Question

Microbial Growth and Urinary Tract Infections

Discouraging Growth

Read this case file, and complete the activities that follow.

Twenty-five-year-old Lisa visited the doctor’s office where I work, complaining of symptoms of a urinary tract infection. Her symptoms included burning discomfort during urination and increased frequency of urination. Lisa has had numerous infections of the urinary tract within the past year for which she had been prescribed antibiotics. Although the antibiotics cleared up the infections quickly, Lisa was frustrated with the frequency of her uncomfortable urinary symptoms. Lisa asked me how she could prevent urinary tract infections in the future. “Well,” I said. “There are a few things you can do to decrease the number of infections you’ve been having. The first is to make sure that you are drinking plenty of water. Another thing you can do is drink cranberry juice daily. There are chemicals in cranberry juice that block the attachment of bacteria to the urinary tract. I’ve also read that the juice will help to create a more acidic environment in your bladder and will hopefully discourage the growth of bacteria."

Environmental factors influence the ability of microbes to survive and flourish. The body is normally maintained in a narrow pH range. Secretion of alkaline or acidic urine via the kidneys is one of the mechanisms used by the body to maintain normal pH. Most bacteria involved in UTIs (urinary tract infections) make the urine more alkaline by splitting urea into ammonia and other alkaline products. Cranberry juice keeps the urine acidic, making urine a less hospitable environment to bacteria attempting to gain a foothold in the bladder. Temperature is another environmental factor that influences microbial growth. Fever is thought to be the body’s natural response to invasion by bacteria, or the body’s way of making the internal environment less favorable for the growth of bacteria. Fever raises the core body temperature as much as 2°C to 3°C above normal. Some bacteria cannot tolerate higher temperatures, preferring a lower body temperature to multiply.

1. In the case, the patient is treated with antibiotics for her UTIs. Which type of organism must the physician suspect is causing her infections?

• Bacterium

• Virus

• Fungus

• Prion

2. The physician suggests that Lisa consume cranberry juice to prevent her recurrent UTIs, due to the fact that the juice makes the urinary tract more ______.

• alkaline

• basic

• acidic

• mucoid

3. The physician informs Lisa that cranberry juice appears to reduce the ability of microbes to attach to the urinary tract. Which structures are used for attachment in microbes causing UTIs?

• Cilia

• Fimbriae

• Endospores

• Pseudopods

4. Most bacteria associated with UTIs make the urine more _______, creating an environment favorable for their growth.

• viscous

• alkaline

• mucoid

• acidic

5. Which of the following signs in the patient would indicate that their body is fighting the microbes causing the UTI?

• Pain in the bladder

• Elevated respiratory rate

• Fever of 102 degrees Fahrenheit

• Low blood pressure

Answer 1

1. In the case, the patient is treated with antibiotics for her UTIs. Which type of organism must the physician suspect is causing her infections?

Ans) Bacterium

2. The physician suggests that Lisa consume cranberry juice to prevent her recurrent UTIs, due to the fact that the juice makes the urinary tract more ______

Ans) acidic

Explanation- The cranberry juice changes the thermodynamic properties of bacteria in the urinary tract, creating an energy barrier preventing bacteria to cause infections.

3. The physician informs Lisa that cranberry juice appears to reduce the ability of microbes to attach to the urinary tract. Which structures are used for attachment in microbes causing UTIs

Ans) fimbriae

Explanation- fimbriae are present on most of the bacteria, including those in the urinary tract, which helps them to attach.

4. Most bacteria associated with UTIs make the urine more _______, creating an environment favorable for their growth.

Ans) alkaline

Explanation-Most bacteria involved in UTIs (urinary tract infections) make the urine more alkaline by splitting urea into ammonia and other alkaline products.

5. Which of the following signs in the patient would indicate that their body is fighting the microbes causing the UTI?

Ans) Fever of 102 degrees Fahrenheit

Explanation- Fever is thought to be the body’s natural response to invasion by bacteria, or the body’s way of making the internal environment less favorable for the growth of bacteria. Fever raises the core body temperature as much as 2°C to 3°C above normal. Some bacteria cannot tolerate higher temperatures, preferring a lower body temperature to multiply.

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