Lung Abscess

Question 1

represents necrosis and cavitation of the lung following microbial infection

Answer 1

Lung abscess

Question 2

Lung abscesses can be single or multiple but usually are marked by

Answer 2

single dominant cavity >2 cm in diameter

Question 3

usually arise from aspiration, are often caused principally by anaerobic bacteria, and occur in the absence of an underlying pulmonary or systemic condition

Answer 3

Primary lung abscesses

Question 4

arise in the setting of an underlying condition, such as a postobstructive process (e.g., a bronchial foreign body or tumor) or a systemic process (e.g., HIV infection or another immunocompromising condition).

Answer 4

Secondary lung abscesses

Question 5

acute (<4–6 weeks in duration)

Chronic

Answer 5

chronic (~40% of cases)

Question 6

particular risk for aspiration, such as those with altered mental status
(5)

Answer 6

altered mental status, alcoholism, 
drug overdose, 
seizures, 
bulbar dysfunction, 
prior cerebrovascular or cardiovascular events, 
or neuromuscular disease

Question 7

important in the development of lung abscesses

Answer 7

colonization of the gingival crevices by anaerobic bacteria or microaerophilic streptococci

combined with a risk of aspiration,

Question 8

Primary Lung Abscesses
originate when chiefly anaerobic bacteria (as well as microaerophilic streptococci) in the gingival crevices are aspirated into the lung parenchyma in a susceptible host

Answer 8

Pneumonitis develops initially (exacerbated in part by tissue damage caused by gastric acid); then, over a period of 7–14 days, the anaerobic bacteria produce parenchymal necrosis and cavitation whose extent depends on host–pathogen interaction

Question 9

Secondary Lung Abscesses

bronchial obstruction from malignancy or a foreign body

Answer 9

Lung abscesses also arise from septic emboli, either in tricuspid valve endocarditis (often involving Staphylococcus aureus) or in Lemierre’s syndrome, in which an infection begins in the pharynx (classically involving Fusobacterium necrophorum) and then spreads to the neck and the carotid sheath (which contains the jugular vein) to cause septic thrombophlebitis

Question 10

Intraperitoneal abscess

Answer 10

Untreated peritonitis if overt gram-negative sepsis either does not develop or develops but not fatal

Question 11

B. Fragile

Answer 11

O.5% of the normal flora
Anaerobes most frequently isolated from intraabdominal infections
Most common anaerobic blood stream isolate.
Can act alone to form abscess

Question 12

Virulence factors for b. Fragility

Answer 12

The capsular polysaccharide complex: zwitterionic characteristics