Ch. 14 Study Questions

Indicate whether each of the following conditions is typical of subacute, chronic, or acute infections. a. The patient experiences a rapid onset of malaise; symptoms last 5 days. b. The patient experiences cough and breathing difficulty for months. c. The patient has no apparent symptoms and is a known carrier.

a. Acute b. Chronic c. Subacute

A Maryland woman was hospitalized with dehydration; Vibrio cholerae and Plesiomonas shigelloides were isolated from the patient. She had neither traveled outside the United States nor eaten raw shellfish during the preceding month. She had attended a party 2 days before her hospitalization. Two other people at the party had acute diarrheal illness and elevated levels of serum antibodies against Vibrio. Everyone at the party ate crabs and rice pudding with coconut milk. Crabs left over from this party were served at a second party. One of the 20 people at the second party had onset of mild diarrhea; specimens from 14 of these people were negative for vibriocidal antibodies. This is an example of a. vehicle transmission. b. airborne transmission. c. transmission by fomites. d. direct contact transmission. e. healthcare-associated transmission.

A

On September 6, a 6-year-old boy experienced fever, chills, and vomiting. On September 7, he was hospitalized with diarrhea and swollen lymph nodes under both arms. On September 3, the boy had been scratched and bitten by a cat. The cat was found dead on September 5, and Yersinia pestis was isolated from the cat. Chloramphenicol was administered to the boy from September 7, when Y. pestis was isolated from him. On September 17, the boy's temperature returned to normal; and on September 22, he was released from the hospital. Identify the incubation period for this case of bubonic plague. a. September 3-5. b. September 3-6. c. September 6-7. d. September 6-17.

A

The emergence of new infectious diseases is probably due to all of the following except a. the need of bacteria to cause disease. b. the ability of humans to travel by air. c. changing environments (e.g., flood, drought, pollution). d. a pathogen crossing the species barrier. e. the increasing human population.

A

Which of the following statements is false? a. E. coli never causes disease. b. E. coli provides vitamin K for its host. c. E. coli often exists in a mutualistic relationship with humans. d. E. coli gets nutrients from intestinal contents.

A

Differentiate the terms communicable disease and noncommunicable disease

A communicable disease is a disease that is spread from one host to another, whereas a noncommunicable disease is not transmitted from one host to another.

All members of a group of ornithologists studying barn owls in the wild have had salmonellosis (Salmonella gastroenteritis). One birder is experiencing her third infection. What is the most likely source of their infections? a. The ornithologists are eating the same food. b. They are contaminating their hands while handling the owls and nests. c. One of the workers is a Salmonella carrier. d. Their drinking water is contaminated.

B

A Maryland woman was hospitalized with dehydration; Vibrio cholerae and Plesiomonas shigelloides were isolated from the patient. She had neither traveled outside the United States nor eaten raw shellfish during the preceding month. She had attended a party 2 days before her hospitalization. Two other people at the party had acute diarrheal illness and elevated levels of serum antibodies against Vibrio. Everyone at the party ate crabs and rice pudding with coconut milk. Crabs left over from this party were served at a second party. One of the 20 people at the second party had onset of mild diarrhea; specimens from 14 of these people were negative for vibriocidal antibodies. The etiologic agent of the disease is a. Plesiomonas shigelloides. b. crabs. c. rice. d. Vibrio cholerae.

C

On September 6, a 6-year-old boy experienced fever, chills, and vomiting. On September 7, he was hospitalized with diarrhea and swollen lymph nodes under both arms. On September 3, the boy had been scratched and bitten by a cat. The cat was found dead on September 5, and Yersinia pestis was isolated from the cat. Chloramphenicol was administered to the boy from September 7, when Y. pestis was isolated from him. On September 17, the boy's temperature returned to normal; and on September 22, he was released from the hospital. Identify the prodromal period for this disease. a. September 3-5. b. September 3-6. c. September 6-7. d. September 6-17.

C

Distinguish symptoms from signs as signals of disease.

Changes in body function that the patient feels are called symptoms. Symptoms such as weakness or pain are not measurable by a physician. Objective changes that the physician can observe and measure are called signs.

Differentiate commensalism, mutualism, and parasitism, and give an example of each.

Commensalism—one of the organisms benefits and the other is unaffected; e.g., corynebacteria living on the surface of the eye. Mutualism—both organisms benefit; e.g., E. coli receives nutrients and a constant temperature in the large intestine and produces vitamin K and certain B vitamins that are useful for the human host. Parasitism—one organism benefits while the other is harmed; e.g., Salmonella enterica receives nutrients and warmth in the large intestine, and the human host experiences gastroenteritis or typhoid fever.

Which of the following is not one of Koch's postulates? a. The same pathogen must be present in every case of the disease. b. The pathogen must be isolated and grown in pure culture from the diseased host. c. The pathogen from pure culture must cause the disease when inoculated into a healthy, susceptible laboratory animal. d. The disease must be transmitted from a diseased animal to a healthy, susceptible animal by direct contact. e. The pathogen must be isolated in pure culture from an experimentally infected lab animal.

D

Which one of the following diseases is not correctly matched to its reservoir? a. influenza— animal b. rabies—animal c. botulism—nonliving d. anthrax—nonliving e. toxoplasmosis—cats

D

This microbe is acquired by humans as infants and is essential for good health. Acquiring a closely related strain causes severe stomach cramps, bloody diarrhea, and vomiting. What is the microbe?

E. Coli

Differentiate the terms etiology and pathogenesis

Etiology is the study of the cause of a disease, whereas pathogenesis is the manner in which the disease develops.

Put the following in the correct order to describe the pattern of disease: period of convalescence, prodromal period, period of decline, incubation period, period of illness.

Incubation period, prodromal period, period of illness, period of decline (may be crisis), period of convalescence.

Of all the hospital patients with infections, one-third do not enter the hospital with an infection. How do they acquire these infections? What is the method of transmission of these infections? What is the reservoir of infection?

Hospital patients may be in a weakened condition and therefore predisposed to infection. Pathogenic microorganisms are generally transmitted to patients by contact and airborne transmission. The reservoirs of infection are the hospital staff, visitors, and other patients.

Differentiate the terms infection and disease

Infection refers to the colonization of the body by a microorganism. Disease is any change from a state of health. A disease may, but does not always, result from infection.

Why are some organisms that constitute the normal microbiota described as commensals, whereas others are described as mutualistic?

Mutualistic microorganisms are providing a chemical or environment that is essential for the host. Commensal organisms are not essential; another microorganism might serve the function as well.

Define symbiosis.

Symbiosis refers to unlike organisms living together.

How can a local infection become a systemic infection?

When microorganisms causing a local infection enter a blood or lymph vessel and are spread throughout the body, a systemic infection can result.