Exam 4: Coxiella and Chlamydia Flashcards
What is Q fever caused by?
Coxiella burnetti
Describe Coxiella burnetti
Gram-negative bacteria that is highly resistant to environmental stresses such as high temperature, osmotic pressure, and ultraviolet light
What kind of pathogen is Coxiella burnetti?
Obligate intracellular bacterial pathogen
What is Q fever?
A zoonotic bacterial infection associated primarily with parturient ruminants and domestic animals such as cats
What are the most common domestic animals to get Q fever?
Sheep
Goats
Cattle
Why is Q fever in animals significant?
It serves as a source of infection for humans
Are dogs and cats the source of human infections of Q fever?
Though many dogs and cats sustain subclinical infections as evidenced by serological studies, but it is not yet known if they are sources
What does Q fever result from?
Inhalation of a spore-like small-cell variant and contact with milk, urine, feces, vaginal mucus, or semen of infected animals
Is Q fever tick-borne?
Rarely
Where does Coxiella burnetti reside and reproduce?
In the acidified phagolysosomes of host monocytes and macrophages
What is the large cell variant of Coxiella burnetti?
A vegetative form found in infected cells
What is the small cell variant of Coxiella burnetti?
The extracellular infectious form shed in milk, urine, and feces
Resistant to heat, drying, and many common disinfectants
Remains viable for weeks to years in the environment
What happens to Coxiella burnetti in Q fever?
It becomes localized in the mammary glands and placenta of infected ruminants and is excreted
What is Coxiella burnetti like in the environment?
It is very stable and has “spore-like” characteristics and may persist in the environment for several weeks
What does Coxiella burnetti persist in?
Contaminated soil
How is Coxiella burnetti transported long distance?
On dust particles and some windborne outbreaks
How is Coxiella burnetti passed?
In milk and people who consume non-pasteurized milk
What is Coxiella burnetti a major reason for?
Pasteurization of milk
What can Q fever cause?
Abortion
Stillbirth
Endometritis
What is the most characteristic sign of Q fever in ruminants?
Placentitis
What is seen with Q fever in goats and cattle?
Fetal pneumonia
How can Coxiella burnetti be identified?
With Ziehl-Neelsen or Gimenez strain
Polymerase chain reaction
What are the serologic tests available for Q fever?
Indirect immunofluorescence
ELISA
Complement fixation
How can Coxiella burnetti be isolated?
In cell cultures, ebryonated chicken eggs, or laboratory animals including mice, hamsters, and guinea pigs, but isolation is dangerous and rarely used for diagnosis
How can animals be protected from Coxiella burnetti?
Long acting injectable tetracyclines