Plague Practice Questions
20 free Plague practice questions for the Microbiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which bacterium is responsible for causing plague?
- A Yersinia pestis
- B Salmonella typhi
- C Vibrio cholerae
- D Bacillus anthracis
Correct answer: Yersinia pestis
Yersinia pestis is a Gram-negative coccobacillus responsible for plague. It is transmitted primarily through flea bites from infected rodents.
What is the primary vector for transmission of plague to humans?
- A Mosquito
- B Tick
- C Louse
- D Flea
Correct answer: Flea
The flea, particularly Xenopsylla cheopis, is the main vector transmitting Yersinia pestis. It becomes infected by feeding on infected rodents and then transmits the bacteria to humans.
Which form of plague presents with painful, swollen lymph nodes in the groin, axilla, or neck?
- A Septicemic plague
- B Pneumonic plague
- C Ocular plague
- D Bubonic plague
Correct answer: Bubonic plague
Bubonic plague presents with painful swollen lymph nodes known as buboes. These usually appear in the groin, axilla, or neck.
Which form of plague is highly contagious and transmitted via respiratory droplets?
- A Bubonic plague
- B Septicemic plague
- C Pneumonic plague
- D Enteric plague
Correct answer: Pneumonic plague
Pneumonic plague affects the lungs and can spread directly from person to person via respiratory droplets. It is the most contagious form of plague.
Which staining characteristic is typical of Yersinia pestis?
- A Acid-fast staining
- B Gram-positive cocci in clusters
- C Bipolar 'safety pin' appearance
- D Spore formation
Correct answer: Bipolar 'safety pin' appearance
Yersinia pestis exhibits bipolar staining, giving a 'safety pin' appearance under microscopy. This is due to uneven uptake of stain at the poles.
Which historical pandemic was caused by Yersinia pestis?
- A Spanish flu
- B Black Death
- C Cholera pandemic
- D Smallpox outbreak
Correct answer: Black Death
The Black Death was a devastating pandemic in the 14th century caused by Yersinia pestis. It resulted in millions of deaths across Europe.
Which virulence factor helps Yersinia pestis evade phagocytosis?
- A Capsule
- B Endospore
- C Pili
- D Teichoic acid
Correct answer: Capsule
Yersinia pestis has a protein capsule (F1 antigen) that inhibits phagocytosis. This enhances its ability to survive in the host.
Which type of plague occurs when bacteria spread directly into the bloodstream?
- A Bubonic plague
- B Septicemic plague
- C Primary pneumonic plague
- D Localized plague
Correct answer: Septicemic plague
Septicemic plague occurs when Yersinia pestis enters and multiplies in the bloodstream. It can lead to disseminated infection and septic shock.
Which animal reservoir is most commonly associated with plague transmission?
- A Dogs
- B Cats
- C Rodents
- D Primates
Correct answer: Rodents
Rodents, especially rats, serve as the primary reservoir for Yersinia pestis. Fleas feeding on infected rodents transmit the bacteria to humans.
Which clinical feature is characteristic of pneumonic plague?
- A Skin rash
- B Bloody sputum
- C Jaundice
- D Joint swelling
Correct answer: Bloody sputum
Pneumonic plague involves the lungs and often presents with cough and bloody sputum. It is rapidly progressive and life-threatening.
Which laboratory test can help identify Yersinia pestis by its bipolar staining?
- A Ziehl-Neelsen stain
- B Gram stain
- C Giemsa stain
- D India ink stain
Correct answer: Giemsa stain
Giemsa stain highlights the bipolar 'safety pin' appearance of Yersinia pestis. This aids in microscopic identification.
Which antibiotic is commonly used to treat plague?
- A Penicillin
- B Streptomycin
- C Vancomycin
- D Erythromycin
Correct answer: Streptomycin
Streptomycin is the drug of choice for treating plague. It is effective against Yersinia pestis and reduces mortality when administered early.
Which route of transmission is most common for bubonic plague?
- A Airborne
- B Flea bite
- C Contaminated water
- D Direct contact
Correct answer: Flea bite
Bubonic plague is typically transmitted through the bite of an infected flea. The bacteria then travel to nearby lymph nodes.
Which form of plague has the highest mortality rate if untreated?
- A Bubonic plague
- B Septicemic plague
- C Pneumonic plague
- D Cutaneous plague
Correct answer: Pneumonic plague
Pneumonic plague has the highest mortality rate if untreated. It progresses rapidly and can lead to respiratory failure.
Which diagnostic method is used to detect Yersinia pestis DNA?
- A Culture
- B PCR assay
- C ELISA
- D Western blot
Correct answer: PCR assay
PCR is used to detect Yersinia pestis DNA in clinical samples. It provides rapid and sensitive diagnosis.
Which structure allows Yersinia pestis to survive within macrophages initially?
- A Lipopolysaccharide endotoxin
- B Outer membrane porins
- C Peptidoglycan cell wall
- D Type III secretion system
Correct answer: Type III secretion system
The Type III secretion system allows Yersinia pestis to inject proteins into host cells. This helps it evade immune responses and survive intracellularly.
Which environmental condition favors the spread of plague among rodent populations?
- A Cold and dry climate zones
- B High-altitude terrain
- C Arid desert climates
- D Warm and humid conditions
Correct answer: Warm and humid conditions
Warm and humid conditions favor flea survival and proliferation. This increases transmission among rodents and subsequently to humans.
Which symptom is commonly associated with septicemic plague?
- A Hemorrhagic skin lesions
- B Swollen inguinal lymph nodes
- C Productive cough
- D Pharyngeal erythema
Correct answer: Hemorrhagic skin lesions
Septicemic plague can cause disseminated intravascular coagulation, leading to hemorrhagic skin lesions. This may result in tissue necrosis.
Which precaution is most important in preventing pneumonic plague transmission?
- A Hand hygiene protocols
- B Insect vector control
- C Respiratory isolation
- D Prophylactic vaccination
Correct answer: Respiratory isolation
Respiratory isolation is crucial to prevent person-to-person transmission of pneumonic plague. It helps limit the spread via droplets.
Which culture characteristic is associated with Yersinia pestis?
- A Slow growth on standard media
- B Rapid lactose fermentation
- C Bright red colony pigmentation
- D Swarming motility
Correct answer: Slow growth on standard media
Yersinia pestis grows slowly on standard culture media. Its identification often requires specific laboratory conditions and techniques.