Diagnosis Microbiology Test Bank – Practice Exam Questions
2026 Latest Update
1. Which of the following is the most common method used to identify bacteria in a clinical
microbiology laboratory?
A. MRI scanning
B. Culture and biochemical testing
C. X-ray imaging
D. Electrocardiography
Answer: B. Culture and biochemical testing
2. Gram-positive bacteria appear what color after Gram staining?
A. Red
B. Pink
C. Purple
D. Green
Answer: C. Purple
3. Which organism is commonly associated with tuberculosis?
A. Escherichia coli
B. Mycobacterium tuberculosis
C. Staphylococcus aureus
D. Vibrio cholerae
Answer: B. Mycobacterium tuberculosis
4. The catalase test is used to differentiate:
A. Viruses from fungi
B. Streptococci from staphylococci
C. Gram-positive from Gram-negative bacteria
D. Aerobes from anaerobes
Answer: B. Streptococci from staphylococci
5. Which culture medium is selective for Gram-negative bacteria?
,A. Blood agar
B. Chocolate agar
C. MacConkey agar
D. Nutrient agar
Answer: C. MacConkey agar
6. The presence of lactose fermentation on MacConkey agar produces:
A. Colorless colonies
B. Black colonies
C. Pink colonies
D. Green colonies
Answer: C. Pink colonies
7. Which microorganism is responsible for malaria?
A. Virus
B. Fungus
C. Protozoan
D. Bacterium
Answer: C. Protozoan
8. Acid-fast staining is primarily used to identify:
A. Fungi
B. Spirochetes
C. Mycobacteria
D. Protozoa
Answer: C. Mycobacteria
9. Which specimen is best for diagnosing urinary tract infection?
A. Saliva
B. Midstream urine
C. Sweat
D. Tears
, Answer: B. Midstream urine
10. ELISA is mainly used to detect:
A. Blood groups
B. Antigens or antibodies
C. Bone fractures
D. Electrolytes
Answer: B. Antigens or antibodies
11. Which bacterial shape is spherical?
A. Bacilli
B. Spirilla
C. Cocci
D. Vibrios
Answer: C. Cocci
12. Anaerobic bacteria grow best:
A. In sunlight
B. Without oxygen
C. In high salt concentration
D. In cold temperatures
Answer: B. Without oxygen
13. The Kirby-Bauer test is used for:
A. Viral detection
B. Blood typing
C. Antibiotic susceptibility testing
D. Fungal staining
Answer: C. Antibiotic susceptibility testing
14. HIV is classified as:
A. DNA virus
B. Retrovirus
2026 Latest Update
1. Which of the following is the most common method used to identify bacteria in a clinical
microbiology laboratory?
A. MRI scanning
B. Culture and biochemical testing
C. X-ray imaging
D. Electrocardiography
Answer: B. Culture and biochemical testing
2. Gram-positive bacteria appear what color after Gram staining?
A. Red
B. Pink
C. Purple
D. Green
Answer: C. Purple
3. Which organism is commonly associated with tuberculosis?
A. Escherichia coli
B. Mycobacterium tuberculosis
C. Staphylococcus aureus
D. Vibrio cholerae
Answer: B. Mycobacterium tuberculosis
4. The catalase test is used to differentiate:
A. Viruses from fungi
B. Streptococci from staphylococci
C. Gram-positive from Gram-negative bacteria
D. Aerobes from anaerobes
Answer: B. Streptococci from staphylococci
5. Which culture medium is selective for Gram-negative bacteria?
,A. Blood agar
B. Chocolate agar
C. MacConkey agar
D. Nutrient agar
Answer: C. MacConkey agar
6. The presence of lactose fermentation on MacConkey agar produces:
A. Colorless colonies
B. Black colonies
C. Pink colonies
D. Green colonies
Answer: C. Pink colonies
7. Which microorganism is responsible for malaria?
A. Virus
B. Fungus
C. Protozoan
D. Bacterium
Answer: C. Protozoan
8. Acid-fast staining is primarily used to identify:
A. Fungi
B. Spirochetes
C. Mycobacteria
D. Protozoa
Answer: C. Mycobacteria
9. Which specimen is best for diagnosing urinary tract infection?
A. Saliva
B. Midstream urine
C. Sweat
D. Tears
, Answer: B. Midstream urine
10. ELISA is mainly used to detect:
A. Blood groups
B. Antigens or antibodies
C. Bone fractures
D. Electrolytes
Answer: B. Antigens or antibodies
11. Which bacterial shape is spherical?
A. Bacilli
B. Spirilla
C. Cocci
D. Vibrios
Answer: C. Cocci
12. Anaerobic bacteria grow best:
A. In sunlight
B. Without oxygen
C. In high salt concentration
D. In cold temperatures
Answer: B. Without oxygen
13. The Kirby-Bauer test is used for:
A. Viral detection
B. Blood typing
C. Antibiotic susceptibility testing
D. Fungal staining
Answer: C. Antibiotic susceptibility testing
14. HIV is classified as:
A. DNA virus
B. Retrovirus
