Infectious Diseases Practice Questions

Q: Which of the following is the most accurate description of thrush?

Is characterized by white patches in the oral cavity. ***Is characterized by white patches in the oral cavity*** - Thrush, or **oral candidiasis**, classically presents as creamy **white patches** on the tongue, inner cheeks, roof of the mouth, and back of the throat. - These patches can often be **scraped off**, revealing reddened and sometimes bleeding tissue underneath. *Occurs in individuals of all ages* - While thrush can occur at any age, it is most common in **infants**, **elderly individuals**, and those with **compromised immune systems**. - It is less common in healthy adults, making this description not the *most* accurate and comprehensive. *Is caused by a fungal infection* - Thrush is indeed caused by the fungus ***Candida albicans***, a type of yeast. - However, simply stating the cause does not fully describe the condition's distinct clinical presentation, which is essential for diagnosis. *Responds to antifungal treatment* - Thrush is typically treated with **antifungal medications** such as nystatin, clotrimazole, or fluconazole. - While true, describing the treatment is not the most direct or accurate description of the condition itself, which focuses on its characteristic features.

Q: A 25-year-old male university student presented with a history of multiple tick bites 45 days prior, followed by recurring episodes of high-grade fever, headache, myalgias, arthralgias, nausea, and occasional vomiting. Each episode lasted approximately 6-7 days with symptom-free intervals of 9-10 days. Physical examination revealed mild splenomegaly and skin lesions. A Wright stain of the patient's peripheral blood smear was performed. What is the first oral drug of choice for this patient?

Doxycycline. ***Doxycycline*** - The patient's presentation is classic for **tick-borne relapsing fever (TBRF)** caused by *Borrelia* species. - The **pathognomonic feature** is the **relapsing pattern**: recurring fever episodes (6-7 days) separated by **afebrile intervals** (9-10 days), which distinguishes TBRF from Lyme disease. - **Wright stain of peripheral blood smear** during febrile episodes typically reveals **spirochetes** (unlike Lyme disease where spirochetes are rarely visible in blood). - **Doxycycline 100 mg twice daily** is the **first-line oral treatment** for TBRF, with excellent activity against *Borrelia* spirochetes. - Also covers potential tick-borne coinfections (Ehrlichia, Anaplasma). *Amoxicillin* - While effective for **Lyme disease**, amoxicillin is **less effective for TBRF** compared to tetracyclines. - Used as an alternative in **pregnant women or children <8 years** when doxycycline is contraindicated. - Does not cover rickettsial coinfections that doxycycline would treat. *Cefuroxime* - This **second-generation cephalosporin** can be used as an alternative for Lyme disease. - However, it is **not the first-line choice** for the relapsing fever pattern seen in this case. - Doxycycline remains superior due to broader coverage and better efficacy for TBRF. *Erythromycin* - **Erythromycin** has **poor efficacy** against *Borrelia* species and is **not recommended** for TBRF or Lyme disease. - Higher relapse rates and treatment failures make it an inappropriate choice. - Modern macrolides (azithromycin) have better activity but still inferior to doxycycline.

Q: Which of the following agents is least likely to cause meningitis in the elderly?

Herpes Simplex Virus - 2 (HSV-2).. Herpes Simplex Virus - 2 (HSV-2) - While HSV-2 can cause meningitis, it is **less common** in the elderly compared to bacterial pathogens, and primarily causes **aseptic meningitis**, often recurrently [1]. - Though immunocompromised elderly can be susceptible, HSV-2 meningitis is generally more prevalent in younger, sexually active individuals. *Listeria Monocytogenes* - This is a significant cause of **bacterial meningitis** in the elderly, particularly those over 60, due to their weakened immune systems. - It's known to affect individuals with **compromised cell-mediated immunity**, which is common in older adults. *Streptococcus pneumoniae* - **Pneumococcal meningitis** is one of the most common and severe forms of bacterial meningitis in all age groups, including the elderly [1]. - Elderly individuals have a higher risk of severe disease and complications from **S. pneumoniae** infections [1]. *Gram Negative bacteria* - **Gram-negative bacilli**, such as *Escherichia coli* and *Klebsiella pneumoniae*, are important causes of meningitis in older adults, especially those with comorbidities or who have undergone neurosurgery. - This risk increases with age due to factors like indwelling catheters, nursing home residence, and weakened immune responses [1].

Q: Most common symptom of tetanus is

Lock-jaw. ***Lock-jaw*** - **Trismus**, or "lock-jaw," is the **hallmark initial symptom** of tetanus, resulting from spasms of the masseter muscles [1]. - It often progresses to generalized muscle rigidity and spasms, making it difficult to open the mouth or swallow [1]. *Tonic-clonic seizures* - While tetanus can cause severe muscle spasms, **generalized tonic-clonic seizures** are not the most common initial or presenting symptom [2]. - Tetanic spasms are characterized by sustained muscle contractions, which are distinct from the rhythmic jerking seen in tonic-clonic seizures. *Hemiplegia* - **Hemiplegia**, or unilateral paralysis, is typically associated with **stroke** or focal brain injury [2]. - Tetanus causes **generalized muscular rigidity** and spasms, not focal paralysis. *Opisthotonus* - **Opisthotonus** is a severe symptom of tetanus characterized by **extreme hyperextension of the head and spine**, forming an arch. - While a classic sign of severe tetanus, it is usually a **later manifestation** after lock-jaw has developed.

Q: Which of the following is NOT a recognized gastrointestinal tract infection in AIDS patients?

Cryptococcus neoformans. ***Cryptococcus neoformans*** - While *Cryptococcus neoformans* is a significant opportunistic infection in AIDS patients, it primarily causes **meningitis** and **pulmonary infections**, not typically a primary gastrointestinal tract infection [1]. - Though dissemination can occur, direct involvement of the GI tract as a primary site of infection is **uncommon** compared to other pathogens listed. *HSV* - **Herpes simplex virus (HSV)** commonly causes **esophagitis** in AIDS patients, leading to painful swallowing and ulcerations. - It can also cause **perianal ulcers** and proctitis in immunocompromised individuals [2]. *CMV* - **Cytomegalovirus (CMV)** is a frequent cause of severe GI disease in AIDS patients, leading to **colitis**, esophagitis, and gastritis [1]. - CMV infection can cause **ulcerations**, bleeding, and perforation throughout the gastrointestinal tract. *Atypical mycobacteria* - **Atypical mycobacteria**, such as *Mycobacterium avium complex (MAC)*, are common causes of widespread **disseminated disease** in AIDS patients, frequently involving the gastrointestinal tract [3]. - MAC infection in the GI tract can cause **malabsorption**, chronic diarrhea, and abdominal pain [3].

Q: A pulled-up caecum is typically associated with which condition?

Tuberculosis. **Tuberculosis** - **Abdominopelvic tuberculosis**, particularly of the ileocecal region, is a common cause of a **pulled-up caecum** due to inflammatory adhesions and fibrosis. - The inflammatory process and subsequent scarring can lead to contracture and retraction of the caecum. *Colorectal cancer* - While it can cause mass effect and obstruction, **colorectal cancer** does not typically result in a "pulled-up caecum." - It more commonly presents with symptoms like **hematochezia**, changes in bowel habits, or abdominal pain. *Intestinal obstruction* - **Intestinal obstruction** is a functional or mechanical blockage of the bowel, leading to symptoms like abdominal distension, vomiting, and obstipation. - It does not inherently cause a **pulled-up caecum**; instead, it's a consequence of the obstruction itself, often involving a distended small bowel. *Crohn's disease* - **Crohn's disease** can affect any part of the gastrointestinal tract and may cause inflammation, strictures, and fistulas. - While it can cause inflammation in the ileocecal region, a **pulled-up caecum** is not a classic or defining feature in the same manner as with tuberculosis.

Q: Which one of the following tests would be most useful in determining the chances of an HIV-positive patient progressing to symptomatic AIDS?

CD4 lymphocyte count. ***CD4 lymphocyte count*** - A **low CD4 count** is inversely correlated with the risk of developing **opportunistic infections** and cancers characteristic of AIDS [1]. - Monitoring changes in CD4 count over time provides crucial information about **disease progression** and the efficacy of antiretroviral therapy [1]. *HIV antibody test* - An **HIV antibody test** indicates the presence of HIV infection but does not provide information about the **disease stage** or progression to AIDS [1]. - It primarily detects the body's immune response to the virus, not the viral load or immune damage. *HIV PCR* - **HIV PCR** (polymerase chain reaction) measures the **viral load**, which indicates the amount of HIV in the blood. - While a high viral load is associated with faster progression, the **CD4 count** is a more direct and universally accepted indicator of immune system damage and risk of AIDS-defining conditions [1]. *Neopterin* - **Neopterin** is a marker of **immune activation** and inflammation, often elevated in HIV infection. - While elevated neopterin can indicate disease activity, it is not as specific or as strong a predictor of progression to AIDS as the CD4 lymphocyte count.

Q: What is the optimum duration of antibacterial treatment for acute bacterial prostatitis?

4-6 weeks. ***4-6 weeks*** - Treatment for **acute bacterial prostatitis** requires a prolonged course of antibiotics to ensure eradication of the infection from the prostate gland, which often has poor antibiotic penetration. - A duration of **4 to 6 weeks** is recommended to prevent recurrence and progression to chronic prostatitis. *3 days* - A 3-day course of antibiotics is **too short** for acute bacterial prostatitis. - Such a short duration would likely lead to incomplete bacterial eradication and a high risk of **relapse or chronic infection**. *7-14 days* - A 7-14 day course of antibiotics is typically sufficient for more superficial or readily accessible infections, but it is **insufficient for acute bacterial prostatitis**. - The prostate's unique anatomy and vascular supply necessitate a **longer treatment period** to achieve therapeutic drug levels and eliminate pathogens. *2-14 days* - While suitable for some acute urinary tract infections, a 2-14 day regimen is **inadequate for acute bacterial prostatitis**. - This duration does not account for the **depth and complexity of prostate infection**, increasing the risk of treatment failure.

Q: Which of the following chest X-ray findings is least likely to be associated with tuberculosis in patients with HIV?

Lupus vulgaris. ***Lupus vulgaris*** * **Lupus vulgaris** is a form of **cutaneous tuberculosis** that affects the skin and is not a chest X-ray finding. * It is a localized skin lesion, typically on the face or neck, and does not manifest with pulmonary radiographic changes. *Miliary pattern* * **Miliary pattern** on chest X-ray appears as diffuse **small nodular infiltrates** (1-3 mm) distributed throughout both lung fields, representing hematogenous dissemination of *Mycobacterium tuberculosis*. * This finding is common in HIV patients with **disseminated (miliary) tuberculosis** and reflects severely impaired cell-mediated immunity. * The term "miliary" refers to the millet seed-like appearance of the nodules. *Pleural effusion* * **Pleural effusion** is a common manifestation of tuberculosis, especially in immunocompromised individuals like those with HIV, often appearing as blunting of the **costophrenic angles** on chest X-ray. * It is caused by an inflammatory reaction to mycobacterial antigens in the pleural space. *Hilar lymphadenopathy* * **Hilar lymphadenopathy** is a common chest X-ray finding in both primary and reactivated tuberculosis, particularly in HIV-infected patients due to an altered immune response. * Enlarged lymph nodes near the **hilum** are often prominently visible and can be a sole chest X-ray finding in early or atypical presentations.

Question 1

Which of the following is the most accurate description of thrush?

Accepted Answer

Is characterized by white patches in the oral cavity

Answer

Occurs in individuals of all ages

Answer

Is caused by a fungal infection

Answer

Responds to antifungal treatment

Question 2

A 25-year-old male university student presented with a history of multiple tick bites 45 days prior, followed by recurring episodes of high-grade fever, headache, myalgias, arthralgias, nausea, and occasional vomiting. Each episode lasted approximately 6-7 days with symptom-free intervals of 9-10 days. Physical examination revealed mild splenomegaly and skin lesions. A Wright stain of the patient's peripheral blood smear was performed. What is the first oral drug of choice for this patient?

Accepted Answer

Doxycycline

Answer

Amoxicillin

Answer

Cefuroxime

Answer

Erythromycin

Question 3

Which of the following agents is least likely to cause meningitis in the elderly?

Accepted Answer

Herpes Simplex Virus - 2 (HSV-2).

Answer

Listeria Monocytogenes

Answer

Gram Negative bacteria

Answer

Streptococcus pneumoniae

Question 4

Winterbottom's sign in sleeping sickness refers to.

Accepted Answer

Posterior cervical lymphadenopathy (indicative of chronic African trypanosomiasis)

Answer

Unilateral conjunctivitis

Answer

Fever and malaise

Answer

Chancre at the site of the tsetse fly bite

Question 5

Most common symptom of tetanus is

Accepted Answer

Lock-jaw

Answer

Tonic-clonic seizures

Answer

Opisthotonus

Answer

Hemiplegia

Question 6

Which of the following is NOT a recognized gastrointestinal tract infection in AIDS patients?

Accepted Answer

Cryptococcus neoformans

Answer

HSV

Answer

Atypical mycobacteria

Answer

CMV

Question 7

A pulled-up caecum is typically associated with which condition?

Accepted Answer

Tuberculosis

Answer

Colorectal cancer

Answer

Intestinal obstruction

Answer

Crohn's disease

Question 8

Which one of the following tests would be most useful in determining the chances of an HIV-positive patient progressing to symptomatic AIDS?

Accepted Answer

CD4 lymphocyte count

Answer

HIV antibody test

Answer

Neopterin

Answer

HIV PCR

Question 9

What is the optimum duration of antibacterial treatment for acute bacterial prostatitis?

Accepted Answer

4-6 weeks

Answer

3 days

Answer

7-14 days

Answer

2-14 days

Question 10

Which of the following chest X-ray findings is least likely to be associated with tuberculosis in patients with HIV?

Accepted Answer

Lupus vulgaris

Answer

Pleural effusion

Answer

Hilar lymphadenopathy

Answer

Miliary pattern

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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