Infectious Diseases — MCQs
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A 19 year old college student presents to the student health clinic complaining of weakness, malaise, and a chronic cough. He has a fever of 100 degrees F and a dry cough; no sputum can be obtained for laboratory analysis, so a bronchial lavage is performed and the washings are submitted to the laboratory. The laboratory reports that the organism is "slow-growing." Serodiagnosis reveals Strep MG agglutinins in the patient's serum. Which of the following organisms is the most likely cause of this student's illness?
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?
Treatment of choice in neurocysticercoses of T. Solium
Complications of measles are all except:
A bacterial disease with oral manifestations is
Optimal /effective duration of short course therapy for pulmonary TB is:
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?
An adult male patient presented in the OPD with complaints of cough and fever for 3 months and haemoptysis off and on. His sputum was positive for AFB. On probing it was found that he had already received treatment with RHZE for 3 weeks from a nearby hospital and discontinued. How will you categorize and manage the patient?
Thrush refers to
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?
Infectious Diseases Indian Medical PG Practice Questions and MCQs
Question 821: A 19 year old college student presents to the student health clinic complaining of weakness, malaise, and a chronic cough. He has a fever of 100 degrees F and a dry cough; no sputum can be obtained for laboratory analysis, so a bronchial lavage is performed and the washings are submitted to the laboratory. The laboratory reports that the organism is "slow-growing." Serodiagnosis reveals Strep MG agglutinins in the patient's serum. Which of the following organisms is the most likely cause of this student's illness?
- A. Respiratory syncytial virus
- B. Mycoplasma pneumoniae (Correct Answer)
- C. Klebsiella pneumoniae
- D. Parainfluenza virus
Explanation: ***Mycoplasma pneumoniae*** - The combination of **weakness**, **malaise**, **dry cough**, and low-grade fever in a young adult is classic for **atypical pneumonia**, often caused by *Mycoplasma pneumoniae*. - The organism being "slow-growing" and the presence of **Strep MG agglutinins** (cold agglutinins, commonly associated with *M. pneumoniae* infections) further point to this diagnosis. *Respiratory syncytial virus* - RSV is a common cause of **bronchiolitis and pneumonia** in infants and young children, less so in healthy young adults. - While it can cause respiratory symptoms, the presence of **Strep MG agglutinins** is not characteristic of RSV infection. *Klebsiella pneumoniae* - *Klebsiella pneumoniae* typically causes **severe, necrotizing pneumonia**, often in older, immunocompromised, or alcoholic individuals [1]. - It presents with a **productive cough** (currant jelly sputum) and rapid onset, not the atypical, slow-growing pattern described [1]. *Parainfluenza virus* - Parainfluenza viruses are common causes of **croup** (laryngotracheobronchitis) in children and can cause respiratory infections in adults. - However, they do not produce **Strep MG agglutinins**, and the "slow-growing" description in a bronchial lavage is not typical for a viral pathogen.
Question 822: 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?
- A. Cryptococcal meningitis
- B. Meningococcal meningitis
- C. Tuberculous meningitis (Correct Answer)
- D. Subarachnoid haemorrhage
Explanation: ***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].
Question 823: Treatment of choice in neurocysticercoses of T. Solium
- A. Metronidazole
- B. Albendazole (Correct Answer)
- C. Mebendazole
- D. Praziquantel
Explanation: ***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.
Question 824: Complications of measles are all except:
- A. Appendicitis
- B. SSPE
- C. Pancreatitis (Correct Answer)
- D. Myocarditis
Explanation: Pancreatitis - While measles can cause systemic inflammation, pancreatitis is not a commonly recognized or significant complication. - Complications of measles primarily affect the respiratory, neurological, and gastrointestinal systems, but direct pancreatic involvement is rare. Appendicitis - Measles can cause inflammation of the lymphoid tissue in the gut, including the Peyer's patches in the appendix. - This inflammation can mimic or, in some cases, truly lead to acute appendicitis. SSPE - Subacute sclerosing panencephalitis (SSPE) is a rare, but fatal, neurodegenerative complication of measles occurring years after the initial infection [1]. - It is caused by persistent infection of the central nervous system with a defective measles virus [1]. Myocarditis - Myocarditis, or inflammation of the heart muscle, can occur during the acute phase of measles infection. - Viral infections, including measles, are known causes of cardiac complications due to direct viral invasion or immune-mediated damage.
Question 825: A bacterial disease with oral manifestations is
- A. measles
- B. Leishmaniasis
- C. Herpes
- D. Diphtheria (Correct Answer)
Explanation: **Diphtheria** - **Diphtheria** is a bacterial infection caused by *Corynebacterium diphtheriae*, which produces a toxin leading to the formation of a **pseudomembrane** in the throat and tonsils, representing an oral manifestation [1]. - This **pseudomembrane** can cause difficulty breathing and swallowing, and if left untreated, the toxin can lead to systemic complications affecting the heart, kidneys, and nervous system [1]. *measles* - **Measles** (rubeola) is a viral infection characterized by a maculopapular rash and fever, and its classic oral manifestation is **Koplik's spots**, which are small white spots with a red halo found on the buccal mucosa. - Although Koplik's spots are an oral manifestation, measles is a **viral** disease, not bacterial. *Leishmaniasis* - **Leishmaniasis** is a parasitic disease caused by *Leishmania* parasites, transmitted by the bite of infected sandflies, and can present as cutaneous, mucocutaneous, or visceral forms. - While **mucocutaneous leishmaniasis** can affect the nose, mouth, and throat with ulcerative lesions, it is a **parasitic** disease, not bacterial. *Herpes* - **Herpes** is primarily caused by the **Herpes Simplex Virus (HSV)**, which is a **viral** infection, leading to cold sores (herpes labialis) or genital lesions. - Oral manifestations like **herpetic gingivostomatitis** are common, but the causative agent is viral, not bacterial [2].
Question 826: Optimal /effective duration of short course therapy for pulmonary TB is:
- A. 6 months (Correct Answer)
- B. 18 months
- C. 12 months
- D. 9 months
Explanation: ***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].
Question 827: 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?
- A. Antituberculous therapy
- B. Needle aspiration
- C. Antibiotics and vigorous attempts to obtain bronchial drainage (Correct Answer)
- D. Urgent thoracotomy
Explanation: ***Antibiotics and vigorous attempts to obtain bronchial drainage*** - This is the **mainstay of therapy** for lung abscesses, especially in immunocompromised patients, to clear the infection and promote healing [1]. - **Immunosuppression** due to renal transplantation increases the patient's susceptibility to severe infections, making aggressive medical management crucial for a positive outcome [1]. *Antituberculous therapy* - This therapy is specific for **tuberculosis**, which typically presents with different clinical and radiological features, such as granulomas and cavitation, not usually an acute abscess after pneumonia. - While immunocompromised patients are at higher risk for tuberculosis, a **lung abscess alone** does not warrant antituberculous therapy without definitive microbiologic evidence. *Needle aspiration* - While needle aspiration can be diagnostic and sometimes therapeutic for lung abscesses, it is generally considered an **adjunctive measure** or for cases not responding to medical therapy. - The primary treatment focuses on **systemic antibiotics** and ensuring drainage, which is often sufficient without invasive procedures unless there's a lack of improvement. *Urgent thoracotomy* - **Urgent thoracotomy** is a surgical procedure reserved for complicated cases of lung abscesses that fail to respond to prolonged medical therapy, are very large, or cause life-threatening complications like empyema or significant hemoptysis [1]. - It carries significant risks, especially in an **immunosuppressed patient**, and is not the initial treatment strategy for a new abscess [1].
Question 828: An adult male patient presented in the OPD with complaints of cough and fever for 3 months and haemoptysis off and on. His sputum was positive for AFB. On probing it was found that he had already received treatment with RHZE for 3 weeks from a nearby hospital and discontinued. How will you categorize and manage the patient?
- A. Category I: New case, intensive phase (2RHZE) (Correct Answer)
- B. Category II: Relapse, intensive phase (2RHZES)
- C. Category IV: Multi-drug resistant TB, intensive phase (individualized regimen)
- D. Category II: Treatment after default, intensive phase (2RHZE)
Explanation: ***Category I: New case, intensive phase (2RHZE)*** - This patient meets the criteria for a **newly diagnosed TB case** as they have not received more than 4 weeks of anti-TB treatment previously [1]. - The standard intensive phase regimen for new cases is **2 months of Rifampicin, Isoniazid, Pyrazinamide, and Ethambutol (2RHZE)** [1]. *Category II: Relapse, intensive phase (2RHZES)* - **Relapse** applies to patients who were previously treated for TB, declared cured, but present again with active disease. This patient had discontinued treatment after only 3 weeks, so it's not a relapse. - The intensive phase for relapse cases typically includes **Streptomycin (S)** in addition to RHZE, which is not indicated here. *Category IV: Multi-drug resistant TB, intensive phase (individualized regimen)* - **Multi-drug resistant TB (MDR-TB)** is diagnosed when the TB bacilli are resistant to at least both Rifampicin and Isoniazid. While treatment discontinuation increases the risk of resistance [2], it cannot be assumed without **drug susceptibility testing (DST)**. - An individualized regimen is appropriate for MDR-TB, but more information (like DST results) is needed before categorizing it as such. *Category II: Treatment after default, intensive phase (2RHZE)* - **Default** usually refers to patients who interrupted their treatment for 2 consecutive months or more. This patient only took treatment for 3 weeks, which does not constitute a default in the context of requiring a re-treatment regimen. - While this option mentions "intensive phase (2RHZE)", the categorization of "Treatment after default" is inaccurate given the short duration of initial treatment.
Question 829: Thrush refers to
- A. Acute atrophic candidiasis
- B. Chronic atrophic candidiasis
- C. Chronic hyperplastic candidiasis
- D. Acute pseudomembranous candidiasis (Correct Answer)
Explanation: ***Acute pseudomembranous candidiasis*** - **Thrush** is the common term for **acute pseudomembranous candidiasis**, characterized by creamy white, cottage cheese-like plaques on the oral mucosa that can be scraped off [1]. - It is typically caused by **Candida albicans** and often seen in infants, immunocompromised individuals, or those using antibiotics or corticosteroids [1]. *Acute atrophic candidiasis* - This form presents as a **red, raw, and painful** area, often after antibiotic use, and does not have the classic white plaques associated with thrush. - It involves mucosal thinning and inflammation due to fungal overgrowth, lacking the pseudomembrane. *Chronic atrophic candidiasis* - Often associated with **denture wearers** (denture stomatitis) and appears as erythema and edema beneath the denture, without significant white lesions. - It is a persistent inflammation and redness of the mucosa due to chronic candidal infection under an ill-fitting or poorly cleaned denture. *Chronic hyperplastic candidiasis* - This is a less common form characterized by **non-scrapable white lesions** that can appear nodular or homogeneous and are often considered potentially malignant. - It involves fungal invasion into the deeper layers of the epithelium, leading to hyperkeratosis and epithelial hyperplasia, making the lesions firmly adherent.
Question 830: 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?
- A. Epstein-Barr virus
- B. Streptococcus viridans
- C. Candida albicans
- D. Beta-hemolytic streptococcus (Correct Answer)
Explanation: ### 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**.
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Principles of Antimicrobial Therapy
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Fever of Unknown Origin
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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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Infection in Immunocompromised Hosts
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