11 Questions
Which statement about Rickettsia is correct?
They have a coccobacillary shape and are weakly Gram-negative
Which diagnostic test is commonly used for rickettsial infections?
Weil-Felix agglutination test
Which of the following is a characteristic clinical manifestation of rickettsial infections?
Vasculitis and rash
Which antibiotic is the preferred treatment for rickettsial infections?
Doxycycline
Which of the following statements about Rickettsia is incorrect?
They can survive outside host cells
Which diagnostic method is commonly used for confirming rickettsial infections?
Both A and B
What is the key feature of the GENUS Rickettsia?
Aerobic, gram-negative coccobacilli
What type of bacteria are Rickettsiae?
Obligate intracellular bacteria
Which of the following is a characteristic symptom of diseases caused by Rickettsiae?
Vasculitis and rash
What is the purpose of the Weil-Felix test in the diagnosis of Rickettsia infections?
It is no longer used for diagnosis
Which antibiotic is recommended for the treatment of Rickettsia infections?
Doxycycline
Study Notes
Rickettsia Species Overview
- Rickettsia are gram-indeterminate, appearing gram-negative due to poor gram staining, and are pleomorphic in shape.
- They are obligate intracellular, requiring the host's ATP to survive.
- Rickettsia colonize endothelial cells, causing endothelial hyperplasia.
Characteristics
- Rickettsia have a coccobacillary shape and are weakly gram-negative.
- They are unable to produce NAD+ and CoA, making these essential for bacterial growth and replication.
Diagnosis
- Weil-Felix agglutination test is used for Rickettsia infections, causing cross-reaction with Proteus Vulgaris antigens.
- PCR and serology can also be used for diagnosis.
Disease Presentation
- Rickettsiosis presents with prodromal headache and fever, followed by vasculitis and rash.
- Vasculitis leads to inflammation and destruction of blood vessels.
- Rash may occur due to vasculitis.
Treatment
- Doxycycline is the primary treatment for Rickettsia infections.
- Chloramphenicol can be used in pregnant women.
- Supportive care with vascular collapse is essential.
Rickettsia Genus Features
- Rickettsia spp. are aerobic, gram-negative, coccobacilli.
- They are obligate intracellular bacteria, requiring host ATP.
- Rickettsia are unable to produce sufficient ATP, CoA, and NAD+.
Diseases Caused by Rickettsiae and Close Relatives
- Rocky Mountain Spotted Fever is caused by R. rickettsii, transmitted by ticks, and affecting ticks, dogs, rodents.
- Epidemic Typhus is caused by R. prowazekii, transmitted by human lice, and affecting humans.
- Endemic Typhus is caused by R. typhi, transmitted by fleas, and affecting rodents.
- Scrub Typhus is caused by Orientia tsutsugamushi, transmitted by mites, and affecting rodents.
- Ehrlichiosis is caused by E. chaffeensis and E. phagocytophila, transmitted by ticks, and affecting small mammals.
Test your knowledge of Rickettsia Tennis species with this quiz covering key characteristics such as gram staining, intracellular lifestyle, and cellular colonization. Identify important features for diagnosis and understanding of this bacterial species.
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