Infectious Diseases Practice Questions

Q: A patient with advanced HIV presents with cryptococcal meningitis. Which CSF finding is most characteristic?

High opening pressure. ***High opening pressure*** - **Elevated intracranial pressure** is a hallmark of cryptococcal meningitis, often due to the **fungal burden** and associated inflammatory response, leading to impaired CSF outflow [1]. - This symptom is crucial for both diagnosis and management, as persistently high pressure can cause **neurological damage** and vision loss. *High protein* - While CSF protein can be mildly elevated in cryptococcal meningitis, it is **not the most characteristic finding** compared to the dramatic increase seen in bacterial meningitis [1]. - Protein levels typically increase with inflammation and breakdown of the **blood-brain barrier**, but less significantly than other findings in cryptococcal infection. *Low glucose* - **Low CSF glucose** (hypoglycorrhachia) is more typical of **bacterial meningitis** due to bacterial consumption of glucose. - In cryptococcal meningitis, glucose levels can be normal or mildly decreased, but **not as consistently low** as in bacterial infections. *Neutrophilic pleocytosis* - **Neutrophilic pleocytosis** (predominance of neutrophils) is a classic finding in **acute bacterial meningitis** [1]. - Cryptococcal meningitis typically presents with a **lymphocytic or mixed pleocytosis**, not neutrophilic, reflecting a more chronic or fungal inflammatory response.

Q: A patient develops sudden onset fever and confusion 2 days post-splenectomy. Most appropriate initial antibiotic?

Ceftriaxone. ***Ceftriaxone*** - Patients post-splenectomy are at high risk for **overwhelming post-splenectomy infection (OPSI)**, often caused by **encapsulated bacteria** like *Streptococcus pneumoniae* [2]. - **Ceftriaxone** provides broad coverage against common pathogens in OPSI, including both Gram-positive and Gram-negative bacteria, and can penetrate the CNS in cases of meningitis, which is crucial given the patient's confusion [1], [2]. *Azithromycin* - Primarily targets **atypical bacteria** (e.g., *Mycoplasma*, *Chlamydia*) and some Gram-positive organisms, but has limited efficacy against the most common encapsulated bacteria responsible for OPSI. - It is not a first-line antibiotic for severe, potentially life-threatening infections in asplenic patients. *Vancomycin* - Effective against **methicillin-resistant *Staphylococcus aureus* (MRSA)** and **multi-drug resistant *Streptococcus pneumoniae***, but does not cover Gram-negative organisms [2], [3]. - While important for resistant Gram-positives, it should typically be used in combination with another antibiotic (like a third-generation cephalosporin) in this critical setting, or reserved for cases where MRSA is suspected [3]. *Piperacillin-tazobactam* - Provides broad-spectrum coverage, including **Gram-positive, Gram-negative, and anaerobic bacteria**, making it suitable for many severe infections. - However, for suspected OPSI with a high risk of encapsulated bacteria like *Streptococcus pneumoniae* and potential meningitis, a third-generation cephalosporin like **ceftriaxone** is often preferred as initial monotherapy due to excellent penetration into the CSF and robust activity against these specific pathogens.

Q: A patient with dengue fever develops warning signs. Which finding indicates severe disease requiring ICU care?

Hematocrit rise >20%. ***Hematocrit rise >20%*** * A significant rise in **hematocrit** (typically >20% from baseline or age/sex-adjusted average) indicates substantial **plasma leakage**, which is a critical sign of severe dengue and impending **shock** [1]. * This necessitates urgent fluid management and often **ICU admission** to prevent further clinical deterioration [1]. *Mild ascites* * While ascites is a sign of **plasma leakage**, mild ascites alone, without rapid accumulation or associated signs of shock, is considered a **dengue warning sign**, but doesn't immediately classify it as severe dengue requiring ICU. * It suggests potential for progression but doesn't, by itself, equate to the severe plasma leakage indicated by a sharp hematocrit rise. *Persistent vomiting* * **Persistent vomiting** is a **dengue warning sign** indicating potential for dehydration and fluid imbalance, but it does not directly signify severe plasma leakage or organ impairment requiring ICU care. * Fluid replacement can often be managed orally or intravenously in a ward setting. *Platelet count <20,000* * A **platelet count <20,000** is considered a **severe dengue criterion** due to the increased risk of severe bleeding [1]. * While it indicates severe disease and requires close monitoring, a **sudden large increase in hematocrit** is a more immediate indicator of life-threatening **plasma leakage and hypovolemic shock**, which often takes precedence for rapid ICU intervention [1].

Q: Patient: fever, joint pain, rash. Recent history of mosquito bite. Most likely diagnosis in urban area?

Chikungunya. ***Chikungunya*** - **Chikungunya** is a viral disease transmitted by mosquitoes that commonly presents with **fever**, severe **joint pain** (polyarthralgia), and a **rash**, fitting the patient's symptoms. - Its high prevalence in **urban areas** and recent history of **mosquito bites** make it a strong diagnostic consideration. *Dengue* - While Dengue also causes **fever** [1] and a **rash**, it is more typically associated with **severe muscle and bone pain** ("breakbone fever"), and **hemorrhagic manifestations** or shock, which are not mentioned. - **Joint pain** in dengue is usually less debilitating than in chikungunya. *Japanese Encephalitis* - This is a serious **neurological infection** characterized by **fever**, **headache**, seizures, and altered mental status, rather than prominent joint pain and rash. - It primarily affects the **brain** and is less likely to present with this specific symptom triad. *Malaria* - Malaria is characterized by **cyclic fevers**, chills, sweating, and fatigue, but typically **does not present with a rash** [1] or significant joint pain. - It is caused by a **parasite** transmitted by *Anopheles* mosquitoes, and its clinical picture differs from the described symptoms.

Q: HIV patient presents with chest X-ray showing bilateral reticulonodular infiltrates. CD4 count 80/µL. Most likely diagnosis?

Pneumocystis pneumonia. ***Pneumocystis pneumonia (PCP)*** - **Pneumocystis pneumonia** is a common opportunistic infection in HIV patients with a **CD4 count below 200 cells/L**, and a CD4 count of 80/L makes it highly likely [1]. - The classic chest X-ray finding for PCP is **bilateral interstitial or reticulonodular infiltrates**, which matches the patient's presentation [1]. *CMV infection* - While **cytomegalovirus (CMV) infection** can occur in advanced HIV disease, pulmonary involvement typically presents with **pneumonitis** or **pleural effusions** rather than exclusively reticulonodular infiltrates. - CMV pneumonitis often manifests with other organ involvement like **retinitis** or **colitis**, which are not mentioned here. *Cryptococcosis* - **Cryptococcus neoformans** primarily causes **meningitis** in HIV patients, though pulmonary cryptococcosis can occur. - Pulmonary involvement often presents as solitary or multiple **nodules** or **masses**, rather than diffuse reticulonodular infiltrates. *Tuberculosis* - **Tuberculosis (TB)** is common in HIV patients and can present with various radiographic patterns, including infiltrates, nodules, or cavitation [1]. - However, in advanced HIV (low CD4 count), **extrapulmonary TB** and atypical presentations are more common, and while pulmonary infiltrates occur, **PCP** is more classically associated with diffuse reticulonodular infiltrates in this specific CD4 range [1].

Q: Which of the following is the most commonly used drug for outpatient management of community acquired pneumonia?

Azithromycin. ***Azithromycin*** - **Azithromycin** is a macrolide antibiotic widely recommended for outpatient treatment of **community-acquired pneumonia (CAP)** due to its efficacy against common causative pathogens like *Streptococcus pneumoniae* and **atypical bacteria** (e.g., *Mycoplasma pneumoniae*, *Chlamydophila pneumoniae*). - Its **once-daily dosing** and good oral bioavailability contribute to patient compliance in an outpatient setting. *Ceftriaxone* - **Ceftriaxone** is a third-generation cephalosporin primarily used for **intravenous administration** in more severe CAP cases requiring hospitalization or for specific resistant strains, not typically for initial outpatient management. - While effective against *Streptococcus pneumoniae*, it lacks coverage for **atypical pathogens** and its parenteral route makes it less suitable for most outpatient settings. *Streptomycin* - **Streptomycin** is an aminoglycoside antibiotic primarily used for **tuberculosis** and severe gram-negative infections, not a standard treatment for typical or atypical pathogens causing CAP. - It has a high risk of **ototoxicity** and **nephrotoxicity**, making it unsuitable for routine outpatient CAP management. *Vancomycin* - **Vancomycin** is a glycopeptide antibiotic primarily used for **methicillin-resistant *Staphylococcus aureus* (MRSA)** infections and severe gram-positive infections, not a first-line agent for typical CAP pathogens. - It is usually administered **intravenously** and requires monitoring for **nephrotoxicity** and **ototoxicity**, making it inappropriate for routine outpatient use.

Q: Most common infection post solid organ transplantation

CMV. ***CMV*** - **Cytomegalovirus (CMV)** is the most common viral infection in solid organ transplant recipients, often reactivating in immunosuppressed patients [1]. - It can cause a wide range of clinical syndromes including **fever**, **leukopenia**, **hepatitis**, **pneumonitis**, and **gastroenteritis**, and is a significant cause of morbidity and mortality [1]. *EBV* - **Epstein-Barr virus (EBV)** is also common in transplant recipients but is most notably associated with **post-transplant lymphoproliferative disorder (PTLD)**, a serious complication [1]. - While present, it is not as frequently the cause of symptomatic infection as CMV in the immediate post-transplant period. *HSV* - **Herpes simplex virus (HSV)** infections can occur, manifesting as mucocutaneous lesions or, less commonly, severe systemic disease in transplant patients. - However, its incidence and severity are generally lower compared to CMV in the overall transplant population. *HPV* - **Human papillomavirus (HPV)** infections are typically associated with **warts** and increased risk of **malignancies** (e.g., anogenital cancers) in immunosuppressed individuals, including transplant recipients. - While important for long-term surveillance, HPV does not represent the most common acute infection post-transplant.

Q: A 60-year-old female with a history of diabetes presents with nasal congestion, facial pain, and black necrotic patches on the palate. What is the most likely diagnosis?

Mucormycosis. ***Mucormycosis*** - The presence of **black necrotic patches on the palate** in a diabetic patient with sinusitis symptoms is highly characteristic of mucormycosis. - **Diabetes** is a significant risk factor for this aggressive fungal infection, which often presents with tissue necrosis. *Bacterial sinusitis* - While facial pain and nasal congestion are consistent with bacterial sinusitis, **black necrotic patches** are not a typical feature. - Bacterial sinusitis rarely causes deep tissue invasion and necrosis of this extent. *Rhinoscleroma* - This is a chronic granulomatous disease of the upper respiratory tract caused by *Klebsiella rhinoscleromatis*, primarily seen in specific endemic regions. - It presents with **progressive inflammatory masses** and **scarring**, not acute necrosis or black patches. *Granulomatosis with Polyangiitis (GPA)* - GPA can cause sinusitis, **nasal crusting**, and **cartilage destruction**, but typically presents with **granulomatous inflammation** and vasculitis, not primary necrotic patches on the palate. - It is often associated with **ANCA positivity** and systemic symptoms affecting the lungs and kidneys.

Q: Which of the following is true about polio?

Risk of paralysis increases with tonsillectomy. ***Risk of paralysis increases with tonsillectomy*** - Tonsillectomy, especially when performed during an active poliovirus infection, has been linked to an **increased risk** of paralytic polio, particularly **bulbar polio**. - The surgical trauma may facilitate viral spread to the **central nervous system** [1] or alter immune responses, making the individual more susceptible to severe disease. *Paralytic polio is most common* - The vast majority of poliovirus infections are **asymptomatic** or cause **mild, non-specific symptoms**. - Only a small percentage of infected individuals (about 1 in 200) develop **paralytic polio**. *Causes spastic paralysis* - Poliovirus primarily affects **anterior horn cells** in the spinal cord, causing **flaccid paralysis** due to damage to lower motor neurons. - **Spastic paralysis** results from upper motor neuron damage, which is not characteristic of polio. *Polio drops given only to children under 3* - Oral polio vaccine (OPV, or "polio drops") is typically given to children in multiple doses from **birth** up to **5 years of age** in endemic regions. - The exact schedule varies by country, but it extends beyond just children under 3 to ensure comprehensive immunity.

Question 1

A patient with HIV develops CMV retinitis at CD4 count of 75/µL. When can prophylaxis be stopped?

Accepted Answer

CD4 >200/µL for 3 months

Answer

CD4 >100/µL

Answer

After 6 months of treatment

Answer

Viral load undetectable

Question 2

A patient with advanced HIV presents with cryptococcal meningitis. Which CSF finding is most characteristic?

Accepted Answer

High opening pressure

Answer

High protein

Answer

Low glucose

Answer

Neutrophilic pleocytosis

Question 3

A patient develops sudden onset fever and confusion 2 days post-splenectomy. Most appropriate initial antibiotic?

Accepted Answer

Ceftriaxone

Answer

Azithromycin

Answer

Vancomycin

Answer

Piperacillin-tazobactam

Question 4

A patient with dengue fever develops warning signs. Which finding indicates severe disease requiring ICU care?

Accepted Answer

Hematocrit rise >20%

Answer

Mild ascites

Answer

Persistent vomiting

Answer

Platelet count <20,000

Question 5

Patient: fever, joint pain, rash. Recent history of mosquito bite. Most likely diagnosis in urban area?

Accepted Answer

Chikungunya

Answer

Dengue

Answer

Japanese Encephalitis

Answer

Malaria

Question 6

HIV patient presents with chest X-ray showing bilateral reticulonodular infiltrates. CD4 count 80/µL. Most likely diagnosis?

Accepted Answer

Pneumocystis pneumonia

Answer

CMV infection

Answer

Cryptococcosis

Answer

Tuberculosis

Question 7

Which of the following is the most commonly used drug for outpatient management of community acquired pneumonia?

Accepted Answer

Azithromycin

Answer

Ceftriaxone

Answer

Streptomycin

Answer

Vancomycin

Question 8

Most common infection post solid organ transplantation

Accepted Answer

CMV

Answer

EBV

Answer

HSV

Answer

HPV

Question 9

A 60-year-old female with a history of diabetes presents with nasal congestion, facial pain, and black necrotic patches on the palate. What is the most likely diagnosis?

Accepted Answer

Mucormycosis

Answer

Bacterial sinusitis

Answer

Rhinoscleroma

Answer

Granulomatosis with Polyangiitis (GPA)

Question 10

Which of the following is true about polio?

Accepted Answer

Risk of paralysis increases with tonsillectomy

Answer

Paralytic polio is most common

Answer

Causes spastic paralysis

Answer

Polio drops given only to children under 3

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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