End of chapter questions Flashcards

Exam 1 (45 cards)

1
Q

Differentiate the role of pili from the role of flagella?

A

Pili, made up of pilin protein, aid in bacterial attachment to solid surfaces such as mucous membranes. Flagella, consisting of flagellin protein, are responsible for motility

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2
Q

What is the role of the capsule in the pathogenesis of infectious disease?

A

Capsules help microorganisms resist phagocytosis. Phagocytic cells are less able to bind to the capsular polysaccharide than they are to surface proteins. In addition, capsules hide antigens on the surface of bacteria, preventing them from interacting with antibodies produced by an animal in response to an infection

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3
Q

Why is lipopolysaccharide a significant outer-membrane structure in gram-negative bacteria?

A

LPS is also known as an endotoxin. This molecule is toxic to animals, inducing nonspecific effects such as fever, inflammation, hypotension, and shock. LPS contains three regions: an antigenic O-specific polysaccharide, a core polysaccharide, and an inner lipid A. The lipid A moiety is responsible for producing fever and shock conditions in patients infected with gram-negative bacteria.

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4
Q

A bacterium that grows only on plates incubated in the absence of oxygen would be categorized as an

A

obligate anaerobe

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5
Q

Fimbriae present on the outer surface of bacteria are used for

A

Adherence to surfaces

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6
Q

All of the following are characteristic of fermentation except:

It begins with the breakdown of pyruvic acid
It follows glycolysis and produces reduced nicotinamide adenine dinucleotide (NADH)
It produces acids, alcohols, and gases
It can occur in the presence of oxygen

A

It follows glycolysis and produces reduced nicotinamide adenine dinucleotide (NADH)

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7
Q

Why are older bacterial cells more easily decolorized than cells from younger colonies?

A

Older bacterial cells are decolorized more easily than younger cells, because as cells age their cell walls become “leaky” and allow molecules to pass more readily out of the cell. In the Gram stain, the crystal violet-iodine complex is more readily lost during the decolorization step

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8
Q

Why are spore-forming organisms more resistant than non-spore-forming species?

A

Bacterial spores have a thick protein coat that makes them highly resistant to chemical agents, temperature changes, dehydration, ultraviolet and gamma radiation, and desiccation. They are also metabolically inactive and can therefore survive periods of startvation

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9
Q

Explain the three ways in which genetic material can be transferred from one bacterium to another

A

The three ways in which genetic material may be transferred from one bacterium to another are transformation, transduction, and conjugation. Transformation is the uptake and incorporation of naked or free DNA into a bacterial cell. Transduction is the transfer of bacterial genes by a bacteriophage from one cell to another. Conjugation is the transfer of genetic material from a donor bacterial strain to a recipient strain. Conjugation requires close contact between the two cells

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10
Q

For the following DNA, write the complementary sequence. Include labeling the 3’ and 5’ end. 3’TTACGGACAAC 5’

A

3’ TTACGGACAAC 5’
5’ AATGCCTGTTG 3’

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11
Q

In RNA, thymine is replaced by

A

Uracil

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12
Q

In bacteriophage, how does lysogeny differ from the lytic cycle?

A

During lysigeny, phage DNA is inserted into the bacterial genome, but virus particles are not produced. When the bacterial cell replicates, the viral genome is copied along with the bacterial chromosome. During the lytic cycle, bacteriophages are produced until the bacterial cell dies and is lysed.

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13
Q

What is the difference between sterilization and disinfection?

A

Sterilization is a chemical or physical process resulting in the destruction of all living organisms. Disinfection can be either a physical or chemical method that reduces the number of viable cells

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14
Q

Explain situations in which you would use a disinfectant and an antiseptic

A

Disinfectant:
Clean surfaces

Antiseptics:
Hand washing

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15
Q

Describe the difference between physical and chemical methods of disinfection and sterilization

A

Physical methods involve heat (boiling water, autoclaving, pasteurization, dry heat). radiation (ionizing, nonionizing), and filtration (liquid, air). Chemical methods involve disinfectants and antiseptics. They include chemicals such as alcohols, aldehydes, halogens, chlorine, quaternary ammonium compounds, phenolics, heavy metals, and gases.

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16
Q

What method is required to kill endospores effectively

A

High-level disinfectants

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17
Q

List and describe factors that influence the degree of killing during disinfection and sterilization

A

Type of organisms
number of organisms
concentration of the disinfecting agent
presence of organic material
contact time
temperature
pH
biofilms

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18
Q

Explain EPA regulations on chemical surface disinfectants and FDA regulations on chemical skin antiseptics

A

Antimicrobial Division of the Environmental Protection Agency (EPA):
regulates the registration of use, sale, and distribution of antimicrobial pesticide products for certain surfaces or pesticide products incorporated into substances under the pesticide law.

The US Food and Drug Administration (FDA):
approves antiseptics through two processes-
new drug application (NDA)
over-the-counter (OTC) drug review

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19
Q

Transient biota of the skin is defined as

A

Organisms that are not part of the established normal biota

20
Q

Which of the following characteristics should be considered when selecting an antimicrobial agent

A

Spectrum of activity
Rate of action
Mechanism of action

21
Q

Give the mechanism of action for each type of chemical agent commonly used in antiseptics and disinfectants

A

Alcohols:
inactivate microorganisms by denaturing proteins

Aldehydes:
denature proteins and inactivate nucleic acids

Iodone and chloride compounds:
active based on oxidative effects

Heavy metals:
less commonly used due to toxicity. Combine with proteins, which inactivates them

Antimicrobial action of cationic detergents:
mediated through disruption of the cellular membrane, resulting in leakage of cell contents.

Phenolics:
denature proteins and disrupt plasma membranes

ethylene oxide:
alkylation and subsequent inactivation of nucleic acids

22
Q

Explain the use of health care personnel handwash, surgical hand scrub, and patient preoperative skin preparations

A

Handwashing:
eliminate transient biota

Surgical scrub:
eliminate transient and resident biota

23
Q

OSHA requires employers to offer the hepatitis B virus vaccine free of charge to employees who are at risk for exposure to the virus. True or false?

24
Q

SDSs are important to employees because they contain information relating to which of the following?

Bloodborne pathogens
fume hoods
chemical safety
fire extinguishers

A

Chemical safety

25
Which of the following would be a correct definition of standard precautions
Viewing all specimens as potentially infectious and using the appropriate protective equipment
26
What type of filter does a class II BSC use to filter out infectious agents
HEPA filters
27
Infectious agents can enter the body through which of the following routes? Inhalation Ingestion Inoculation All of the above
All of the above
28
Employees can remember the steps to take in case of a fire by remembering what acronym?
RACE
29
How often must safety training for laboratory employees be conducted for compliance with OSHA regulations?
annually
30
Brtieflyt describe the NFPA hazard-rating diamond found on all chemical containers to warn employees of potential hazards associated with that chemical
The NFPA hazard-rating diamond states risk for flammability, reactivity, and health. Each criterion is rated on a scale of 0-4, from stable or safe to highly dangerous
31
Washing hands frequently, disinfecting work areas, using needle resheathing devices, performing procedures in a manner to reduce splashes, and transporting specimens in well-constructed leak-proof containers are examples of which of the following
work practice protocols
32
The OSHA bloodborne pathogens standard outlines the safety requirements that an employer must have in place to protect the employee from bloodborne pathogens. This is called
exposure control plan
33
A patient with active tuberculosis is admitted to the hospital. What type of precautions above and beyond standard precautions will be followed for this patient?
airborne precautions
34
The following BSL practice is required for agents that may cause serious disease
BSL-3
35
The risk group classification for infectious agents that can cause human disease but for which effective treatments can preventative measures are available is
Risk group 3
36
Surveillance is defined as
The systematic collection and analysis of data
37
Microbes commonly encountered in health-care associated infections in hospitals include
Staphylococcus aureus, pseudomonas aeruginosa, MRSA, Escherichia coli
38
Pulsed-field gel electrophoresis (PFGE) might be performed to
Assist in an outbreak investigation
39
The occurrence of surgical site infections is generally calculated as
The percentage of infections in surgical sites or procedures
40
Health departments frequently require the reporting by the laboratory of
Diseases of major health concerns (smallpox) Diseases needing timely response (foodborne outbreaks) Outbreaks of public health concern (scabies)
41
Microbial pathogens of potential bioterrorism activity include
Bacillus anthracis, Yersinia pestis, francisella tularensis
42
Environmental cultures are usually to be avoided, except in
An outbreak investigation The occurrence of infections following construction Compliance with specific regulatory requirements
43
The formal steps in an outbreak investigation include
Establishing a case definition, forming and testing a hypothesis, and communicating findings
44
Infection control programs rely on microbiology laboratory support in
Public health settings acute care facilities home care settings
45
The microbiology laboratory interacts with the infection control program by providing
Culture results antibiograms and pathogen prevalence reports Environmental cultures when appropriate