LAB FINAL: part 1 (6 & 7)
Temperatures above the maximum growth temperature for a microorganism are likely to result in ___.
denaturation of enzymes
Atmospheric gases, nutrients, pH, energy sources, and radiation are all examples of ___ factors that affect microbial growth.
envuronmental
The slowed growth of lack of growth of an organism at temperature or pH outside of its ideal range is most likely due to changes in its ___.
enzymes
Rank the following, from the highest growth temperature range (at the top) to the lowest growth temperature range (at the bottom).
extreme thermophile, thermophile, mesophile, psychrotroph, psychrophile
Which of the following are risks associated with UV exposure?
eye damage, skin cancer
A tube of fluid thioglycollate medium is inoculated with a bacterial isolate. After incubation, the bacteria appear to be growing throughout the tube. This bacterial isolate is most likely a(n) ___.
facultative anaerobe
Based on this FTM tube result, how would you classify this organism?
facultative anaerobe
A zone of inhibition around a chemical-saturated disk indicates ___.
the chemical is effective at inhibiting the growth of the test organism
Rank these from the easiest to remove or destroy to the most difficult to remove or destroy.
1 - Mycobacterium tuberculosis 2 - Envelopes viruses (such a influenza virus) 3 - prions
Which of the following reflects the wavelength range of UV radiation?
100 - 380 nm
the zone of inhibition is ___.
21 mm
To promote the development of red pigmented colonies by Serratia marcescens, cultures should be incubated at ___.
25 degrees celsius
Which of the following would be used to provide the optimum growth temperature for microorganisms that typically grow in humans?
37 degrees Celsius incubator
Which two types of bacteria listed below are moderately resistant to microbial control methods?
Mycobacterium tuberculosis, Pseudomonas aeruginosa
Human skin provides an environment with NaCl levels slightly above that of most bacterial cells. Which organism would most likely be found on the skin?
Staphylococcus aureus; a halotolerant organism
How does this white card work to produce a control side of the plate?
UV light cannot penetrate...
The air entering an operating room and the surfaces in the operating rooms are often disinfected with ___.
UV radiation
Which of the following are disadvantages or limitations of using UV radiation for disinfection purposes?
UV radiation does not penetrate well, UV radiation can damage the skin and eyes when used on other objects
Which statement correctly describes the growth of an organism across the pH scale?
a microorganism will grow across the range of pH that allows for normal enzymatic function
Which statement best describes the growth patterns of microorganisms based on their temperature preferences?
a microorganism will grow across the range of temperatures tolerated by its enzymes
Which of the following is indicative of drug sensitivity?
a zone of inhibition that falls under the sensitive column in a standard chart
If an anaerobe jar, oxygen is ___.
absent
The lower the pH, the more ___ the environment.
acidic
Match the descriptive term with the optimal pH for growth. *___ - pH<5.5 *___ - pH=7 *___ - pH>8.5
acidophile, neutrophile, alkalinophile
When are the chemical-saturated disks placed on the plate?
after streaking out the test organisms, but before incubation
Which of the following can be disinfected using UV radiation?
air, surfaces, liquids such as water and cider
A(n) ___ jar could be used to provide an oxygen-free atmosphere for bacteria that thrive in the absence of oxygen and are inhibited by its presence.
anaerobe
Which of the following are chemical means of microbial growth?
antibiotics; disinfectant
Chlorhexidine, chlorxylenol, or iodine compounds are often found in antimicrobial soaps used as surgical scrubs. These are examples of ___.
antiseptics
If comparing growth of a microbe in broth tubes incubated at different temperatures, the tube incubated at the organism's optimum temperature would ___.
be the most turbid (cloudy)
Both of these organisms are susceptible to what compound?
bleach
Based on these results, what can you conclude about the susceptibility of these two organisms?
both of these organisms are likely resistant to penicillin and erythromycin
What conclusion can you draw by looking at these Kirby-Bauer results?
both of these organisms could be sensitive to SXT; the antibiotic tested here appear to be more effective against gram-positive organisms
A drug that is effective against a large variety of bacterial types including gram positive, gram negative, intracellular pathogens, and bacterial without cell walls (mycoplasmas) is a ___ antimicrobial.
broad spectrum
T or F: this organism is sensitive to gentamycin (GM 10).
cannot be determined with this information alone
Which of the following are direct targets of antimicrobial control methods?
cell membrane, metabolic enzymes, cell wall, nucleic acid synthesis, protein synthesis
A particular microbial control agent weaken and destroys peptidoglycan. This would specifically damage the ___.
cell wall
In which circumstances would we attempt to optimize conditions for microbial growth?
culturing a urine specimen to detect a urinary tract infection; manufacturing yogurt; composting yard waste
Which of the following may occur at temperatures below a microorganism's minimum growth temperature?
decreased fluidity of the plasma membrane, slowing of metabolic activity, membrane transport may be disrupted
The change or breakdown of three dimensional protein structure that may result from a pH outside of an organism's growth range is referred to as ___.
denaturation
Which of the following organisms is most flexible with regard to its oxygen requirements?
facultative anaerobe
Match the oxygen requirement classification with the correct description of the expected FTM tube result... *___ - growth throughout the tube *___ - growth towards the bottom of the tube *___ - growth towards the top of the tube
facultative anaerobe, obligate anaerobe, obligate aerobe
T or F: All microorganisms use oxygen in their metabolism.
false
T or F: The antimicrobial disk producing the largest zone of inhibition is always the drug that the bacterial isolate is most sensitive to.
false
T or F: The sources of all antimicrobial drugs are fungi and other microorganisms.
false
You test four different antibiotics against a beta-hemolytic streptococcus. Based on these results, which drugs are possible options for treating an infection with this bacterial pathogen?
gentamycin, erythromycin
Based on the results seen here, are these antimicrobial compounds more effective against gram-negative or gram-positive organisms?
gram-positive
Bacteria classified as ___ would thrive in the Great Salt Lake.
halophiles
Halobacterium salinarium will only grow at high salt concentrations, generally 15% to 30% NaCl. Which term below describes this environmental preference?
halophilic
The organisms indicated by the arrow would be classified as ___ organisms.
halophilic
An organism such as Staphlococcus aureus which grows best at a salt concentration of 1%, but is able to grow at salt concentrations as high as 10% is best described as ___.
halotolerant
An organism such as Staphylococcus aureus which grows best at a salt concentration of 1%, but is able to grow at salt concentration as high as 10% is best described as ___.
halotolerant
An alkalinophile is a microorganism that prefers a growth environment that ___.
has a pH>8.5
Distilled water would be ___ to bacterial cells.
hypotonic
A microorganism growing in a pond or steam is most likely in a(an) ___.
hypotonic environment
Match the solution description with the direction of water movement when cells are placed into each solution... *___ - a net movement of water into the cells will occur *___ - there will be NO net movement of water either into or out of the cells *___ - there will be a net movement of water out of the cells
hypotonic solution, isotonic solution, hypertonic solution
Identify the types of laboratory items that can be used to enhance growth of most commonly-encountered microbes by altering their environmental conditions.
incubator, anaerobe jar, isotonic culture media
The clear area where no bacteria are growing around the chemical disk is called a zone of ___.
inhibition
Microorganisms growing on mucous membranes such as the oral mucosa or vaginal mucosa are most likely in a(an) ___ environment.
isotonic
Which term would describe the tonicity of an environment in which the solute concentration is the same as that of the interior of the microbial cells?
isotonic
Match the term with the appropriate description... *___ - a solution with a solute concentration equal to that of a cell *___ - a solution with a solute concentration greater than that of a cell *___ - a solution with a solute concentration less then that of a cell
isotonic, hypertonic, hpotonic
What is the purpose of the white card seen in this image?
it blocks the UV light from one side of the plate to produce a control
Based on this filter paper disk test of Streptococcus agalactiae, what can can you conclude about the effectiveness of these antiseptics and disinfectants against this organism?
it is likely resistant to several of these antimicrobial compounds
Where would you expect an obligate anaerobe to grow in a tube of fluid thioglycollate medium?
lower part of the tube
Which of the following correctly describes measurement of the zone of inhibition?
measure the complete diameter of the zone, from the edge of the zone on one side of the disk, across the disk to the edge of the zone on the other side, in mm
Microorganisms whose optimal growth temperature is 37 degrees celsius (normal human body temperature) are classified as ___.
mesophiles
Most human pathogens are classified as ___.
mesophiles
Which of the following are used to describe the range of temperatures over which a microbe will grow?
minimum growth temperature, optimum growth temperature, maximum growth temperature
What is the preferred medium for use with the Kirby-Bauer susceptibility test?
mueller hinton agar
Which type of antibiotic is most likely to target the pathogen without causing a decrease in the normal microbiota?
narrow spectrum
A solution with a pH of 7 is ___.
neutral
Match each description with the appropriate category: *___ - uses oxygen in its energy metabolism; can process toxic oxygen by-products *___ - does not use gaseous oxygen in its energy metabolism; unable to process toxic oxygen by-products *___ - can conduct aerobic or anaerobic metabolism; can process toxic oxygen by-products *___ - unable to grow in the presence of atmospheric levels of gaseous oxygen, but needs a small amount of oxygen for its metabolism
obligate aerobe, obligate anaerobe, facultative anaerobe, microaerophile
If an organism grows in the anaerobe jar but not under normal atmospheric oxygen levels, it would be classified as a(n) ___.
obligate anaerobe
Which organism(s) should be able to grow in the anaerobe jar?
obligate anaerobe, facultative anaerobe
Where would you expect to see growth for an obligate aerobe?
on the plate placed on the incubator shelf, not within an anaerobe jar
The fastest growth rate of a microorganism occurs at its ___ temperature.
optimum
Determine the correct oxygen requirement classification for each of the organisms seen in this image. *___ - facultative anaerobe *___ - obligate aerobe *___ - obligate anaerobe
organism at #1, organism at #2, neither organism...
Which of the following terms refers to microorganisms capable of growing in jams, corn syrup, and maple syrup?
osmophilic
The activated chemical pack that is added to an anaerobe jar effectively removes ___.
oxygen
The terms aerobic, anaerobic, and microaerophilic are used to categorize microorganism based on their ___ requirements.
oxygen, atmospheric
Which of the following drugs would be a poor choice in treating an infection with Pseudomonas aeruginosa based on the results of this Kirby-Bauer test?
penicillin (P10); erythromycin (E15); vnacomycin (V30)
Which of the following are toxic by-products formed in the presence of oxygen?
peroxide, superoxide ion, hydroxyl radical
Which of the following would NOT be destroyed by UV radiation?
prions
An antibiotic which interferes with the activity of ribosomes would have the most direct effect on ___.
protein synthesis
Which of the following are most likely to be affected by pH changes?
proteins
Which of these terms categorize microorganisms based on their temperature preference?
psychrophile, thermophile, mesophile
Which classifications of organisms can be a concern for growth in refrigerated foods?
psychrophiles, psychrotrophs
Which of these laboratory items are usually used to inhibit the growth of most types of microorganisms by altering their environment?
refrigerator, salt plates
On a plate inoculated with Staphylococcus aureus and incubated for 16 hours, you measure the diameter of the zone of inhibition around the penicillin disk. It measures 25 mm. This means that S. aureus is ___ to penicillin.
resistant
Based on results of a disk diffusion antimicrobial susceptibility test, an organism may be described as sensitive, intermediate, or resistant to the drug. Match the term with its description... *___ - the growth of the microorganisms is significantly inhibited by the drug *___ - the drug demonstrates moderate inhibition of the microorganism *___ - the microorganism is not affected by the drug and can grow in its prescence
sensitive, intermediate, resistant
The wavelength of ultraviolet radiation is ___ than the wavelengths of visible light.
shorter
Which of the following processes removes or destroys endospores?
sterilization
In which items or situations might you want to reduce or limit microbial growth?
storing leftover food, surgical incision, drinking water
A microorganism is classified as a psychrophile, a mesophile, or a thermophile based on its optimum growth ___.
temperature
Which of the following are examples of physical methods of microbial control?
temperature, irradiation
Which of the following are environmental factors that affect microbial growth?
temperature, pH, nutrients, osmotic pressure, atmospheric gases
A bacterial strain has been isolated from a patient's urine specimen and a Kirby-Bauer susceptibility test has been done on the bacterial strain. There is no zone of inhibition around antibiotic X. Which statement correctly describes this situation?
the bacteria is resistant to antibiotic X
A hypertonic solution is prepared by the addition of sucrose. Which of the following will happen to bacteria placed in this solution?
the bacterial cells will undergo plasmolysis
Which of the following are correct statements regarding this FTM tube?
the bottom region represents an area where oxygen is absent, the top pink area has oxygen present
How should the zone of inhibition be measured?
the diameter of the zone (in mm) is measured, from one edge of the zone, across the disk, to the other edge of the zone
How do antimicrobial drugs affect target microorganisms?
the drugs may stop the growth of the microorganisms without killing them; the drugs may kill the microorganisms
What factors influence the size of the zone of inhibition for an antibiotic?
the growth rate or inhibition of growth of the bacteria in the presence of the antibiotic; the rate of diffusion of the antibiotic through the mueller hinton agar
What best explains the results in the image seen here?
the left side of the plate does not show...
What are possible outcomes of selecting an antibiotic that is ineffective to treat a particular infection?
the normal microbiota may be destroyed enabling the targeted pathogen to grow even better, the infection may worsen, the targeted pathogen will continue to grow and cause disease
You inoculate a plate with two different organisms and incubate in an anaerobic jar for 24 hours. This is the result you see after incubation. Which of the following are possible conclusions regarding these organisms?
they may be obligate anaerobes, they cannot be obligate aerobes, they can grow in the absence of oxygen, they may be facultative anaerobes but that cannot be determined from these results alone
UV radiation causes the formation of ___.
thymine dimers
T or F: A drug which reduces the normal microbiota but doesn't effectively target the causative agent of an infection may actually make the infection worse.
true
T or F: Some microorganisms are adapted to living at either very hot temperatures, very cold temperatures, or very low pH.
true
A thymine dimer forms between ___.
two adjacent thymines, on the same DNA strand
Which of the following environmental conditions are preferred by a majority of organisms?
warm temperatures, isotonic environments, neutral pH
Choose the answer that represents the ideal environment for a majority of microbes.
warm, isotonic, neutral pH
The area around an antibiotic disk where microorganisms are NOT growing is referred to as the ___ of ___.
zone of inhibition
