Infectious Diseases Practice Questions

Q: Rose spots are seen in which of the following conditions?

Typhoid. **Explanation:** **Typhoid fever (Enteric fever)**, caused by *Salmonella typhi*, is the classic condition associated with **Rose spots**. These are small (2–4 mm), blanching, salmon-pink maculopapules typically found on the chest and abdomen. They appear during the second week of illness [1] in approximately 30% of patients and represent bacterial emboli to the dermis. **Analysis of Options:** * **Malaria:** Presents with a paroxysmal fever pattern, anemia, and splenomegaly. While it can cause jaundice (biliary malaria), it does not typically present with a specific rash like rose spots. * **Chikungunya fever:** Characterized by high fever and severe, often debilitating polyarthralgia. The typical rash is maculopapular and diffuse, appearing early in the disease, unlike the localized rose spots of typhoid. * **Tuberculosis:** A chronic granulomatous infection. While "Lupus vulgaris" or "miliary TB" can have skin manifestations, rose spots are not a feature of any TB variant. **NEET-PG High-Yield Pearls:** * **Timing:** Rose spots appear in the **2nd week** of Typhoid fever [1]. * **Step-ladder pyrexia:** The characteristic fever pattern seen in the 1st week. * **Faget’s Sign:** Relative bradycardia (pulse does not rise proportionately with temperature), a classic finding in Typhoid. * **Diagnosis:** The **Widal test** becomes positive in the 2nd week, but **Blood culture** is the gold standard in the 1st week (Mnemonic: **BASU** – Blood (1st wk), Agglutination/Widal (2nd wk), Stool (3rd wk), Urine (4th wk)). * **Drug of Choice:** Ceftriaxone (for empirical/multidrug-resistant cases); Azithromycin is also commonly used.

Q: Meningitis is characterized by the acute onset of fever and stiff neck. Aseptic meningitis may be caused by a variety of microbial agents. During the initial 24 hours of the course of aseptic meningitis, what is the characteristic finding in an affected person's cerebrospinal fluid?

Polymorphonuclear leukocytosis. **Explanation:** The term **aseptic meningitis** refers to a clinical syndrome of meningeal inflammation where routine bacterial cultures are negative, most commonly caused by viruses (e.g., Enteroviruses). **Why Option D is Correct:** While viral meningitis is classically associated with **lymphocytosis**, the "early phase" (initial 24–48 hours) is a high-yield exception. During this hyperacute period, the inflammatory response often begins with a transient **Polymorphonuclear (PMN) leukocytosis**. This "neutrophilic shift" can mimic bacterial meningitis, making early diagnosis challenging. As the infection progresses beyond 24–48 hours, the cellular profile typically shifts to the characteristic lymphocytic predominance. **Why the other options are incorrect:** * **A & B:** In viral meningitis, the **glucose concentration is typically normal** (unlike bacterial meningitis where it is low), and the **protein content is normal to mildly elevated** (never decreased). * **C:** Lymphocytosis is the hallmark of viral meningitis in the *subacute* phase, but it is not the characteristic finding during the *initial 24 hours* described in the question. **NEET-PG High-Yield Pearls:** * **Most common cause of aseptic meningitis:** Enteroviruses (Coxsackievirus, Echovirus). * **CSF Profile in Viral Meningitis:** Normal glucose, normal/slightly high protein, and lymphocytic pleocytosis (after the first 24 hours). * **Mollaret Meningitis:** Recurrent aseptic meningitis often associated with HSV-2. * **Diagnostic Gold Standard:** PCR of the CSF is more sensitive than viral culture for identifying the causative agent.

Q: All of the following are seen in severe Falciparum malaria infection EXCEPT?

Hyperglycemia. Severe Falciparum malaria is a medical emergency characterized by vital organ dysfunction and high parasite counts. [1] **1. Why Hyperglycemia is the Correct Answer (The Exception):** In severe malaria, **Hypoglycemia** (not hyperglycemia) is a common and dangerous complication. It occurs due to two primary mechanisms: * **Host factors:** Failure of hepatic gluconeogenesis and increased consumption of glucose by both the host and the parasites. * **Drug-induced:** Quinine and quinidine (traditionally used for treatment) [1] are potent stimulators of pancreatic insulin secretion, leading to hyperinsulinemic hypoglycemia. **2. Analysis of Incorrect Options (Features of Severe Malaria):** * **Severe Anemia (Option A):** Defined as a hemoglobin <5 g/dL or hematocrit <15%. It results from the direct destruction of parasitized RBCs, splenic clearance of non-parasitized RBCs, and bone marrow suppression. [1] * **Renal Failure (Option B):** Acute Kidney Injury (AKI) is common in adults, often presenting as "Blackwater Fever" (hemoglobinuria) due to massive intravascular hemolysis or acute tubular necrosis. * **Acidosis (Option D):** Metabolic acidosis (pH 3 mg/dL), and Hyperparasitemia (>10% or 500,000/μL). [1] * **Drug of Choice:** Intravenous **Artesunate** is the gold standard for severe malaria. [1] * **Sequestration:** The hallmark of *P. falciparum* is "cytoadherence," where infected RBCs stick to vascular endothelium, causing organ ischemia. [1]

Q: A 26-year-old patient presents with suspected pneumococcal meningitis. CSF culture is sent for antibiotic sensitivity. Which empirical antibiotic should be given until culture sensitivity results are available?

Cefotaxime + vancomycin. **Explanation:** The management of bacterial meningitis is a medical emergency requiring immediate empirical antibiotic therapy. The choice of drugs is guided by the most likely pathogens and current resistance patterns. [2] **1. Why Option D is Correct:** * **Streptococcus pneumoniae** is the most common cause of community-acquired bacterial meningitis in adults. [1] * Due to the rising prevalence of **penicillin-resistant** and **cephalosporin-resistant** pneumococci, monotherapy with a third-generation cephalosporin (Cefotaxime or Ceftriaxone) is no longer sufficient. * **Vancomycin** is added empirically to ensure coverage against these highly resistant strains. Once culture sensitivity results are available, the regimen can be narrowed. **2. Why Other Options are Incorrect:** * **Option A (Penicillin G):** While historically the drug of choice, it is no longer used empirically due to widespread high-level penicillin resistance in *S. pneumoniae*. * **Option B (Ceftriaxone + Metronidazole):** Ceftriaxone is appropriate, but Metronidazole is used for anaerobic coverage (e.g., brain abscesses) and has no role in the standard empirical treatment of community-acquired pneumococcal meningitis. [3] * **Option C (Doxycycline):** This is a bacteriostatic drug with poor CNS penetration and is not indicated for the treatment of acute bacterial meningitis. **Clinical Pearls for NEET-PG:** * **Steroids:** Dexamethasone should be administered **before or with** the first dose of antibiotics to reduce neurological complications (hearing loss, edema). [1] * **Age-specific coverage:** In patients >50 years or those who are immunocompromised, **Ampicillin** must be added to the regimen to cover *Listeria monocytogenes*. * **CSF Findings:** Classic bacterial meningitis shows high opening pressure, high protein (>45 mg/dL), low glucose (<40 mg/dL), and neutrophilic pleocytosis. [1]

Q: Which of the following drug regimens is true for Typhoid carriers?

Amoxicillin plus probenecid. ### Explanation **Correct Answer: C. Amoxicillin plus probenecid** #### Why it is correct: Typhoid carriers are individuals who continue to excrete *Salmonella typhi* in their stools for more than one year after the initial infection. The primary site of carriage is the **gallbladder** (often associated with gallstones). * **Amoxicillin** is highly effective against *S. typhi* and achieves good concentrations in the bile. * **Probenecid** is added because it inhibits the renal tubular secretion of amoxicillin, thereby increasing and sustaining its plasma and biliary concentrations. * **Standard Regimen:** Amoxicillin (4–6 g/day) plus Probenecid (2 g/day) for **6 weeks**. If gallstones are present, cholecystectomy may be required alongside antibiotics to achieve a permanent cure. #### Why other options are incorrect: * **A. Ciprofloxacin plus azithromycin:** While Ciprofloxacin is a drug of choice for *acute* typhoid fever, it is not the standard textbook regimen for long-term carrier eradication in this specific combination. * **B. Cotrimoxazole:** Although previously used for typhoid, widespread resistance has limited its efficacy. It is no longer the primary recommendation for carrier states compared to high-dose amoxicillin. #### NEET-PG High-Yield Pearls: * **Definition of Carrier:** * *Temporary:* Excretion for 3 months to 1 year. * *Chronic:* Excretion for >1 year. * **Types of Carriers:** Fecal carriers (more common, gallbladder focus) and Urinary carriers (rare, associated with *Schistosoma haematobium*). * **Drug of Choice for Acute Typhoid:** Ceftriaxone (Injectable) or Azithromycin (Oral) due to increasing Fluoroquinolone resistance (NALD - Nalidixic Acid Resistant *S. typhi*). * **Public Health Significance:** The "Typhoid Mary" phenomenon highlights the role of carriers in food handling and disease transmission.

Question 1

An adult male with a history of pneumonia, who is unconscious and has a 10-year history of alcoholism, requires treatment. What is the drug of choice for treating pneumonia in this patient?

Accepted Answer

Inj Clindamycin 600mg

Answer

Tab Amoxicillin 500mg

Answer

Tab Azithromycin 500mg

Answer

Inj Levofloxacin 500mg

Question 2

A 32-year-old soldier presents with a generalized seizure. He reports two episodes of loss of consciousness in the past two years. He is otherwise healthy with no abnormal findings on general physical examination. A CT scan with contrast shows two small hyperintense foci in the right frontal lobe and a 1 cm cystic lesion with a nodular focus within it in the left frontal region. The cyst wall of the latter enhances with contrast, while the two right lesions do not enhance. What is the most likely diagnosis?

Accepted Answer

Neurocysticercosis

Answer

Tabes dorsalis

Answer

Progressive multifocal leukoencephalopathy (PMLE)

Answer

Bartonella henselae encephalitis

Question 3

A 25-year-old man presented with fever, cough, expectoration, and breathlessness of 2 months' duration. Contrast-enhanced computed tomography of the chest showed bilateral upper lobe fibrotic lesions and mediastinal enlarged necrotic nodes with peripheral rim enhancement. Which one of the following is the most probable diagnosis?

Accepted Answer

Tuberculosis

Answer

Sarcoidosis

Answer

Lymphoma

Answer

Silicosis

Question 4

A 46-year-old male with HIV and severe penicillin allergy, receiving zidovudine, indinavir, and stavudine, presents with fever, nonproductive cough, and severe hypoxia. Chest x-ray reveals diffuse increased interstitial markings and a possible lobar consolidation in the left lower lobe. After appropriate evaluation, the patient receives levofloxacin, trimethoprim-sulfamethoxazole, and acyclovir. Initial serum creatinine is 1.6 mg/dL. On day 4, it has risen to 3.8 mg/dL and a normal serum potassium has risen to 7.1 mg/dL. Urinalysis reveals no casts, 10 to 20 WBC/HPF, and rare RBCs. Which drug is the most likely cause of renal failure?

Accepted Answer

Trimethoprim-sulfamethoxazole

Answer

Levofloxacin

Answer

Acyclovir

Answer

Indinavir

Question 5

Rose spots are seen in which of the following conditions?

Accepted Answer

Typhoid

Answer

Malaria

Answer

Chikungunya fever

Answer

Tuberculosis

Question 6

Meningitis is characterized by the acute onset of fever and stiff neck. Aseptic meningitis may be caused by a variety of microbial agents. During the initial 24 hours of the course of aseptic meningitis, what is the characteristic finding in an affected person's cerebrospinal fluid?

Accepted Answer

Polymorphonuclear leukocytosis

Answer

Decreased protein content

Answer

Elevated glucose concentration

Answer

Lymphocytosis

Question 7

Toxic shock syndrome caused by Staphylococcus is due to which of the following?

Accepted Answer

Superantigens

Answer

Hemolytic antigen

Answer

Hyaluronidase

Answer

Coagulase

Question 8

All of the following are seen in severe Falciparum malaria infection EXCEPT?

Accepted Answer

Hyperglycemia

Answer

Severe normocytic normochromic anemia

Answer

Renal failure

Answer

Acidemia/acidosis

Question 9

A 26-year-old patient presents with suspected pneumococcal meningitis. CSF culture is sent for antibiotic sensitivity. Which empirical antibiotic should be given until culture sensitivity results are available?

Accepted Answer

Cefotaxime + vancomycin

Answer

Penicillin G

Answer

Ceftriaxone + metronidazole

Answer

Doxycycline

Question 10

Which of the following drug regimens is true for Typhoid carriers?

Accepted Answer

Amoxicillin plus probenecid

Answer

Ciprofloxacin plus azithromycin

Answer

Cotrimoxazole

Answer

None of the above

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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