Infectious Diseases Practice Questions

Q: Earliest and often the only presentation of TB kidney is

Blood in urine. ***Blood in urine*** - **Hematuria** (blood in urine) is a common initial presentation of renal TB, often microscopic and sometimes macroscopic, appearing early due to inflammation and ulceration of the urinary tract. - The presence of **blood in urine** without significant pain or other classic infection signs can confuse the diagnosis, making it an "early" and *misleading* symptom without further investigation. *Sterile pyuria* - While **sterile pyuria** (pus cells in urine without bacterial growth on routine cultures) is highly suggestive of **TB kidney**, it tends to appear later in the disease progression as more significant renal damage and inflammation occur. - Early stages might not show prominent pyuria, and **hematuria** often precedes it as the initial symptom of tissue damage. *Colicky abdominal pain* - **Colicky abdominal pain** is more commonly associated with obstruction, such as from stone passage or severe hydronephrosis, which are typically later complications of TB kidney, not early presentations. - Early renal TB typically involves the parenchyma and calyces, not usually leading to significant obstruction that would cause colicky pain. *Kidney stones* - **Kidney stones** (renal calculi) are a potential long-term complication of renal TB due to metabolic changes, inflammation, and cellular debris, but they are not an *early* or *initial* symptom [1]. - The formation of stones usually indicates more advanced disease or chronic inflammation within the urinary tract [1].

Q: Which of the following is NOT more commonly seen in Klebsiella Pneumonia compared to Pneumococcal Pneumonia?

Lower lobe involvement. ***Lower lobe involvement*** - **Pneumococcal pneumonia** classically presents with **lobar pneumonia**, often affecting a single lobe, which can be any lobe but frequently involves the lower lobes. - While Klebsiella pneumonia can involve any lobe, the frequency of lower lobe involvement is not definitively higher than in pneumococcal pneumonia, making it a feature not *more* commonly seen in Klebsiella. *Abscess Formation* - **Klebsiella pneumonia** is notoriously associated with **necrosis** and abscess formation within the lung parenchyma due to its highly virulent polysaccharide capsule. - Abscesses are less common in uncomplicated **pneumococcal pneumonia**, which more typically causes lobar consolidation without significant tissue destruction [1]. *Pleural Effusion* - **Klebsiella pneumonia** is well-known for causing severe inflammation and an increased likelihood of developing a **parapneumonic pleural effusion**, often a complicated or empyematous one. - While pleural effusions can occur in pneumococcal pneumonia, they are generally less frequent and less severe than those seen with Klebsiella. *Cavitation* - **Cavitation** (breakdown of lung tissue forming cavities) is a hallmark of severe **Klebsiella pneumonia**, often observed as a consequence of extensive necrosis [1]. - Cavitation is a rare finding in **pneumococcal pneumonia**, which tends to resolve with consolidation rather than destructive changes.

Q: Tropical pulmonary eosinophilia is specifically associated with which of the following conditions?

Occult filariasis. ***Occult filariasis*** - **Tropical pulmonary eosinophilia (TPE)** is a hypersensitivity reaction specifically caused by infection with **filarial parasites**, primarily *Wuchereria bancrofti* or *Brugia malayi*, in individuals living in endemic areas [1]. - The disease involves migration of microfilariae to the lungs, stimulating a strong **IgE-mediated immune response** leading to high eosinophil counts in the blood and lung tissue [1]. *Cerebral malaria* - **Cerebral malaria** is caused by the parasite *Plasmodium falciparum* and is characterized by neurological complications, not pulmonary eosinophilia. - It involves sequestration of parasitized red blood cells in the brain's microvasculature, leading to coma and other neurological symptoms. *Pneumonic plague* - **Pneumonic plague** is a severe bacterial infection caused by *Yersinia pestis*, affecting the lungs and leading to pneumonia. - It is not associated with eosinophilia and requires antibiotic treatment. *Asthmatic bronchitis* - **Asthmatic bronchitis** is a general term referring to inflammation of the bronchi combined with features of asthma, often triggered by allergens, irritants, or infections. - While it can involve eosinophilic inflammation, it is a broader syndrome and not specifically linked to occult filariasis in the way TPE is.

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: The most common cause of seizures in a patient of AIDS is

Toxoplasmosis. ***Toxoplasmosis*** - **Cerebral toxoplasmosis** is the most common cause of focal neurological deficits and seizures in patients with AIDS [1]. - It typically presents with multiple **ring-enhancing lesions** on MRI, often in the basal ganglia [1]. *Cryptococcal meningitis* - While common in AIDS, **cryptococcal meningitis** primarily causes headache, fever, and altered mental status, but seizures are less frequent. - It is diagnosed by identifying **Cryptococcus neoformans** in CSF. *Progressive multifocal leucoencephalopathy* - PML is a demyelinating disease caused by the **JC virus** and results in progressive neurological deficits due to white matter lesions [2]. - Seizures can occur, but this condition primarily affects **cognition** and motor function [2]. *CNS lymphoma* - **Primary CNS lymphoma** is another common CNS complication in AIDS, often presenting as a solitary or multiple ring-enhancing lesion [1]. - While it can cause seizures, it is less common than toxoplasmosis as the primary cause of seizures in this population [1].

Q: What serum markers are indicative of a high level of Hepatitis B virus (HBV) infection?

HBsAg, HBeAg, and HBV DNA. **HBsAg, HBeAg, and HBV DNA** - The presence of **HBsAg** indicates ongoing HBV infection [1], while **HBeAg** signifies active viral replication and high infectivity [1]. - **HBV DNA levels** directly quantify the amount of viral genetic material, providing a direct measure of viral load and disease activity [1]. *HBsAg only* - While **HBsAg** indicates the presence of HBV infection, it doesn't provide a complete picture of viral replication or load [1]. - It doesn't differentiate between active replication and chronic carriage with low viral activity [1]. *HBsAg and HBV DNA* - This combination is better than HBsAg alone, as **HBV DNA** directly measures viral load [1]. - However, it misses **HBeAg**, which is a crucial marker for active viral replication and high infectivity, especially in the early phases of chronic infection [2]. *Anti-HBsAg and HBV DNA* - **Anti-HBsAg** (HBsAb) indicates immunity to HBV, either from vaccination or resolved infection, and its presence suggests the absence of active infection [1]. - Therefore, the co-existence of **Anti-HBsAg** with significant **HBV DNA** levels is contradictory and unlikely to represent a high level of active HBV infection.

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: What is a rare condition associated with Hepatitis B infection?

Polyarteritis nodosa. ***Polyarteritis nodosa*** - **Polyarteritis nodosa (PAN)** is a **necrotizing vasculitis** [1] strongly associated with **Hepatitis B virus (HBV)** infection, particularly in areas where HBV is endemic. - The circulating **immune complexes** formed by HBV antigens and antibodies are deposited in the walls of small and medium-sized arteries, leading to inflammation and tissue damage. *Wegener's granulomatosis* - Now known as **Granulomatosis with Polyangiitis (GPA)**, this condition is primarily associated with **antineutrophil cytoplasmic antibodies (ANCAs)**, particularly **c-ANCA**, and is not typically linked to Hepatitis B infection. - It is characterized by necrotizing granulomatous inflammation and vasculitis affecting the respiratory tract and kidneys. *Systemic lupus erythematosus* - **Systemic lupus erythematosus (SLE)** is an **autoimmune disease** characterized by widespread inflammation and damage to various organ systems, often involving **antinuclear antibodies (ANAs)** [2], [3]. - While it can be triggered by various factors, a direct and strong association with Hepatitis B infection is not a known characteristic. *Sjogren syndrome* - **Sjogren syndrome** is a chronic autoimmune disorder primarily affecting the **exocrine glands**, leading to **dry eyes** and **dry mouth**, and is associated with **anti-Ro/SSA** and **anti-La/SSB antibodies** [2]. - While autoimmune conditions can rarely coexist or be triggered by viral infections, a direct or common association between Sjogren syndrome and Hepatitis B infection is not established.

Q: Which of the following is the most common bacterial cause of community-acquired pneumonia?

Streptococcus pneumoniae. ***Streptococcus pneumoniae*** - **_Streptococcus pneumoniae_** is the most frequent bacterial cause of **community-acquired pneumonia (CAP)**, responsible for a significant percentage of cases [1]. - It often leads to classical lobar pneumonia with acute onset of fever, chills, cough with purulent sputum, and pleuritic chest pain [2]. *Staphylococcus aureus* - While a cause of pneumonia, **_Staphylococcus aureus_** is more commonly associated with **hospital-acquired pneumonia** or pneumonia in individuals with predisposing factors such as influenza, IV drug use, or cystic fibrosis [1]. - It can cause severe necrotizing pneumonia and empyema, but it is not the most common cause of CAP. *Staphylococcus epidermidis* - **_Staphylococcus epidermidis_** is a common **commensal organism** of the skin and a frequent contaminant in cultures. - It is rarely a primary cause of pneumonia in immunocompetent individuals but can cause infections in the presence of **foreign bodies** like prosthetic devices [1]. *Staphylococcus saprophyticus* - **_Staphylococcus saprophyticus_** is primarily known as a cause of **urinary tract infections (UTIs)**, especially in young women. - It is not a common pathogen for respiratory tract infections or pneumonia.

Question 1

Earliest and often the only presentation of TB kidney is

Accepted Answer

Blood in urine

Answer

Sterile pyuria

Answer

Colicky abdominal pain

Answer

Kidney stones

Question 2

Which of the following is NOT more commonly seen in Klebsiella Pneumonia compared to Pneumococcal Pneumonia?

Accepted Answer

Lower lobe involvement

Answer

Abscess Formation

Answer

Pleural Effusion

Answer

Cavitation

Question 3

Tropical pulmonary eosinophilia is specifically associated with which of the following conditions?

Accepted Answer

Occult filariasis

Answer

Asthmatic bronchitis

Answer

Pneumonic plague

Answer

Cerebral malaria

Question 4

Most common presentation of extra- pulmonary TB

Accepted Answer

Tubercular lymphadenitis

Answer

Peritoneal TB

Answer

Pericardial TB

Answer

Tubercular meningitis

Question 5

The most common cause of seizures in a patient of AIDS is

Accepted Answer

Toxoplasmosis

Answer

Cryptococcal meningitis

Answer

Progressive multifocal leucoencephalopathy

Answer

CNS lymphoma

Question 6

What serum markers are indicative of a high level of Hepatitis B virus (HBV) infection?

Accepted Answer

HBsAg, HBeAg, and HBV DNA

Answer

HBsAg only

Answer

HBsAg and HBV DNA

Answer

Anti-HBsAg and HBV DNA

Question 7

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 8

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 9

What is a rare condition associated with Hepatitis B infection?

Accepted Answer

Polyarteritis nodosa

Answer

Wegener's granulomatosis

Answer

Systemic lupus erythmatosus

Answer

Sjogren syndrome

Question 10

Which of the following is the most common bacterial cause of community-acquired pneumonia?

Accepted Answer

Streptococcus pneumoniae

Answer

Staphylococcus aureus

Answer

Staphylococcus epidermidis

Answer

Staphylococcus saprophyticus

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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