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Questions and Answers
What is the main vector responsible for the transmission of Yersinia pestis in the U.S.?
What is the main vector responsible for the transmission of Yersinia pestis in the U.S.?
Which of the following statements accurately describes the urban plague's relationship to human populations?
Which of the following statements accurately describes the urban plague's relationship to human populations?
During which months is the highest human case activity for Yersinia pestis typically observed?
During which months is the highest human case activity for Yersinia pestis typically observed?
What is the characteristic hematogenous spread of Yersinia pestis after initial infection?
What is the characteristic hematogenous spread of Yersinia pestis after initial infection?
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What condition must be met for Yersinia pestis to be trapped in the gut of a flea?
What condition must be met for Yersinia pestis to be trapped in the gut of a flea?
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What is the primary morphological characteristic of Yersinia pestis?
What is the primary morphological characteristic of Yersinia pestis?
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Which characteristic distinguishes Yersinia pestis from other Yersinia species?
Which characteristic distinguishes Yersinia pestis from other Yersinia species?
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What function do the virulence plasmids of Yersinia pestis serve?
What function do the virulence plasmids of Yersinia pestis serve?
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What is the role of Yersinia outer membrane proteins (Yops) in Yersinia pestis?
What is the role of Yersinia outer membrane proteins (Yops) in Yersinia pestis?
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Which of the following features is not associated with Yersinia pestis?
Which of the following features is not associated with Yersinia pestis?
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What type of antigen is found in the cell wall of Yersinia pestis?
What type of antigen is found in the cell wall of Yersinia pestis?
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How does Yersinia pestis's adhesin compare to other Yersinia species?
How does Yersinia pestis's adhesin compare to other Yersinia species?
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What kind of enzymes does Yersinia pestis produce as part of its virulence plasmids?
What kind of enzymes does Yersinia pestis produce as part of its virulence plasmids?
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What is the initial symptom that marks the onset of the plague?
What is the initial symptom that marks the onset of the plague?
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What is the percentage of patients who may progress to bacteremia without treatment?
What is the percentage of patients who may progress to bacteremia without treatment?
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Which symptom develops later in the course of primary pneumonic plague?
Which symptom develops later in the course of primary pneumonic plague?
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What characterizes the sputum in advanced pneumonic plague?
What characterizes the sputum in advanced pneumonic plague?
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What is commonly seen on the second or third day of illness in pneumonic plague?
What is commonly seen on the second or third day of illness in pneumonic plague?
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What does the term 'Black Death' refer to in the context of pneumonic plague?
What does the term 'Black Death' refer to in the context of pneumonic plague?
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How soon should antibiotic therapy be administered to prevent fatal outcomes from plague pneumonia?
How soon should antibiotic therapy be administered to prevent fatal outcomes from plague pneumonia?
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What type of organism is typically observed in gram-stained smears from a bubo?
What type of organism is typically observed in gram-stained smears from a bubo?
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What is the estimated mortality rate of human cases of plague in developed countries?
What is the estimated mortality rate of human cases of plague in developed countries?
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Which method is NOT effective for preventing sylvatic plague?
Which method is NOT effective for preventing sylvatic plague?
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What is the recommended chemoprophylaxis for those who have had close contact with a pneumonic plague case?
What is the recommended chemoprophylaxis for those who have had close contact with a pneumonic plague case?
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Why is the formalin-killed plague vaccine no longer available?
Why is the formalin-killed plague vaccine no longer available?
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What poses a risk of urban plague extension and epidemic disease?
What poses a risk of urban plague extension and epidemic disease?
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What types of media are used for isolating Yersinia pestis?
What types of media are used for isolating Yersinia pestis?
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What is the recommended treatment for both bubonic and pneumonic plague?
What is the recommended treatment for both bubonic and pneumonic plague?
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Which specimen is NOT recommended for confirming a diagnosis of plague?
Which specimen is NOT recommended for confirming a diagnosis of plague?
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Which of the following is a potential alternative treatment if meningitis is present?
Which of the following is a potential alternative treatment if meningitis is present?
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What is key for laboratories regarding suspected cases of plague?
What is key for laboratories regarding suspected cases of plague?
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What is characteristic of Yersinia pestis growth requirements?
What is characteristic of Yersinia pestis growth requirements?
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Which of the following antibiotics is NOT typically used for treating plague?
Which of the following antibiotics is NOT typically used for treating plague?
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What is the significance of hemolysis in microbiological media?
What is the significance of hemolysis in microbiological media?
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Study Notes
Yersinia pestis Overview
- Non-motile, non-spore-forming, gram-negative bacillus exhibiting pleomorphism and bipolar staining.
- Part of the Enterobacteriaceae family, alongside other pathogenic Yersinia species like Y. pseudotuberculosis and Y. enterocolitica.
- Contains virulence plasmids that encode F1 antigen (a glycoprotein capsule) and various enzymes (phospholipase, protease, fibrinolytic activities).
- Has adhesins similar to other Yersinia invaders.
Pathogenesis and Disease Transmission
- Carried via the lymphatic system to regional lymph nodes, where Y. pestis multiplies within phagocytes.
- May spread hematogenously, leading to hemorrhagic lesions in multiple organs.
- Sylvatic plague occurs in wild rodent populations, while urban plague involves domestic rodents.
Disease Cycles
- Sylvatic Plague: No significant rodent mortality (enzootic phase); high mortality and expansion into human areas (epizootic phase).
- Urban Plague: Infected fleas/rodents invade urban settings, resulting in high mortality and disease spread among domestic animals and humans, linked to poverty.
Modes of Transmission
- Transmission through flea bites, contact with infected animal tissues or fluids, and aerosol.
- Human outbreaks predominantly occur from April to November due to flea and host activity.
Flea Vectors
- Fleas can survive off hosts for extended periods; Oropsylla montana is a key vector in the U.S.
- Xenopsylla cheopis is notable for causing epidemics in Asia, Africa, and South America.
Clinical Presentation
- Onset includes fever and painful bubo, commonly found in the groin or axilla.
- Without treatment, serious outcomes include bacteremia leading to septic shock or pneumonic plague, with mortality rates as high as 75%.
- Pneumonic plague also presents rapidly and requires immediate antibiotic intervention.
Laboratory Diagnosis
- Recognized via gram-stained smear of bubo aspirates, typically showing bipolar-staining gram-negative bacilli.
- Culturing on blood agar or MacConkey agar; specimen collection includes bubo aspirate, blood, and sputum.
- Notification of suspicion is critical for prompt diagnosis and hazard prevention.
Treatment
- First-line treatments include gentamicin or streptomycin, often combined with doxycycline for both bubonic and pneumonic plague.
- Alternatives include ciprofloxacin or chloramphenicol when meningitis is present, with timely treatment reducing mortally rates significantly.
Prevention and Control
- Urban plague prevention via rat control and public health measures; difficult to eliminate sylvatic plague due to extensive rodent reservoirs.
- Recommendations include avoiding contact with sick or dead rodents and treating pets for fleas to minimize infection spread.
- Chemoprophylaxis with doxycycline or ciprofloxacin is advised for close contacts of infected individuals.
- The previous formalin-killed plague vaccine for high-risk populations is no longer available, making awareness and proactive measures essential.
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Description
This quiz covers the microbiological properties of Yersinia pestis, including its cultural techniques, epidemiology, and pathophysiology. It also addresses clinical presentations, specimen collection for culture, treatment options, and prevention strategies related to this pathogen. Perfect for students in Basic Medical Sciences focusing on the Blood and Lymphatic System.
