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Biology/Gram staining positive/negative

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Expert: - 12/15/2009


Question
What significance does the positive or negative result of gram staining actually tell us besides that the cell wall has more of less peptidologlycan?  

Answer
Knowing whether an organism is Gram positive or Gram negative tells you more about the organism than simply its relative amount of LPS and peptidoglycan.  It is an important first step in the identification of an organism, as it will determine which direction you take the identification (what media to inoculate? what bench tests to perform? what test kits are appropriate?).  It can also indicate something with regards to where the organism might have originated.  Gram negative organisms (in general) are frequently found in association with water.  Many Gram positive organisms are found as part of human skin or respiratory flora.  Knowing whether an organism is Gram positive or Gram negative is also beneficial when it comes to choosing an antibiotic.  Not all antibiotics are broad-spectrum, many act only against Gram positive OR Gram negative organisms.

I hope this has helped answer your question!

Chris

Biology

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Chris Bemis

Expertise

I will answer questions relating to the identification of bacterial and fungal isolates using phenotypic (macroscopic/microscopic appearance, biochemical bench tests, fatty-acid analysis) as well as genotypic (RiboPrinting) methods. I can also answer questions relating to environmental microbiology, especially those specifically relating to the pharmaceutical industry. I am less familiar with clinical microbiology.

Experience

I have worked within the biotech industry for 9 years, most of that time spent in a Quality Control Microbiology laboratory setting. Within the laboratory, I routinely performed bioburden testing; sterility testing; gel-clot and kinetic LAL testing; biological indicator testing; stability testing; microbial limits testing; media performance/growth promotion testing; microbial identifications testing using API, Vitek, MIDI (GC-MIS) and RiboPrinter identifications systems; total/fecal coliform testing; environmental monitoring; media preparation; stock culture maintenance; qualification of identification test kits and QuantiCult Plus organisms. I executed the QC validation of the DuPont Qualicon RiboPrinter Microbial Characterization System. I also supported sites internationally with the fungal/microbial identification process, the RiboPrinter assay, stock culture maintenance and the microbial identification process flow.

Organizations
Nationally Registered Microbiologist, American Society of Microbiology (2005)

Publications
Applied and Environmental Microbiology

Education/Credentials
B.S. in Microbiology (2000)

Awards and Honors
Received my company's 'Best Practice Award' for the Validation of the RiboPrinter Microbial Characterization System, 2004

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