Question 1

Microarrays,hybridization tests,and ribotyping are increasing in frequency in their use in clinical labs for diagnosis of infectious diseases and the microorganisms causing them.Why is this?

Accepted Answer

The answer of Microarrays,hybridization tests,and ribotyping are increasing in frequency...

Question 2

Staphylococcus aureus can be identified by mixing the organism with specific antibody and visually recognizing a clumping reaction between the antigen and the antibody.This is a(n)_______ test.

Accepted Answer

The description provided suggests an agglutination test, which involves seeing a clumping reaction between an antigen and a specific antibody. Microarray and ELISA tests are not based on clumping, but rather involve binding or detection of molecules. Biochemical tests typically involve measuring enzymatic activity or metabolic pathways, which is not described in the question stem.

Question 3

The difference between presumptive and confirmatory data in specimen identification is that

Accepted Answer

Presumptive data provides a preliminary identification, usually to the genus level, while confirmatory data provides a specific identification of the species. Therefore, option A accurately describes the difference between presumptive and confirmatory data in specimen identification. Option B is incorrect as presumptive data is not an educated guess, but rather a preliminary identification based on specific tests. Option C is also incorrect as presumptive data is only an initial identification and may not be fully accurate until confirmatory testing is done. Option D is also incorrect as it provides the opposite of what is true since presumptive data usually only identifies the genus, not the species.

Question 4

You have a very sore throat with symptoms indicating strep throat.Since you are taking microbiology right now,you decide that you will take a swab from your throat and swab it onto an enrichment medium like a blood agar plate or a brain-heart infusion agar plate.Why is this not a good idea?
A. Due to the fact that you cannot easily see the sampling site, there is a high probability that you will not be able to obtain your own specimen without contaminating the sample with your own normal biota.
B. You are on a diet now, and you are afraid that the food that you are eating will in some way impact the growth of the bacteria. As a result, you will not get valid results.
C. You use a mouthwash a couple of times a day, so you think that the antibacterial properties of the mouthwash will inhibit or kill the oral bacteria and results in invalid results.
D. All of these statements are correct.

Accepted Answer

The answer of You have a very sore throat with...

Question 5

You are the supervisor of a new reference microbiology laboratory,which will receive clinical specimens for identification of bacterial pathogens.When choosing the types of media to order for culture and isolation procedures in your laboratory,what question(s)do you need to answer?

Accepted Answer

All of the questions listed are important considerations when choosing the types of media to use in a new microbiology laboratory. The types of bacteria that will be cultured and the growth factors required will determine the types of specialized media that may be needed, while knowledge of the microbiota in patient specimens can help guide the selection of general purpose media.

Question 6

Scanning the whole genome of every infectious agent in a patient sample and comparing that to known genome sequences maintained in libraries would be the most accurate and efficient way to diagnose disease.We are moving closer to this becoming a reality largely because

Accepted Answer

The cost of high throughput genetic analysis has decreased in recent years, making it more feasible to scan entire genomes for infectious agents. This has helped to move us closer to the reality of using this method for disease diagnosis. A, B, and C are not accurate reasons for why this method is becoming more feasible.

Question 7

Nucleic acid testing is appropriate as a testing method when one is not sure what microorganisms are present in the specimen.

Accepted Answer

Nucleic acid testing allows for the identification of specific genetic material in the specimen, which can help determine the presence of certain microorganisms. This is useful when the identity of the microorganism is unknown.

Question 8

You would like to identify as many bacterial species as possible in the human mouth. Why is biochemical testing not the most efficient and accurate method of completing this task?

Accepted Answer

Biochemical testing relies on the growth characteristics and metabolic properties of bacteria, so if you do not know these properties, you will not be able to accurately identify all bacterial species present in the human mouth. Additionally, since there are many different types of media required to identify all bacterial species, it would be cost-prohibitive to use this method.

Question 9

You place an inoculum of your bacterium on a glass slide and add a drop of hydrogen peroxide reagent.Promptly you see bubbles appear,indicating the presence of a particular enzyme that the bacterium produces.What type of identification test does this exemplify?

Accepted Answer

This exemplifies a biochemical test, as it involves adding a reagent to detect the presence of a specific enzyme produced by the bacterium.

Question 10

A method of identification using immobilized,known antigens to identify unknown antibodies and vice versa,where the presence of the agent being tested for immediately brings about a color change is called ______.

Accepted Answer

The method described is immunochromatography, in which the unknown antibody or antigen is tested against immobilized known antigens or antibodies, respectively. If the target molecule is present, it will bind to the immobilized molecule, causing a visible color change. ELISA and Western blotting also use immobilized antigens, but do not necessarily produce an immediate color change in the presence of the target. Radioimmunoassay uses radioisotopes to detect the presence of the target molecule.

Question 11

Which of these tests is an in vivo test?

Accepted Answer

An in vivo test is a test that is performed within a living organism. The tuberculin test is a type of in vivo test used to diagnose tuberculosis.

Question 12

Which statement about clinical identification tests is true?

Accepted Answer

Clinical tests cannot identify all diseases, as some diseases may not have specific diagnostic markers or may require more specialized testing methods.

Question 13

Technology has introduced a range of specific,rapid tests for identifying and diagnosing infectious disease.While culturing a pathogen from a patient is always advantageous,what disadvantage(s)exist for traditional diagnostic techniques?

Accepted Answer

All of the mentioned options are valid disadvantages of traditional diagnostic techniques. For example, culturing a pathogen may not always isolate the exact pathogen causing the disease, critically ill patients may have to wait several hours for a culture to grow, certain pathogens may not be cultured in vitro, and some diseases may be caused by more than one organism. Rapid diagnostic techniques can help overcome these limitations.

Question 14

Antibiotics are often added to biochemical media to restrict the growth to only those organisms that are being looked for in the specimens.

Accepted Answer

Antibiotics are commonly added to biochemical media in order to inhibit the growth of unwanted organisms and selectively cultivate the target organisms being studied.

Question 15

The polymerase chain reaction can be used for identification of

Accepted Answer

The polymerase chain reaction (PCR) is a technique used to amplify (or make many copies) of a small piece of DNA. This can be used for identification of microorganisms by specifically targeting and amplifying their unique genetic material. PCR can be used to detect pathogens, genetic mutations, and even identify different species of bacteria or viruses. PCR is not commonly used for identification of antibodies, growth characteristics of microorganisms, or proteins.

Question 16

Microarrays are a powerful diagnostic tool because

Accepted Answer

Microarrays can simultaneously test for thousands of suspected pathogens in a single patient sample, making it a powerful diagnostic tool. Ribosomal RNA sequencing (A) and PCR analysis (B) can also be useful diagnostic tools, but they do not have the same high-throughput capabilities as microarrays. Analysis of a pathogen's genome (C) can also provide useful information for diagnosis, but it may be more time-consuming and expensive than microarray analysis.

Question 17

Phenotypic testing is often beneficial in identifying infectious agents from patient samples; however,some disadvantages include

Accepted Answer

Phenotypic testing can be time-consuming, with lengthy culturing times and the inability to grow some bacteria in vitro being major disadvantages. These issues can delay diagnosis and treatment of infections. There are also limitations in the identification of certain organisms using traditional biochemical tests, making it necessary to use additional testing methods for confirmation. However, it is still a useful method for identifying many infectious agents.

Question 18

In your microbiology lab,your class is identifying bacteria.You are using dichotomous keys to aid in the identification process using the data from a variety of biochemical tests.What problems do you foresee in this procedure?

Accepted Answer

The main problem with using dichotomous keys for identification is human error. If you misread or record a result incorrectly, it can lead you to an incorrect identification. Therefore, it is important to be very careful and precise when conducting the biochemical tests and using the dichotomous key. A and C are not accurate as dichotomous keys are a valid form of identification and the simplicity of the key actually makes it easier to use. D is not accurate as the dichotomous key should contain information on a variety of bacteria.

Question 19

If you were going to identify microorganisms within a specimen containing large numbers of organisms (seawater,normal microbiota,etc.),you would have to

Accepted Answer

Amplifying gene sequences within the sample using techniques such as polymerase chain reaction (PCR) would allow for the identification of each of the different organisms within the specimen, even if it contains a large number of different microorganisms. This method can target specific genes or regions of DNA that are unique to each microorganism, allowing for rapid and accurate identification. The other options listed may not be as effective for identifying all of the microorganisms in the specimen.

Question 20

Which test cannot be used for identification of a person's HIV status?

Accepted Answer

Biochemical tests cannot be used for identification of a person's HIV status as they do not detect the presence of specific antibodies or antigens. Immunochromatographic testing, Western Blot, and ELISA are commonly used tests for detecting HIV antibodies or antigens in a person's blood.

Quiz 17: Diagnosing Infections