30 Questions
Which of the following is an example of an obligate intracellular bacterium?
Rickettsia
Which of the following is NOT an obligate intracellular bacterium?
Salmonella
Which of the following diseases is associated with Anaplasma?
Rocky Mountain spotted fever
Which of the following bacteria is associated with Q fever?
Coxiella
Which of the following is a method of diagnosis for Rickettsia, Ehrlichia, Anaplasma, and Coxiella organisms?
Blood culture
What is the advantage of intracellular growth from a microbial perspective?
Access to essential nutrients
Which organism is the etiological agent of Q (Query) fever?
Coxiella burnetii
What is the primary means of transmission for Q fever?
Inhalation of infected aerosols
Which cells does Coxiella burnetii preferentially target?
Mononuclear phagocytes
What is the incubation period for Q fever?
2 to 3 weeks
Which form of Q fever comprises the majority of chronic cases?
Endocarditis
What is the most common diagnostic technique for Q fever?
Detection of antibodies in paired serum samples
Which of the following is a characteristic of Rickettsia bacteria?
They spread from cell to cell using host-cell actin
Which tick-borne illness has the highest case fatality rate in the United States?
Rocky Mountain Spotted Fever
What is the primary vector of Rocky Mountain Spotted Fever in North America?
Dermacento variabilis
Which organ is primarily affected by acute Q fever?
Lungs
What is a characteristic feature of the rash in Rocky Mountain Spotted Fever?
It is maculopapular and progresses to petechial
Which of the following is NOT a symptom of Anaplasmosis?
CNS symptoms
Which test is considered the gold standard for diagnosing rickettsial disease?
Indirect immuno-fluorescent assay (IFA)
What is the recommended treatment for rickettsial, ehrlichia, and coxiella infections?
Doxycycline
Which test may be used on skin biopsies or post-mortem tissue to diagnose rickettsial disease?
Immunohistochemistry
What is a contraindication for vaccination against C. burnetii?
Previous exposure to C. burnetii
What is the recommended action regarding therapy for rickettsial, ehrlichia, and coxiella infections?
Start therapy immediately
Which option is NOT a preventive measure for rickettsial, ehrlichia, and coxiella infections?
Consume raw milk or raw milk products
Which of the following is a classic feature of Rocky Mountain spotted fever (RMSF)?
Centripetal spread of rash starting on wrists, arms, and ankles
What is the recommended empirical treatment for RMSF?
Doxycycline
How is the diagnosis of RMSF confirmed?
By a 4-fold change between acute and convalescent titers
Which etiological agent causes epidemic typhus?
Rickettsia prowazekii
What is the potential for recurrence years later after an acute infection of Rickettsia prowazekii?
Recurrence is common within a few years
Which cells do Ehrlichia and Anaplasma target for replication?
Monocytes/neutrophils
Study Notes
Obligate Intracellular Bacteria
- Anaplasma is an example of an obligate intracellular bacterium.
- Coxiella is an example of an obligate intracellular bacterium.
Diseases Associated with Organisms
- Anaplasma is associated with Anaplasmosis.
- Coxiella is associated with Q fever.
- Rickettsia is associated with Rocky Mountain Spotted Fever (RMSF) and epidemic typhus.
Diagnosis and Testing
- Immunofluorescence assay (IFA) is a method of diagnosis for Rickettsia, Ehrlichia, Anaplasma, and Coxiella organisms.
- The gold standard for diagnosing rickettsial disease is the immunofluorescence assay (IFA).
- PCR may be used on skin biopsies or post-mortem tissue to diagnose rickettsial disease.
Characteristics of Organisms
- Rickettsia bacteria are characterized by their ability to grow intracellularly.
- Coxiella burnetii preferentially targets macrophages and monocytes.
- Ehrlichia and Anaplasma target granulocytes and monocytes for replication.
Q Fever
- The primary means of transmission for Q fever is through inhalation of contaminated aerosols.
- The incubation period for Q fever is 2-3 weeks.
- The majority of chronic cases of Q fever are comprised of endocarditis.
- The most common diagnostic technique for Q fever is serology.
- The primary organ affected by acute Q fever is the liver.
Rocky Mountain Spotted Fever
- The primary vector of Rocky Mountain Spotted Fever in North America is the American dog tick.
- The characteristic feature of the rash in Rocky Mountain Spotted Fever is a maculopapular rash that begins on the wrists and ankles.
- The recommended empirical treatment for RMSF is doxycycline.
- The diagnosis of RMSF is confirmed by PCR or serology.
Treatment and Prevention
- The recommended treatment for rickettsial, ehrlichia, and coxiella infections is doxycycline.
- The recommended action regarding therapy for rickettsial, ehrlichia, and coxiella infections is to initiate treatment promptly.
- Avoiding tick bites and taking precautions when working with animals or tissues are preventive measures for rickettsial, ehrlichia, and coxiella infections.
- Pregnancy is a contraindication for vaccination against C.burnetii.
Test your knowledge on the principles and practice of pediatric infectious diseases with this quiz. Learn about Rickettsii, a bacterium that targets endothelial cells and causes vasculitis. Explore the incubation period, symptoms like fever and rash, and other important aspects of this disease.
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