Infectious Diseases Practice Questions

Q: A patient is diagnosed with Cryptococcal meningitis. What is the treatment?

Flucytosine + L.Amp. ***Correct: Flucytosine + L.Amp (Liposomal Amphotericin B)*** - This is the **standard induction therapy** for Cryptococcal meningitis as per WHO and CDC guidelines [1] - **Combination therapy** is superior to monotherapy, reducing mortality and improving outcomes [1] - The induction phase lasts **2 weeks**, followed by consolidation with fluconazole [1] - Liposomal Amphotericin B has **better CNS penetration** and fewer nephrotoxic effects compared to conventional Amphotericin B - Flucytosine enhances fungicidal activity and reduces the risk of resistance [1] *Incorrect: L.Amp alone* - Monotherapy with Amphotericin B is **less effective** than combination therapy [1] - Higher rates of treatment failure and relapse when used alone - Should always be combined with flucytosine when available [1] *Incorrect: Fluconazole alone* - Fluconazole is used in **consolidation phase** (after induction) and maintenance therapy - **Not recommended for induction** due to its fungistatic (not fungicidal) action - Slower CSF sterilization compared to combination therapy *Incorrect: Flucytosine alone* - **Never used as monotherapy** due to rapid development of resistance - Must always be combined with Amphotericin B or Azoles - Has good CSF penetration but inadequate as sole agent

Q: Which of the following is the management of a HIV positive patient with multiple dog bites?

Rabies vaccine + Immunoglobulin + Wound management. ***Rabies vaccine + Immunoglobulin + Wound management***- **Category III exposure** (multiple/deep transmural bites) mandates both **Passive Immunization** (Human Rabies Immune Globulin - **HRIG**) and **Active Immunization** (**Rabies Vaccine**) for immediate and long-term protection [1].- Given the patient's **HIV-positive status**, they are considered **immunocompromised**; therefore, the highest level of post-exposure prophylaxis (PEP) is required to ensure adequate viral neutralization and immune response.*Rabies vaccine + wound management*- This regimen is inadequate for **Category III exposure** because it omits **Rabies Immunoglobulin (RIG)**, which provides immediate, neutralizing antibodies before the vaccine takes effect [1].- Omitting RIG is particularly dangerous in an **immunocompromised patient** as the onset of antibody production from the vaccine may be delayed or suboptimal.*Immunoglobulin only*- **Rabies Immunoglobulin (RIG)** provides vital passive immunity but its effects are short-lived, offering only temporary protection.- Effective rabies prevention requires the simultaneous administration of the **active vaccine** series to stimulate sustained, long-term protective antibody production [1].*Wound management*- While essential for reducing local bacterial infections and viral load, **wound management alone** is never sufficient for managing **Category III rabies exposure**.- This option neglects both the immediate (RIG) and subsequent (Vaccine) specific measures required to prevent the invariably fatal neurological disease caused by the **Rabies virus**.

Q: A patient presents with fever, neck rigidity, headache, vomiting, and petechial rashes on the lower limbs. What is the most likely causative organism?

Neisseria meningitidis. ***Neisseria meningitidis***- This gram-negative diplococcus is the most likely causative agent as it classically causes **meningococcal meningitis** combined with **meningococcemia**, which highly correlates with the presence of **petechial or purpuric rashes** on the skin.- The rash results from **endotoxin** (lipooligosaccharide) damage to the blood vessel walls, leading to **vasculitis** and hemorrhage, often progressing to severe complications like the **Waterhouse-Friderichsen syndrome**.*Clostridium perfringens*- This organism is primarily known for causing **gas gangrene** (myonecrosis) and tissue necrosis, often following severe trauma or surgery.- It is not a common cause of primary community-acquired bacterial meningitis, and its clinical presentation focuses on localized **soft tissue infection** rather than systemic meningoencephalitis.*Cryptococcus neoformans*- This is a **fungal pathogen** that causes meningitis, usually in patients with **severe immunosuppression** (e.g., uncontrolled HIV infection).- Although it causes fever and signs of meningeal irritation, the presentation is typically subacute or chronic, and a hemorrhagic rash is not a standard clinical feature.*Clostridium difficile*- This bacterium is the causative agent of **antibiotic-associated diarrhea** and **pseudomembranous colitis**.- Its effects are localized almost exclusively to the colon, and it does not cause acute bacterial meningitis with systemic rash.

Q: A farmer presents with fever and subconjunctival hemorrhage. The microscopic agglutination test is found to be positive. What is the diagnosis?

Leptospira. ***Leptospira***- The clinical presentation of fever in a patient with an occupation involving exposure to animal habitats (farmer), coupled with the classic finding of **subconjunctival hemorrhage** (conjunctival suffusion), highly suggests **Leptospirosis** (Weil's disease) [1]. - The **Microscopic Agglutination Test (MAT)** is the gold standard serological test for the diagnosis of **Leptospirosis**, supporting this etiology [1]. *Brucella* - *Brucella* causes **Brucellosis** (Undulant Fever), characterized primarily by cyclical undulating fevers, night sweats, and localized infection (e.g., osteomyelitis or epididymitis), not typically subconjunctival hemorrhage. - Diagnosis usually involves blood culture or the Standard Tube Agglutination Test (SAT), not MAT. *E coli* - *E. coli* is a common cause of GI infections, UTIs, and sepsis; systemic *E. coli* disease does not typically manifest with the specific finding of subconjunctival hemorrhage. - MAT is not used for the diagnosis of *E. coli* infections, which are confirmed primarily through culture. *Staph aureus* - *S. aureus* can cause a wide range of infections (skin infections, endocarditis, sepsis) but is not associated with the specific syndrome presenting here (farmer, subconjunctival hemorrhage). - Diagnosis relies on culture, not serological tests like MAT, which is specific for spirochetes.

Q: A patient admitted with fever and nuchal rigidity. CSF analysis shows decreased glucose and increased protein and neutrophils. Which is the MOST IMPORTANT antibiotic for initial empirical treatment?

Ceftriaxone. Ceftriaxone - Ceftriaxone, a third-generation cephalosporin, is the most essential component of empirical treatment for bacterial meningitis due to its excellent CSF penetration and broad coverage [1]. - It effectively covers the most common bacterial causes of community-acquired meningitis: Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae [1]. - Note: Current guidelines recommend Ceftriaxone + Vancomycin as the optimal empirical regimen to cover penicillin-resistant S. pneumoniae (PRSP), but Ceftriaxone remains the primary/essential antibiotic in this combination [1]. Vancomycin - Vancomycin is critical for covering penicillin-resistant S. pneumoniae (PRSP) and is typically used in combination with Ceftriaxone in the empirical regimen. - It is not used as monotherapy due to poor CSF penetration and incomplete coverage of other common pathogens like N. meningitidis. Penicillin - Penicillin is no longer recommended for empirical treatment due to high prevalence of penicillin-resistant S. pneumoniae (PRSP) globally. - While effective against sensitive N. meningitidis, the need for broader coverage necessitates third-generation cephalosporins. Ampicillin - Ampicillin is added to cover Listeria monocytogenes in specific high-risk groups: patients >50 years, immunocompromised, pregnant women, or neonates. - It is ineffective as monotherapy for routine bacterial meningitis and lacks coverage for resistant strains of common pathogens.

Q: A TB patient with HIV begins ART and experiences deterioration in health after 2 months. What is the likely cause?

Immunological changes in the body. ***Immunological changes in the body*** - The patient's deterioration 2 months after initiating ART is highly suggestive of **Immune Reconstitution Inflammatory Syndrome (IRIS)** [1]. - IRIS occurs when the partially restored immune system mounts an intense, often paradoxical, inflammatory response against high existing **Mycobacterium tuberculosis** antigen loads [1]. *Development of drug resistance to TB drugs* - If resistance developed, the patient would typically fail to improve or experience gradual worsening, consistent with inadequate **TB coverage**, not an acute, paradoxical inflammatory reaction. - Worsening due to drug resistance is usually not temporally linked to the start of ART and would require specific **drug sensitivity testing (DST)** for confirmation [1]. *Drug-drug interactions between TB and ART medications* - Significant drug-drug interactions (e.g., between **rifampicin** and certain ART drugs) typically lead to systemic toxicity or subtherapeutic drug levels, manifesting as virologic failure or liver injury, not acute inflammatory worsening of the underlying TB. - Interactions lead to either rapid ART failure or toxicity, but not the specific clinical picture of **paradoxical TB-IRIS** where infectious signs temporarily worsen. *Development of drug resistance to ART* - Resistance to ART typically manifests as a failure of the **HIV viral load** to decrease or subsequent increase, leading to chronic progression of AIDS, not acute deterioration via inflammation of latent or subclinical TB [1]. - Developing drug resistance often requires prolonged exposure to a suboptimal regimen and usually takes longer than 2 months to cause significant clinical decline via **virologic failure**.

Q: Which of the following microorganisms is likely responsible for causing bilateral infiltrates in an HIV-positive patient?

Pneumocystis Jirovecii. ***Pneumocystis Jirovecii***- **Pneumocystis Pneumonia (PCP)** is the most common AIDS-defining infection affecting the lungs, typically presenting with **diffuse, bilateral, perihilar interstitial infiltrates** in HIV patients [1]. - This infection is strongly associated with a **CD4 cell count below 200 cells/mm³** and often manifests clinically with gradual onset of dyspnea, fever, and a non-productive cough [1].*Cryptococcus*- Although *Cryptococcus neoformans* is a common opportunistic infection in HIV, it predominantly causes **meningitis** or **meningoencephalitis**. - Pulmonary involvement usually presents as **nodules** or localized consolidations, not the classic diffuse bilateral interstitial pattern seen with PCP.*Histoplasmosis*- *Histoplasma capsulatum* is an endemic pathogen (e.g., Ohio and Mississippi River Valleys) that typically causes **disseminated disease** in advanced HIV. - While pulmonary infection may occur, it often presents with **hilar/mediastinal lymphadenopathy** [2] or a miliary pattern, rather than isolated bilateral interstitial infiltrates.*Aspergillus*- **Invasive Aspergillosis** generally occurs in patients with profound and prolonged **neutropenia** (e.g., following chemotherapy or transplantation), which is less common in typical AIDS patients with low CD4 counts. - Pulmonary findings usually involve localized **cavities** or **nodules with a halo sign** (angioinvasive disease), contrasting with the diffuse bilateral infiltrates of PCP.

Q: An HIV-positive man presents with a high-grade fever. Examination reveals a positive Kernig's sign. CSF shows reduced glucose, increased protein, and increased leukocytes. A diagnosis of cryptococcal meningitis is made. What is the appropriate management for this patient?

Liposomal amphotericin B. ***Liposomal amphotericin B***- **Liposomal amphotericin B** (often combined with **flucytosine**) is the standard of care for the **induction phase** (first 2 weeks) of severe cryptococcal meningitis treatment in HIV-positive patients due to its potent fungicidal activity [1].- The severity of the presentation (high fever, positive **Kernig's sign**, and abnormal CSF findings) necessitates this regimen to rapidly reduce the fungal burden in the central nervous system.*Vancomycin*- **Vancomycin** is an antibiotic used specifically to treat severe infections caused by **Gram-positive bacteria**, notably **MRSA**.- This drug has absolutely no therapeutic efficacy against the fungal pathogen *Cryptococcus neoformans*.*High dose fluconazole with flucytosine*- While fluconazole is an effective antifungal against *Cryptococcus*, this regimen is typically reserved for the **consolidation phase** (post-induction) or for milder disease.- Severe meningitis, indicated by the clinical signs and CSF profile, requires the superior fungicidal activity of **amphotericin B** during the induction phase [1].*Voriconazole*- **Voriconazole** is a broad-spectrum triazole mainly used for treating invasive **Aspergillus** and some *Candida* infections [1], [2].- It has **limited efficacy** against *Cryptococcus neoformans* and is not recommended as primary induction therapy for cryptococcal meningitis.

Q: A patient presented with a fever for 11 days with neck rigidity. A lumbar puncture was done, and it showed predominantly lymphocytes, sugar- 50mg, and protein- 3000mg/dl. Gram-staining was negative. The patient's chest X-ray shows upper lobe involvement with hilar lymph node enlargement. What is the probable diagnosis?

Tuberculous meningitis. ***Tuberculous meningitis***- The CSF analysis combines **lymphocytic predominance** (suggesting non-pyogenic cause), subacute onset (11 days of fever), and critically high protein (3000 mg/dL), which are hallmarks of TBM [1]. - The chest X-ray findings of **upper lobe involvement** and **hilar lymph node enlargement** confirm active systemic tuberculosis, providing the strongest evidence for TBM as the underlying cause of meningitis [4].*Bacterial meningitis*- Typically presents acutely (hours to a few days) and CSF analysis shows a predominance of **neutrophils** (neutrophilic pleocytosis) [3].- Although CSF protein is high and glucose is low, the presence of lymphocytes and a negative Gram stain makes typical pyogenic bacterial meningitis less likely [3].*Fungal meningitis*- Fungal infections like **Cryptococcosis** can cause lymphocytic pleocytosis and elevated protein, but the protein level (3000 mg/dL) is excessively high, even for fungal causes.- While systemic involvement can occur, the specific pulmonary findings (upper lobe infiltrates, hilar nodes) are classic diagnostic features of **Mycobacterium tuberculosis**.*Viral meningitis*- Viral meningitis typically causes an acute, self-limiting illness and is generally associated with relatively low protein levels (usually <100 mg/dL) and normal CSF glucose [2].- The protein level of 3000 mg/dL in this patient is incompatible with a typical viral etiology, which mostly resolves spontaneously [2].

Q: A 65-year-old male presented with unexplained fever and prolonged respiratory distress despite appropriate treatment. A diagnosis of cryptic tuberculosis was made. Which of the following is the correct statement related to this condition?

Negative skin tuberculin test and negative chest X-ray. ***Negative skin tuberculin test and negative chest X-ray***- **Cryptic tuberculosis (TB)**, or occult TB, often presents with non-specific systemic symptoms (like prolonged unexplained fever) without typical clinical or radiological signs expected in classic TB [1].- In older patients or those with disseminated disease, the immune response is often diminished, leading to a false negative result (anergy) on the **tuberculin skin test (TST)**, alongside a frequently normal chest X-ray (CXR) [1]. *Positive skin tuberculin test and negative chest X-ray*- A **positive TST** indicates prior exposure to *M. tuberculosis* but doesn't necessarily confirm active, symptomatic disease like cryptic TB. - Although the CXR is negative (consistent with cryptic TB), the positive TST contradicts the common finding of **anergy** seen in severely ill or elderly patients with cryptic disease. *Positive skin tuberculin test and positive chest X-ray*- This combination is characteristic of typical, **active pulmonary tuberculosis**, where the disease is localized and clinically/radiologically apparent. - By definition, cryptic TB lacks the **classic radiological findings** on chest X-ray, making this option incorrect. *Negative skin tuberculin test and positive chest X-ray*- While a **negative TST** can occur in active TB due to anergy or immunosuppression, a **positive CXR** strongly indicates radiologically apparent TB. - If the TB is radiologically apparent, the designation "cryptic" (meaning hidden or obscure) is inappropriate.

Question 1

A patient is diagnosed with Cryptococcal meningitis. What is the treatment?

Accepted Answer

Flucytosine + L.Amp

Answer

L.Amp

Answer

Fluconazole

Answer

Flucytosine

Question 2

Which of the following is the management of a HIV positive patient with multiple dog bites?

Accepted Answer

Rabies vaccine + Immunoglobulin + Wound management

Answer

Immunoglobulin only

Answer

Wound management

Answer

Rabies vaccine + wound management

Question 3

A patient presents with fever, neck rigidity, headache, vomiting, and petechial rashes on the lower limbs. What is the most likely causative organism?

Accepted Answer

Neisseria meningitidis

Answer

Cryptococcus neoformans

Answer

Clostridium difficile

Answer

Clostridium perfringens

Question 4

A farmer presents with fever and subconjunctival hemorrhage. The microscopic agglutination test is found to be positive. What is the diagnosis?

Accepted Answer

Leptospira

Answer

Brucella

Answer

E coli

Answer

Staph aureus

Question 5

A patient admitted with fever and nuchal rigidity. CSF analysis shows decreased glucose and increased protein and neutrophils. Which is the MOST IMPORTANT antibiotic for initial empirical treatment?

Accepted Answer

Ceftriaxone

Answer

Vancomycin

Answer

Penicillin

Answer

Ampicillin

Question 6

A TB patient with HIV begins ART and experiences deterioration in health after 2 months. What is the likely cause?

Accepted Answer

Immunological changes in the body

Answer

Development of drug resistance to ART

Answer

Development of drug resistance to TB drugs

Answer

Drug-drug interactions between TB and ART medications

Question 7

Which of the following microorganisms is likely responsible for causing bilateral infiltrates in an HIV-positive patient?

Accepted Answer

Pneumocystis Jirovecii

Answer

Histoplasma

Answer

Aspergillus

Answer

Cryptococcus

Question 8

An HIV-positive man presents with a high-grade fever. Examination reveals a positive Kernig's sign. CSF shows reduced glucose, increased protein, and increased leukocytes. A diagnosis of cryptococcal meningitis is made. What is the appropriate management for this patient?

Accepted Answer

Liposomal amphotericin B

Answer

High dose fluconazole with flucytosine

Answer

Voriconazole

Answer

Vancomycin

Question 9

A patient presented with a fever for 11 days with neck rigidity. A lumbar puncture was done, and it showed predominantly lymphocytes, sugar- 50mg, and protein- 3000mg/dl. Gram-staining was negative. The patient's chest X-ray shows upper lobe involvement with hilar lymph node enlargement. What is the probable diagnosis?

Accepted Answer

Tuberculous meningitis

Answer

Bacterial meningitis

Answer

Fungal meningitis

Answer

Viral meningitis

Question 10

A 65-year-old male presented with unexplained fever and prolonged respiratory distress despite appropriate treatment. A diagnosis of cryptic tuberculosis was made. Which of the following is the correct statement related to this condition?

Accepted Answer

Negative skin tuberculin test and negative chest X-ray

Answer

Positive skin tuberculin test and negative chest X-ray

Answer

Positive skin tuberculin test and positive chest X-ray

Answer

Negative skin tuberculin test and positive chest X-ray

Infectious Diseases — MCQs

Infectious Diseases — MCQs

On this page

Practice by Chapter

Want unlimited practice?