Infectious Diseases Practice Questions

Q: The intracranial tumor most likely to be encountered in a middle-aged man with the acquired immunodeficiency syndrome (AIDS) is:

Lymphoma. ***Lymphoma*** - **Primary central nervous system lymphoma (PCNSL)** is the most common intracranial tumor in patients with acquired immunodeficiency syndrome (AIDS), particularly in those with a **CD4 count below 50 cells/mm³**. [1] - It is typically associated with **Epstein-Barr virus (EBV) infection** and presents with focal neurological deficits, cognitive changes, and seizures. [1] *Glioblastoma multiforme* - This is the most common primary brain tumor in the general population, but its incidence is **not specifically increased** in patients with AIDS. - While highly aggressive, its association with AIDS is **less direct** than lymphoma. *Meningioma* - Meningiomas are typically **benign tumors** arising from the meninges and are more common in older adults, especially women. - There is **no strong correlation** between meningioma incidence and AIDS. *Ependymoma* - Ependymomas are rare tumors that arise from **ependymal cells lining the ventricles** or central canal of the spinal cord, more commonly seen in children. - Their occurrence is **not specifically elevated** in individuals with AIDS.

Q: Oophoritis, Orchitis, Chipmunk cheeks seen in:

Mumps.. ***Mumps*** - **Mumps** is a viral infection that commonly presents with **bilateral parotid gland swelling**, leading to the characteristic "chipmunk cheeks" appearance. - It can also cause complications such as **oophoritis** (inflammation of the ovaries) in females and **orchitis** (inflammation of the testes) in males, which are key features seen in this clinical description. *Sialadenosis* - **Sialadenosis** refers to a non-inflammatory, non-neoplastic enlargement of the salivary glands, often the parotid glands. - While it can cause swollen glands, it is typically associated with systemic conditions like **diabetes** or **alcoholism** and does not cause oophoritis or orchitis. *Mucocele* - A **mucocele** is a common lesion of the oral mucosa that results from either rupture of a salivary gland duct and spillage of mucin into the surrounding soft tissues (extravasation type) or obstruction of a salivary gland duct (retention type). - It usually presents as a benign, fluid-filled swelling, most commonly on the **lower lip**, and is not associated with systemic inflammation or widespread glandular involvement. *Sialadenitis* - **Sialadenitis** is an inflammation of a salivary gland, often due to bacterial infection or duct obstruction (e.g., by salivary stones). - While it can cause painful swelling of the salivary glands, it typically affects only one gland and does not lead to complications like oophoritis or orchitis.

Q: Which of the following is NOT seen in an HIV patient with a CD4 count less than 100 per microliter, who has a non-productive cough?

Mycoplasma pneumoniae. ***Mycoplasma pneumoniae*** - *Mycoplasma pneumoniae* is an atypical bacterium that causes **community-acquired pneumonia** in immunocompetent individuals. - While it can cause a non-productive cough, it is **not considered an opportunistic infection** in HIV patients with advanced immunosuppression (CD4 < 100), as its incidence is not significantly higher or more severe in this population compared to the general population. *Pneumocystis jirovecii* - **Pneumocystis pneumonia (PCP)** is a classic opportunistic infection in HIV patients, especially when the **CD4 count is below 200 cells/µL** [1]. - It commonly presents with a **non-productive cough**, fever, and dyspnea, and is a strong consideration in this clinical scenario [2]. *Cryptococcal infection* - **Pulmonary cryptococcosis**, caused by *Cryptococcus neoformans*, is an opportunistic infection in advanced HIV disease (CD4 < 100 cells/µL). - It often presents with **non-specific respiratory symptoms** including a non-productive cough, and can disseminate to the central nervous system. *Mycobacterium tuberculosis* - **Tuberculosis (TB)** is a common and serious opportunistic infection in HIV patients, particularly with **advanced immunosuppression** [1]. - Pulmonary TB can present with a **non-productive or productive cough**, fever, and weight loss, and is a significant cause of morbidity and mortality in this population [1].

Q: A CSF/serum glucose ratio of < 0.4 is highly suggestive of:

Bacterial Meningitis. Bacterial Meningitis - A **CSF/serum glucose ratio of < 0.4** is a classic finding in bacterial meningitis, indicating that bacteria are consuming glucose in the CSF [1]. - This ratio, along with other CSF findings like **elevated protein** and **pleocytosis** (predominantly neutrophils), helps differentiate bacterial from other forms of meningitis [1]. *Viral Meningitis* - In viral meningitis, the **CSF glucose is typically normal** or only slightly decreased, leading to a normal to slightly decreased CSF/serum glucose ratio (usually > 0.6) [1]. - The cell count primarily shows a **lymphocytic predominance**, differentiating it from bacterial meningitis [1]. *Carcinomatous Meningitis* - While CSF glucose can be decreased in carcinomatous meningitis due to tumor cell metabolism, it is often **not as profoundly low** as in bacterial meningitis. - The diagnosis is usually confirmed by finding **malignant cells** in the CSF and/or imaging evidence of leptomeningeal spread. *Acanthamoeba meningitis* - **Acanthamoeba meningitis** is a rare and severe form of meningitis caused by a free-living amoeba, leading to meningoencephalitis. - While it can cause inflammatory changes and glucose consumption, a specific **CSF/serum glucose ratio of < 0.4** is not a hallmark and it is often associated with a granulomatous inflammatory response.

Q: In which of the following conditions is the 23-serotype pneumococcal vaccine most useful?

Sickle cell anaemia. ***Sickle cell anaemia*** - Patients with **sickle cell anaemia** are highly susceptible to **encapsulated bacterial infections**, particularly _Streptococcus pneumoniae_, due to functional **asplenia** [1]. - The **23-serotype pneumococcal vaccine (PPSV23)** provides protection against a broad range of pneumococcal serotypes, crucial for preventing severe infections in this vulnerable population. *Child less than 2 years* - Children under 2 years typically receive the **pneumococcal conjugate vaccine (PCV13 or PCV15)**, which elicits a T-cell-dependent immune response, rather than the PPSV23. - **PPSV23** is a polysaccharide vaccine and is **less immunogenic** in very young children due to their immature immune systems. *Recurrent otitis media & sinusitis* - While pneumococcal infections can cause these conditions, the **conjugated pneumococcal vaccines (PCV13/15)** are generally preferred for preventing recurrent infections in children, targeting common causative serotypes. - The benefit of PPSV23 is more pronounced in **immunocompromised individuals** or those with specific high-risk conditions. *Cystic fibrosis* - Individuals with **cystic fibrosis** are at increased risk for respiratory infections, but primarily from organisms like **_Pseudomonas aeruginosa_** and **_Staphylococcus aureus_**, rather than solely _Streptococcus pneumoniae_. - While pneumococcal vaccination is recommended, their primary risk for severe disease isn't exclusively tied to pneumococcal disease to the same extent as persons with functional asplenia.

Q: The following about leptospirosis is true except?

Tetracycline is the drug of choice. ***Tetracycline is the drug of choice*** - While tetracyclines (e.g., **doxycycline**) can be used, the primary drug of choice for severe leptospirosis is typically **intravenous penicillin G** or **ceftriaxone**. - For milder cases, oral **doxycycline** or **amoxicillin** may be used, but labeling tetracycline as *the* drug of choice above penicillin for all severities is inaccurate. *Seen in sewage workers* - **Leptospirosis** is an occupational hazard for individuals exposed to contaminated water or soil, including **sewage workers**, farmers, and veterinarians [1]. - This is because the bacteria, *Leptospira*, are shed in the urine of infected animals and can survive in moist environments [1]. *High fever with chills* - The **initial phase** of leptospirosis (leptospiremic phase) commonly presents with **acute onset of high fever** and **chills**, along with headaches and myalgia [1]. - These are non-specific symptoms that can make early diagnosis challenging [1]. *Jaundice is present* - **Jaundice** is a characteristic symptom of severe leptospirosis, particularly in the form known as **Weil's disease**. - It indicates **hepatic involvement** and often accompanies other severe manifestations like renal dysfunction (leading to **oliguria** or **anuria**) and hemorrhage [1].

Q: In tuberculous meningitis, what is NOT seen:

Increased CSF glucose. ***Increased CSF glucose*** - In **tuberculous meningitis**, the meningeal inflammation and metabolic activity of the Mycobacterium tuberculosis consume glucose, leading to **decreased CSF glucose levels**, not increased. [1] - An increased CSF glucose level would be highly atypical and suggests an alternative diagnosis or a procedural error. *Turbidity of CSF* - **CSF turbidity** is a common finding in many forms of meningitis, including tuberculous meningitis, due to the presence of inflammatory cells and proteins. [1] - The appearance can range from opalescent to frankly purulent depending on the severity of inflammation. [2] *Increased lymphocytes* - **Tuberculous meningitis** is typically characterized by a **lymphocytic pleocytosis** in the CSF, meaning an increase in the number of lymphocytes. - This is a hallmark of chronic inflammatory processes affecting the central nervous system. *Decreased protein levels* - The inflammatory process in **tuberculous meningitis** leads to increased vascular permeability and protein leakage into the CSF, resulting in **elevated CSF protein levels**, not decreased. [2] - Decreased CSF protein levels would be an unusual finding in this condition.

Q: Not true about meningococcal meningitis

Carriers are treated with penicillin. ***Carriers are treated with penicillin*** - **Penicillin** is not the recommended treatment for eradicating *Neisseria meningitidis* from carriers, as it does not reliably eliminate nasopharyngeal carriage. - Recommended prophylactic regimens for carriers include **rifampicin**, **ceftriaxone**, or **ciprofloxacin** [1]. *Transmitted via droplet infection* - **Meningococcal meningitis** is indeed highly contagious and primarily spreads through **respiratory droplets**, making close contact a significant risk factor. - This mode of transmission is why outbreaks can occur rapidly in crowded settings like dormitories or military barracks. *Is gram negative organism* - *Neisseria meningitidis*, the causative agent of meningococcal meningitis, is a **Gram-negative diplococcus**. - Its unique Gram stain morphology helps in initial laboratory identification. *Carriers are treated with Rifampicin.* - **Rifampicin** is a highly effective antibiotic for eliminating *Neisseria meningitidis* carriage in asymptomatic individuals and is commonly used for prophylaxis [1]. - Its mechanism allows it to penetrate host cells and target the bacteria in the nasopharynx. *Carriers are the source of infection* - **Asymptomatic carriers** of *Neisseria meningitidis*, who harbor the bacteria in their nasopharynx without developing disease, are the primary **reservoir and source of infection**. - These carriers facilitate the spread of the pathogen within communities, often unknowingly.

Q: All are caused by Parvo virus infection except:

Gianotti crosti syndrome. ***Gianotti crosti syndrome*** - This syndrome is typically caused by **Epstein-Barr virus**, **Hepatitis B virus**, coxsackievirus, echovirus, or enterovirus, NOT parvovirus B19. - It presents with a **papulovesicular rash** mainly on the face, buttocks, and extremities, often linked to distinct viral etiologies. *Aplastic crisis* - **Parvovirus B19** has a tropism for **erythroid progenitor cells**, causing their destruction and leading to temporary cessation of red blood cell production [1]. - This can precipitate an **aplastic crisis**, especially in individuals with underlying hemolytic anemias like sickle cell disease [1]. *Papular- purpuric gloves and socks syndrome (PPGSS)* - PPGSS is a rare but characteristic manifestation of **Parvovirus B19** infection, presenting with a sharply demarcated papular-purpuric rash. - The rash typically affects the **hands ("gloves") and feet ("socks")**, often accompanied by fever and oral erosions. *Erythema infectiosum* - Also known as **Fifth Disease**, this is a common benign childhood rash caused by **Parvovirus B19** [1]. - It presents with a characteristic **"slapped cheek" rash** on the face, followed by a lacy, reticular rash on the trunk and extremities [1].

Q: The commonest cause of spinal or joint infection in a young person is -

Tuberculosis. ***Tuberculosis*** - In a young person, especially in endemic areas, **spinal tuberculosis (Pott's disease)** and **tuberculous arthritis** are significant causes of joint and spinal infections [1]. - Tuberculosis can lead to **chronic osteomyelitis** and **destructive arthritis**, often with a more insidious onset than acute bacterial infections [1]. *Gonococcal* - **Gonococcal arthritis** typically presents as an acute, migratory polyarthritis or tenosynovitis, or as a septic arthritis, usually affecting one or two large joints. - While it is a common cause of septic arthritis in sexually active young adults, it is less likely to be the **commonest cause of chronic spinal or joint infection** compared to tuberculosis. *Staphylococcus aureus* - **Staphylococcus aureus** is the most common cause of acute **septic arthritis** and **vertebral osteomyelitis** in adults across all age groups. - However, for "spinal or joint infection" in a young person, especially in a chronic or indolent presentation, **tuberculosis** might be more prevalent in certain populations and regions. *Syphilis* - **Syphilis** can cause joint manifestations, particularly in congenital syphilis and tertiary syphilis (e.g., **Charcot joint** from neurosyphilis). - These presentations are less common overall as a direct infectious cause of joint or spinal infection in young people compared to tuberculosis or acute bacterial infections.

Question 1

The intracranial tumor most likely to be encountered in a middle-aged man with the acquired immunodeficiency syndrome (AIDS) is:

Accepted Answer

Lymphoma

Answer

Glioblastoma multiforme

Answer

Meningioma

Answer

Ependymoma

Question 2

Oophoritis, Orchitis, Chipmunk cheeks seen in:

Accepted Answer

Mumps.

Answer

Sialadenosis.

Answer

Mucocele.

Answer

Sialadenitis.

Question 3

Which of the following is NOT seen in an HIV patient with a CD4 count less than 100 per microliter, who has a non-productive cough?

Accepted Answer

Mycoplasma pneumoniae

Answer

Pneumocystis jirovecii

Answer

Cryptococcal infection

Answer

Mycobacterium tuberculosis

Question 4

A CSF/serum glucose ratio of < 0.4 is highly suggestive of:

Accepted Answer

Bacterial Meningitis

Answer

Viral Meningitis

Answer

Carcinomatous Meningitis

Answer

Acanthamoeba meningitis

Question 5

In which of the following conditions is the 23-serotype pneumococcal vaccine most useful?

Accepted Answer

Sickle cell anaemia

Answer

Child less than 2 years

Answer

Recurrent otitis media & sinusitis

Answer

Cystic fibrosis

Question 6

The following about leptospirosis is true except?

Accepted Answer

Tetracycline is the drug of choice

Answer

Seen in sewage workers

Answer

High fever with chills

Answer

Jaundice is present

Question 7

In tuberculous meningitis, what is NOT seen:

Accepted Answer

Increased CSF glucose

Answer

Turbidity of CSF

Answer

Increased lymphocytes

Answer

Decreased protein levels

Question 8

Not true about meningococcal meningitis

Accepted Answer

Carriers are treated with penicillin

Answer

Transmitted via droplet infection

Answer

Is gram negative organism

Answer

Carriers are treated with Rifampicin.

Answer

Carriers are the source of infection

Question 9

All are caused by Parvo virus infection except:

Accepted Answer

Gianotti crosti syndrome

Answer

Aplastic crisis

Answer

Papular- purpuric gloves and socks syndrome (PPGSS)

Answer

Erythema infectiosum

Question 10

The commonest cause of spinal or joint infection in a young person is -

Accepted Answer

Tuberculosis

Answer

Gonococcal

Answer

Staphylococcus aureus

Answer

Syphilis

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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