Pathology and Microbiology Flashcards

Which type of necrosis is most commonly associated with ischemic infarction of the heart?

Answer: Coagulative necrosis

Coagulative necrosis preserves cell outlines and is the hallmark of ischemic infarcts in solid organs like the heart.

A postmortem culture of lung tissue grows Streptococcus pneumoniae. Which staining technique best identifies this organism in tissue sections?

Answer: Gram stain

Gram stain differentiates bacteria by cell wall composition and readily identifies S. pneumoniae as gram-positive diplococci.

Which virulence factor allows Clostridium perfringens to rapidly spread through tissue postmortem?

Answer: Alpha toxin (lecithinase)

Alpha toxin destroys cell membranes by cleaving phospholipids, enabling the rapid tissue destruction seen in gas gangrene.

Petechiae on the epicardial surface observed during autopsy are most indicative of:

Answer: Disseminated intravascular coagulation

DIC causes widespread microthrombi and concurrent hemorrhage, producing petechial hemorrhages on serosal surfaces.

Which organism is the most common cause of bacterial endocarditis and may be identified at autopsy on cardiac valves?

Answer: Staphylococcus aureus

S. aureus is the leading cause of acute bacterial endocarditis, producing large destructive vegetations on heart valves.

At autopsy, a 'nutmeg liver' appearance is most consistent with:

Answer: Chronic passive congestion

Chronic passive congestion from right heart failure causes centrilobular congestion alternating with periportal pallor, resembling a cut nutmeg.

Which postmortem change is caused by the action of anaerobic bacteria producing gases within body cavities?

Answer: Putrefaction

Putrefaction involves microbial decomposition that generates sulfur-containing gases and CO2, causing bloating and discoloration.