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Ch. 20 - Urinary and Reproductive System Infections
Norman-McKay- Microbiology: Basic and Clinical Principles 2nd Edition
Norman-McKay2nd EditionMicrobiology: Basic and Clinical PrinciplesISBN: 9780137661619Not the one you use?Change textbook
All textbooksNorman-McKay 2nd EditionCh. 20 - Urinary and Reproductive System InfectionsProblem 5
Chapter 20, Problem 5

How do lactobacilli limit infections in the vagina? Select all that apply.
a. They competitively exclude potential pathogens
b. They make hydrogen peroxide
c. They ferment fructose to make lactic acid
d. They lower the vaginal pH, which limits pathogen growth
e. They increase the rate of vaginal mucus secretion

Verified step by step guidance
1
Understand that lactobacilli are beneficial bacteria that help maintain vaginal health by creating an environment that is hostile to pathogens.
Recognize that lactobacilli competitively exclude potential pathogens by occupying adhesion sites on the vaginal epithelium, preventing harmful microbes from establishing themselves.
Know that lactobacilli produce hydrogen peroxide (H\_2O\_2), which has antimicrobial properties that inhibit the growth of many pathogens.
Recall that lactobacilli ferment sugars such as fructose to produce lactic acid, which lowers the vaginal pH.
Understand that the lowered vaginal pH (acidic environment) created by lactic acid production limits the growth of many pathogenic organisms, helping to prevent infections.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Competitive Exclusion by Lactobacilli

Lactobacilli occupy adhesion sites on vaginal epithelial cells, preventing harmful pathogens from attaching and colonizing. This competitive exclusion reduces the chance of infection by limiting space and nutrients available to pathogens.
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Enzyme Inhibition

Production of Antimicrobial Substances

Lactobacilli produce substances like hydrogen peroxide and lactic acid, which inhibit the growth of many pathogens. Hydrogen peroxide acts as a potent antimicrobial agent, while lactic acid lowers pH, creating an environment unfavorable for harmful microbes.
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Chemical Preservation of Perishable Products

Maintenance of Vaginal pH

By fermenting sugars such as fructose, lactobacilli produce lactic acid, which lowers the vaginal pH to around 3.8-4.5. This acidic environment suppresses the growth of many pathogenic bacteria and fungi, helping to maintain vaginal health.
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Related Practice
Textbook Question

A patient you are assessing reports an increase in vaginal discharge that has a foul odor, but she does not report other symptoms. The patient has been in a monogamous relationship for 3 years. Which of the following would be the most useful for this patient? Select all that apply.

a. Evaluate her urine for increased white blood cells

b. Perform a Gram stain on the vaginal discharge

c. Run a pregnancy test

d. Test for an STI

e. Perform a whiff test

627
views
Textbook Question

A patient you are assessing reports an increase in vaginal discharge that has a foul odor, but she does not report other symptoms. The patient has been in a monogamous relationship for 3 years. Which of the following would be the most useful for this patient? Select all that apply.

a. Evaluate her urine for increased white blood cells

b. Perform a Gram stain on the vaginal discharge

c. Run a pregnancy test

d. Test for an STI

e. Perform a whiff test

1191
views
Textbook Question

A male patient is complaining of frothy discharge and painful urination. After negative NAAT testing, you will most likely prescribe:

a. Penicillin

b. Tetracycline

c. A cephalosporin

d. Metronidazole

1125
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Textbook Question

Factors that contribute to vulvovaginal candidiasis include:

a. Low vaginal pH

b. High nitrates in urine

c. Increased blood bilirubin levels

d. Increased estrogen levels

e. Taking a fluconazole drug

1286
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Textbook Question

Patients can contract chlamydia more than once because:

a. It is so commonly antibiotic resistant

b. Long-term immunity is not established after infection

c. It hides in neurons and reactivates, lysing cells

d. It is sexually transmitted

e. All of the above apply

1288
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Textbook Question

You see a corkscrew-like bacterial cell under dark field microscopy. If the sample came from __________, it is likely __________.

a. Genital lesions, leptospirosis

b. Urine, gonorrhea

c. Urine, syphilis

d. Genital lesions, syphilis

e. Vaginal discharge, chlamydia

1351
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