Infectious Diseases Practice Questions

Q: What is the most common cause of death in a patient with chronic bronchiectasis?

Infection. ***Infection*** - Chronic bronchiectasis creates a favorable environment for **bacterial colonization** and recurrent infections due to impaired mucociliary clearance and dilated, damaged airways. [1] - These infections, often by **Pseudomonas aeruginosa** or **Haemophilus influenzae**, can lead to acute exacerbations, progressive lung damage, and ultimately **respiratory failure** or overwhelming sepsis, which are common causes of death. [1], [2] *Right-sided heart failure* - **Cor pulmonale**, or right-sided heart failure, can develop as a complication of severe bronchiectasis due to **pulmonary hypertension** from chronic hypoxemia and vascular remodeling. - While it contributes to morbidity and mortality, it is not the most common direct cause of death; the underlying lung disease and subsequent infections are usually the primary drivers. *Hemoptysis* - **Severe hemoptysis** can occur in bronchiectasis due to erosion of inflamed bronchial arteries, which can be life-threatening if massive. [2], [3] - Although it is a serious complication and can be fatal, it is not the most frequent cause of death compared to the cumulative effect of chronic infections and progressive respiratory decline. *Carcinoma* - While patients with chronic lung conditions, including bronchiectasis, may have an **increased risk of lung cancer**, it is not the most common cause of death directly attributable to bronchiectasis itself. [3] - The direct and immediate threats to life in bronchiectasis are typically related to **exacerbations, infections, and respiratory failure**.

Q: A complicated urinary tract infection (UTI) is defined as an infection that fails to resolve or recurs within how much time of standard therapy?

2 weeks. **2 weeks** - A complicated urinary tract infection (UTI) is defined by its failure to resolve or recurrence within **two weeks** of completing standard antimicrobial therapy [1]. - This time frame is crucial for identifying UTIs that may be associated with **structural or functional abnormalities** of the urinary tract [1]. *1 week* - While recurrence within one week is certainly concerning, the standard definition for a complicated UTI due to treatment failure or recurrence extends to the two-week mark. - Assessing treatment efficacy over one week might be too short to definitively label a UTI as complicated in all cases. *3 weeks* - If a UTI recurs after three weeks, it is often considered a **reinfection** rather than a failure of the initial treatment or an indicator of a complicated UTI from the original episode [1]. - The focus for defining complicated UTI is typically on earlier recurrence or failure to achieve cure within a shorter, defined period. *4 weeks* - Recurrence after four weeks is generally considered a new infection or reinfection, rather than a failure of the initial therapy for a complicated UTI [1]. - The timeframe for classifying a UTI as complicated due to inadequate initial treatment response is specifically within weeks, not months.

Q: Most common mode of spread for genital tuberculosis is?

Hematogenous. ***Hematogenous*** - **Genital tuberculosis** most commonly spreads via the bloodstream from a primary site of infection, typically the **lungs** [2]. - This mode of spread allows the **Mycobacterium tuberculosis** bacilli to reach diverse pelvic organs, establishing secondary foci [2]. *Lymphatic* - While lymphatic spread can occur in tuberculosis, it is less common for disseminating infection to the genital tract compared to the **hematogenous route** [1]. - Lymphatic spread often leads to regional lymph node involvement rather than widespread dissemination to reproductive organs [1]. *Direct* - **Direct spread** from an adjacent organ infected with tuberculosis is rare for genital involvement. - This mode would involve local extension, which is not the primary mechanism for establishing genital tuberculosis. *Ascending* - **Ascending infection** is typically seen in other sexually transmitted infections or bacterial vaginosis, where pathogens move upwards from the lower genital tract. - This is not the characteristic mode of spread for **Mycobacterium tuberculosis** to cause genital tuberculosis.

Q: Which of the following statements about amoebic liver abscess is false?

Amoebic liver abscess is not treatable with antibiotics. Amoebic liver abscess is not treatable with antibiotics - This statement is false because **amoebic liver abscess** (ALA) is caused by *Entamoeba histolytica*, a **protozoan parasite**, and is effectively treated with **anti-parasitic drugs**, which are a type of antimicrobial and can be considered antibiotics in a broader sense for non-bacterial infections. - While traditional **antibiotics** (designed for bacteria) are not directly effective against the parasite, **metronidazole** (an antimicrobial) is the **drug of choice** for ALA. The liquid contents of the abscess typically have a characteristic pinkish or chocolate-brown color, often referred to as 'anchovy sauce' [1]. *More common in males than females* - This statement is **true**; amoebic liver abscess is indeed observed more frequently in **males**, particularly those between **20 and 50 years** of age. - The reasons for this disparity are not fully understood but may relate to hormonal factors or exposure differences. *More common in the right lobe of the liver* - This statement is **true**; the **right lobe** of the liver is the most common site for amoebic liver abscess formation. - This is attributed to the **anatomic fact** that the right lobe receives **more blood flow** from the superior mesenteric vein, which drains the colon where *Entamoeba histolytica* typically resides. *Metronidazole is the mainstay of treatment* - This statement is **true**; **metronidazole** is the **drug of choice** for the treatment of amoebic liver abscess [1]. - It is highly effective in eradicating the **trophozoites** of *Entamoeba histolytica* from the liver.

Q: Most common cause of diarrhea in AIDS patients?

Cryptosporidium. ***Cryptosporidium*** - **Cryptosporidium parvum** is a common opportunistic pathogen in AIDS patients, causing chronic, watery diarrhea, especially when the **CD4 count is low** [1]. - This parasite is resistant to routine chlorination, making **waterborne transmission** a significant concern. *Salmonella typhimurium* - While *Salmonella* can cause severe and recurrent gastroenteritis in AIDS patients, it is **not the most common cause** of chronic diarrhea in this population. - Salmonella infections in immunocompromised individuals often disseminate, leading to **bacteremia** beyond just diarrheal symptoms. *Candida* - *Candida albicans* is a common opportunistic pathogen in AIDS, primarily causing **oral candidiasis (thrush)** or esophagitis [2]. - While it can sometimes cause gastrointestinal symptoms, **Candida is not typically a prominent cause of diarrhea** in AIDS patients [2]. *Isospora* - **Isospora belli** is another coccidian parasite that causes chronic diarrhea in AIDS patients, particularly in tropical and subtropical regions [1]. - Although significant, it is **less common overall** compared to *Cryptosporidium* as a primary cause of diarrhea in this population [1].

Q: Which of the following statements about hydatid cyst of the liver is true?

Most common causative organism is Echinococcus granulosus.. **Most common causative organism is *Echinococcus granulosus*** - *Echinococcus granulosus* is the **predominant species** responsible for the majority of human hydatid cysts globally, particularly in the liver and lungs [1]. - This parasite is transmitted through the **fecal-oral route**, involving canids (dogs) as definitive hosts and livestock (sheep, cattle) as intermediate hosts [1]. *Mostly asymptomatic* - While some small uncomplicated cysts can be asymptomatic, many hydatid cysts, especially in the liver, eventually become **symptomatic** due to their size, mass effect, or complications [1]. - Symptoms often include **abdominal pain, jaundice**, or signs of rupture, making them clinical rather than primarily asymptomatic. *Most commonly located in the right lobe of the liver* - While the liver is the most common organ affected by hydatid disease, the cysts show **no particular predilection for the right or left lobe** and can be found throughout the hepatic parenchyma. - The **liver is the primary site** because it is the first capillary bed encountered by the oncospheres after penetration of the intestinal wall, but a specific lobe predominance is not consistently observed. *Hepatic resection is a treatment option, but not the first-line treatment* - **Hepatic resection (surgical removal)** of hydatid cysts is often considered the **definitive treatment** for accessible, symptomatic, or complicated cysts, aiming for complete cyst removal and prevention of recurrence. - While percutaneous aspiration, injection, and re-aspiration (PAIR) with scolicidal agents is an alternative for selected cases, **surgical resection remains a primary and frequently preferred treatment option**, especially for larger or complicated cysts and when feasible.

Q: Which of the following statements about Koplik spots is true?

All of the options.. All of the options. - Koplik spots are pathognomonic of measles, meaning their presence is a definitive indicator of the disease [1]. - They typically appear as tiny, white spots on an erythematous base on the buccal mucosa, often opposite the molars [1]. Pathognomonic of measles. - While Koplik spots are a hallmark sign of measles, stating this is true alone doesn't encompass all true aspects for this question [1]. - Their presence, however, is a strong diagnostic indicator of rubeola. Present on buccal mucosa opposite the molars. - This is a correct description of their typical location, but not a complete answer to the question "Which of the following statements about Koplik spots is true?" if other options also hold true [1]. - These spots are found on the mucous membrane lining the inside of the cheeks [1]. Not always present. - Koplik spots are transient and may not be present throughout the entire course of measles, particularly if a patient is seen later in the disease [1]. - They also can be missed if not specifically looked for or if they are very few in number.

Question 1

What is the most common cause of death in a patient with chronic bronchiectasis?

Accepted Answer

Infection

Answer

Hemoptysis

Answer

Carcinoma

Answer

Right-sided heart failure

Question 2

Which of the following statements about amoebiasis is correct?

Accepted Answer

Amoebic liver abscess occurs in 10% of intestinal amoebiasis cases in tropical regions

Answer

The abscess wall provides the highest yield for Entamoeba histolytica culture

Answer

The portal circulation prevents systemic spread of Entamoeba histolytica

Answer

Amoebic liver abscesses are formed primarily due to bacterial suppuration

Question 3

A complicated urinary tract infection (UTI) is defined as an infection that fails to resolve or recurs within how much time of standard therapy?

Accepted Answer

2 weeks

Answer

1 week

Answer

3 weeks

Answer

4 weeks

Question 4

Which of the following is the PRIMARY risk factor most commonly associated with healthcare-associated pneumonia (HCAP)?

Accepted Answer

Acute care hospitalization for at least 2 days in the preceding 90 days

Answer

Home infusion therapy

Answer

Immunosuppressive disease or immunosuppressive therapy

Answer

Antibiotic therapy in the preceding 90 days

Question 5

Most common mode of spread for genital tuberculosis is?

Accepted Answer

Hematogenous

Answer

Lymphatic

Answer

Direct

Answer

Ascending

Question 6

Which of the following statements about amoebic liver abscess is false?

Accepted Answer

Amoebic liver abscess is not treatable with antibiotics

Answer

More common in males than females

Answer

More common in the right lobe of the liver

Answer

Metronidazole is the mainstay of treatment

Question 7

Most common cause of diarrhea in AIDS patients?

Accepted Answer

Cryptosporidium

Answer

Salmonella typhimurium

Answer

Candida

Answer

Isospora

Question 8

Which of the following statements about hydatid cyst of the liver is true?

Accepted Answer

Most common causative organism is Echinococcus granulosus.

Answer

Mostly asymptomatic.

Answer

Most commonly located in the right lobe of the liver.

Answer

Hepatic resection is a treatment option, but not the first-line treatment.

Question 9

Which of the following statements about Koplik spots is true?

Accepted Answer

All of the options.

Answer

Pathognomonic of measles.

Answer

Present on buccal mucosa opposite the molars.

Answer

Not always present.

Question 10

A 10-year-old boy presents with an ulcerated lesion with undermined edges over the upper chest, accompanied by a satellite lesion in the anterior axillary fold for two months. Axillary lymph nodes are palpable. Histopathology reveals a dermal abscess with ill-defined histiocytes. AFB staining of the tissue is positive. Chest X-ray shows infiltrations and cavities. Mantoux test is positive. What is the most likely diagnosis?

Accepted Answer

Scrofuloderma

Answer

Skin abscess

Answer

Furuncle

Answer

Cellulitis

Answer

Erysipelas

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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