Free infectious diseases MCQ exam model for clinical students

Explanation:

• Pneumocystis jirovecii pneumonia → Correct because it is most common with low CD4 counts.

• Tuberculosis → Incorrect because it is common but not most frequent opportunistic infection.

• Candidiasis → Incorrect because it commonly affects oral cavity.

• Toxoplasmosis → Incorrect because it affects CNS.

• Cryptococcal meningitis → Incorrect because it is less common.

Explanation:

• Neutrophilia → Correct because neutrophils respond to bacterial infections.

• Lymphocytosis → Incorrect because it is seen in viral infections.

• Eosinophilia → Incorrect because it is seen in parasitic infections.

• Basophilia → Incorrect because it is rare.

• Monocytosis → Incorrect because it is seen in chronic infections.

Explanation:

• Artemisinin-based combination therapy → Correct because it is first-line for severe falciparum malaria.

• Chloroquine → Incorrect because resistance is common.

• Quinine → Incorrect because it is no longer first-line.

• Primaquine → Incorrect because it targets hypnozoites.

• Doxycycline → Incorrect because it is an adjunct only.

Explanation:

• Pathogenic microorganisms → Correct because bacteria, viruses, fungi, and parasites cause infectious diseases.

• Genetic mutations → Incorrect because they cause inherited disorders.

• Autoimmune reactions → Incorrect because they cause autoimmune diseases.

• Metabolic abnormalities → Incorrect because they cause metabolic disorders.

• Hormonal imbalance → Incorrect because they cause endocrine disorders.

Explanation:

• Streptococcus pneumoniae → Correct because it is the leading cause of CAP worldwide.

• Staphylococcus aureus → Incorrect because it is common post-influenza.

• Klebsiella pneumoniae → Incorrect because it occurs in alcoholics and diabetics.

• Mycoplasma pneumoniae → Incorrect because it causes atypical pneumonia.

• Haemophilus influenzae → Incorrect because it is less common.

Explanation:

• Epstein–Barr virus → Correct because it infects B lymphocytes causing mono.

• Cytomegalovirus → Incorrect because it causes mono-like illness.

• Herpes simplex virus → Incorrect because it causes oral/genital lesions.

• Adenovirus → Incorrect because it causes respiratory infections.

• Hepatitis B virus → Incorrect because it causes hepatitis.

Explanation:

• Clostridioides difficile → Correct because toxin-mediated colitis follows antibiotic use.

• Escherichia coli → Incorrect because it causes diarrheal illness.

• Salmonella typhi → Incorrect because it causes enteric fever.

• Shigella dysenteriae → Incorrect because it causes dysentery.

• Vibrio cholerae → Incorrect because it causes watery diarrhea.

Explanation:

• Nosocomial infection → Correct because it refers to infections acquired in hospitals.

• Community-acquired infection → Incorrect because it is acquired outside hospitals.

• Opportunistic infection → Incorrect because it occurs in immunocompromised hosts.

• Latent infection → Incorrect because it is inactive infection.

• Subclinical infection → Incorrect because it is asymptomatic.

Explanation:

• Airborne droplet nuclei → Correct because Mycobacterium tuberculosis spreads via inhalation.

• Fecal–oral route → Incorrect because TB is not transmitted this way.

• Blood transfusion → Incorrect because it is extremely rare.

• Sexual contact → Incorrect because TB is not sexually transmitted.

• Vector-borne transmission → Incorrect because no insect vector is involved.

Explanation:

• Hepatitis B → Correct because effective vaccine is available.

• Malaria → Incorrect because no widely effective vaccine is used clinically.

• Tuberculosis → Incorrect because BCG does not fully prevent infection.

• HIV infection → Incorrect because no vaccine exists.

• Common cold → Incorrect because multiple viruses cause it.