BMS Pathology and Microbiology 2 — Questions and Answers
Question 1: Which type of necrosis is most commonly associated with ischemic infarction of the heart?
- Coagulative necrosis (Correct answer)
- Liquefactive necrosis
- Caseous necrosis
- Fat necrosis
Correct answer: Coagulative necrosis
Coagulative necrosis preserves cell outlines and is the hallmark of ischemic infarcts in solid organs like the heart.
Question 2: A postmortem culture of lung tissue grows Streptococcus pneumoniae. Which staining technique best identifies this organism in tissue sections?
- Gram stain (Correct answer)
- Ziehl-Neelsen stain
- Periodic acid-Schiff stain
- Gomori methenamine silver stain
Correct answer: Gram stain
Gram stain differentiates bacteria by cell wall composition and readily identifies S. pneumoniae as gram-positive diplococci.
Question 3: Which virulence factor allows Clostridium perfringens to rapidly spread through tissue postmortem?
- Alpha toxin (lecithinase) (Correct answer)
- Protein A
- Capsule
- Pili
Correct answer: Alpha toxin (lecithinase)
Alpha toxin destroys cell membranes by cleaving phospholipids, enabling the rapid tissue destruction seen in gas gangrene.
Question 4: Petechiae on the epicardial surface observed during autopsy are most indicative of:
- Disseminated intravascular coagulation (Correct answer)
- Arteriosclerosis
- Cardiac tamponade
- Pulmonary embolism
Correct answer: Disseminated intravascular coagulation
DIC causes widespread microthrombi and concurrent hemorrhage, producing petechial hemorrhages on serosal surfaces.
Question 5: Which organism is the most common cause of bacterial endocarditis and may be identified at autopsy on cardiac valves?
- Staphylococcus aureus (Correct answer)
- Treponema pallidum
- Mycobacterium tuberculosis
- Candida albicans
Correct answer: Staphylococcus aureus
S. aureus is the leading cause of acute bacterial endocarditis, producing large destructive vegetations on heart valves.
Question 6: At autopsy, a 'nutmeg liver' appearance is most consistent with:
- Chronic passive congestion (Correct answer)
- Acute hepatitis
- Hepatic steatosis
- Cirrhosis
Correct answer: Chronic passive congestion
Chronic passive congestion from right heart failure causes centrilobular congestion alternating with periportal pallor, resembling a cut nutmeg.
Question 7: Which postmortem change is caused by the action of anaerobic bacteria producing gases within body cavities?
- Putrefaction (Correct answer)
- Rigor mortis
- Livor mortis
- Algor mortis
Correct answer: Putrefaction
Putrefaction involves microbial decomposition that generates sulfur-containing gases and CO2, causing bloating and discoloration.
BMS Pathology and Microbiology 2
Which type of necrosis is most commonly associated with ischemic infarction of the heart?