Mastering Microbiology Homework Ch. 14

Which of the following would be considered a fomite?

an infected toy

infectious disease

disease directly caused by microorganisms and not by other means, for example genetic or degenerative diseases

Which of the following is an example of the symbiotic relationship known as mutualism?

ecoli within the large intestine

The following choices list several types of diseases, along with factors that may contribute to their emergence. Which disease and associated factor do NOT match?

emergence of avian influenza A (H5N1): use of antibiotics

Arboviruses

get their name because they are typically arthropod-borne viruses that remain in nature because of biological transmission between susceptible hosts by blood-feeding arthropods, such as mosquitoes.

Benefits of Koch's Postulates

- the steps are designed to systematically link a pathogen to a specific infectious disease -laboratory finding provides experimental evidence that support the germ theory of disease -healthy susceptible animals can be used as model organisms when testing many types of infections thus avoiding the unethical inoculation of healthy human hosts

What is meant by the term arbovirus?

-An arbovirus is an arthropod-borne virus. -An arbovirus is maintained in nature through biological transmission.

Which of the following statements BEST describe the conclusion(s) that can be drawn from this experiment?

-Microorganism X might not be linked to Floppy Ear disease, since the inoculated mouse remained healthy. -A laboratory mouse might not be an appropriate, susceptible host; an experiment with a laboratory rabbit may be needed.

What features of West Nile virus make it an emerging disease of special concern?

-West Nile virus is an arthropod-borne virus transmitted by mosquitoes. -West Nile virus has a high mortality rate in immunosuppressed humans and infects many species of birds in southern Europe, the Mediterranean basin, and North America. -West Nile virus is maintained in nature through biological transmission between susceptible hosts by blood-feeding arthropods.

Limitations of using Koch's postulates

-some infectious agents have specific growth requirements that prevent it from being artificially cultured in the laboratory -some pathogens cause several different diseases which makes it difficult to link one pathogen to one disease -different pathogens can produce the same signs and symptoms making it difficult to determine which microorganism is causing a disease

According to the animation, surgical infections account for what percentage of nosocomial infections?

20%

Which of the following would be an example of disease transmission via INDIRECT contact?

A student sneezes on her test booklet. The instructor grades it and catches her cold.

What type of nosocomial infection is likely to arise from intravenous catheterizations?

Bacteremia

Which of the following statements is true regarding hand washing?

Frequent and proper hand washing should be routinely done by patients and by healthcare workers, both prior to and after interaction.

Probable reasons for emerging infectious disease

Emerging infectious diseases are ones that are new or changing, have increased in incidence in the recent past, or show a potential to increase in the near future. Over half of known emerging infectious diseases are zoonotic, mainly of viral origin, and are likely to be vector-borne.

what is encephalitis, and why should this type of infection cause concern among health care professionals?

Encephalitis is an inflammation of the brain tissue. It is a concern to health care professionals because an infection in the brain means the virus has breached protective measures.

In the last segment of the animation, when does the first epidemic occur?

January of year three

Reasons for using Koch's postulates

Koch's postulates provides evidence that microorganisms cause infectious disease, which supports the germ theory of disease. Using a series of experimental steps, Koch's postulates systematically link a specific microbe to a specific infectious disease by using healthy, susceptible model organisms; as a result, healthy human subjects are not harmed. Such techniques have been key in determining the cause, or etiology, of many infectious diseases.

Role of diseased and healthy animals

Koch's postulates state that a pathogen must be isolated from a diseased animal and inoculated into a healthy, susceptible laboratory animal.

Role of growth media and microscope

Koch's postulates state that same pathogen must be isolated from the original (diseased) and inoculated (also, diseased) animals. The isolated pathogens are cultured on growth media and viewed using a microscope.

Which of the following statements concerning pathology, infection, and disease is true?

Pathology refers to the study of structural and functional changes that occur in the body as a result of a disease.

How can health care workers reduce the occurrence of nosocomial infections?

Practice more stringent aseptic techniques

What are Koch's postulates?

Robert Koch developed a series of experimental steps, now known as Koch's postulates, to systematically link a specific microbe to a specific infectious disease -the pathogen must be isolated from the inoculated animal and must be shown to be the original organism -the same pathogen must be present in every case of the disease -the pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal. -the pathogen must be isolated from the diseased host and grown in pure culture

Transmission of West Nile Virus

The West Nile virus is transmitted via mosquitoes in the genus Culex. These mosquitoes are able to survive the winter as adults in regions with a temperate climate. Humans are infected when they are bitten by a mosquito and the virus enters into their bloodstream.

In the sixth segment of the animation, why is the disease epidemic in North America?

The disease occurs at a higher rate than what would normally be expected in this region.

Expected prevalence of a disease is

the expected occurrence of a disease based on past observations.

Koch's postulates established criteria for proving that a specific organism causes a specific disease. Which of the following is NOT one of the criteria given by Koch's postulates?

The pathogen must be isolated from inoculated animals and must be different from the original organism.

Which of the following statements about the development of infectious diseases is correct?

The period of convalescence is the time during which the person regains health and fully recovers (back to the pre-disease state).

why did the students in Bill's virology class focus on finding the virus in the dead birds rather than collecting mosquitoes to examine?

The students tried to isolate and identify West Nile virus from birds because they are an amplifying host for the virus, making it more likely that the virus can be isolated from these animals.

Why are invasive procedures likely to increase the risk of nosocomial infections?

These procedures allow microbes from the skin to enter the bloodstream of the patient.

How can surgeons help to limit nosocomial infections?

They should perform surgeries and invasive procedures only when absolutely necessary.

Germ Theory of Disease

This theory state that microorganisms cause infectious diseases

Life cycle of West Nile virus

Viruses require a host for replication of new virus particles. In the case of West Nile virus, the virus is actually maintained through a bird-mosquito-bird cycle. Birds are the reservoir for the virus. The mosquito becomes infected when it ingests blood from an infected bird. The cycle continues when that infected mosquito then feeds on an uninfected bird and passes the pathogen to this new host. Some birds, such as house sparrows, can tolerate an extremely high viral load without dying. Others, such as crows and blue jays, are more susceptible to death from this pathogen.

Which of the following best describes why West Nile Virus is considered to be an emerging infectious disease?

West Nile virus outbreaks have increased in number and affected areas since 1937.

Which of the following would be considered a vector?

a fly carrying disease from fecal matter to food

How might a patient who is not being treated with an antibiotic still be exposed to an antibiotic?

antibiotics can be used in aerosols, thereby entering the environment

When aerosols containing pathogens spread disease from a distance of less than one meter, it is considered

contact transmission

Which of the following is considered a major category of transmission of disease?

contact, vehicle, and vector transmission

If a disease occurs at a fairly stable rate, it is said to be

endemic

Malaria is an infectious disease caused by infection with a protozoan. In certain tropical regions, malaria is constantly present. We would say that malaria is a(n) _________ disease in these regions.

endemic

Koch's Postulates

experimental requirements for identifying the agent of an infectious disease

In the last segment of the animation, how many regions of the world experience the pandemic during April of year four?

five

Which of the following is the best mode of controlling the spread of West Nile infections?

limit exposure to mosquitoes to prevent the transmission of West Nile virus.

growth media

nutrient-rich environment for isolating and culturing microorganisms

pandemic

occurs when a disease is epidemic on more than one continent at the same time, the disease goes world wide

What is an emerging infectious disease?

one that is new or changing, has increased in incidence in the recent past, or shows a potential to increase in the near future. It can be caused by a helminth, protozoan, fungus, bacterium, or virus. Vector-borne viral infections account for around 75% of emerging infectious diseases.

Healthy Laboratory animal

organism injected with a potential infectious agent

Diseased or dead animal

original source of the infectious microbial agent

Which of the following is a fungal zoonosis that can be transmitted by direct contact?

ringworm

Which of the following is classified as a latent disease?

shingles

The health of the patient

should be the primary concern of the healthcare worker.

Which of the following characteristics of a catheter should be considered, to help minimize the spread of nosocomial infections?

single use

Koch's 3rd postulate

the pathogen from the pure culture must cause the disease when it it inoculated into a healthy susceptible laboratory animal

Koch's 2nd postulate

the pathogen must be isolated from the diseased host and grown in pure culture

Koch's 4th postulate

the pathogen must be isolated from the inoculated animal and must be shown to be the original organism

which is an example of vehicle disease transmission

the presence of Listeria on under cooked chicken served for dinner

Koch's first postulate

the same pathogen must be present in every case of the disease

Etiology

the study of the cause of a disease

If a patient notices a healthcare worker not following suggested precautions,

they should immediately bring it to the attention of the healthcare worker

What is the role of epidemiology?

to learn how to treat and prevent various diseases

microscope

tool used to view and identify individual microorganisms

what is the MOST important thing I can do to avoid this?

wash hands before interacting with any patient

Epidemiology is defined as the study of

where and when a disease occurs and how it is transmitted