C H A P T E R 6 Normal Flora

1. The colon is the site of the largest number of normal flora

bacteria. Which one of the following bacteria is found in the

greatest number in the colon?

(A) Bacteroides fragilis

(B) Clostridium perfringens

(C) Enterococcus faecalis

(D) Escherichia coli

(E) Lactobacillus species

1. A 76-year-old woman with a prosthetic (artificial) hip comes

to you complaining of fever and pain in that joint. You are

concerned about an infection by S. epidermidis. Using your

knowledge of normal flora, what is the most likely source of

this organism?

(A) Dental plaque

(B) Mouth

(C) Skin

(D) Stomach

(E) Vagina

1. Your patient is a 30-year-old woman with a previous history

of rheumatic fever who has had fever for the past 2 weeks.

On examination, you find a new heart murmur. You suspect

endocarditis and do a blood culture, which grows a viridans

group streptococcus later identified as S. sanguinis. Using

your knowledge of normal flora, what is the most likely

source of this organism?

(A) Duodenum

(B) Skin

(C) Throat

(D) Urethra

(E) Vagina

1. An outbreak of postsurgical wound infections caused by S.

aureus has occurred in the hospital. The infection control

team was asked to determine whether the organism could be

carried by one of the operating room personnel. Using your

knowledge of normal flora, which one of the following body

sites is the most likely location for this organism?

(A) Colon

(B) Gingival crevice

(C) Mouth

(D) Nose

(E) Throat