Impaired pulmonary defenses
Predisposing host factors for pneumonia

• Tracheostomy
• Endotracheal tube
• Mouth breathing

Glottic closure: Aspiration

• Endotracheal tubes, nasogastric feeding tubes, tracheostomy, and pharyngeal anesthesia.
• Deglutition and Dysphagia from neurologic disease or esophageal disease.
• Reduced levels of consciousness that result in dysfunction of the glottic closure and cough reflex: e.g. ethanol abuse, seizures, drug overdose, general anesthesia, CVA, and metabolic encephalopathy

Cough reflex

• Periodontal disease and gingivitis are associated with increased anaerobic inoculums
• Cardiac sphincter problems

Damaged clearance mechanisms 

• smoking

• chronic bronchitis 

• asthma

• viral respiratory infections

 Systemic defects 

• malnourished persons

• alcoholics

• residents of nursing home

• patients with heart disease, diabetes mellitus, liver disease, kidney disease 

Inability to mount an antibody response

• lymphoma

• myeloma

• cancer 

• splenectomy

Phagocytic and cellular  defects

• Leucopenia

• T cell defects ( AIDS)