SUNY at Binghamton Microbiology Discussion Questions

Identifying microbes is a key reason to culture them. It has been a major focus of this lab. Select a pathogenic bacterium and compose a 1-2 page essay explaining the clinical significance of your microbe, culture- or staining-based methods for identifying your organism, other techniques for identifying the microorganism, that do not involve culturing or staining the bacterium, like detection with antibodies or PCR. The selected organism should not be an organism discussed in lab. A list of organisms not permitted is included below. The essay should cite at least two peer-reviewed journal articles, and cite either the CDC (Links to an external site.) or The WHO (Links to an external site.). This is means the essay should have a minimum of 3 citations.

Here is an outline to help you write your essay. This assignment is to write a complete essay using complete sentences. The outline is designed to help you organize the essay and score full points on the rubric.

• Introduction:
  • Identify the organism you will be writing about. The organism must NOT be on the list below
    • Bacillus cereus
    • Escherichia coli
    • Klebsiella pneumoniae
    • Micrococcus luteus
    • Mycobacterium smegmatis
    • Pseudomonas aeruginosa
    • Proteus vulgaris
    • Salmonella typhimurium
    • Serratia marcescens
    • Staphylococcus aureus
    • Staphylococcus epidermidis
    • Streptococcus pyogenes
  • Indicate if your organism is gram positive, gram negative, and its cellular morphology. A virus is also acceptable, please explain its taxonomy, Baltimore Classification, and it’s capsid morphology.
  • What disease does the selected organism cause? What are the symptoms?
• Clinical Significance
  • Who is at risk for infection with this organism?
    • Is the risk group the general populous? Are certain people at risk based on age group or pre-existing condition? Are people at risk if they live in a particular region? Is it a nosocomial or opportunistic pathogen?
  • What are the morbidity and mortality rates of people infected with your pathogen?
• Culture or Staining Based Methods of Identification
  • What methods using culture media or microscopy are routinely used to identify your microorganism? Is a single test sufficient or are multiple tests needed to confirm the organism’s identity?
  • If the microbe is cultured, what kind of media is used – is it selective and differential? Enrichment and differential? How does the media work?
  • If the microbe is viewed microscopically, how is it stained? Is the stain positive or negative? Fluorescent? What kind of microscope is used to view the organism – brightfield? Epifluorescent? darkfield? phase contrast?
  • How long does it take to produce data with this kind of test?
  • How accurate is the test? (probability of a false positive or false negative expressed as a percent)
• Other methods of identification
  • What other methods can be used to identify this organism?
    • Polymerase Chain Reaction – what gene do the primers amplify?
    • ELISA – how does the test work? What piece of the microbe is the ELISA targeting?
    • How long does this kind of test take to produce results?
    • How accurate is the test? (probability of a false positive or false negative expressed as a percent)
• Conclusion
  • Summarize your findings
  • Which testing method is better?
    • This may be a situational answer e.g. ELISA is faster but less accurate so a follow up with a culture-based test is necessary, or a molecular technique might be more accurate, but only used in difficult cases because of the cost.