Infectious Diseases Practice Questions

Q: A resident of North-East India, presents with fever and chills. Peripheral blood smear shows P. falciparum malaria. Which of the following treatment regimens should be given?

Artemether –Lumefantrine + Primaquine. ***Artemether–Lumefantrine + Primaquine*** - This regimen represents the **Artemisinin-based Combination Therapy (ACT)**, which is the **first-line recommended treatment** for uncomplicated *Plasmodium falciparum* malaria in India, including North-East regions where chloroquine resistance is high. - **Primaquine** is added as a **gametocytocide** to prevent the transmission of the parasite to mosquitoes, though it should be used cautiously after screening for **G6PD deficiency**. *Chloroquine + Primaquine* - While historically useful, **Chloroquine** is no longer effective for *P. falciparum* in most parts of India, particularly in **North-East India**, due to high levels of **antimalarial drug resistance**. - This combination is currently reserved specifically for **P. vivax malaria** treatment in regions where chloroquine sensitivity is maintained. *Oral quinine* - **Oral quinine** is not the first-line treatment for uncomplicated malaria and is associated with significant side effects like **cinchonism** (tinnitus, headache, dizziness). - It is generally reserved for **second-line therapy** or in specific cases of **severe malaria** when parenteral therapy is transitioned to oral, or where ACTs are unavailable. *Artesunate + Sulfadoxine-Pyrimethamine + Primaquine* - This combination was previously used in specific areas, but its efficacy has declined significantly due to the widespread emergence of **Sulfadoxine-Pyrimethamine resistance**. - Modern treatment guidelines prioritize **Artemether-Lumefantrine** or **Artesunate-Pyronaridine** over older ACT combinations for more reliable patient outcomes.

Q: Foreigner with rice water stool

Cholera toxin. ***Cholera toxin*** - The **rice-water stool** is pathognomonic for **Vibrio cholerae** infection, which is mediated by the **cholera toxin**. - This toxin increases **cAMP** levels within enterocytes, leading to massive, secretory, non-inflammatory diarrhea and profound fluid loss. *Shigella toxin* - Associated with **bacillary dysentery**, characterized by **bloody stools**, mucus, and abdominal cramps rather than watery diarrhea. - This toxin, known as **Shiga toxin**, primarily inhibits protein synthesis by targeting the **60S ribosomal subunit**. *Heat labile E.Coli* - Also known as **Enterotoxigenic E. coli (ETEC)**, it causes **traveler's diarrhea** that is generally much milder than the epidemic cholera. - While it acts via a similar mechanism of increasing **cAMP**, it typically does not produce the extreme, rapidly dehydrating **rice-water stool** characteristic of cholera. *Rotavirus* - A major cause of **viral gastroenteritis** in infants and young children, typically presenting with watery diarrhea, fever, and vomiting. - Transmission is usually fecal-oral, and it is distinct from the **bacterial toxin**-mediated pathology seen in adult cholera cases.

Q: A patient with HIV infection who is also on immunosuppressive therapy presents with dry cough, progressive weight loss, and generalized weakness. What is the most likely diagnosis?

Pneumocystis jirovecii. ***Pneumocystis jirovecii*** - This organism remains the most common **opportunistic infection** in patients with HIV and significantly low **CD4 counts** (<200 cells/µL). - Classically presents with an **insidious onset** of non-productive (dry) **cough**, progressive dyspnea, and systemic symptoms like fever and **weight loss**. *Histoplasma capsulatum* - Typically presents with symptoms resembling **tuberculosis**, such as fever, cough, and hepatosplenomegaly, often in endemic areas like the **Ohio and Mississippi River valleys**. - Diagnosis usually requires detecting **urinary antigen** or visualization of small yeasts in macrophages, which is less specific to the presentation of dry cough without other endemic findings. *Candida albicans* - Primarily associated with **oropharyngeal candidiasis** (thrush) or **esophagitis** in HIV patients, not pulmonary disease. - Pulmonary involvement is extremely rare and usually superficial, not causing the profound systemic **respiratory symptoms** described here. *Mycobacterium tuberculosis* - While a major consideration, it typically presents with **hemoptysis**, night sweats, and **upper lobe cavitation** or miliary patterns on chest imaging. - Distinguishing features often include a more chronic course and specific exposures, whereas *Pneumocystis* is the classic cause of **interstitial pneumonia** in this clinical context.

Q: A 32-year-old man returned from a malaria -endemic area with high -grade fever for 5 days. On examination he is drowsy, confused, and has altered sensorium. Peripheral smear shows Plasmodium falciparum. What is the most appropriate treatment?

Intravenous artesunate. ***Intravenous artesunate*** - This patient presents with **severe malaria** manifested by **cerebral malaria** (altered sensorium, confusion), which is a medical emergency requiring parenteral therapy. - **Intravenous (IV) artesunate** is the **first-line treatment** of choice for severe *Plasmodium falciparum* malaria, as evidence shows it significantly reduces mortality compared to quinine. *Intravenous artesunate with sulfadoxine-pyrimethamine* - **Sulfadoxine-pyrimethamine** is an oral antimalarial primarily used for uncomplicated malaria or as intermittent preventive treatment during pregnancy. - Combining it with IV artesunate provides no additional clinical benefit for the management of the acute **severe malaria** emergency and adds unnecessary potential for adverse drug reactions. *Oral artemether-lumefantrine* - This combination is the **first-line therapy** for uncomplicated *Plasmodium falciparum* malaria. - It is unsuitable for this patient because **oral medications** are contraindicated in patients with **altered sensorium** or those who cannot tolerate oral intake due to the high risk of aspiration and failure of absorption. *Oral chloroquine* - **Chloroquine** is no longer the treatment of choice for *Plasmodium falciparum* malaria worldwide, given the widespread prevalence of **chloroquine-resistant Pf strains**. - Furthermore, this drug is strictly oral and inappropriate for treating a patient showing signs of **severe disease** and neurological impairment.

Q: A 52-year-old diabetic patient with poorly controlled blood glucose presents with facial pain, nasal blockage, and a black necrotic lesion over the nasal turbinate (black sinus) along with fever. Imaging shows involvement of the maxillary sinus. What is the most appropriate management?

Surgical debridement with antifungal therapy. ***Surgical debridement with antifungal therapy*** - This patient presents with classic signs of **rhino-orbital-cerebral mucormycosis**, characterized by necrotic black eschars on the nasal turbinates in the setting of **uncontrolled diabetes**. - The cornerstone of management is **aggressive surgical debridement** of infected tissue combined with systemic **antifungal therapy** (typically **liposomal amphotericin B**), as tissue necrosis limits drug penetration. *Surgical debridement only* - While surgery is vital to remove necrotic tissue and reduce organism burden, relying on surgery alone is insufficient to address the **invasive fungal infection**. - Without concurrent **antifungal systemic therapy**, the infection risk of disseminating to the brain or orbit remains critically high. *Surgical debridement with antibiotics* - **Antibiotics** are ineffective against fungal pathogens like *Mucorales*. - Using antibiotics instead of antifungals allows the **fungal infection** to propagate unchecked, likely leading to rapid progression and high morbidity. *Antibiotics only* - Mucormycosis is a fulminant **fungal** infection which does not respond to antibacterial drugs. - Delaying antifungal treatment and surgical intervention due to a reliance on antibiotics is life-threatening, as the infection exhibits **angioinvasion** and rapid tissue necrosis.

Q: A 52 year old man with the past history of Type-2 DM & Chronic sinusitis presented with continuous high grade fever for 2 days along with severe headache, photophobia, nuchal rigidity, confusion and vomiting. Kernig’s sign is positive. Which among the following is the most appropriate empirical therapy?

Ceftriaxone + Vancomycin. ### **Ceftriaxone + Vancomycin** - This combination covers the most common pathogens causing **community-acquired bacterial meningitis** in adults, specifically *Streptococcus pneumoniae* and *Neisseria meningitidis*. - The addition of **Vancomycin** is critical to provide adequate coverage for potential **penicillin-resistant Streptococcus pneumoniae** strains, while **Ceftriaxone** (or another third-generation cephalosporin) provides excellent bactericidal activity against common meningeal pathogens. *Clindamycin* - This antibiotic is primarily effective against **anaerobes** and certain Gram-positive cocci but lacks significant **meningeal penetration** and activity against common meningitis pathogens. - It is not indicated for the empirical treatment of **acute bacterial meningitis**. *Vancomycin* - While it provides coverage against resistant *Streptococcus pneumoniae*, it is **insufficient as monotherapy** because it does not adequately cover *Neisseria meningitidis* or *Haemophilus influenzae*. - Empirical treatment for suspected meningitis must include a coverage regimen that addresses the most frequent **Gram-negative** and **Gram-positive** causative organisms. *Meropenem* - While a potent antibiotic, it is typically reserved for cases of **hospital-acquired meningitis** or when *Pseudomonas aeruginosa* is suspected, given its broad-spectrum profile. - It is not the standard first-line empirical choice for **community-acquired** presentations without specific risk factors like recent neurosurgery or trauma.

Q: A 35-year-old man presents with high-grade fever, severe myalgia (predominantly calf pain), and redness of eyes for the last 4 days. He gives a history of wading through flood water one week ago. On examination, conjunctival suffusion is noted. There isno jaundice or renal impairment at present. This clinical presentation most likely corresponds to which phase of leptospirosis?

Septicemic phase. ***Septicemic phase*** - This phase corresponds to the first 4–7 days of illness, characterized by the **sudden onset of fever**, severe **myalgia** (classically involving **calf muscles**), and **conjunctival suffusion** without purulent discharge. - During this period, the bacteria (leptospires) are actively circulating in the blood, making them detectable by **blood culture** or **PCR**, as the patient has not yet cleared the infection or developed high titers of **anti-leptospiral antibodies**. *Incubation phase* - This is the asymptomatic period lasting usually between **7 to 12 days** (range 2–30 days) following exposure to the **spirochete**. - There are no clinical symptoms or signs during this time as the organism is establishing its presence in the host's body. *Immune phase* - This phase typically begins after a short afebrile period, which marks the host's immune response characterized by the appearance of **IgM antibodies**. - Clinical features here are often milder, but complications like **aseptic meningitis** (severe headache, nuchal rigidity) may occur due to the inflammatory response even as the bacteria are cleared from the blood. *Weil's disease* - This is the severe form of leptospirosis, characterized by the triad of **jaundice**, **acute kidney injury**, and **hemorrhage**. - The patient explicitly lacks jaundice and renal impairment, excluding this severe pattern at the present time.

Q: A 25-year-old college student presents with progressive headache, vomiting, and double vision. Examination reveals bilateral 6th nerve palsy and papilledema. CT brain shows hydrocephalus. CSF analysis reveals lymphocytic dominance, markedly low glucose, and elevated protein. What is the most likely diagnosis?

Tubercular meningitis. ***Tubercular meningitis*** - The classic CSF triad of **lymphocytic pleocytosis**, **markedly low glucose (hypoglycorrhachia)**, and **elevated protein** is highly characteristic of tuberculous meningitis. - The presentation of **hydrocephalus** and **cranial nerve palsies (like CN VI palsy)** is a hallmark complication caused by the thick, gelatinous **basilar exudates** associated with this condition. *Viral meningitis* - Typically presents with **normal glucose levels** in the CSF and generally does not cause profound hydrocephalus or cranial nerve palsies. - This condition is often self-limiting, whereas the progression of symptoms here suggests a more chronic, invasive process. *Fungal meningitis* - While fungal infections like *Cryptococcus* can cause lymphocytic meningitis and high intracranial pressure, the classic profile strongly pointing to TB is the profound glucose consumption and typical basilar inflammation. - Cryptococcal meningitis is more commonly seen in heavily **immunocompromised patients (e.g., AIDS)**, and diagnostic testing for cryptococcal antigen would be the first line of investigation. *Bacterial meningitis* - Typically exhibits **neutrophilic predominance** in the CSF, rather than the lymphocytic dominance described in this case. - CSF glucose levels in typical bacterial meningitis are usually low, but the clinical course is generally **acute and fulminant** (hours to days), unlike the subacute progression often seen in tuberculosis.

Q: A 35-year-old HIV-positive female on irregular ART presents with headache, confusion, fever, and right-sided weakness. Her CD4 count is 40 cells/mm³. MRI brain shows multiple ring-enhancing lesions in the basal ganglia. What is the most likely diagnosis?

Cerebral toxoplasmosis. ***Cerebral toxoplasmosis*** - This is the most common cause of **multiple ring-enhancing lesions** in HIV-positive patients with CD4 counts < 100 cells/mm³. - The clinical presentation of **fever**, **headache**, and focal neurologic deficits (like the patient's right-sided weakness) often localizing to the **basal ganglia** is classic for this opportunistic infection. *Primary CNS lymphoma* - Typically presents as a **solitary lesion** on MRI rather than multiple lesions, though it can occasionally be multifocal. - It is generally associated with **Epstein-Barr virus (EBV)** DNA detection in the cerebrospinal fluid and often appears as a **periventricular mass**. *Progressive multifocal leukoencephalopathy (PML)* - Caused by the **JC virus**, this condition typically presents with **non-enhancing** white matter lesions on MRI. - It usually leads to progressive cognitive decline, ataxia, and visual disturbances without the **mass effect** or **ring enhancement** seen with abscesses or tumors. *Neurocysticercosis* - Characterized by lesions in varying stages of development, often showing **calcified nodules** or **cysts with scolex** on imaging. - While it can manifest as ring-enhancing lesions, it is a **parasitic infection** (Taenia solium) not specifically linked to the profound immunosuppression and opportunistic profile seen in this HIV-positive case.

Question 1

A resident of North-East India, presents with fever and chills. Peripheral blood smear shows P. falciparum malaria. Which of the following treatment regimens should be given?

Accepted Answer

Artemether –Lumefantrine + Primaquine

Answer

Chloroquine + Primaquine

Answer

Oral quinine

Answer

Artesunate + Sulfadoxine -Pyrimethamine + Primaquine

Question 2

Foreigner with rice water stool

Accepted Answer

Cholera toxin

Answer

Shigella toxin

Answer

Heat labile E.Coli

Answer

Rotavirus

Question 3

A patient with HIV infection who is also on immunosuppressive therapy presents with dry cough, progressive weight loss, and generalized weakness. What is the most likely diagnosis?

Accepted Answer

Pneumocystis jirovecii

Answer

Histoplasma capsulatum

Answer

Candida albicans

Answer

Mycobacterium tuberculosis

Question 4

A 32-year-old man returned from a malaria -endemic area with high -grade fever for 5 days. On examination he is drowsy, confused, and has altered sensorium. Peripheral smear shows Plasmodium falciparum. What is the most appropriate treatment?

Accepted Answer

Intravenous artesunate

Answer

Intravenous artesunate with sulfadoxine -pyrimethamine

Answer

Oral artemether-lumefantrine

Answer

Oral chloroquine

Question 5

A 52-year-old diabetic patient with poorly controlled blood glucose presents with facial pain, nasal blockage, and a black necrotic lesion over the nasal turbinate (black sinus) along with fever. Imaging shows involvement of the maxillary sinus. What is the most appropriate management?

Accepted Answer

Surgical debridement with antifungal therapy

Answer

Surgical debridement only

Answer

Surgical debridement with antibiotics

Answer

Antibiotics only

Question 6

A 52 year old man with the past history of Type-2 DM & Chronic sinusitis presented with continuous high grade fever for 2 days along with severe headache, photophobia, nuchal rigidity, confusion and vomiting. Kernig’s sign is positive. Which among the following is the most appropriate empirical therapy?

Accepted Answer

Ceftriaxone + Vancomycin

Answer

Clindamycin

Answer

Vancomycin

Answer

Meropenem

Question 7

A 35-year-old man presents with high-grade fever, severe myalgia (predominantly calf pain), and redness of eyes for the last 4 days. He gives a history of wading through flood water one week ago. On examination, conjunctival suffusion is noted. There isno jaundice or renal impairment at present. This clinical presentation most likely corresponds to which phase of leptospirosis?

Accepted Answer

Septicemic phase

Answer

Incubation phase

Answer

Immune phase

Answer

Weil's disease

Question 8

A 25-year-old college student presents with progressive headache, vomiting, and double vision.
Examination reveals bilateral 6th nerve palsy and papilledema. CT brain shows hydrocephalus. CSF
analysis reveals lymphocytic dominance, markedly low glucose, and elevated protein. What is the
most likely diagnosis?

Accepted Answer

Tubercular meningitis

Answer

Viral meningitis

Answer

Fungal meningitis

Answer

Bacterial meningitis

Question 9

A 35-year-old HIV-positive female on irregular ART presents with headache, confusion, fever, and
right-sided weakness. Her CD4 count is 40 cells/mm³. MRI brain shows multiple ring-enhancing
lesions in the basal ganglia. What is the most likely diagnosis?

Accepted Answer

Cerebral toxoplasmosis

Answer

Primary CNS lymphoma

Answer

Progressive multifocal leukoencephalopathy (PML)

Answer

Neurocysticercosis

Question 10

A 72-year-old woman with end-stage renal disease on hemodialysis develops fever (103°F/39.4°C) with rigors during dialysis. Blood cultures from both the dialysis catheter and peripheral site grow gram-positive cocci. Despite appropriate antibiotics and catheter removal, she has persistent fevers of 101-102°F (38.3-38.9°C) for 7 days. She feels better and inflammatory markers are decreasing. Evaluate the most likely explanation for persistent fever.

Accepted Answer

Appropriate lag in temperature resolution despite adequate treatment

Answer

Undrained abscess requiring surgical intervention

Answer

Antibiotic-resistant organism requiring regimen change

Answer

Inadequate dialysis causing uremic fever

Answer

Drug fever from antibiotic therapy

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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