Question 1

Which of the following best describes the role of normal microbiota in the human body?

Accepted Answer

They inhibit pathogenic microbes from colonizing the host through microbial antagonism.

Question 2

A urine sample is collected using the 'clean catch' method. Why is it important to process the sample immediately?

Accepted Answer

To avoid overgrowth of normal microbiota, which can result in false positive results.

Question 3

Which organism is the primary culprit in urinary tract infections (UTIs)?

Accepted Answer

Escherichia coli

Question 4

A patient presents with symptoms of a UTI. The dipstick test is positive for esterase and nitrate reductase. What is the next step in diagnosis?

Accepted Answer

Culture a urine specimen for the presence of bacteria.

Question 5

Which of the following is TRUE regarding the colonization of skin and throat by bacteria?

Accepted Answer

Surface tissues such as skin and throat are in continuous contact with environmental microbes.

Question 6

Which genus includes fastidious organisms that require special media for growth and can be found as normal microbiota in the throat?

Accepted Answer

Neisseria

Question 7

A urine sample is streaked onto a nutrient agar plate using a sterile 10 μl calibrated loop. After incubation, 50 colonies are counted. Calculate the number of CFU/ml in the original urine sample.

Accepted Answer

$$CFU/ml = \frac{50}{0.001} = 50000$$

Question 8

Which of the following best defines transient microbiota?

Accepted Answer

Microbes that are present for only a short time before disappearing.

Question 9

Which species is commonly found in drier areas of the skin and is considered part of the normal skin microbiota?

Accepted Answer

Staphylococcus epidermidis

Question 10

A urine culture from a clean catch sample shows $$1 	imes 10^4$ CFU/ml. The patient presents with mild symptoms. What does this result most likely indicate?

Accepted Answer

Possible early phase of UTI, as recent studies suggest lower counts may be significant.

Question 11

Which of the following is NOT a common cause of urinary tract infections?

Accepted Answer

Staphylococcus epidermidis

Question 12

Why are different types of media used to culture human microbiota from various body sites?

Accepted Answer

Because bacteria colonize different niches due to variations in moisture, pH, and secretions.

Question 13

Which of the following best describes the HardyCHROM™ UTI agar?

Accepted Answer

A selective and differential medium used to tentatively identify specific organisms in urine.

Question 14

Which of the following is a correct statement about Staphylococcus aureus?

Accepted Answer

It is widely known as a troublesome opportunistic pathogen.

Question 15

A patient’s urine sample is cultured and shows multiple colony types on HardyCHROM™ UTI agar. What does this most likely indicate?

Accepted Answer

There are multiple types of bacteria present, possibly indicating contamination or polymicrobial infection.

Question 16

Which of the following is TRUE regarding Neisseria meningitidis?

Accepted Answer

It can be found in approximately 20-40% of young adults as a normal resident of the nasopharynx.

Question 17

Which equation correctly calculates the number of CFU/ml from a urine sample using a 0.01 ml calibrated loop?

Accepted Answer

$$CFU/ml = \frac{	ext{Number of colonies}}{0.01}$$

Question 18

Which of the following is a correct definition of cystitis?

Accepted Answer

An infection involving the bladder.

Question 19

Which of the following procedures is LEAST likely to introduce contamination when collecting a urine specimen?

Accepted Answer

Collecting a midstream sample after cleansing the external genitalia.

Question 20

Which of the following statements about Streptococcus pyogenes is correct?

Accepted Answer

It is found in approximately 5-15% of individuals as part of the normal throat microbiota.

Normal Microbiota and Cultivation of Urine Specimens: Microbiology Lab Study Notes

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