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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 7
Chapter 20, Problem 7

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

Verified step by step guidance
1
Step 1: Identify the symptoms described: frothy discharge and painful urination. These symptoms are commonly associated with infections caused by Trichomonas vaginalis, a protozoan parasite.
Step 2: Understand that NAAT (Nucleic Acid Amplification Test) is typically used to detect bacterial infections such as Chlamydia trachomatis and Neisseria gonorrhoeae. A negative NAAT suggests these bacterial infections are unlikely.
Step 3: Recognize that the treatment choice should target the most likely causative agent given the symptoms and negative bacterial test. Since Trichomonas is a protozoan, antibiotics like penicillin, tetracycline, or cephalosporins, which target bacteria, are not effective.
Step 4: Recall that metronidazole is the drug of choice for treating infections caused by anaerobic protozoa such as Trichomonas vaginalis.
Step 5: Conclude that based on the clinical presentation and test results, prescribing metronidazole is the most appropriate treatment.

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Key Concepts

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

Frothy Discharge and Painful Urination Symptoms

Frothy vaginal or urethral discharge combined with dysuria (painful urination) often indicates an infection caused by anaerobic protozoa or bacteria. These symptoms are characteristic of infections like Trichomoniasis, which is caused by the protozoan Trichomonas vaginalis, rather than typical bacterial STIs.
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Nucleic Acid Amplification Test (NAAT) and Its Limitations

NAAT is a highly sensitive molecular test used to detect bacterial pathogens such as Neisseria gonorrhoeae and Chlamydia trachomatis. A negative NAAT result suggests the absence of these common bacterial STIs, prompting consideration of other causes like protozoal infections that NAAT does not detect.
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Metronidazole as Treatment for Protozoal Infections

Metronidazole is an antibiotic effective against anaerobic bacteria and protozoa, including Trichomonas vaginalis. It is the drug of choice for treating trichomoniasis, which presents with frothy discharge and dysuria, especially when bacterial STI tests are negative.
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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

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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

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

1210
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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

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Textbook Question

Indicate if the statement is true or false and then correct each false statement so that it is true:

a. Sexually transmitted infections always affect the reproductive tract

b. CAUTIs are usually classified as uncomplicated UTIs

c. Candida species are the leading cause of uncomplicated UTIs

d. Syphilis can be vertically transmitted from a mother to her fetus

e. Herpes simplex virus 2 can be transmitted to a partner without intercourse

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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

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