institute (Dr Steele), Toronto, Ontario, Canada. Corresponding author: Minn N. Yoon, BSc, Department of Speech-Language Pathology, University of Toronto, 550 University Ave, 12th Floor, Toronto, Ontario, Canada M5G 2A2 (e-mail: [email protected]).
The diagnosis of aspiration pneumonia can be further inferred from characteristic chest radiographic abnormalities involving infiltrates in the superior segment of the lower lobes and the posterior segment of the upper lobes.9,18 The differential diagnosis of aspiration pneumonia in the elderly can be challenging. These patients may present with fewer and more subtle signs and symptoms, which frequently take the form of nonspecific deteriorations in general health.19 Comorbidities such as congestive heart failure and chronic obstructive pulmonary disease may further confound the diagnosis by mimicking the classic symptoms of pneumonia.
20 Furthermore, aspiration pneumonitis (defined as an acute lung injury characterized by acute inflammation of lung airways and parenchyma after the inhalation of regurgitated gastric contents9,17 ) presents similar radiographic findings to those observed in aspiration pneumonia. As a result, the diagnostic label of aspiration pneumonia is likely to be overapplied, and estimates of the prevalence of aspiration pneumonia are unlikely to be accurately reflected in the literature. BACTERIOLOGY Bacteria are most commonly classified according to observable microscopic and physiologic characteristics. Gram-stain reaction (positive or negative) and dependency on oxygen for growth (aerobic vs anaerobic) are the 2 primary characteristics used to describe bacteria.
The structure of the cell wall, determined from the Gram-stain reaction, plays a key role in the resistance of bacteria to various substances. Gram-negative bacteria have cells walls that are more resistant to antibiotics, enzymes, and detergents, and are therefore more likely to be pathogenic.21 BACTERIAL PNEUMONIA Bacterial pneumonia is traditionally divided into 2 etiologically distinct classifications: community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP), otherwise known as nosocomial pneumonia.
These 2 varieties of bacterial pneumonia can be differentiated on the basis of the usual location or timeline of their development, their bacteriology, and characteristics of the patient populations in which they most frequently occur (Table 1). CAP is the diagnostic label applied to pneumonia that develops outside the institutional setting or in patients who have been hospitalized for fewer than 3 days.18 The incidence of CAP is reported to be highest in patients with histories of smoking, alcoholism, chronic pulmonary disease, and/or prior viral infections.18 The main causative organisms of CAP are Streptococcus pneumoniae (an aerobic gram-positive bacterium, or AGPB) and Haemophilus influenzae (an aerobic gram-negative bacterium, or AGNB).2,9,18,19,22
Table 1. Differentiating characteristics of bacterial pneumonia
Community-acquired pneumonia Timeline Causative agents At-risk population Outside hospital or after