Rickettsia rickettsii is a gram-negative, obligate intracellular pathogen. Which of the following statements about the R. rickettsii life cycle is FALSE?

1-Like viruses, R. rickettsii requires a eukaryotic host in order to carry out its life cycle. 2-In order to cause RMSF, R. rickettsii must enter host cells. 3-After entering a host, R. rickettsii multiplies to levels high enough to successfully invade cells and establish an infection. 4-During infection, R. rickettsii is able to survive and replicate within eukaryotic cells.

The correct answer is option 3. After entering a host, R. rickettsii multiplies to levels high enough to successfully invade cells and establish an infection.

Explanation:

Rickettsia rickettsii is a gram-negative coccobacillus bacteria that is an obligate intracellular pathogen. It causes mountain rock fever and gets into the body with contaminated food.

R. rickettsii is reproduced through binary fission in the host. This bacteria needs to get in the host first to carry out the life cycle. After entering into the cell this bacteria replicate inside the host by binary fission mainly and survive.

Thus, the correct answer is option 3. After entering a host, R. rickettsii multiplies to levels high enough to successfully invade cells and establish an infection.