Chapter 17, Problem 1MCQ

Summary Introduction

Introduction:

Bacteria are prokaryotic organisms. There are four basic shapes of bacteria; rod-shaped, spherical, comma-shaped, and spiral. Bacteria are cosmopolitan in nature. There are some bacteria, which are pathogenic in nature. These bacteria cause diseases in plants and animals. Tuberculosis, cholera, pneumonia, and gonorrhea are some of the diseases that are caused by pathogenic bacteria.

Answer to Problem 1MCQ

Correct answer:

The most likely interpretation of isolation of two colonies of E. coli on a plate streaked from a urine sample is normal biota. Therefore, option (b) is correct.

Option (b) is given as “normal biota”.

Explanation of Solution

Justify reasons for the correct statement:

Normal biota refers to the microbes that are present within the humans. They are present in the deep layers of skin or on the surface of the skin, in the oral mucosa, in the saliva, GI (gastrointestinal) tract, and in the conjunctiva. If two colonies of E. coli (Escherichia coli) are isolated from a streaked plate of urine sample, then it is because this microbe is a member of the normal biota of the body and can be present in the sample.

Hence, option (b) is correct.

Justify reasons for the incorrect statements:

Option (a) is given as “probable infection”.

Presence of E. coli does not indicate a probable infection as this microbe is a part of normal biota of the body. Hence, it is a wrong answer.

Option (c) is given as “contamination”.

Presence of E. coli does not indicate contamination as this microbe is a part of the normal biota of the body. Hence, it is a wrong answer.

Hence, options (a) and (c) are incorrect.

Conclusion

E. coli is a member of the normal biota of the body and is not harmful. Its presence in a sample does not indicate contamination or probable infection.