Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 1211: Which type of leprosy does not involve nerve damage?

A. Indeterminate leprosy (Correct Answer)
B. Borderline tuberculoid leprosy
C. Tuberculoid leprosy
D. Lepromatous leprosy

Explanation: ***Indeterminate leprosy*** - This is the earliest form of leprosy and often presents with only a **single skin lesion** and no demonstrable nerve damage. - Due to the minimal immune response, it can be difficult to classify and may progress to other forms if left untreated. *Tuberculoid leprosy* - Characterized by a **strong cell-mediated immune response** to *Mycobacterium leprae*, leading to significant nerve involvement [1]. - Patients typically present with well-demarcated, **hypopigmented patches** with definite **sensory loss** due to nerve damage [1]. *Borderline tuberculoid leprosy* - This form sits between tuberculoid and borderline lepromatous leprosy, showing features of both, including **nerve involvement** [2]. - It presents with a few to several skin lesions that are usually smaller and less clearly defined than tuberculoid lesions, often with **palpable nerves** and mild sensory loss [2]. *Lepromatous leprosy* - Characterized by a **weak or absent cell-mediated immune response**, leading to widespread bacterial proliferation and extensive nerve damage, often symmetrical [1]. - Patients show numerous, poorly defined skin lesions, nodules, and severe nerve involvement, which can result in significant **deformities** [2].

Question 1212: In which condition is a frozen pelvis commonly observed?

A. Chronic pelvic inflammatory disease
B. Severe endometriosis (Correct Answer)
C. Post-radiation pelvic fibrosis
D. Advanced cervical carcinoma

Explanation: ***Severe endometriosis*** - A **frozen pelvis** is a classic finding in severe endometriosis, characterized by extensive adhesions and fibrosis that fix pelvic organs together, making them immobile. - This condition involves the presence of **endometrial-like tissue** outside the uterus, leading to chronic inflammation, scarring, and adherence of structures like the uterus, ovaries, and bowel. *Advanced cervical carcinoma* - While advanced cervical carcinoma can cause widespread pelvic involvement and **fixation of organs**, the term "frozen pelvis" is not as commonly or specifically associated with it as it is with severe endometriosis. - The dominant findings would typically relate to the **tumor mass**, local invasion, and potential involvement of lymph nodes or distant metastasis. *Post-radiation pelvic fibrosis* - **Radiation therapy** can certainly lead to significant pelvic fibrosis and adhesions, restricting organ mobility. - However, this is largely an iatrogenic condition following cancer treatment, and while it may present similarly, the term "frozen pelvis" is primarily used in a descriptive fashion for the severe adhesion formations seen in endometriosis. *Chronic pelvic inflammatory disease* - Chronic PID can cause significant pelvic adhesions, tubo-ovarian abscesses, and scarring, leading to pain and infertility. - While it can result in fixed pelvic organs, the extent and specific nature of adhesion formation in PID generally differ from the diffuse, "frozen" quality seen in severe endometriosis, which often involves broader tissue planes.

Question 1213: Most common cause of retropharyngeal abscess in adults?

A. Tonsillitis
B. Lymphadenitis (Correct Answer)
C. Tooth extraction
D. TB

Explanation: ***Lymphadenitis*** - **Lymphadenitis** in the retropharyngeal space, often secondary to an upper respiratory tract infection, is the most common cause of retropharyngeal abscesses in adults. - The infection spreads from inflamed lymph nodes to form a **purulent collection** in the potential space behind the pharynx. *TB* - **Tuberculosis (TB)** can cause retropharyngeal abscesses, particularly in immunocompromised individuals or endemic areas, but it is less common than pyogenic infections [1]. - TB abscesses tend to be more **chronic** and may be associated with vertebral involvement (Pott's disease) [1]. *Tooth extraction* - While dental infections, including complications from **tooth extraction**, can lead to deep neck space infections, they are not the most common cause of retropharyngeal abscess specifically. - Infections from teeth more often spread to the **submandibular** or **parapharyngeal spaces**. *Tonsillitis* - **Tonsillitis** is a common cause of pharyngeal inflammation and can lead to peritonsillar abscesses, which are distinct from retropharyngeal abscesses. - While severe tonsillitis can occasionally spread to the retropharyngeal space, it is primarily local and less common than direct lymphatic seeding.

Question 1214: What is the most common cause of lobar consolidation?

A. Mycoplasma
B. Chlamydia
C. Streptococcus (Correct Answer)
D. Legionella

Explanation: ***Streptococcus*** - **_Streptococcus pneumoniae_** is the **most common bacterial cause** of community-acquired pneumonia, frequently leading to lobar consolidation. [1] - It often presents with classic symptoms such as **sudden onset of fever**, productive cough with **rusty sputum**, and pleuritic chest pain. [1] *Mycoplasma* - **_Mycoplasma pneumoniae_** typically causes **"walking pneumonia"**, characterized by a more indolent course and often presents with **interstitial infiltrates** rather than dense lobar consolidation. - Though common, it is a less frequent cause of true lobar consolidation compared to _Streptococcus pneumoniae_. *Chlamydia* - **_Chlamydia pneumoniae_** causes atypical pneumonia, similar to _Mycoplasma_, presenting with less severe symptoms and **patchy infiltrates** or **interstitial patterns** rather than lobar consolidation. - It is a common cause of **atypical pneumonia** but not the leading cause of lobar consolidation. *Legionella* - **_Legionella pneumophila_** can cause severe pneumonia with consolidation, but it is **less common overall** than pneumococcal pneumonia. [1] - **Legionnaires' disease** is often associated with exposure to contaminated water sources and may present with **gastrointestinal and neurological symptoms** in addition to respiratory manifestations.

Question 1215: What is the most common cause of pleural effusion in AIDS patients?

A. Pneumocystis Jiroveci
B. Mycoplasma
C. Kaposi sarcoma
D. TB (Correct Answer)

Explanation: ***TB*** - **Tuberculosis (TB)** is a common opportunistic infection in **AIDS patients**, and pleural effusion is a frequent manifestation, often an **exudative effusio**n [1]. - The high prevalence of TB in immunocompromised individuals due to **HIV** makes it the leading cause of pleural effusions in this population [1]. *Kaposi sarcoma* - While Kaposi sarcoma can affect the pleura and cause effusions, it is **less common** than TB as a cause of pleural effusion in AIDS patients. - Pleural effusions from Kaposi sarcoma are typically **serosanguinous** or **hemorrhagic**. *Pneumocystis Jiroveci* - **Pneumocystis pneumonia (PJP)** is a very common infection in AIDS patients but **rarely causes significant pleural effusions** [1]. - PCP primarily leads to **interstitial lung disease** rather than large effusions [1]. *Mycoplasma* - **Mycoplasma pneumoniae** can cause pneumonia and mild pleural effusions, but it's **not an opportunistic infection specifically linked to AIDS** and is less common than TB in this population. - The effusions associated with Mycoplasma are usually **small and transient**.

Question 1216: What condition is associated with Lemierre's syndrome?

A. Carotid sinus aneurysm
B. Traumatic occlusion of IJV
C. Any of the above
D. Thrombophlebitis of IJV (Correct Answer)

Explanation: ***Thrombophlebitis of IJV*** - **Lemierre's syndrome** is classically defined as **septic thrombophlebitis of the internal jugular vein (IJV)** following an oropharyngeal infection [1]. - The infection, most commonly caused by *Fusobacterium necrophorum*, spreads from the pharynx to the parapharyngeal space, leading to IJV inflammation and thrombosis [1]. *Carotid sinus aneurysm* - A **carotid sinus aneurysm** is an abnormal focal dilation of the carotid sinus, often associated with atherosclerosis or connective tissue disorders. - It is not directly linked to the pathogenesis or complications of **Lemierre's syndrome**. *Traumatic occlusion of IJV* - **Traumatic occlusion of the IJV** results from direct injury to the neck, leading to vessel compression or damage. - While it affects the IJV, it does not involve the septic thrombophlebitis or preceding oropharyngeal infection characteristic of **Lemierre's syndrome**. *Any of the above* - This option is incorrect because **Lemierre's syndrome** is specifically associated with **septic thrombophlebitis of the IJV**, not with other unrelated vascular conditions affecting the neck.

Question 1217: What is the primary cause of Waterhouse-Friderichsen syndrome?

A. Adrenal hemorrhage post malignancy
B. Adrenal hemorrhage after meningococcal infection (Correct Answer)
C. Adrenal hemorrhage after corticosteroid withdrawal
D. Congenital adrenal deficiency

Explanation: ***Adrenal hemorrhage after meningococcal infection*** - **Waterhouse-Friderichsen syndrome** is characterized by **massive, bilateral adrenal hemorrhage**, leading to acute adrenal insufficiency [1]. - It is most commonly associated with overwhelming **meningococcal sepsis**, particularly due to *Neisseria meningitidis* [1]. *Adrenal hemorrhage post malignancy* - While malignancies can cause adrenal hemorrhage, it is not the primary cause of **Waterhouse-Friderichsen syndrome**. - This syndrome is specifically linked to severe **bacterial sepsis**, not typically cancer-related adrenal bleeding [1]. *Congenital adrenal deficiency* - **Congenital adrenal hyperplasia (CAH)** involves genetic defects affecting cortisol synthesis, leading to chronic adrenal insufficiency. - It does not involve acute **adrenal hemorrhage** as seen in Waterhouse-Friderichsen syndrome. *Adrenal hemorrhage after corticosteroid withdrawal* - Abrupt withdrawal of corticosteroids can precipitate an **adrenal crisis** due to suppression of the hypothalamic-pituitary-adrenal (HPA) axis [2]. - However, it does not typically cause the characteristic **massive adrenal hemorrhage** seen in Waterhouse-Friderichsen syndrome [2].

Question 1218: In which condition is Cepacia syndrome most commonly associated?

A. Immotile cilia syndrome
B. Sarcoidosis
C. Cystic fibrosis (Correct Answer)
D. Tuberculosis

Explanation: ***Cystic fibrosis*** - **Cepacia syndrome** is a severe and often fatal complication in patients with **cystic fibrosis** caused by infection with bacteria of the *Burkholderia cepacia complex*. - Patients with cystic fibrosis have impaired mucociliary clearance, making them highly susceptible to chronic bacterial infections, including those leading to Cepacia syndrome. *Sarcoidosis* - **Sarcoidosis** is a multisystem inflammatory disease characterized by the formation of **non-caseating granulomas**, primarily affecting the lungs and lymph nodes. - It is not associated with bacterial infections causing Cepacia syndrome. *Tuberculosis* - **Tuberculosis** is caused by *Mycobacterium tuberculosis* and primarily affects the lungs, leading to granuloma formation and tissue destruction. - While it is a chronic bacterial infection, it does not typically lead to or interact with the *Burkholderia cepacia complex* in the way seen in Cepacia syndrome. *Immotile cilia syndrome* - Also known as **primary ciliary dyskinesia**, this condition involves defective ciliary function leading to recurrent respiratory infections and other issues like situs inversus. - Although patients have recurrent respiratory infections, **Cepacia syndrome** is not a characteristic or commonly associated complication.

Question 1219: Most common sinus to be involved in acute sinusitis?

A. Ethmoid
B. Maxillary (Correct Answer)
C. Sphenoid
D. Frontal

Explanation: ***Maxillary*** - The **maxillary sinuses** are the largest paranasal sinuses and are the most commonly involved in acute sinusitis due to their anatomical position and drainage characteristics. - Their ostia (drainage openings) are located on the superior aspect of the sinus, which can make drainage difficult when the patient is upright, leading to stasis of secretions and increased susceptibility to infection. *Ethmoid* - The ethmoid sinuses are a group of small air cells located between the eyes and are the second most commonly infected in sinusitis. - While frequently involved, especially in children, they are not as commonly affected as the maxillary sinuses in the general adult population with acute sinusitis. *Sphenoid* - The sphenoid sinuses are located deep within the skull, behind the eyes, and are the least commonly involved in acute sinusitis. - Inflammation here can be serious due to proximity to important structures like the optic nerves and carotid arteries, but it's not the most frequent site of infection. *Frontal* - The frontal sinuses are located in the forehead and are less commonly involved in acute sinusitis compared to the maxillary and ethmoid sinuses. - Their development is not complete until adolescence, and they are typically drained via the frontonasal duct, which can become easily obstructed.

Question 1220: Pea soup diarrhea is seen in -

A. Cholera
B. Typhoid (Correct Answer)
C. Yersinosis
D. Hepatitis

Explanation: ***Typhoid*** - **Pea soup diarrhea** is a classic symptom of **typhoid fever**, caused by *Salmonella Typhi* [1]. - This characteristic stool is a greenish-yellow watery diarrhea due to inflammation and ulceration of the Peyer's patches in the small intestine [1]. *Cholera* - Characterized by **rice-water stools**, which are profuse, watery, and often contain flecks of mucus, resembling water in which rice has been rinsed [2]. - This type of diarrhea is due to the potent **cholera toxin** causing massive fluid and electrolyte secretion [2]. *Yersinosis* - Causes diarrhea that can range from watery to bloody, often associated with severe **abdominal pain** mimicking appendicitis. - While it can cause enterocolitis, the stool consistency is not typically described as "pea soup" like in typhoid. *Hepatitis* - Hepatitis primarily affects the **liver** and typically does **not cause diarrhea** as a prominent symptom. - Common symptoms include jaundice, dark urine, and pale stools due to impaired bilirubin metabolism.

Practice by Chapter

Principles of Antimicrobial Therapy

Practice Questions

Fever of Unknown Origin

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HIV/AIDS and Related Infections

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Tuberculosis and Mycobacterial Diseases

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Tropical and Parasitic Infections

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Viral Infections (Hepatitis, Herpes, etc.)

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Healthcare-Associated Infections

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Fungal Infections

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Sepsis and Septic Shock

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Infection in Immunocompromised Hosts

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Emerging and Re-emerging Infections

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Antimicrobial Resistance

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Vaccination Principles

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