Infectious Diseases — MCQs

A 20-year-old woman presents with headache, fever, and neck stiffness. On examination, her blood pressure is 100/70 mm Hg, pulse 100/min, temperature 38.6, and the neck is stiff and painful to flex and extend. The ears, throat, and sinuses are normal, there are no focal neurologic signs, and the remaining examination is normal. There are no reported similar cases in the community. Which of the following is the most likely source of her infection?

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 871: Induration of seminal vesicle is seen most often in

A. Lymphogranuloma venereum
B. Syphilis
C. Gonorrhea
D. Tuberculosis (Correct Answer)

Explanation: ***Tuberculosis*** - **Tuberculosis** of the male genital tract often affects the seminal vesicles, leading to extensive tissue damage and **induration** due to granuloma formation and fibrosis. - This involvement can be part of disseminated tuberculosis or primary genitourinary tuberculosis, presenting with symptoms like **hematuria**, **epididymo-orchitis**, and painful ejaculation. *Lymphogranuloma venereum* - Characterized by **lymphadenopathy**, **genital ulcers**, and **proctitis**, but does not typically cause induration of the seminal vesicles. - Primarily affects **lymphatic tissues** in the inguinal and pelvic regions. *Syphilis* - Manifests with **chancres**, **rashes**, and later neurological or cardiovascular complications, but direct involvement and induration of seminal vesicles are not typical features. - While it can affect various organs, induration of the seminal vesicles is not a classic presentation. *Gonorrhea* - Causes **urethritis**, **epididymitis**, and sometimes prostatitis, but significant **induration** of the seminal vesicles is uncommon. - It primarily involves mucous membranes and often leads to purulent discharge.

Question 872: True about tuberculin test are all except:

A. Recent conversion in adult is an indication for ATT
B. No risk of developing TB, if tuberculin test is negative (Correct Answer)
C. May be false negative in immunocompromised patients
D. INH prophylaxis is started, if the test is positive

Explanation: ***No risk of developing TB, if tuberculin test is negative*** - A negative tuberculin skin test (TST) does not completely rule out the risk of developing **tuberculosis (TB)**, especially in certain populations. - Individuals may have a **false-negative result** if they are immunocompromised, have recent TB infection (before sensitization occurs), or have overwhelming active TB disease. *Recent conversion in adult is an indication for ATT* - A **recent tuberculin conversion** (a change from negative to positive TST within a 2-year period) in an adult indicates new infection and a high risk of progression to active TB, thus warranting **anti-tuberculosis therapy (ATT)**. [1] - This is a critical indicator for initiating **prophylactic treatment** to prevent active disease. *May be false negative in immunocompromised patients* - **Immunocompromised patients**, such as those with HIV, on immunosuppressive therapy, or with severe malnutrition, may not mount a sufficient immune response to the TST, leading to a **false-negative result**. - This phenomenon is called **anergy** and can be life-threatening if it leads to delayed diagnosis and treatment of active TB. *INH prophylaxis is started, if the test is positive* - A **positive tuberculin test** with no evidence of active TB typically indicates **latent tuberculosis infection (LTBI)**. - In such cases, **isoniazid (INH) prophylaxis** is often recommended, especially for individuals at high risk of developing active disease, to prevent progression from latent to active TB. [1]

Question 873: Sputum positive TB is diagnosed when:

A. 2 out of 3 sputum sample +ve (Correct Answer)
B. Mantoux test positive
C. 1 out of 2 sputum sample +ve
D. BACTEC +ve

Explanation: **2 out of 3 sputum sample +ve** - The diagnosis of sputum-positive **tuberculosis (TB)** typically requires at least two out of three sputum samples to be positive for **acid-fast bacilli (AFB)** on smear microscopy [1]. - This criterion helps to ensure the presence of active, transmissible disease and to minimize false positives. *Mantoux test positive* - A positive Mantoux test (or tuberculin skin test) indicates **latent TB infection** or prior exposure to *Mycobacterium tuberculosis*, not necessarily active disease [2]. - It does not confirm active, sputum-positive TB and can be positive even in individuals who have received the BCG vaccine. *1 out of 2 sputum sample +ve* - While one positive sputum sample is highly suspicious, the standard diagnostic criteria for sputum-positive TB usually require **at least two positive samples** to establish a definitive diagnosis [1]. - Relying on only one positive sample might lead to an increased risk of false positives or inadequate classification for public health reporting. *BACTEC +ve* - **BACTEC** is a rapid culture method for *Mycobacterium tuberculosis* and a positive result indicates the presence of viable bacteria. - While BACTEC culture positivity confirms active TB, sputum-positive TB specifically refers to the presence of **AFB on smear microscopy**, which indicates high bacillary load and contagiousness [1].

Question 874: Tuberculin test is positive in general population (immunocompetent individuals with no specific risk factors) if induration is?

A. >7mm
B. >5mm
C. >2mm
D. >10mm (Correct Answer)

Explanation: >10mm - For **immunocompetent** individuals without specific risk factors, a tuberculin skin test (TST) induration of **≥10 mm** is considered positive. - This threshold indicates a likely **exposure to Mycobacterium tuberculosis** and a cellular immune response. *>7mm* - This is not a standard threshold for a positive TST in any risk group. - TST interpretation is based on specific **induration sizes** corresponding to different risk factors. *>5mm* - An induration of **≥5 mm** is considered positive for individuals with compromised immunity, those in close contact with active TB cases, or those with fibrotic changes on chest X-ray. - This lower threshold is used for **high-risk groups** due to their increased susceptibility to developing active tuberculosis. *>2mm* - An induration of **≥2 mm** is not typically used as a positive threshold for the tuberculin test in any established guidelines. - Such a small induration is generally considered **negative** or clinically insignificant.

Question 875: True statement about Neurocysticercosis is:

A. Albendazole is more effective than praziquantel (Correct Answer)
B. Usually presents with 6th nerve palsy and hemiparesis
C. Usually presents with generalized seizures
D. High dose steroids are given for hydrocephalus

Explanation: ***Albendazole is more effective than praziquantel*** - **Albendazole** has shown better efficacy in terms of cyst resolution and clinical improvement, especially in patients with multiple parenchymal cysts. - It has superior tissue penetration and a broader spectrum of activity against different stages of the parasite compared to praziquantel [1]. *Usually presents with 6th nerve palsy and hemiparesis* - While **cranial nerve palsies** and **hemiparesis** can occur in neurocysticercosis, they are not the typical initial presentations. - These focal neurological deficits usually indicate specific cyst locations that compress nerves or brain regions, rather than routine presentation. *Usually presents with generalized seizures* - **Seizures** are the most common presentation of neurocysticercosis, but they are often **focal seizures** that may secondarily generalize, rather than primarily generalized seizures. - The type of seizure depends on the location and number of viable or degenerating cysts in the brain parenchyma. *High dose steroids are given for hydrocephalus* - **Steroids** are typically used in neurocysticercosis to reduce **perilesional edema** around degenerating cysts and to mitigate the inflammatory response to antiparasitic treatment. - For **hydrocephalus**, the primary treatment is usually surgical intervention, such as shunt placement, to relieve the increased intracranial pressure, rather than high-dose steroids alone [1].

Question 876: Pathognomonic clinical feature of measles is -

A. Bitot spots
B. Brushfield spots
C. Koplik spots (Correct Answer)
D. Erythematous macular rash

Explanation: ***Koplik spots*** - **Koplik spots** are small, white, or bluish-white spots surrounded by a red halo, typically found on the buccal mucosa opposite the molars [1]. - They are considered **pathognomonic** for measles and usually appear 1-2 days before the generalized rash [1]. *Bitot spots* - **Bitot spots** are foamy, triangular patches on the conjunctiva, characteristic of severe **vitamin A deficiency**. - They are unrelated to measles infection. *Brushfield spots* - **Brushfield spots** are white or grayish/brown spots on the periphery of the iris. - They are a clinical feature often seen in individuals with **Down syndrome** (Trisomy 21). *Erythematous macular rash* - An **erythematous macular rash** is a common feature of measles, but it is not pathognomonic as similar rashes can be seen in other viral exanthems [1]. - The rash typically starts on the face and spreads downwards, becoming confluent [1].

Question 877: All of the following are true about dengue fever except:

A. Thrombocytosis (Correct Answer)
B. Elevated hematocrit
C. Transmitted by Aedes
D. Also called as breakbone fever

Explanation: ***Thrombocytosis*** - **Thrombocytosis** (elevated platelet count) is generally **not true** in dengue fever; instead, **thrombocytopenia** (low platelet count) is a characteristic feature and a marker of disease severity. [1] - A significant drop in platelet count often necessitates monitoring and can be an indicator of impending **dengue hemorrhagic fever**. [1] *Elevated hematocrit* - **Elevated hematocrit** is a significant finding in severe dengue, indicating **plasma leakage** due to increased vascular permeability. [1] - This suggests **hemoconcentration** and is a key criterion for defining **dengue hemorrhagic fever**. *Transmitted by Aedes* - Dengue fever is primarily transmitted by the **Aedes aegypti** mosquito, and less commonly by **Aedes albopictus**. - These mosquitoes are **day-biting** and thrive in urban environments with stagnant water. *Also called as breakbone fever* - Dengue fever is commonly known as **"breakbone fever"** due to the severe generalized **myalgia** and **arthralgia** that can accompany the infection. [1] - Patients often experience **intense muscle and joint pain**, making movement very painful.

Question 878: Which of the following is true regarding Hepatitis A?

A. Causes mild illness in children (Correct Answer)
B. Sexual route common
C. 3% incidence of carrier state
D. 10% transform into HCC

Explanation: ***Causes mild illness in children*** - Hepatitis A infection in children is typically **asymptomatic or a mild, self-limiting illness**, often mistaken for a common gastrointestinal bug [1]. - This contrasts with adults, who tend to experience more severe symptoms and a higher incidence of **jaundice** [1]. *Sexual route common* - While **fecal-oral transmission** is the primary route, sexual transmission (especially via anal-oral contact) can occur but is not considered the **most common or primary mode** of spread for Hepatitis A. - The virus is present in high concentrations in the feces of infected individuals, leading to easy spread via **contaminated food, water, or person-to-person contact**. *3% incidence of carrier state* - Hepatitis A **does not cause a chronic carrier state**; the virus is cleared from the body after the acute infection. - The concept of a carrier state is primarily associated with **Hepatitis B** and **Hepatitis C** viruses, which can establish chronic infections. *10% transform into HCC* - Hepatitis A is an **acute infection** and does not lead to **chronic liver disease or hepatocellular carcinoma (HCC)**. - **HCC** is a complication of chronic liver damage, mainly seen with chronic **Hepatitis B** and **Hepatitis C** infections.

Question 879: Female treated for Urinary tract infection now has vaginal discharge. The most likely organism is?

A. Candida (Correct Answer)
B. Trichomonas
C. Ureaplasma urealyticum
D. Chlamydia

Explanation: ***Candida*** - Antibiotic treatment for a **urinary tract infection** can disrupt the normal vaginal flora, leading to an overgrowth of **Candida albicans**, which is a common cause of vaginal discharge. - This often presents as **vulvovaginal candidiasis** with thick, white, "cottage cheese-like" discharge and intense pruritus. *Trichomonas* - **Trichomonas vaginalis** is a sexually transmitted infection (STI) that causes greenish-yellow, frothy vaginal discharge with a foul odor [1]. - While it can cause vaginal discharge, it is less likely to be directly precipitated by antibiotic use for a UTI compared to candidiasis. *Ureaplasma urealyticum* - **Ureaplasma urealyticum** can cause non-gonococcal urethritis and cervicitis, and sometimes vaginal discharge, but it is not typically associated with a flare-up following antibiotic treatment for a UTI. - It is often considered part of the normal genitourinary flora or an opportunistic pathogen. *Chlamydia* - **Chlamydia trachomatis** is a common sexually transmitted bacterium [2] that can cause cervicitis, leading to vaginal discharge, often mucopurulent and subtle [1]. - It would not typically emerge as a direct consequence or overgrowth due to antibiotic treatment for a UTI, unlike fungal infections.

Question 880: A 20-year-old woman presents with headache, fever, and neck stiffness. On examination, her blood pressure is 100/70 mm Hg, pulse 100/min, temperature 38.6, and the neck is stiff and painful to flex and extend. The ears, throat, and sinuses are normal, there are no focal neurologic signs, and the remaining examination is normal. There are no reported similar cases in the community. Which of the following is the most likely source of her infection?

A. skin
B. oral ingestion
C. an infected heart valve
D. nasopharynx (Correct Answer)

Explanation: ***Nasopharynx*** - The nasopharynx is a common reservoir for **meningitis-causing bacteria** such as *Neisseria meningitidis* and *Streptococcus pneumoniae*. - These bacteria can colonize the nasopharynx without causing local illness and then cross the mucosal barrier to enter the bloodstream, eventually reaching the **meninges**. *Skin* - Skin infections typically cause **localized symptoms** such as redness, swelling, and pain, possibly with pus formation. - While skin infections can lead to bacteremia and distant infections, there are no skin lesions or signs of infection mentioned in this case. *Oral ingestion* - Oral ingestion typically leads to **gastrointestinal symptoms** such as nausea, vomiting, or diarrhea. - While some pathogens ingested orally can spread systemically, it is not the most direct or common route for the symptoms described. *An infected heart valve* - An infected heart valve (endocarditis) would commonly present with **new heart murmurs**, **constitutional symptoms** (fever, fatigue), and signs of **embolism**, which are not mentioned here [1]. - While endocarditis can cause bacteremia and systemic spread, it would typically have more distinct cardiac findings. *General Clinical Presentation* - Headache, fever, and neck stiffness (meningism) are the classic presenting features of bacterial meningitis [1].

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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