Caused by anaerobes e.g. Peptostreptococcus, Fusobacterium, Bacteroides, Prevotella Risk factors include an altered level of consciousness which is often due to: seizures, brain injury, dementia generalized anesthesia or sedation drug or alcohol intoxication elderly Aspiration most often occurs on the right side because the right main stem bronchus is larger and more vertical than the left Symptoms can include cough, fever, dyspnea on exertion Aspiration pneumonia often leads to lung abscesses