Infectious Diseases Practice Questions

Q: Cardiovascular complications of HIV infection include all of the following, except:

Aortic aneurysm. Explanation: HIV infection can involve any layer of the heart (pericardium, myocardium, or endocardium), primarily due to opportunistic infections, malignancy, or the direct effects of the virus and antiretroviral therapy (ART). **Why Aortic Aneurysm is the Correct Answer:** Aortic aneurysm is **not** a classic or direct cardiovascular complication of HIV. While chronic inflammation in HIV can lead to premature atherosclerosis and coronary artery disease, it does not typically manifest as aortic aneurysms. In contrast, infectious (mycotic) aneurysms are more commonly associated with *Syphilis* or *Salmonella* rather than HIV itself. **Analysis of Incorrect Options:** * **Pericardial Effusion:** This is the **most common** cardiovascular manifestation of HIV. It is often asymptomatic but can be caused by opportunistic infections (TB, Cryptococcus) or malignancies like Kaposi sarcoma. * **Cardiac Tamponade:** Large pericardial effusions, particularly those caused by Tuberculosis (the most common cause of symptomatic effusion in HIV patients), can progress to life-threatening cardiac tamponade. * **Congestive Cardiac Failure (CCF):** HIV-associated cardiomyopathy is a well-recognized entity leading to dilated cardiomyopathy and CCF. It can result from direct HIV invasion of myocytes, nutritional deficiencies (Selenium), or myocarditis caused by CMV or Coxsackie virus. **NEET-PG High-Yield Pearls:** * **Most common cardiac finding in HIV:** Pericardial effusion. * **Most common cause of CCF in HIV:** HIV-associated dilated cardiomyopathy. * **Drug-related complication:** Protease Inhibitors (PIs) are strongly linked to metabolic syndrome, dyslipidemia, and increased risk of **Myocardial Infarction**. * **Marantic Endocarditis:** HIV patients are at risk for Non-Bacterial Thrombotic Endocarditis (NBTE).

Q: Which of the following is NOT a disease caused by Chlamydia?

Granuloma inguinale. ### Explanation The correct answer is **C. Granuloma inguinale**. #### 1. Why Granuloma Inguinale is the Correct Answer Granuloma inguinale (also known as **Donovanosis**) is caused by the Gram-negative intracellular bacterium ***Klebsiella granulomatis*** (formerly *Calymmatobacterium granulomatis*), not by *Chlamydia*. It is characterized by painless, beefy-red, highly vascularized ulcerative lesions that bleed easily on contact. A hallmark diagnostic feature is the presence of **Donovan bodies** (safety-pin appearance) within macrophages on a tissue smear. #### 2. Analysis of Incorrect Options * **A. Lymphogranuloma venereum (LGV):** This is caused by ***Chlamydia trachomatis* serotypes L1, L2, and L3**. It typically presents with a transient primary genital lesion followed by painful regional lymphadenopathy (buboes) and the "Groove sign." * **B. Trachoma:** This is the leading infectious cause of blindness worldwide, caused by ***Chlamydia trachomatis* serotypes A, B, Ba, and C**. * **D. Nonspecific cervicitis:** *Chlamydia trachomatis* (**serotypes D–K**) is the most common bacterial cause of sexually transmitted infections, frequently leading to cervicitis in women and non-gonococcal urethritis (NGU) in men. #### 3. Clinical Pearls for NEET-PG * **Chlamydia Serotypes Memory Aid:** * **A, B, C:** **A**frican **B**lindness (**C**hronic infection/Trachoma). * **D–K:** **D**irect contact (Genital infections, Neonatal conjunctivitis). * **L1–L3:** **L**ymphatics (LGV). * **Donovanosis vs. LGV:** Donovanosis is **painless** and has no true lymphadenopathy (pseudobuboes), whereas LGV involves **painful** lymph node suppuration. * **Drug of Choice:** For most Chlamydial infections, **Azithromycin** (single dose) or **Doxycycline** (7 days) is preferred. For Granuloma inguinale, Azithromycin is the first-line treatment.

Q: What is the best and least toxic treatment for amoebic dysentery?

Metronidazole. **Explanation:** The treatment of amoebic dysentery (caused by *Entamoeba histolytica*) requires an agent that can effectively eliminate trophozoites in the intestinal wall and systemic sites [1]. **Why Metronidazole is correct:** Metronidazole is the **drug of choice** for invasive amoebiasis (amoebic dysentery and liver abscess). It is highly effective against the trophozoite form of the parasite. While it has side effects like a metallic taste and disulfiram-like reaction, it is significantly **less toxic** and more effective than older alternatives like Emetine. **Analysis of Incorrect Options:** * **Emetine (A):** Once a mainstay for severe amoebiasis, it is now rarely used due to its **high toxicity**, particularly its potential for serious cardiotoxicity (arrhythmias, hypotension) and neuromuscular weakness. * **Chloroquine (B):** This drug reaches high concentrations in the liver but not in the intestinal wall. Therefore, it is used only as an adjunct for **amoebic liver abscess**, not for intestinal dysentery. * **Diloxanide furoate (D):** This is a **luminal amoebicide**. It is excellent for treating asymptomatic cyst passers or for eradicating cysts remaining in the gut after a course of metronidazole, but it is ineffective against the invasive trophozoites that cause dysentery. **NEET-PG High-Yield Pearls:** * **Standard Regimen:** Treatment usually involves a "Nitroimidazole" (Metronidazole or Tinidazole) followed by a "Luminal Amoebicide" (Diloxanide furoate or Paromomycin) to prevent relapse. * **Drug of Choice for Asymptomatic Cyst Passers:** Diloxanide furoate. * **Drug of Choice for Amoebic Liver Abscess:** Metronidazole. * **Key Side Effect:** Avoid alcohol with Metronidazole due to the **Disulfiram-like reaction**.

Q: Regarding actinomyces infection, all are true except?

Good response to sulfonamide. Actinomycosis is a chronic, granulomatous infection caused by *Actinomyces israelii*, a Gram-positive, anaerobic, non-acid-fast commensal bacterium. **Why Option D is the Correct Answer (The "Except" statement):** The drug of choice for Actinomycosis is **High-dose Penicillin G** (intravenous followed by oral therapy for 6–12 months). While sulfonamides are the treatment of choice for *Nocardia* [1], they are **not** the standard or effective treatment for *Actinomyces*. This is a high-yield distinction: *Actinomyces* (Anaerobic) = Penicillin; *Nocardia* (Aerobic) = Sulfonamides (TMP-SMX) [1]. **Analysis of Other Options:** * **Option A (Rib periostitis):** Thoracic actinomycosis is known for its "aggressive" nature, crossing anatomical boundaries. It can involve the pleura, chest wall, and ribs, leading to periostitis or osteomyelitis. * **Option B (Multiple sinus formation):** A hallmark of this infection is the formation of chronic, indurated abscesses that eventually drain through multiple cutaneous sinus tracts [1]. * **Option C (Sulfur granules):** These are pathognomonic macroscopic yellow clumps found in the pus. They represent colonies of organisms trapped in a matrix of calcium phosphate and are not actually made of sulfur. **NEET-PG High-Yield Pearls:** * **Morphology:** Gram-positive branching filaments (resembling fungi, but are bacteria). * **Clinical Forms:** Cervicofacial ("Lumpy Jaw") is the most common, followed by Thoracic, Abdominal, and Pelvic (associated with long-term IUD use). * **Diagnosis:** Presence of "Sulfur granules" and growth on anaerobic culture (Molar tooth appearance on agar). * **Key Differentiator:** Unlike *Nocardia*, *Actinomyces* is **not** acid-fast and is an **obligate anaerobe** [1].

Question 1

A 23-year-old woman develops vesicular lesions on an erythematous base on her vulvar area. She has tender lymphadenopathy and dysuria. Which of the following is the most likely causative organism?

Accepted Answer

herpes simplex virus type 2 (HSV-2)

Answer

cytomegalovirus (CMV)

Answer

gonococcus

Answer

Treponema pallidum

Question 2

A 35-year-old woman presented with swelling and pain of her left wrist of ten days' duration. Twelve days prior, she was bitten on the left hand by her pet cat. Two days after the bite, she developed pain, redness, and swelling of her hand. On examination, she had mild fever, an erythematous left wrist and thenar eminence, and reduced range of motion of her fingers. Her white blood cell count was 13,000/ml, with a marked increase in the percentage of immature granulocytes. Gram stain of the wrist fluid was performed. What is the most likely cause?

Accepted Answer

Pasteurella multocida

Answer

Bartonella henselae

Answer

Streptobacillus moniliformis

Answer

Lactobacillus casei

Question 3

Which maturation stage of RBCs is infected by Plasmodium falciparum?

Accepted Answer

RBC of all ages

Answer

Reticulocyte stage only

Answer

Normoblast stage

Answer

Old RBC

Question 4

A person suffers from B27 associated reactive arthritis, urethritis, and conjunctivitis. Which is the most likely organism involved in this case?

Accepted Answer

Ureaplasma urealyticum

Answer

Borrelia burgdorferi

Answer

Beta-hemolytic streptococci

Answer

Streptococcus bovis

Question 5

Cardiovascular complications of HIV infection include all of the following, except:

Accepted Answer

Aortic aneurysm

Answer

Pericardial effusion

Answer

Cardiac tamponade

Answer

Congestive cardiac failure

Question 6

A 50-year-old chronic alcoholic male agricultural worker presented with a one-week history of high-grade fever with chills and rigor. Examination of the respiratory system revealed bilateral crepitations with scattered rhonchi. Multiple subcutaneous nodules were found on the extensor surfaces of the left forearm, arm, and left leg. Direct microscopy of pus aspirated from a skin nodule revealed numerous Gram-negative bacilli with bipolar staining. Culture revealed distinct rough corrugated grey-white colonies on blood agar. The organisms were motile and oxidase-positive. What is the most likely diagnosis?

Accepted Answer

Melioidosis

Answer

Plague

Answer

Bartonellosis

Answer

Actinomycosis

Question 7

A resident doctor sustains a needle-stick injury with a suture needle used on an HIV-infected patient. The patient has been compliant with therapy for several years, recently changed medications due to altered appearance, and has a last CD4 count of 360 cells/mm³. What is the recommended post-exposure prophylaxis regimen for the resident doctor?

Accepted Answer

Zidovudine, Lamivudine, and Indinavir

Answer

Zidovudine and Lamivudine

Answer

Zidovudine, Lamivudine, and Stavudine

Answer

Zidovudine, Lamivudine, and Abacavir

Question 8

Which of the following is NOT a disease caused by Chlamydia?

Accepted Answer

Granuloma inguinale

Answer

Lymphogranuloma venereum (LGV)

Answer

Trachoma

Answer

Nonspecific cervicitis

Question 9

What is the best and least toxic treatment for amoebic dysentery?

Accepted Answer

Metronidazole

Answer

Emetine

Answer

Chloroquine

Answer

Diloxanide furoate

Question 10

Regarding actinomyces infection, all are true except?

Accepted Answer

Good response to sulfonamide

Answer

Rib periostitis/subcutaneous infection

Answer

Multiple sinus formation

Answer

Sulfur granule

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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