Infectious Diseases Practice Questions

Q: The probable interval between throat infection and onset of rheumatic fever is:

2-4 weeks. ***2-4 weeks*** - The latency period between a **streptococcal pharyngeal infection** (strep throat) and the onset of acute rheumatic fever is typically 2 to 4 weeks [1]. - This interval is necessary for the immune response to the *Streptococcus pyogenes* infection to develop and cross-react with host tissues, leading to the autoimmune manifestations of rheumatic fever [1]. *2-4 months* - An interval of 2-4 months is generally too long for the typical presentation of **acute rheumatic fever** following a strep throat [1]. - Such a prolonged period would make the direct immunological link less probable for the initial acute event. *2-4 hours* - An interval of 2-4 hours is far too short for the development of **acute rheumatic fever**, which is an autoimmune complication. - Autoimmune responses require time for antigen presentation, lymphocyte activation, and antibody production. *2-4 days* - An interval of 2-4 days is generally too short for the immune system to mount a sufficient **autoimmune response** leading to the clinical manifestations of acute rheumatic fever. - While other post-streptococcal conditions like **scarlet fever** may manifest within this timeframe, rheumatic fever takes longer.

Q: NOT a good prognostic factor for TB spine

Rapid onset. ***Rapid onset*** - A **rapid onset** of symptoms in TB spine can indicate aggressive disease progression and may be associated with a poorer prognosis [1]. - This suggests the infection is advancing quickly, potentially leading to more severe neurological deficits or bone destruction before effective treatment can be initiated [1]. *Young age* - **Young age** is generally considered a good prognostic factor for TB spine, as younger patients often have better bone healing capacity and immune responses. - They tend to respond more effectively to antitubercular treatment and have a lower incidence of severe complications compared to older adults. *Good immunity* - A **robust immune system** is crucial for controlling *Mycobacterium tuberculosis* infection and is a key factor in achieving a favorable outcome in TB spine. - Patients with good immunity are more likely to clear the infection, prevent widespread dissemination, and experience less severe bone and neurological damage. *Early diagnosis* - **Early diagnosis** allows for prompt initiation of appropriate antitubercular therapy, which is essential for preventing disease progression and minimizing complications. - **Timely treatment** reduces the risk of spinal deformities, neurological deficits, and the need for extensive surgical intervention, leading to a better prognosis.

Q: A 25-year-old man presents with fever and altered sensorium. The CSF analysis revealed – Pressure : Raised, Appearance : Opalescent and on standing cobweb formation seen, Protein : 220 mg%, Sugar : 30 mg%, Cells : 1250 per field mostly lymphocytes, Globulin : Positive. Which one of the following is the most likely diagnosis?

Tuberculous meningitis. ***Tuberculous meningitis*** - The CSF analysis showing **raised pressure**, **opalescent appearance** with **cobweb formation**, **high protein**, **low sugar**, and **lymphocytic pleocytosis** along with a **positive globulin reaction** is highly characteristic of tuberculous meningitis [1]. - **Cobweb formation** upon standing is a classic sign due to the presence of fibrinogen in the CSF, which precipitates and forms a delicate clot. *Cryptococcal meningitis* - While it can cause similar CSF findings (lymphocytic pleocytosis, low glucose, high protein), the characteristic **cobweb formation** is less common, and a positive India ink stain or cryptococcal antigen test would be expected. - It often occurs in immunocompromised individuals, which is not stated in the patient description [1]. *Meningococcal meningitis* - This is a form of **bacterial meningitis** typically characterized by **neutrophilic predominance** (high white blood cell count with majority neutrophils), very low glucose, and very high protein [2]. - The presented CSF shows a **lymphocytic predominance**, which rules out acute bacterial meningitis like meningococcal [2]. *Subarachnoid haemorrhage* - CSF in subarachnoid haemorrhage is typically **uniformly bloody** or **xanthochromic** (yellowish due to bilirubin breakdown products of red blood cells), not opalescent [3]. - While pressure can be raised, protein can be elevated, and glucose is usually normal; the cellular response is typically red blood cells, not predominantly lymphocytes as seen here [3].

Q: Treatment of choice in neurocysticercoses of T. Solium

Albendazole. ***Albendazole*** - **Albendazole** is considered the drug of choice for neurocysticercosis due to its superior efficacy and better penetration into the **central nervous system (CNS)** compared to other anthelmintics [1]. - It works by inhibiting microtubule polymerization, leading to the death of the **parasite cysts**. *Metronidazole* - **Metronidazole** is an antimicrobial highly effective against **anaerobic bacteria** and **protozoa**, but it has no activity against **helminths** like *Taenia solium*. - It is primarily used for infections such as **giardiasis**, **trichomoniasis**, and **bacterial vaginosis**. *Mebendazole* - **Mebendazole** is an anthelmintic similar to albendazole but generally has poorer absorption and lower efficacy in the treatment of **neurocysticercosis** [1]. - While effective for **intestinal helminthic infections**, its use in CNS infections is limited compared to albendazole [1]. *Praziquantel* - **Praziquantel** is an effective anthelmintic used for various **trematode** and **cestode infections**, including neurocysticercosis [2]. - However, **albendazole** is generally preferred as the first-line treatment due to its better efficacy profile, especially in cases of multiple cysts, and fewer reported adverse effects than praziquantel.

Q: Optimal /effective duration of short course therapy for pulmonary TB is:

6 months. ***6 months*** - The standard **short-course therapy** for **drug-sensitive pulmonary tuberculosis** involves a regimen of RIPE (Rifampicin, Isoniazid, Pyrazinamide, Ethambutol) for 2 months, followed by Rifampicin and Isoniazid for 4 months, totaling **6 months** [1]. - This duration has been proven effective in achieving **cure** and preventing **relapse** in the vast majority of cases [1]. *18 months* - An 18-month duration is significantly longer than the standard short-course therapy and is typically reserved for **drug-resistant tuberculosis** or complex cases requiring extended treatment. - Using an 18-month regimen for drug-sensitive pulmonary TB would lead to unnecessary **treatment burden** and potential **side effects**. *12 months* - A 12-month regimen was common before the advent of widely adopted short-course chemotherapy but is now considered suboptimal for **drug-sensitive pulmonary TB**. [1] - Current guidelines recommend 6 months for most cases, given its equivalent efficacy and improved **patient adherence** [1]. *9 months* - A 9-month regimen might be used in specific circumstances, such as for individuals with **HIV co-infection** or those who cannot tolerate pyrazinamide, leading to a lengthened continuation phase. - However, for the **optimal/effective duration** in general, 6 months remains the gold standard for drug-sensitive pulmonary TB [1].

Q: A 10-year-old boy with a 2-week history of an upper respiratory infection was admitted to the hospital with malaise, fever, joint swelling and diffuse rash. The patient is treated and discharged. However, the patient suffers from recurrent pharyngitis and a few years later, develops a heart murmur. This patient's heart murmur is most likely caused by exposure to which of the following pathogens?

Beta-hemolytic streptococcus. ### Beta-hemolytic streptococcus - The history of an **upper respiratory infection**, followed by **joint swelling**, **rash**, and later a **heart murmur**, strongly suggests Rheumatic Fever, which is caused by a preceding infection with **Group A Beta-hemolytic Streptococcus (GAS)** [2]. - Recurrent pharyngitis (strep throat) is a key risk factor for developing Rheumatic Fever and its cardiac sequelae, as the immune response to GAS antigens leads to **molecular mimicry** affecting heart valves [1], [2]. ### Epstein-Barr virus - This virus primarily causes **infectious mononucleosis**, characterized by fatigue, fever, and lymphadenopathy, but it is not directly associated with the development of rheumatic heart disease or a new-onset heart murmur in this context. - While EBV can cause various symptoms, **cardiac involvement is rare** and typically presents as myocarditis or pericarditis, not a progressive valvular disease. ### Streptococcus viridans - *Streptococcus viridans* is a common cause of **subacute bacterial endocarditis**, especially in patients with pre-existing valvular heart disease [1]. - However, it does not typically cause the initial constellation of symptoms (joint swelling, rash) associated with **Rheumatic Fever**, nor is it linked to recurrent pharyngitis in the same way as Group A Streptococcus. ### Candida albicans - This is a **fungal pathogen** that can cause opportunistic infections, including candidemia or endocarditis, particularly in immunocompromised individuals or those with intravenous drug use. - It is not associated with the initial presentation of fever, arthralgia, rash, or recurrent pharyngitis described in the case, and does not cause **rheumatic heart disease**.

Q: Characteristic features of rabies include all except-

Hemotogenous spread to brain. Characterstic features of rabies include all except- ***Hemotogenous spread to brain*** - Rabies virus spreads to the brain via **retrograde axonal transport** along peripheral nerves, not primarily through the bloodstream (hematogenous spread). - The virus travels from the site of infection up the nerve pathways to the central nervous system. *Can be transmitted by bites other than dogs also* - While dogs are a common vector, rabies can be transmitted by bites from other **mammals**, such as bats, raccoons, foxes, and skunks. - The transmission occurs when infected saliva enters a wound, typically a bite [1]. *Can manifest as ascending paralysis* - Rabies can present in two main forms: **furious rabies** (characterized by hyperactivity and hydrophobia) and **paralytic rabies**, which manifests as an ascending paralysis. - This **paralytic form** can be difficult to distinguish from other neurological syndromes. *Is invariably fatal* - Once **symptoms of rabies** appear, the disease is almost universally fatal, often within days. - Survival is extremely rare and usually only with intensive medical intervention, making prevention and post-exposure prophylaxis critical [1].

Q: Locomotor ataxia, a late manifestation of syphilis due to parenchymatous involvement of the spinal cord, is called

Tabes dorsalis. ***Tabes dorsalis*** - This condition is a **late manifestation of tertiary syphilis** caused by the demyelination and degeneration of the posterior columns and dorsal roots of the spinal cord [1], [2]. - It specifically leads to **locomotor ataxia** due to the loss of proprioception and vibration sense, characteristic of parenchymatous involvement [2]. *Syphilitic amyotrophy* - This is a rare form of neurosyphilis that presents with neurological symptoms primarily affecting **motor neurons**, leading to muscle weakness and atrophy. - It does not typically present as **locomotor ataxia** with sensory deficits as the primary feature. *Meningovascular syphilis* - This form of neurosyphilis predominantly affects the **blood vessels and meninges of the brain and spinal cord**, leading to infarcts and stroke-like symptoms. - While it can cause neurological deficits, it does not typically manifest as the specific sensory ataxia described as **tabes dorsalis**. *General paralysis of insane* - Also known as **general paresis**, this is another late manifestation of neurosyphilis primarily affecting the brain, leading to **dementia, personality changes, and psychiatric symptoms**. - While it involves parenchymatous brain damage, it does not present with **locomotor ataxia** as its defining feature.

Q: A sewerage worker presents to OPD with acute febrile illness alongwith jaundice and conjunctivitis. His blood sample was taken and sent to lab . Lab findings are suggestive of kidney failure and elevated hepatic enzymes. Which of following is likely diagnosis ?

Leptospirosis. ***Leptospirosis*** - The patient's occupation as a **sewerage worker** points to potential exposure to contaminated water, a known risk factor for leptospirosis [1]. - The classic triad of **febrile illness**, **jaundice**, and **conjunctivitis**, combined with **kidney failure** and **elevated hepatic enzymes**, is highly characteristic of severe leptospirosis (Weil's disease) [1], [2]. *Typhoid* - While typhoid can cause fever and, in severe cases, liver dysfunction, it is typically associated with **gastrointestinal symptoms** like abdominal pain and constipation/diarrhea [2]. - **Conjunctivitis** and significant **jaundice** with acute kidney failure are not typical presenting features of typhoid [2]. *Malaria* - Malaria presents with **cyclical fevers**, **chills**, and **sweats**, and can cause jaundice and kidney injury in severe cases [2]. - However, **conjunctivitis** as a prominent symptom is less common, and the distinct occupational exposure makes leptospirosis more likely [1], [2]. *Hepatitis A* - Hepatitis A causes **jaundice** and **elevated hepatic enzymes**, but it is primarily a liver infection and does not typically lead to acute **kidney failure** [3]. - While fever can be present, **conjunctivitis** and rapid progression to kidney failure are not characteristic of Hepatitis A [3].

Question 1

The probable interval between throat infection and onset of rheumatic fever is:

Accepted Answer

2-4 weeks

Answer

2-4 months

Answer

2-4 hours

Answer

2-4 days

Question 2

NOT a good prognostic factor for TB spine

Accepted Answer

Rapid onset

Answer

Young age

Answer

Good immunity

Answer

Early diagnosis

Question 3

A 25-year-old man presents with fever and altered sensorium. The CSF analysis revealed –
  Pressure : Raised, Appearance : Opalescent and on standing cobweb formation seen, Protein : 220 mg%, Sugar : 30 mg%, Cells : 1250 per field mostly lymphocytes, Globulin : Positive. Which one of the following is the most likely diagnosis?

Accepted Answer

Tuberculous meningitis

Answer

Cryptococcal meningitis

Answer

Meningococcal meningitis

Answer

Subarachnoid haemorrhage

Question 4

Treatment of choice in neurocysticercoses of T. Solium

Accepted Answer

Albendazole

Answer

Metronidazole

Answer

Mebendazole

Answer

Praziquantel

Question 5

Optimal /effective duration of short course therapy for pulmonary TB is:

Accepted Answer

6 months

Answer

18 months

Answer

12 months

Answer

9 months

Question 6

After suffering a severe bout of pneumonia, a 46-year-old renal transplantation patient develops a lung abscess. She has been receiving immunosuppression therapy since her last kidney transplantation 3 years ago. What is the most appropriate treatment?

Accepted Answer

Antibiotics and vigorous attempts to obtain bronchial drainage

Answer

Antituberculous therapy

Answer

Needle aspiration

Answer

Urgent thoracotomy

Question 7

A 10-year-old boy with a 2-week history of an upper respiratory infection was admitted to the hospital with malaise, fever, joint swelling and diffuse rash. The patient is treated and discharged. However, the patient suffers from recurrent pharyngitis and a few years later, develops a heart murmur. This patient's heart murmur is most likely caused by exposure to which of the following pathogens?

Accepted Answer

Beta-hemolytic streptococcus

Answer

Epstein-Barr virus

Answer

Streptococcus viridans

Answer

Candida albicans

Question 8

Characteristic features of rabies include all except-

Accepted Answer

Hemotogenous spread to brain

Answer

Can be transmitted by bites other than dogs also

Answer

Can manifest as ascending paralysis

Answer

Is invariably fatal

Question 9

Locomotor ataxia, a late manifestation of syphilis due to parenchymatous involvement of the spinal cord, is called

Accepted Answer

Tabes dorsalis

Answer

Syphilitic amyotrophy

Answer

Meningo vascular syphilis

Answer

General paralysis of insane

Question 10

A sewerage worker presents to OPD with acute febrile illness alongwith jaundice and conjunctivitis. His blood sample was taken and sent to lab . Lab findings are suggestive of kidney failure and elevated hepatic enzymes. Which of following is likely diagnosis ?

Accepted Answer

Leptospirosis

Answer

Typhoid

Answer

Malaria

Answer

Hepatitis A

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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