Case Study Week 1
Scenario: You are a member of a diagnostic laboratory responsible for
evaluating patient specimens collected at a local clinic in a rural area. The
isolation and subsequent identification of specific pathogens from these
samples must be conducted “in-house” with basic laboratory equipment.
Through the evaluation of patient symptoms and background information
there appears to be an outbreak of gastroenteritis among a number of
families that are sharing the same well as a water source. Through stains,
bright-field microscopic examination, and basic biochemical tests you
conclude that the organism causing the problem may be Salmonella.
Salmonella is a motile bacterium that is an active “swimmer,” and therefore
the laboratory manager suggests that you determine whether the organism
you have isolated is motile. Motility medium would take at least 24 hours to
produce a result. Your laboratory has bright-field, dark-field, phase-contrast,
and fluorescence microscopes.
1. What can you do to determine the motility of the suspected pathogen
short of the 24-hour motility medium test?
I could use the dark-field or phase-contrast without staining to
see movement (motility) and compare it to something without
motility under the same microscope to get a better judgement.
2. What are the advantages and disadvantages of your proposed method(s)?
The advantages of this method are better clarity because of 3D
visibility, and getting results quickly. The disadvantages of this
method are maybe more setup time and easier to mess up the slide
before being able to view properly.
Scenario: You are a member of a diagnostic laboratory responsible for
evaluating patient specimens collected at a local clinic in a rural area. The
isolation and subsequent identification of specific pathogens from these
samples must be conducted “in-house” with basic laboratory equipment.
Through the evaluation of patient symptoms and background information
there appears to be an outbreak of gastroenteritis among a number of
families that are sharing the same well as a water source. Through stains,
bright-field microscopic examination, and basic biochemical tests you
conclude that the organism causing the problem may be Salmonella.
Salmonella is a motile bacterium that is an active “swimmer,” and therefore
the laboratory manager suggests that you determine whether the organism
you have isolated is motile. Motility medium would take at least 24 hours to
produce a result. Your laboratory has bright-field, dark-field, phase-contrast,
and fluorescence microscopes.
1. What can you do to determine the motility of the suspected pathogen
short of the 24-hour motility medium test?
I could use the dark-field or phase-contrast without staining to
see movement (motility) and compare it to something without
motility under the same microscope to get a better judgement.
2. What are the advantages and disadvantages of your proposed method(s)?
The advantages of this method are better clarity because of 3D
visibility, and getting results quickly. The disadvantages of this
method are maybe more setup time and easier to mess up the slide
before being able to view properly.
