Chapter 21, Problem 1MC

Most human infections caused by species of Rickettsia _______.

1. a. are acquired from fomites
2. b. could be prevented by handwashing
3. c. are transmitted via vectors
4. d. are sexually transmitted

Summary Introduction

Introduction:

Rickettsia is Gram negative, non spore forming bacteria. They are obligate parasite that lives inside host cell. Rickettsia species synthesized less amount of peptidoglycan and hence, appear as cell wall less organisms. Thus, these organisms are also called as pleomorphic organism; they have ability to change their shape.

Answer to Problem 1MC

Correct answer:

Most human infection caused by species of Rickettsia bacteria are transmitted via vectors.

Therefore, option (c) is correct.

Option (c) is given as “are transmitted via vectors.”

Explanation of Solution

Justify reason for the correct statement:

Rickettsia belongs to Gram negative family. They are small, pleomorphic and wall less organisms. They are obligate parasites and cause Rocky Mountain spotted fever in humans. Rickettsia was first identified by scientists named Howard Ricketts who identified that these bacteria are transmitted through tick vector.

Hence, option (c) is correct.

Justify reasons for the incorrect statements:

Option (a) is given as “are acquired from fomites.”

Rickettsia bacteria are not acquired through fomites. Hence, it is a wrong answer.

Option (b) is given as “could be prevented by handwashing.”

Rickettsia bacteria are transmitted through vectors. So, they are not prevented by handwashing. Hence, it is a wrong answer.

Option (d) is given as “are sexually transmitted.”

Rickettsia bacteria are not sexually transmitted. Hence, it is a wrong answer.

Hence, options (a), (b), and (d) are incorrect.

Conclusion

Rickettsia bacteria belong to Gram negative family and transmitted through tick vector.