Infectious Diseases Practice Questions

Q: Most common presentation of extra- pulmonary TB

Tubercular lymphadenitis. ***Tubercular lymphadenitis*** - This is the **most common form** of extrapulmonary tuberculosis, often presenting as painless, swollen lymph nodes, especially in the cervical region [1]. - It develops when *Mycobacterium tuberculosis* disseminates from a primary pulmonary focus to regional lymph nodes, leading to granulomatous inflammation [1], [3]. *Peritoneal TB* - While a significant form of extrapulmonary TB, it is **less common** than lymphadenitis, typically presenting with abdominal pain, distension, and ascites. - Involvement of the peritoneum usually indicates hematogenous spread or direct extension from adjacent organs. *Pericardial TB* - This is a **rare but serious** form of extrapulmonary TB, often leading to pericardial effusion, constriction, or tamponade [2]. - It results from retrograde lymphatic spread or direct extension from mediastinal lymph nodes and is not the most common presentation. *Tubercular meningitis* - A **severe and life-threatening** form of extrapulmonary TB, involving the meninges of the brain and spinal cord, but it is less frequent than lymphadenitis [2]. - It is often seen in immunocompromised individuals or young children and presents with neurological symptoms [4].

Q: Which of these is least effective for the treatment of typhoid?

Ciprofloxacin. ***Ciprofloxacin*** - While ciprofloxacin was historically a first-line treatment, increasing rates of **quinolone resistance** among *Salmonella Typhi* isolates in many regions have significantly reduced its effectiveness. - The presence of **mutations** in the *gyrA* gene reduces the susceptibility of the bacteria to fluoroquinolones, making it a less reliable empirical treatment. *Chloramphenicol* - **Chloramphenicol** was one of the earliest effective antibiotics for typhoid fever and remains active against many strains, particularly in regions where resistance has not extensively developed. - Its use is limited by potential severe side effects such as **bone marrow suppression** (aplastic anemia), which makes it a less preferred option when safer alternatives are available. *Ceftriaxone* - **Ceftriaxone**, a third-generation cephalosporin, is often used for the treatment of severe or multidrug-resistant (MDR) typhoid fever due to its good activity against *Salmonella Typhi*. - It is typically administered parenterally, making it suitable for hospitalized patients with serious infections, and boasts a favorable **safety profile**. *Cefixime* - **Cefixime** is an oral third-generation cephalosporin that is effective against *Salmonella Typhi* and is often used for outpatient treatment of uncomplicated typhoid fever. - Its primary advantage is its **oral bioavailability**, which allows for step-down therapy after initial parenteral treatment or as a primary treatment in less severe cases.

Q: Which type of pulmonary TB is most likely to give sputum positive ?

Cavitary. ***Cavitary*** - **Cavitary lesions** in pulmonary tuberculosis indicate extensive tissue destruction and high bacterial load, leading to a much higher likelihood of finding **acid-fast bacilli** in the sputum [1]. - The communication of these cavities with the airways allows for the expulsion of bacilli-laden material, making sputum microscopy a sensitive diagnostic tool [1]. *Fibronodular* - While fibronodular lesions indicate pulmonary TB, they typically represent areas of **healing or chronic, lower-grade infection** where the bacterial load may be lower. - Sputum positivity is possible but less frequent compared to cavitary disease, as the organisms are more contained within **granulomas** [2]. *Pleural effusion* - **Pleural effusions** in TB are often a result of a hypersensitivity reaction to mycobacterial antigens rather than direct mycobacterial invasion of the pleural space with high bacterial load. - Sputum smears are typically **negative** in cases of isolated tuberculous pleural effusion because the infection is primarily contained within the pleural space, not actively expelled from the lungs. *None of the options* - This option is incorrect because **cavitary pulmonary TB** is well-established as the form most frequently associated with sputum positivity [1]. - The presence of open cavities directly correlates with the ability to detect bacteria in expectorated samples.

Q: A 17 years old female presents with sore throat and lymphadenopathy. A diagnostic test reveals the presence of heterophile antibodies. Diagnosis is?

Infectious mononucleosis (IM). ***Infectious mononucleosis (IM)*** - The presence of **heterophile antibodies** in a patient with **sore throat** and **lymphadenopathy** is the diagnostic hallmark of infectious mononucleosis, commonly caused by the **Epstein-Barr virus (EBV)** [1]. - This clinical presentation, especially in a young adult, is highly suggestive of IM [1]. *Tuberculosis (TB)* - While TB can cause **lymphadenopathy** (e.g., scrofula), it typically presents with other systemic symptoms like **fever**, **night sweats**, and **weight loss**, and its diagnosis relies on microbial cultures, PCR, or biopsy, not heterophile antibodies [2]. - A sore throat is not a characteristic primary symptom of TB lymphadenitis. *Cytomegalovirus infection* - **Cytomegalovirus (CMV)** can cause a mononucleosis-like syndrome with symptoms similar to EBV, including fever, fatigue, and lymphadenopathy [3]. - However, CMV infection does **not typically produce heterophile antibodies**, which differentiates it from IM [3]. *Streptococcal throat infection* - **Streptococcal pharyngitis** causes a sore throat and can lead to cervical lymphadenopathy but is diagnosed by **rapid strep test** or **throat culture**. - It does **not involve heterophile antibody production** and typically lacks the widespread lymphadenopathy and fatigue seen in IM.

Q: A young male came to the hospital with a clean-cut wound without any bleeding. The patient received a full course of tetanus vaccination 10 years ago. What is the best management for this patient?

Single-dose tetanus toxoid. ***Single-dose tetanus toxoid*** - For a **clean wound** in a patient who completed **primary tetanus vaccination** and received their last dose **≥10 years ago**, a **single booster dose** of tetanus toxoid is recommended. - The patient's last vaccination was exactly **10 years ago**, meeting the threshold for booster administration to maintain adequate **tetanus immunity**. *Human tetanus immunoglobulin only* - **Tetanus immunoglobulin (TIG)** provides **passive immunity** and is reserved for patients with **unknown vaccination status** or **high-risk contaminated wounds**. - This patient has a **clean-cut wound** and **documented vaccination history**, making active immunization with toxoid more appropriate than passive immunization. *Human tetanus immunoglobulin and a full course of vaccine* - This combination is indicated for **unvaccinated patients** or those with **unknown vaccination status** who have **contaminated wounds** (dirty, puncture wounds). - The patient has **completed primary vaccination** and has a **clean wound**, making a full course excessive and TIG unnecessary. *No treatment required* - **Tetanus immunity wanes** over time, and for **clean wounds**, booster is recommended when the last dose was **≥10 years ago** (vs. ≥5 years for dirty wounds). - Since the patient's last vaccination was **exactly 10 years ago**, a booster dose is required to maintain protective immunity levels.

Q: A patient diagnosed to be HIV-positive was started on highly active antiretroviral therapy (HAART). Which of the following can be used to monitor treatment efficacy?

Viral load. ***Viral load*** - **Viral load** (HIV RNA copies per milliliter of plasma) is the most direct and sensitive measure of HAART efficacy, as it indicates the amount of actively replicating virus [1]. - A successful HAART regimen aims to reduce the **viral load** to undetectable levels, signaling effective suppression of viral replication [1]. *CD4+ T cell count* - While important for monitoring immune status and disease progression, **CD4+ T cell count** changes more slowly than viral load [1]. - An increase in **CD4+ T cell count** is a positive sign of immune reconstitution but is a lagging indicator of immediate treatment efficacy [1]. *p24 antigen* - **p24 antigen** is a core structural protein of HIV, primarily detectable early in acute infection and in advanced stages when viral replication is very high. - It is generally not used for routine monitoring of HAART efficacy in chronic HIV infection because its levels fluctuate and become undetectable as the immune system produces antibodies. *Viral serotype* - **Viral serotype** refers to the specific strain or subtype of HIV (e.g., HIV-1 vs. HIV-2, or different clades within HIV-1). - It is determined at diagnosis to understand the specific virus but does not change significantly during the course of treatment and is not used to monitor HAART efficacy.

Q: A bronchial asthma patient on inhalational steroids presented with white patchy lesions on the tongue and buccal mucosa. What condition is likely to be present in this patient?

Oral candidiasis. **Oral candidiasis** - **Inhaled corticosteroids** can suppress the local immune response in the oral cavity, creating an environment conducive to the overgrowth of *Candida albicans*. - The classic presentation includes **white patchy lesions** on the tongue and buccal mucosa, which can often be scraped off. *Oral lichen planus* - Characterized by **reticular (Wickham's striae)**, papular, or erosive lesions, which are often bilateral and symmetric [1]. - While it can present with white lesions, they are typically not easily scraped off and are not primarily associated with inhaled corticosteroid use [1]. *Aphthous ulcers* - These are typically **painful, solitary, or multiple ulcers** with a red halo and a yellowish-gray center [2]. - They are distinct from widespread white patchy lesions and are not directly caused by inhaled corticosteroid use [2]. *Oral leukoplakia* - Defined as a **white patch or plaque** on the oral mucosa that cannot be characterized clinically or pathologically as any other disease, and which is not removable by scraping. - It is often associated with tobacco use and alcohol consumption, and carries a risk of malignancy; it does not typically appear as a direct side effect of inhaled corticosteroids.

Q: A patient hailing from Delhi presents with fever, arthralgia, and extensive petechial rash for 3 days. Lab investigations revealed a hemoglobin of 9 g/ dL, a white blood cell count of 9000 cells/mm3, a platelet count of 20000 cells/mm3, and a prolonged bleeding time. The clotting time was normal. What is the most likely diagnosis?

Dengue. Dengue - The combination of **fever, arthralgia, extensive petechial rash**, and severe **thrombocytopenia** (platelet count 20,000/mm³) with **prolonged bleeding time** is highly characteristic of severe dengue infection, especially in an endemic area like Delhi [1]. - While leukocytosis (WBC 9000/mm³) is not typical for dengue (usually causes leukopenia), the other features strongly point to dengue hemorrhagic fever [1]. *Malaria* - Typically presents with **intermittent high fever**, chills, and sweats. While it can cause some thrombocytopenia and anemia, the **extensive petechial rash** is not a characteristic feature. - **Thrombocytopenia** in malaria is usually milder than observed here, and prolonged bleeding time is less common [2]. *Scrub typhus* - Caused by Orientia tsutsugamushi, it is characterized by **fever, headache, myalgia, and a characteristic eschar** (necrotic ulcer) at the bite site, which is not mentioned. - While it can cause rash and some thrombocytopenia, the **petechial rash** and such severe thrombocytopenia with prolonged bleeding time are less typical. *Typhoid* - Presents with **sustained high fever**, headache, bradycardia, and sometimes a **rose spot rash** (maculopapular), which is different from a petechial rash. - Typhoid typically causes **leukopenia** and can lead to gastrointestinal complications like intestinal bleeding, but severe thrombocytopenia and extensive petechiae are not common presenting features.

Q: Punched out ulcers in the esophagus are most commonly associated with which of the following conditions?

CMV. ***Oesophagitis*** - Characterized by **punched-out ulcers** in the esophagus, often related to infectious causes. - Common in patients with **immunocompromised** states, where mucosal inflammation leads to these distinctive lesions [1]. *cmv* - Typically associated with **shallow ulcers** and **larger lesions**, not specifically "punched-out" ulcers. - CMV esophagitis usually presents with **linear ulcerations** and is less common in the absence of immune deficiency [1]. *candida* - Characterized by **white plaques** or pseudomembranes rather than **punched-out ulcers**. - Common in individuals with **oral thrush** and presents as **esophageal symptoms** such as dysphagia [1]. *herpes* - Often leads to **sharp, serpiginous ulcers** that are distinct from the punched-out variety. - Typically associated with **oral lesions** and presents with acute severe pain while swallowing [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 347-348.

Question 1

Most common presentation of extra- pulmonary TB

Accepted Answer

Tubercular lymphadenitis

Answer

Peritoneal TB

Answer

Pericardial TB

Answer

Tubercular meningitis

Question 2

Which of these is least effective for the treatment of typhoid?

Accepted Answer

Ciprofloxacin

Answer

Ceftriaxone

Answer

Chloramphenicol

Answer

Cefixime

Question 3

Which type of pulmonary TB is most likely to give sputum positive ?

Accepted Answer

Cavitary

Answer

Fibronodular

Answer

Pleural effusion

Answer

None of the options

Question 4

A 17 years old female presents with sore throat and lymphadenopathy. A diagnostic test reveals the presence of heterophile antibodies. Diagnosis is?

Accepted Answer

Infectious mononucleosis (IM)

Answer

Tuberculosis (TB)

Answer

Cytomegalovirus infection

Answer

Streptococcal throat infection

Question 5

A young male came to the hospital with a clean-cut wound without any bleeding. The patient    received a full course of tetanus vaccination 10 years ago. What is the best management for    this patient?

Accepted Answer

Single-dose tetanus toxoid

Answer

Human tetanus immunoglobulin only

Answer

Human tetanus immunoglobulin and a full course of vaccine

Answer

No treatment required

Question 6

A patient diagnosed to be HIV-positive was started on highly active antiretroviral therapy (HAART). Which of the following can be used to monitor treatment efficacy?

Accepted Answer

Viral load

Answer

CD4+ T cell count

Answer

p24 antigen

Answer

Viral serotype

Question 7

A bronchial asthma patient on inhalational steroids presented with white patchy lesions on the tongue and buccal mucosa. What condition is likely to be present in this patient?

Accepted Answer

Oral candidiasis

Answer

Oral lichen planus

Answer

Aphthous ulcers

Answer

Oral leukoplakia

Question 8

A patient hailing from Delhi presents with fever, arthralgia, and extensive petechial rash for 3    days. Lab investigations revealed a hemoglobin of 9 g/ dL, a white blood cell count of 9000    cells/mm3, a platelet count of 20000 cells/mm3, and a prolonged bleeding time. The clotting    time was normal. What is the most likely diagnosis?

Accepted Answer

Dengue

Answer

Malaria

Answer

Scrub typhus

Answer

Typhoid

Question 9

Punched out ulcers in the esophagus are most commonly associated with which of the following conditions?

Accepted Answer

CMV

Answer

Reflux esophagitis

Answer

Herpes simplex virus (HSV)

Answer

Candida

Question 10

An 11-year-old boy presented with a cough for 15 days. On examination, he was found to have cervical lymphadenopathy. Lymph node biopsy showed the following findings, and acid-fast staining was positive for acid-fast bacilli. What could be the diagnosis?

Accepted Answer

Tuberculosis

Answer

Leprosy

Answer

Sarcoidosis

Answer

Syphilis

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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