This section uses case studies and real-life infection scenarios to apply concepts related to disease-causing microorganisms in analytical and problem-solving contexts. It is designed for Class 11–12 students, NEET aspirants, and undergraduate learners to strengthen conceptual application and higher-order reasoning skills.
In this section, you will study:
Case studies based on bacterial, viral, fungal, and protozoan infections
Scenarios involving modes of transmission and disease spread
Analysis of host–pathogen interactions
Case-based problems on virulence and pathogenic mechanisms
Situational studies involving outbreaks and epidemic control
Interpretation of clinical symptoms linked to specific pathogens
NCERT-based case studies and exam-oriented questions
The content is structured to improve analytical reasoning, enhance concept application, and prepare students for case-based and higher-order questions in school examinations, NEET, and undergraduate assessments.
Develop the ability to analyze infectious disease scenarios by applying microbiology concepts to real-world and exam-based case studies with clarity and precision.
Q. A 28-year-old woman presents with a sore throat and swollen lymph nodes. A rapid strep test is positive. What is the most likely causative agent?
A.
Streptococcus pyogenes
B.
Streptococcus pneumoniae
C.
Haemophilus influenzae
D.
Corynebacterium diphtheriae
Solution
Streptococcus pyogenes is the most common cause of pharyngitis and is detected by rapid strep tests.
Q. A 30-year-old woman develops a urinary tract infection. A urine culture shows the presence of a gram-negative bacillus. Which organism is the most common cause of such infections?
A.
Escherichia coli
B.
Proteus mirabilis
C.
Enterococcus faecalis
D.
Klebsiella pneumoniae
Solution
Escherichia coli is the most common cause of urinary tract infections.
Q. A 45-year-old man presents with fever, cough, and chest pain. A chest X-ray shows a cavitary lesion in the right upper lobe. Which microorganism is most likely responsible for this condition?
A.
Streptococcus pneumoniae
B.
Mycobacterium tuberculosis
C.
Klebsiella pneumoniae
D.
Legionella pneumophila
Solution
The cavitary lesion in the right upper lobe is characteristic of pulmonary tuberculosis, which is caused by Mycobacterium tuberculosis.
Q. A 50-year-old man presents with fever, night sweats, and weight loss. A biopsy of a lymph node reveals granulomas. Which infectious agent is most likely responsible?
A.
Histoplasma capsulatum
B.
Mycobacterium tuberculosis
C.
Coccidioides immitis
D.
Brucella spp.
Solution
Granulomas in the lymph nodes are characteristic of tuberculosis, which is caused by Mycobacterium tuberculosis.
Q. A laboratory technician is exposed to a needle stick injury from a patient with hepatitis B. What is the most appropriate post-exposure prophylaxis?
A.
Hepatitis B vaccine
B.
Hepatitis A vaccine
C.
Intravenous immunoglobulin
D.
No treatment necessary
Solution
Post-exposure prophylaxis for hepatitis B includes administering the hepatitis B vaccine.
Q. A patient presents with a sudden onset of high fever, chills, and a petechial rash. Blood cultures reveal Neisseria meningitidis. What is the most effective preventive measure?
A.
Antibiotic prophylaxis
B.
Meningococcal vaccine
C.
Isolation of the patient
D.
Intravenous immunoglobulin
Solution
The meningococcal vaccine is the most effective preventive measure against Neisseria meningitidis infection.
Q. A patient presents with severe diarrhea and dehydration. Stool culture reveals the presence of a toxin-producing organism. Which organism is most likely responsible?
A.
Escherichia coli
B.
Clostridium difficile
C.
Salmonella enterica
D.
Vibrio cholerae
Solution
Clostridium difficile is known for causing antibiotic-associated diarrhea and produces toxins that lead to severe gastrointestinal symptoms.
Q. A patient with a history of travel to tropical regions presents with fever, jaundice, and abdominal pain. Which virus is most likely responsible for these symptoms?
A.
Hepatitis A virus
B.
Hepatitis B virus
C.
Dengue virus
D.
Yellow fever virus
Solution
Yellow fever virus is endemic in tropical regions and can cause fever, jaundice, and abdominal pain.
