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Answers to Questions in the Book, Chapter 5, Infection
Answers to Exercises in Book: Stop and Consider Questions and Practice Exam Questions Short Answer (Stop and Consider Questions)
1. What aspects of bacteria would be effective targets for pharmacologic treatment?
Answer: Disruption of cell wall synthesis is the most common antibacterial target.
2. Why are antiviral drugs difficult to develop and use effectively?
Answer: The virus uses the host machinery for metabolism and reproduction; therefore, targeting and destroying the virus would also destroy the host cell.
3. What sources of infection would not be considered communicable?
Answer: Some microorganisms can live outside of the human host and can therefore reproduce on foods, in water, and on other environmental surfaces. Also, many microorganisms are considered resident flora and live on the surface of nonsterile areas of the body and only become pathogenic when the three lines of defense are disrupted or when the resident flora becomes imbalanced, such as with prolonged antibiotic treatment.
4. How can you break the chain of infection at each of the different modes of transmission?
Answer: Direct contact: avoid touching, kissing, or otherwise coming in contact with reservoir. Droplet transmission: wearing gloves, gown, and mask to prevent droplet spread of infection. Airborne transmission: avoid breathing same air as reservoir, appropriate room ventilation. Vector transmission: avoiding contact with vectors, wearing repellent, and avoiding foods that are contaminated.
5. What is the role of bile and why is obstruction of bile flow problematic?
Answer: Bile contains bile salts, cholesterol, bilirubin, electrolytes, and water. Bile is needed for fat emulsification and absorption. Damage to hepatocytes therefore inhibits bile production and can affect fat absorption causing problems with altered nutrition and bowel elimination.
6. Compare fulminant hepatitis and cirrhosis to general infection complications
(septicemia and chronic infection). Answer: Fulminant hepatitis and septicemia both represent severe acute manifestations of infection; cirrhosis is representative of a complication of chronic infection. Multiple Choice (Practice Exam Questions)
1. You are looking to break the chain of infection by washing your hands frequently
as you provide care for patients. Which of the following links in the chain will be broken by this activity? a. Reservoir b. Host c. Portal of entry d. Mode of transmission Answer: d
2. Which of the following may make a person more susceptible to getting an infection?
a. Age between 6 and 46 years b. Experiencing a surgery that is healing by primary intention c. Final examinations week d. A functioning immune system
6. Given the mode of transmission for influenza, how would you break the chain of
infection and prevent spread?
a. Administer antibiotics as directed.
b. Wash hands after toileting.
c. Disinfect table surfaces in the room.
d. Wear a mask.
Answer: d
7. Which of the following diagnostic tests would give information to the presence of a
carrier-state asymptomatic hepatitis B infection?
a. Hepatitis B surface antigen (HBsAg).
b. Hepatitis B core antigen (HBcAg).
c. Prothrombin time (PTT).
d. There is no way to distinguish the different forms of hepatitis B.
Answer: a
8. What is the most likely complication of an untreated UTI?
a. Glomerulonephritis
b. Pyelonephritis
c. Fulminant UTI
d. Urethritis
Answer: b
9. Treatment for tinea unguium must include:
a. oral antifungals.
b. topical antifungals.
c. both topical and oral antifungals.
d. nail removal and topical antifungals.
Answer: a
10. Which of the following scenarios is most likely in the CSF of a patient with
bacterial meningitis?
a. CSF has high neutrophil count and high protein count.
b. CSF has high neutrophil count and low protein count.
c. CSF has high glucose level and high red blood cell count.
d. CSF has high lymphocyte count and low red blood cell count.
Answer: a
11. Which of the following is an important characteristic of M. tuberculosis (the microbe
that causes TB) and helps to explain its pathogenesis?
a. It is a large and fast growing microbe.
b. It produces toxins, and these toxins destroy lung tissue.
c. It is resistant to destruction and can sit dormant for years.
d. It cannot be detected or diagnosed until the disease is well advanced.
Answer: c
12. An important aspect of infection is prevention. Which of the following would be an
effective prevention measure for malaria?
a. Antibiotics
b. Avoiding international travel
c. Handwashing
d. Wearing long sleeves, pants, and a hat with face netting
Answer: d
c. They provide a type of natural immunity.
d. The do not compete with disease-producing microorganisms.
Answer: d
2. Which best describes why yeast infections are common in women on antibiotics?
a. Yeast grows well when exposed to the sugar, which is found as a carrier
substance in most antibiotics.
b. Destroying one type of resident flora (bacteria) can allow overproliferation of
another competing type (yeast).
c. Yeast prefer a warm, moist, dark environment, such as that present in the
female perineum.
d. Antibiotics allow yeast to access sterile environments in the body.
Answer: b
3. All of the following describe communicable disease except:
a. all infectious diseases are communicable.
b. communicable diseases are spread from person to person.
c. blood is a common carrier for communicable diseases.
d. communicable diseases are caused by infections that live and reproduce in a human
host. Answer: a
4. Which characteristic explains why some pathogens do not cause disease in humans?
a. Receptor binding
b. Pathogenicity
c. Invasiveness
d. Potency
Answer: a
5. Which is not a mechanism by which a pathogen causes disease in humans?
a. Direct destruction of the host cell
b. Interference with the host cell’s metabolic function
c. Attack of the pathogen by the host cells immune cells
d. Exposure of the host cell to toxins
Answer: c
6. Disruption of the cell wall of a bacterium by antibacterial drugs will interrupt:
a. protein and DNA synthesis.
b. phagocytosis.
c. motility.
d. adherence.
Answer: a
7. A specific type of gram-negative bacteria contains endotoxin in the bacterial cell
envelope. What is the likely clinical manifestation if these bacteria become pathogenic?
a. Constipation
b. Leukopenia
c. Fever
d. Vomiting
Answer: c
8. Which best explains why some viruses are capable of eliciting a chronic infection in the
Answer: a
12. You are diagnosed with strep pharyngitis and are prescribed an antibiotic. You are
instructed to take the antibiotic three times a day for 10 days. After the 4th day, you are feeling pretty good and decide that you do not need to finish the medication. What is the likely complication to result from this practice?
a. Septicemia
b. Bacteremia
c. Septic shock
d. Chronic infection
Answer: d
13. Your mother has a clinic appointment for a possible infection and is told that she has
a high neutrophil count. This implies:
a. she has a streptococcal infection.
b. she has an acute infection.
c. she has a chronic infection.
d. she does not have an infection.
Answer: b
14. You believe that you have “athlete’s foot” because you have burning and itching along
with redness between your toes. You look in your bathroom drawer where all of your medications are kept. You pull out the antibiotic ointment and apply this to the reddened areas. After 3 days of application, you have noticed no improvement. Why is this medicine not working?
a. Topical medications usually take at least 7 days to be effective.
b. Antibacterial medications are not effective against fungi.
c. This type of infection requires oral antibiotics.
d. You are probably immunocompromised.
Answer: b
15. Your roommate has influenza. All of the following are appropriate measures to
avoid this infection except:
a. immunization.
b. sterilization.
c. frequent handwashing.
d. avoid close contact with roommate.
Answer: b
16. This is a process by which influenza viruses are well adapted to escape host
defenses and gradually change genetic composition during replication in the human host cell:
a. reassortment.
b. receptor binding.
c. vaccination.
d. trivalence.
Answer: a
17. Who is at greatest risk of significant morbidity and mortality with influenza infection?
a. Pregnant women
b. The elderly
c. School-age children
21. A patient arrives to the clinic for evaluation. The clinician reports that the patient is
experiencing acute hepatitis. The patient is visibly jaundiced and reports dark urine and clay- colored stools. The liver is enlarged and tender. Which phase of acute hepatitis does this represent?
a. Prodrome
b. Icterus
c. Recovery
d. Incubation
Answer: b
22. Which lab test would confirm the presence of acute hepatitis B in the previous question?
a. Positive anti-HBc
b. Positive anti-Hbe
c. Positive anti-Hbs
d. Elevated serum bilirubin levels
Answer: a
23. Which of the following explains why a low-fat diet is recommended for those with
hepatitis?
a. Fat emulsification and absorption and bile production may be impaired during liver
disease.
b. Weight gain will exacerbate hepatocyte destruction.
c. Those with hepatitis are more vulnerable to the development of atherosclerosis.
d. Ascites, a complication of liver disease, can be alleviated with moderate weight loss.
Answer: a
24. Urinary tract infection and pelvic inflammatory disease share which characteristic?
a. Exclusive to females.
b. Ascending infections.
c. Most commonly cause by E. coli.
d. Pyuria is present in both.
Answer: b
25. Which of the following is characteristic of tinea versicolor?
a. Presents as hypopigmented patches
b. Leads to hair loss and breakage at the site of infection
c. Spreads circumferentially like a reddened bull’s-eye
d. Leads to thickened, discolored, and dystrophic changes to the nails
Answer: a Short Answer
26. Describe the difference between droplet and airborne transmission.
Answer: With droplet transmission, larger respiratory particles, produced by sneezing, coughing, or talking, can pass through the air from the reservoir to the host. In order for droplet transmission to occur, the host must be within three feet of the reservoir. The heavy droplet particles drop to the ground beyond this distance. Most respiratory illnesses are spread through droplet transmission. With airborne transmission, smaller respiratory particles can remain suspended in the air and are subject to airborne transmission. The particles can remain in the area of the reservoir for an extended period of time. Infection can be transmitted to a person entering this area and breathing the air.
You are reading your local newspaper and notice that there has been an outbreak of hepatitis A in a metro city about 75 miles from your home. The reported incidence is 100 per 100,000 population. Health officials have tracked the source to contaminated water from a series of connected lakes throughout that metro area.
1. How did the people in this community contract hepatitis A? How long was the time
between contact with the virus and the development of symptoms for these people? Is this an acute or chronic infection? Answer: Fecal–oral transmission is a problem of hand contact with infected feces, transmitting the virus to another when coming in contact with the oral mucosa. The contaminated water source harbored the pathogen, where it was then consumed or placed in contact with oral mucosa of individuals in and around the lakes. The incubation of hepatitis A is 1 to 2 months. It is an acute infection and does not typically display a carrier or chronic state.
2. What signs and symptoms are likely to present in those infected with hepatitis A?
Answer: Fatigue, anorexia, malaise, headache, and low-grade fever lasting about 2 weeks. Jaundice, dark urine, and clay-colored stools (icterus) lasting about 2 to 6 weeks follow this prodrome. The liver is enlarged and tender. Recovery is identified by the resolution of jaundice around 8 weeks after the initial exposure to the virus. Signs and symptoms improve with the exception of the liver, which remains enlarged and tender for an additional 1 to 4 weeks.
3. How would those infected individuals be diagnosed?
Answer: Presence of anti-HAV antibodies. Other tests that may aid in diagnosis and prognosis include the detection of bilirubin in the urine, elevated serum bilirubin levels (>30 mg/dL indicates more severe disease), and prolonged clotting time (a grave finding indicating impaired liver function).
4. What treatment strategies need to be employed?
Answer: Treatment of acute viral hepatitis, as with other viral infections, is symptomatic. Fluids, rest, and analgesics are recommended, particularly during the icteric phase of illness. Avoidance of strenuous physical activity or contact sports is often recommended due to liver enlargement. Since bile helps with fat emulsification and absorption and bile production may be impaired during liver disease, a low-fat diet is recommended. Avoidance of transmission to others is critical through careful handwashing, avoidance of contact with infected fecal material, and avoidance of contact with blood and body fluids where appropriate. The contaminated water sources need to be avoided until water testing no longer exhibits the presence of hepatitis A. Reference Case Study 4 (instructor resource only; not in text) Elizabeth is a 16-year-old Caucasian female who is a goalie on her high school soccer team. On October 15th, 2 days after a conference soccer match, she complained to her mother of not feeling well. She reported that she had nasal congestion, coughing, a low- grade fever, and a mild headache. Two days later, Elizabeth needed to stay home from school because her symptoms continued to get worse and progressed to a severe headache, photophobia, and a stiff neck. Her low-grade fever and poor appetite continued. On October 19th, her mother took her into the emergency room, concerned that her symptoms were just getting worse and that Elizabeth may have a brain tumor. She underwent blood and cerebrospinal fluid analyses. Her lymphocyte count was elevated; cerebrospinal fluid was negative (it did not contain bacteria or glucose). Physical examination was significant for positive Kernig and Brudzinski signs. She is diagnosed with aseptic meningitis.
1. What is the most likely source of this viral infection?
