Infectious Diseases Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Infectious Diseases. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Infectious Diseases Indian Medical PG Question 1: Zoonotic diseases are -
- A. Anthrax
- B. Plague
- C. Salmonellosis
- D. All of the options (Correct Answer)
Infectious Diseases Explanation: ***All of the options***
- **Anthrax**, **Plague**, and **Salmonellosis** are all well-established examples of zoonotic diseases, which are infections naturally transmitted between vertebrate animals and humans.
- These diseases represent a diverse spectrum of bacterial infections with significant public health implications worldwide.
**Anthrax**
- Caused by *Bacillus anthracis*, a spore-forming bacterium naturally found in soil that primarily affects livestock and wild herbivores.
- Humans acquire infection through contact with infected animals or contaminated animal products (hides, wool, meat).
- Clinical forms include cutaneous (most common), inhalational (most severe), and gastrointestinal anthrax.
- Remains an important occupational hazard for veterinarians, farmers, and those handling animal products.
**Plague**
- Caused by *Yersinia pestis*, maintained in nature through rodent-flea cycles.
- Transmission to humans occurs primarily via bites from infected fleas or direct contact with infected animals.
- Historically responsible for devastating pandemics including the Black Death.
- Clinical manifestations include bubonic (most common), pneumonic (person-to-person transmission possible), and septicemic plague.
**Salmonellosis**
- Caused by non-typhoidal *Salmonella* species, commonly colonizing the intestines of various animals including poultry, cattle, reptiles, and pets.
- Humans typically acquire infection through consumption of contaminated food (undercooked meat, eggs, unpasteurized dairy) or direct animal contact.
- Presents as acute gastroenteritis with diarrhea, fever, and abdominal cramps.
- One of the most common foodborne zoonotic infections globally.
Infectious Diseases Indian Medical PG Question 2: Consider the following characteristics of biological agents :
1. Infectivity
2. Pathogenicity
3. Virulence
4. Communicability
Among the above characteristics, which are used to measure the ability of biological agents to induce clinically apparent illness?
- A. 3 only
- B. 2 and 3 (Correct Answer)
- C. 2 only
- D. 1 and 2
Infectious Diseases Explanation: ***2 and 3***
- **Pathogenicity** is the ability of an infectious agent to cause disease (clinically apparent illness) in infected individuals, measured as the proportion of infected persons who develop clinical disease.
- **Virulence** is the ability of an agent to produce severe disease, measured as the proportion of clinical cases that are severe or fatal.
- **Both characteristics measure different aspects of the ability to induce clinically apparent illness**: pathogenicity measures whether clinical illness occurs, while virulence measures the severity of that clinical illness.
- Together, they comprehensively describe an agent's capacity to produce clinically apparent disease.
*2 only*
- While pathogenicity does measure the ability to cause clinically apparent illness, this is incomplete.
- Virulence is also a measure of the ability to induce clinically apparent illness, specifically measuring the severity spectrum of that illness.
*3 only*
- Virulence alone is insufficient as it only measures severity among those who are already clinically ill.
- Pathogenicity is also needed to measure the ability to produce clinical illness in the first place.
*1 and 2*
- **Infectivity** measures the ability of an agent to enter, survive, and multiply in a host, which is a prerequisite for disease but does not measure clinical illness itself.
- An agent can have high infectivity but low pathogenicity (causing mostly subclinical infections).
- Only pathogenicity and virulence directly measure aspects of clinically apparent illness.
Infectious Diseases Indian Medical PG Question 3: A 30-year-old male presents with chills and a high fever of 40°C. Which of the following symptoms would most likely suggest an infectious cause?
- A. Rigors (Correct Answer)
- B. Excessive sweating
- C. Skin rash
- D. Vomiting
Infectious Diseases Explanation: ***Rigors***
- **Rigors** (generalized shivering with a sensation of cold) are strong indicators of a rapid and significant rise in body temperature, often seen with **bacteremia** or other severe infections [1].
- The body's defense mechanisms are fighting off a severe infection, leading to an exaggerated physiological response.
*Excessive sweating*
- **Excessive sweating (diaphoresis)** typically occurs as the body attempts to cool down during the defervescence (fever reduction) phase [1].
- While associated with fever, it is less specific for the *onset* or active phase of an infection compared to rigors [1].
*Skin rash*
- A **skin rash** can be a symptom of certain infections (e.g., viral exanthems, meningococcemia) but is not a universal or primary indicator of *any* infectious cause [2].
- Many febrile illnesses do not present with a rash, and rashes can also be non-infectious in origin (e.g., allergic reactions).
*Vomiting*
- **Vomiting** can accompany many illnesses, both infectious (e.g., gastroenteritis, meningitis) and non-infectious (e.g., migraine, drug reaction).
- It is a non-specific symptom that does not singularly point to an infectious etiology as strongly as rigors in the context of a high fever.
Infectious Diseases Indian Medical PG Question 4: Continued suppression of bacterial growth after antibiotic levels have fallen below the Minimum Inhibitory Concentration (MIC) is known as?
- A. Time dependent killing
- B. Sequential blockade
- C. Concentration dependent killing
- D. Post antibiotic effect (Correct Answer)
Infectious Diseases Explanation: ***Post antibiotic effect***
- The **post-antibiotic effect (PAE)** refers to the continued suppression of bacterial growth after antibiotic levels have fallen below the **Minimum Inhibitory Concentration (MIC)**.
- This phenomenon allows for less frequent dosing while maintaining efficacy, which is important for drug scheduling.
*Time dependent killing*
- **Time-dependent killing** means that the duration for which the antibiotic concentration stays above the **MIC** is the most important factor for efficacy, not necessarily the peak concentration.
- Antibiotics with this characteristic, such as **beta-lactams**, often require frequent dosing or continuous infusion.
*Sequential blockade*
- **Sequential blockade** occurs when two drugs act on consecutive steps in a metabolic pathway, leading to a synergistic effect that results in enhanced microbial killing.
- A classic example is the combination of **sulfamethoxazole and trimethoprim**, which inhibit different enzymes in the folic acid synthesis pathway.
*Concentration dependent killing*
- **Concentration-dependent killing** indicates that the rate and extent of bacterial killing increase as the antibiotic concentration rises, particularly when it exceeds the **MIC**.
- Antibiotics like **aminoglycosides** exhibit this effect, often benefiting from high peak concentrations to maximize efficacy.
Infectious Diseases Indian Medical PG Question 5: Which of the following is the most commonly used drug for outpatient management of community acquired pneumonia?
- A. Ceftriaxone
- B. Streptomycin
- C. Azithromycin (Correct Answer)
- D. Vancomycin
Infectious Diseases Explanation: ***Azithromycin***
- **Azithromycin** is a macrolide antibiotic widely recommended for outpatient treatment of **community-acquired pneumonia (CAP)** due to its efficacy against common causative pathogens like *Streptococcus pneumoniae* and **atypical bacteria** (e.g., *Mycoplasma pneumoniae*, *Chlamydophila pneumoniae*).
- Its **once-daily dosing** and good oral bioavailability contribute to patient compliance in an outpatient setting.
*Ceftriaxone*
- **Ceftriaxone** is a third-generation cephalosporin primarily used for **intravenous administration** in more severe CAP cases requiring hospitalization or for specific resistant strains, not typically for initial outpatient management.
- While effective against *Streptococcus pneumoniae*, it lacks coverage for **atypical pathogens** and its parenteral route makes it less suitable for most outpatient settings.
*Streptomycin*
- **Streptomycin** is an aminoglycoside antibiotic primarily used for **tuberculosis** and severe gram-negative infections, not a standard treatment for typical or atypical pathogens causing CAP.
- It has a high risk of **ototoxicity** and **nephrotoxicity**, making it unsuitable for routine outpatient CAP management.
*Vancomycin*
- **Vancomycin** is a glycopeptide antibiotic primarily used for **methicillin-resistant *Staphylococcus aureus* (MRSA)** infections and severe gram-positive infections, not a first-line agent for typical CAP pathogens.
- It is usually administered **intravenously** and requires monitoring for **nephrotoxicity** and **ototoxicity**, making it inappropriate for routine outpatient use.
More Infectious Diseases Indian Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
