Infectious Diseases Practice Questions

Q: A 33-year-old woman presented with a 1-day history of fever and chills. On examination, she was febrile with a blood pressure of 70/40 mmHg. Over several hours, a widespread erythrodermic rash developed, and she collapsed. Further questioning revealed that the patient had removed a tampon shortly before presentation as she had just ceased menstruating. What is the most likely diagnosis?

Toxic shock syndrome. ### Explanation **Correct Answer: D. Toxic shock syndrome (TSS)** The clinical presentation is classic for **Staphylococcal Toxic Shock Syndrome**. The diagnosis is based on the rapid onset of high fever, hypotension (shock), and a diffuse erythrodermic rash (resembling a sunburn) that typically desquamates 1–2 weeks later. The mention of **tampon use** is a high-yield "buzzword" for TSS, as highly absorbent tampons provide a niche for *Staphylococcus aureus* to provide **TSST-1 (Toxic Shock Syndrome Toxin-1)**. This toxin acts as a **superantigen**, non-specifically cross-linking MHC II and T-cell receptors, leading to a massive "cytokine storm" (IL-1, IL-2, TNF-α, and IFN-γ) [1]. **Why the other options are incorrect:** * **A. Haemolytic uraemic syndrome (HUS):** Typically follows a prodrome of bloody diarrhea (EHEC O157:H7). It is characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury, not an erythrodermic rash and sudden shock. * **B. E. coli sepsis:** While it can cause hypotension and fever, it does not typically present with a diffuse erythrodermic rash or a specific association with tampon use. * **C. Fungal infection:** Systemic fungal infections (like Candidemia) usually occur in immunocompromised patients and follow a more subacute course rather than this hyper-acute presentation. **NEET-PG High-Yield Pearls:** * **Causative Agent:** *S. aureus* (TSST-1) or *S. pyogenes* (Exotoxin A). Streptococcal TSS is more likely to have an associated necrotizing soft tissue infection [1]. * **Criteria:** Fever >38.9°C, SBP <90 mmHg, diffuse rash, and involvement of ≥3 organ systems (GI, Muscular, Renal, Hepatic, Hematologic, or CNS). * **Management:** Aggressive fluid resuscitation, removal of the source (tampon/packing), and antibiotics (Clindamycin is added to inhibit toxin production).

Q: A patient infected with HIV presents with a "Pizza Pie Appearance" on fundoscopy and dysphagia. An upper GI endoscopy biopsy specimen from this patient shows the following. What is the likely diagnosis?

CMV. ***CMV*** - The classic **"pizza pie appearance"** on fundoscopy is pathognomonic for **CMV retinitis**, a common opportunistic infection in HIV patients with CD4+ counts <50 cells/μL. - CMV esophagitis shows characteristic **owl-eye intranuclear inclusions** on histology, and commonly presents with **dysphagia** and **odynophagia** in immunocompromised patients. *Candidiasis* - Esophageal candidiasis typically presents with **white plaques** that can be scraped off, not the pizza pie fundoscopic appearance. - Histology shows **budding yeasts** and **pseudohyphae**, not the characteristic viral inclusions seen in CMV. *Herpes* - HSV esophagitis causes **shallow ulcerations** and shows **multinucleated giant cells** with **Cowdry type A inclusions** on histology. - HSV retinitis is rare and does not produce the characteristic **pizza pie appearance** seen with CMV retinitis. *Eosinophilic Esophagitis* - This condition is associated with **allergies** and **asthma**, not typically seen in HIV patients as an opportunistic infection. - Histology shows **eosinophilic infiltration** (>15 eosinophils per high-power field) and **basal layer hyperplasia**, not viral inclusions.

Q: A resident doctor sustained a needle stick injury while sampling blood from an HIV-positive patient. A decision is made to offer the doctor post-exposure prophylaxis. Which one of the following would be the best recommendation?

Zidovudine + Lamivudine + Indinavir for 4 weeks. **Explanation:** The management of needle stick injuries (NSI) in healthcare workers depends on the risk assessment of the exposure. In this scenario, the source is a known HIV-positive patient, necessitating **Post-Exposure Prophylaxis (PEP)**. **1. Why Option C is Correct:** According to the classic NACO and WHO guidelines (often tested in NEET-PG), PEP is categorized into Basic and Expanded regimens. For **high-risk exposures** (large bore needle, deep injury, or source with high viral load/advanced AIDS), an **Expanded Regimen** is indicated. This consists of **two NRTIs (Zidovudine + Lamivudine)** plus a **Protease Inhibitor (Indinavir or Lopinavir/Ritonavir)**. The standard duration for PEP is **4 weeks (28 days)**. **2. Why the Other Options are Incorrect:** * **Option A:** This is a "Basic Regimen." While used for low-risk exposures, the presence of a known HIV-positive source often warrants the addition of a third drug for maximum efficacy. * **Option B & D:** These include **Nevirapine**. Nevirapine is strictly **contraindicated** in PEP because it carries a high risk of severe hepatotoxicity and Stevens-Johnson Syndrome in HIV-negative individuals receiving it for prophylaxis. * **Option D:** Combining Zidovudine and Stavudine is avoided due to pharmacological antagonism (both compete for the same phosphorylation pathway). **3. High-Yield Clinical Pearls for NEET-PG:** * **Ideal Timing:** PEP should be started as soon as possible, ideally within **2 hours**, and definitely within **72 hours** of exposure. * **Current NACO Update:** While older questions focus on Indinavir, the current preferred NACO regimen is **Tenofovir (300mg) + Lamivudine (300mg) + Dolutegravir (50mg)** as a single daily pill for 28 days. * **Testing Schedule:** Follow-up HIV testing for the exposed professional should be done at baseline, 6 weeks, 12 weeks, and occasionally at 6 months.

Q: A dipstick kit was found to be positive. What is the treatment of choice?

Amphotericin B. ***Amphotericin B*** - **Liposomal Amphotericin B** is the first-line treatment for **visceral leishmaniasis** (Kala-azar) as per **NVBDCP guidelines** in India. - The **rK39 dipstick test** is highly specific for visceral leishmaniasis, and amphotericin B has excellent efficacy with fewer side effects than conventional treatments. *Albendazole* - This is an **antihelminthic drug** used to treat parasitic worm infections like **roundworms**, **hookworms**, and **tapeworms**. - It has **no activity against Leishmania parasites**, which are protozoa causing visceral leishmaniasis. *Doxycycline* - This is a **tetracycline antibiotic** effective against bacterial infections and some **rickettsial diseases** like scrub typhus. - It has **no anti-leishmanial activity** and cannot treat the protozoan infection causing positive rK39 test. *Praziquantel* - This is an **antihelminthic drug** specifically used to treat **schistosomiasis** and other **trematode infections**. - It is completely **ineffective against Leishmania** parasites and would not treat visceral leishmaniasis.

Q: In the management of complications of falciparum malaria, which of the following is generally avoided?

Dexamethasone. In the management of severe falciparum malaria (specifically cerebral malaria), **Dexamethasone** is strictly contraindicated. ### Why Dexamethasone is Avoided Historically, steroids were used to reduce suspected cerebral edema in malaria. However, landmark clinical trials demonstrated that Dexamethasone is not only **ineffective** in reducing mortality but is actually **harmful**. It is associated with an increased risk of secondary infections, gastrointestinal bleeding, and prolonged duration of coma. Current WHO guidelines explicitly state that corticosteroids should not be used in cerebral malaria [1]. ### Analysis of Other Options * **Phenobarbitone (A):** While high prophylactic doses are avoided due to respiratory depression, it remains a standard treatment for controlling active seizures in cerebral malaria. * **Quinine (C):** Although Artesunate is now the first-line drug for severe malaria, Quinine remains an effective alternative and a mainstay of treatment in many protocols, especially when parenteral artesunate is unavailable [1]. * **Blood Transfusion (D):** This is a life-saving intervention in severe malaria complicated by severe anemia (Hemoglobin <5 g/dL or Hematocrit <15%) or hyperparasitemia [1]. ### NEET-PG High-Yield Pearls * **Drug of Choice (DOC):** IV Artesunate is the DOC for all cases of severe malaria (including cerebral malaria and pregnancy) [1]. * **Other Avoided Adjuvants:** Besides steroids, osmotic diuretics (like Mannitol), Heparin, and Adrenaline are generally avoided in cerebral malaria unless specific indications exist. * **Blackwater Fever:** This is a complication of falciparum malaria (often associated with irregular Quinine use) characterized by massive intravascular hemolysis and hemoglobinuria [2].

Question 1

A 33-year-old woman presented with a 1-day history of fever and chills. On examination, she was febrile with a blood pressure of 70/40 mmHg. Over several hours, a widespread erythrodermic rash developed, and she collapsed. Further questioning revealed that the patient had removed a tampon shortly before presentation as she had just ceased menstruating. What is the most likely diagnosis?

Accepted Answer

Toxic shock syndrome

Answer

Haemolytic uraemic syndrome

Answer

E. coli sepsis

Answer

Fungal infection

Question 2

A young male admitted for pneumonia for 5 days develops gripping abdominal pain and loose stools. Which drug(s) might be beneficial in managing these new symptoms?

Accepted Answer

Tablet Ciprofloxacin 500 mg twice daily

Answer

Capsule Imodium 4-8 mg/day

Answer

Oral Metronidazole

Answer

Capsule Diphenoxylate

Question 3

A 30-year-old patient presented with a 30-day history of jaundice. Liver function tests showed a bilirubin of 100mg/dL, SGOT/SGPT of 100/1450, and serum alkaline phosphatase of 240 IU. The patient was positive for HBsAg. What is the confirmatory test to establish acute Hepatitis B infection?

Accepted Answer

IgM Anti-HBc antibody

Answer

HBeAg

Answer

HBV DNA by PCR

Answer

Anti-HBc antibody

Question 4

A patient infected with HIV presents with a "Pizza Pie Appearance" on fundoscopy and dysphagia. An upper GI endoscopy biopsy specimen from this patient shows the following. What is the likely diagnosis?

Accepted Answer

CMV

Answer

Candidiasis

Answer

Herpes

Answer

Eosinophilic Esophagitis

Question 5

A resident doctor sustained a needle stick injury while sampling blood from an HIV-positive patient. A decision is made to offer the doctor post-exposure prophylaxis. Which one of the following would be the best recommendation?

Accepted Answer

Zidovudine + Lamivudine + Indinavir for 4 weeks

Answer

Zidovudine + Lamivudine for 4 weeks

Answer

Zidovudine + Lamivudine + Nevirapine for 4 weeks

Answer

Zidovudine + Stavudine + Nevirapine for 4 weeks

Question 6

Which of the following is NOT included in the diagnostic criteria for AIDS?

Accepted Answer

Presence of any of the opportunistic infections like tuberculosis, Pneumocystis carinii pneumonia, or cytomegalovirus disease

Answer

CD4 count < 200 cells/mm³

Answer

CD8 count < 500 cells/mm³

Answer

CD4:CD8 ratio = 1

Question 7

What is the empirical antibiotic treatment for a suspected case of pneumonia in an outpatient who has not received antibiotics in the past three months?

Accepted Answer

Oral Clarithromycin

Answer

Oral fluoroquinolone

Answer

Oral beta-lactam with injectable aminoglycoside

Answer

Oral linezolid

Question 8

A dipstick kit was found to be positive. What is the treatment of choice?

Accepted Answer

Amphotericin B

Answer

Albendazole

Answer

Doxycycline

Answer

Praziquantel

Question 9

A farmer from Central Asia presents with an acute onset of swinging pyrexia, rigor, sweating, and monoarticular arthritis of the hip. He also complained of headache and insomnia. On examination, he is found to have small firm splenomegaly and hepatomegaly. His counts showed leucopenia with relative lymphocytosis. What is the most likely diagnosis?

Accepted Answer

Brucellosis

Answer

Bagassosis

Answer

Byssionosis

Answer

Chikungunya fever

Question 10

In the management of complications of falciparum malaria, which of the following is generally avoided?

Accepted Answer

Dexamethasone

Answer

Phenobarbitone

Answer

Quinine

Answer

Blood transfusion

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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