Q.1 Which organism is the most common cause of community-acquired pneumonia worldwide?
Klebsiella pneumoniae
Streptococcus pneumoniae
Mycoplasma pneumoniae
Haemophilus influenzae
Explanation - Streptococcus pneumoniae is the leading cause of community-acquired pneumonia globally, especially in adults.
Correct answer is: Streptococcus pneumoniae
Q.2 Which of the following infections is most commonly associated with AIDS?
Toxoplasmosis
Cryptococcus neoformans meningitis
Pneumocystis jirovecii pneumonia
Cytomegalovirus retinitis
Explanation - Pneumocystis jirovecii pneumonia (PCP) is the most common opportunistic infection in patients with untreated or advanced HIV/AIDS.
Correct answer is: Pneumocystis jirovecii pneumonia
Q.3 Which virus is primarily transmitted by Aedes aegypti mosquitoes?
Zika virus
Hantavirus
Rabies virus
Influenza virus
Explanation - Zika virus is transmitted mainly through Aedes aegypti mosquitoes, which also spread dengue and chikungunya.
Correct answer is: Zika virus
Q.4 Which hepatitis virus is transmitted primarily via the fecal-oral route?
Hepatitis A
Hepatitis B
Hepatitis C
Hepatitis D
Explanation - Hepatitis A spreads mainly through contaminated food and water, unlike Hepatitis B and C which are blood-borne.
Correct answer is: Hepatitis A
Q.5 What is the first-line treatment for tuberculosis (TB)?
Amoxicillin
Isoniazid, Rifampicin, Pyrazinamide, Ethambutol
Ciprofloxacin
Erythromycin
Explanation - The standard initial therapy for TB includes a 4-drug regimen: isoniazid, rifampicin, pyrazinamide, and ethambutol.
Correct answer is: Isoniazid, Rifampicin, Pyrazinamide, Ethambutol
Q.6 Which fungal infection is commonly seen in diabetic ketoacidosis patients?
Candida albicans
Aspergillus fumigatus
Mucor species
Histoplasma capsulatum
Explanation - Mucormycosis is particularly seen in patients with uncontrolled diabetes and ketoacidosis.
Correct answer is: Mucor species
Q.7 The 'bull neck' appearance is characteristic of which infection?
Diphtheria
Tetanus
Mumps
Scarlet fever
Explanation - Corynebacterium diphtheriae infection causes massive cervical lymphadenopathy, leading to a 'bull neck' appearance.
Correct answer is: Diphtheria
Q.8 What is the causative organism of syphilis?
Treponema pallidum
Borrelia burgdorferi
Leptospira interrogans
Chlamydia trachomatis
Explanation - Syphilis is caused by the spirochete bacterium Treponema pallidum.
Correct answer is: Treponema pallidum
Q.9 Which infection is associated with Koplik spots?
Measles
Rubella
Chickenpox
Scarlet fever
Explanation - Koplik spots are small, white lesions on the buccal mucosa, pathognomonic for measles.
Correct answer is: Measles
Q.10 Which bacterial infection can cause a 'rice-water stool'?
Cholera
Salmonellosis
Shigellosis
Giardiasis
Explanation - Vibrio cholerae infection causes profuse watery diarrhea, described as 'rice-water stools'.
Correct answer is: Cholera
Q.11 What is the primary vector for malaria transmission?
Aedes mosquito
Anopheles mosquito
Culex mosquito
Sandfly
Explanation - Malaria is transmitted through the bite of female Anopheles mosquitoes carrying Plasmodium species.
Correct answer is: Anopheles mosquito
Q.12 Which drug is used as prophylaxis against Pneumocystis jirovecii pneumonia in HIV patients?
Azithromycin
Cotrimoxazole
Fluconazole
Clindamycin
Explanation - Cotrimoxazole (TMP-SMX) is used as prophylaxis against PCP in immunocompromised patients, especially HIV-positive cases.
Correct answer is: Cotrimoxazole
Q.13 A positive Widal test is associated with which disease?
Cholera
Typhoid fever
Tuberculosis
Brucellosis
Explanation - Widal test detects antibodies against Salmonella typhi antigens, commonly used in typhoid diagnosis.
Correct answer is: Typhoid fever
Q.14 The classic triad of fever, night sweats, and weight loss is seen in:
Tuberculosis
Malaria
Leptospirosis
Dengue
Explanation - Chronic tuberculosis typically presents with fever, night sweats, and weight loss.
Correct answer is: Tuberculosis
Q.15 What is the incubation period of rabies?
1–3 days
7–10 days
1–3 months
1 year
Explanation - The incubation period of rabies varies but is commonly 1–3 months depending on the site of the bite and viral load.
Correct answer is: 1–3 months
Q.16 Which test is the gold standard for diagnosing malaria?
Rapid diagnostic test
Thick and thin blood smear microscopy
ELISA
PCR
Explanation - Microscopy of stained thick and thin blood smears remains the gold standard for malaria diagnosis.
Correct answer is: Thick and thin blood smear microscopy
Q.17 Which disease is caused by Borrelia burgdorferi?
Lyme disease
Leptospirosis
Syphilis
Relapsing fever
Explanation - Borrelia burgdorferi is a spirochete that causes Lyme disease, transmitted by Ixodes ticks.
Correct answer is: Lyme disease
Q.18 What is the drug of choice for treating severe falciparum malaria?
Chloroquine
Quinine
Artemisinin-based combination therapy
Mefloquine
Explanation - WHO recommends artemisinin-based combination therapy (ACT) as first-line treatment for falciparum malaria.
Correct answer is: Artemisinin-based combination therapy
Q.19 Which of the following causes leprosy?
Mycobacterium tuberculosis
Mycobacterium leprae
Mycoplasma pneumoniae
Corynebacterium diphtheriae
Explanation - Leprosy is a chronic infection caused by Mycobacterium leprae, affecting skin and peripheral nerves.
Correct answer is: Mycobacterium leprae
Q.20 Which infection is prevented by BCG vaccination?
Leprosy
Tuberculosis
Tetanus
Diphtheria
Explanation - BCG vaccination provides protection against severe forms of tuberculosis, especially in children.
Correct answer is: Tuberculosis
Q.21 Which antiviral drug is used for influenza treatment?
Acyclovir
Oseltamivir
Ribavirin
Remdesivir
Explanation - Oseltamivir is a neuraminidase inhibitor used in the treatment and prophylaxis of influenza A and B.
Correct answer is: Oseltamivir
Q.22 Which of the following is a zoonotic viral hemorrhagic fever?
Ebola
Polio
Measles
Hepatitis B
Explanation - Ebola virus disease is a zoonotic hemorrhagic fever with high mortality, transmitted from animals to humans.
Correct answer is: Ebola
Q.23 Which parasite causes sleeping sickness?
Plasmodium falciparum
Trypanosoma brucei
Leishmania donovani
Toxoplasma gondii
Explanation - Trypanosoma brucei, transmitted by the tsetse fly, causes African sleeping sickness.
Correct answer is: Trypanosoma brucei
Q.24 Which infection is characterized by a 'ground-glass appearance' on chest X-ray in HIV patients?
Tuberculosis
Pneumocystis jirovecii pneumonia
Histoplasmosis
Cytomegalovirus
Explanation - Pneumocystis pneumonia often shows a diffuse ground-glass opacity on chest radiographs.
Correct answer is: Pneumocystis jirovecii pneumonia
Q.25 What is the causative agent of kala-azar?
Leishmania donovani
Plasmodium vivax
Trypanosoma cruzi
Giardia lamblia
Explanation - Kala-azar, or visceral leishmaniasis, is caused by Leishmania donovani transmitted by sandflies.
Correct answer is: Leishmania donovani