Infectious Diseases Practice Questions

Q: Which one of the following is typically associated with the given clinical finding?

Treatment with a sulfonylurea. ***Treatment with a sulfonylurea*** - **Diabetes mellitus** is the most typical association with **rhinocerebral mucormycosis**, accounting for approximately **70% of cases**. - **Sulfonylureas** are antidiabetic medications indicating underlying diabetes, which creates the **hyperglycemic** and **acidotic** environment that favors **Mucor** growth. *Bulimia nervosa* - Not a recognized risk factor for **mucormycosis** as it doesn't create the immunocompromised state necessary for fungal invasion. - Primarily associated with **dental erosion** and **electrolyte imbalances**, not opportunistic fungal infections. *Recent endotracheal intubation* - While trauma can predispose to infections, **endotracheal intubation** is not a classic risk factor for **mucormycosis**. - More commonly associated with **bacterial pneumonia** or **aspiration pneumonia** rather than invasive fungal infections. *Acquired immunodeficiency syndrome (AIDS)* - Although **AIDS** can predispose to mucormycosis, it is **less commonly** the typical association compared to diabetes. - **AIDS patients** are more prone to **Candida**, **Cryptococcus**, and **Pneumocystis** infections rather than mucormycosis.

Q: A 24-year-old patient complains of diarrhea, vomiting, and abdominal pain aggravated on ingestion of food for 1 week. Stool microscopy reveals findings suggestive of parasitic infection. What is the appropriate treatment for this condition?

Ivermectin. ***Ivermectin*** - The combination of **diarrhea, vomiting, and abdominal pain** with stool microscopy showing **rhabditiform larvae** is pathognomonic of **Strongyloides stercoralis** infection. - **Ivermectin** is the **first-line treatment** for strongyloidiasis, with excellent efficacy against both intestinal and disseminated forms. *Tinidazole* - Primarily effective against **anaerobic bacteria** and **protozoa** like **Giardia** and **Entamoeba histolytica**. - Not effective against **helminths** like Strongyloides, which require antiparasitic agents with different mechanisms. *Praziquantel* - Specifically used for **trematode** (flukes) and **cestode** (tapeworm) infections like **Schistosoma** and **Taenia**. - Has **no activity** against **nematodes** like Strongyloides stercoralis, making it inappropriate for this case. *Niclofolan* - An **anthelmintic** primarily used for **liver flukes** and other **trematode infections** in veterinary medicine. - **Rarely used** in human medicine and **ineffective** against Strongyloides, which is a nematode parasite.

Q: Hemorrhagic rashes are typically seen in which of the following conditions?

Meningococcal infection. Explanation: The correct answer is **Meningococcal infection**. This condition, caused by *Neisseria meningitidis*, is a classic cause of a rapidly progressing hemorrhagic rash. **1. Why Meningococcal infection is correct:** The hallmark of meningococcemia is a **petechial or purpuric rash**. The underlying mechanism is **disseminated intravascular coagulation (DIC)** and perivascular inflammation (vasculitis). Bacterial endotoxins trigger widespread endothelial damage, leading to capillary leak and microvascular thrombosis. This manifests clinically as non-blanching petechiae that can coalesce into large ecchymoses known as **purpura fulminans**. **2. Why the other options are incorrect:** * **Malaria:** While severe *P. falciparum* can cause DIC and bleeding manifestations in late stages, it typically presents with fever, chills, and anemia. A hemorrhagic rash is not a primary diagnostic feature. * **Enteric Fever (Typhoid):** This is associated with **"Rose Spots"**—faint, salmon-colored, blanching macules usually found on the trunk. They are not hemorrhagic. * **Pneumonia:** Typical bacterial pneumonia (e.g., *S. pneumoniae*) presents with cough, fever, and pleuritic chest pain. Skin rashes are not a standard feature unless associated with specific pathogens like *Mycoplasma* (Erythema Multiforme). **Clinical Pearls for NEET-PG:** * **Waterhouse-Friderichsen Syndrome:** Adrenal hemorrhage secondary to severe meningococcemia, leading to acute adrenal insufficiency and shock. * **Glass Test:** A simple bedside test where a glass tumbler is pressed against the rash; if the spots do not fade (non-blanching), it suggests a medical emergency like meningococcal sepsis. * **Other Hemorrhagic Fevers:** Always consider Dengue (thrombocytopenia) and Rickettsial diseases (Rocky Mountain Spotted Fever) in the differential diagnosis of petechial rashes [1].

Q: A 45-year-old male patient presents with cough and diarrhea for the past 3 weeks. He is diagnosed as HIV positive with Tuberculosis. What should be the next line of management?

Start ATT followed by A. **Explanation:** The management of HIV-TB co-infection is a high-yield topic for NEET-PG. The primary goal is to treat the life-threatening opportunistic infection (TB) first while minimizing the risk of **Immune Reconstitution Inflammatory Syndrome (IRIS)** [1]. **1. Why Option A is Correct:** According to WHO and National Guidelines (NACO), **Anti-Tubercular Therapy (ATT)** should always be initiated first [3]. **Antiretroviral Therapy (ART)** is then added after a short interval (usually 2 weeks to 2 months). Starting ATT first reduces the mycobacterial load, which significantly lowers the risk and severity of IRIS once the immune system begins to recover under ART [1]. **2. Why Other Options are Incorrect:** * **Option B:** Starting ART before ATT is contraindicated. It increases the risk of severe IRIS and high pill burden, leading to poor compliance and potential drug-drug interactions (e.g., between Rifampicin and Protease Inhibitors) [2]. * **Option C:** Starting ATT alone is insufficient. Without ART, the patient remains severely immunocompromised, leading to further opportunistic infections and increased mortality [4]. * **Option D:** While waiting 6–8 weeks was previously common for patients with high CD4 counts, current guidelines emphasize starting ART as soon as ATT is tolerated (within 2 weeks if CD4 50/mm³, start ART within **8 weeks** [3]. * **Exception:** In **TB Meningitis**, ART should be delayed for 4–8 weeks regardless of CD4 count to prevent life-threatening intracranial IRIS. * **Drug Choice:** Efavirenz is the preferred NNRTI with Rifampicin-based ATT, though Dolutegravir (standard in current regimens) requires a dose increase to 50mg twice daily due to enzyme induction by Rifampicin [2].

Q: What is occult hepatitis B?

HBV DNA < 104 copies/ml with HBsAg negative. **Explanation:** **Occult Hepatitis B Infection (OBI)** is defined by the presence of replication-competent HBV DNA in the liver (and sometimes the serum) of individuals who test **negative for Hepatitis B surface antigen (HBsAg)** using routine assays. 1. **Why Option A is correct:** The hallmark of occult HBV is the absence of HBsAg despite the presence of HBV DNA [1]. In OBI, the viral load is typically very low, usually **<200 IU/ml** (roughly equivalent to **<10⁴ copies/ml**) [1]. This occurs because the virus persists in the hepatocytes as covalently closed circular DNA (cccDNA), but viral gene expression is suppressed by the host immune system, keeping HBsAg levels below the detection threshold. 2. **Why the other options are incorrect:** * **Option B:** If HBsAg is positive, the infection is by definition "Overt" rather than "Occult." This would be classified as chronic HBV infection or an inactive carrier state depending on other markers. * **Options C & D:** The status of HBeAg (envelope antigen) does not define occult hepatitis. While OBI is almost always HBeAg negative, the defining criteria must involve the absence of HBsAg. **High-Yield Clinical Pearls for NEET-PG:** * **Serology:** Most OBI patients are **anti-HBc positive** (indicating past exposure), but "seronegative" OBI (anti-HBc negative) can also occur. * **Clinical Significance:** OBI is a significant risk factor for **Hepatocellular Carcinoma (HCC)** and can lead to **reactivation** (fulminant hepatitis) in patients undergoing chemotherapy or immunosuppression (especially Anti-CD20 therapy like Rituximab). * **Transmission:** OBI can be transmitted via blood transfusion or liver transplantation; hence, nucleic acid testing (NAT) is used in blood banks to screen donors.

Q: Which of the following is the most common oral manifestation of infectious mononucleosis?

Pinpoint petechiae on the palate. **Explanation:** **Infectious Mononucleosis (IM)**, primarily caused by the **Epstein-Barr Virus (EBV)**, is a systemic viral infection characterized by the triad of fever, pharyngitis, and lymphadenopathy. **Why the correct answer is right:** The most characteristic and common oral manifestation of IM is the presence of **palatal petechiae**. These are pinpoint, non-blanching red spots typically located at the junction of the hard and soft palate. They occur in approximately 25–60% of cases and are a high-yield diagnostic sign for clinicians. **Analysis of incorrect options:** * **A. Bluish red spots opposite maxillary molars:** These are **Koplik spots**, which are pathognomonic for **Measles (Rubeola)**, not IM. * **B. Pseudomembrane on gingiva:** While IM can cause an exudative pharyngitis/tonsillitis (pseudomembrane on tonsils), a pseudomembrane localized to the gingiva is more characteristic of **Acute Necrotizing Ulcerative Gingivitis (ANUG)** or Diphtheria. * **D. Gingival hyperplasia:** This is typically associated with medications (Phenytoin, Cyclosporine, Nifedipine) or conditions like AML (M5 subtype), but not viral infections like EBV. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** Heterophile antibody test (**Monospot test**) is the screening test of choice. * **Hematology:** Peripheral smear shows **Atypical Lymphocytes (Downey cells)**, which are actually activated T-cells (CD8+). * **Clinical Caution:** Administration of **Ampicillin or Amoxicillin** in a patient with IM often results in a characteristic maculopapular skin rash. * **Complication:** Splenic rupture is a rare but life-threatening complication; patients are advised to avoid contact sports.

Question 1

Which one of the following is typically associated with the given clinical finding?

Accepted Answer

Treatment with a sulfonylurea

Answer

Bulimia nervosa

Answer

Recent endotracheal intubation

Answer

Acquired immunodeficiency syndrome (AIDS)

Question 2

A 24-year-old patient complains of diarrhea, vomiting, and abdominal pain aggravated on ingestion of food for 1 week. Stool microscopy reveals findings suggestive of parasitic infection. What is the appropriate treatment for this condition?

Accepted Answer

Ivermectin

Answer

Tinidazole

Answer

Praziquantel

Answer

Niclofolan

Question 3

Hemorrhagic rashes are typically seen in which of the following conditions?

Accepted Answer

Meningococcal infection

Answer

Malaria

Answer

Enteric fever

Answer

Pneumonia

Question 4

A patient presents with arthralgia, a rash, lymphadenopathy, and pneumonia, but no fever. Which of the following conditions is most likely given these symptoms?

Accepted Answer

Dengue fever

Answer

St. Louis encephalitis

Answer

Infectious mononucleosis

Answer

Hepatitis

Question 5

A 31-year-old Haitian woman is evaluated for infertility. Pelvic examination shows a markedly enlarged vulva, inguinal lymph node enlargement, and rectal stricture. Biopsy of an inguinal lymph node reveals necrotizing granulomas, neutrophilic infiltrates, and inclusion bodies within macrophages. Which of the following is the most likely etiology of infertility in this patient?

Accepted Answer

Chlamydia trachomatis

Answer

Gardnerella vaginalis

Answer

Molluscum contagiosum

Answer

Mycobacterium tuberculosis

Question 6

A 45-year-old male patient presents with cough and diarrhea for the past 3 weeks. He is diagnosed as HIV positive with Tuberculosis. What should be the next line of management?

Accepted Answer

Start ATT followed by A

Answer

Start A followed by ATT

Answer

Start ATT

Answer

Start A then start ATT after 6-8 weeks

Question 7

In fever of unknown origin, how many blood samples should ideally be drawn?

Accepted Answer

3

Answer

2

Answer

4

Answer

5

Question 8

Trophic ulcers are seen in which of the following conditions?

Accepted Answer

Leprosy

Answer

Poliomyelitis

Answer

Syringomyelia

Answer

Tuberculous Meningitis

Question 9

What is occult hepatitis B?

Accepted Answer

HBV DNA < 104 copies/ml with HBsAg negative

Answer

HBV DNA < 104 copies/ml with HBsAg positive

Answer

HBV DNA < 104 copies/ml with HBeAg negative

Answer

HBV DNA < 104 copies/ml with HBeAg positive

Question 10

Which of the following is the most common oral manifestation of infectious mononucleosis?

Accepted Answer

Pinpoint petechiae on the palate

Answer

Bluish red spots opposite maxillary molars

Answer

Pseudomembrane on gingiva

Answer

Gingival hyperplasia

Infectious Diseases — MCQs

Infectious Diseases — MCQs

On this page

Practice by Chapter

Want unlimited practice?