![]() Asked why bacteria would have evolved into two distinct types, he replies, “I imagine it’s just a matter of evolution and specialization of organisms. ![]() “They’re both pretty impermeable, but the gram negatives have as some of their major virulence factors a component of the cell wall called endotoxin or lipopolysaccaride,” Stevens says. Stevens explains that the different types of bacteria have different types of cell walls. Gram-negative organisms include salmonella, shigella, escherichia coli, and pseudomonas gram-positive organisms include staphylococcus, streptococcus, clostridium and anthrax. has a lot to do with the composition of their cell wall on whether or not they stain positive or negative,” says Dennis Stevens, MD, professor of medicine and chief of infectious diseases at the Department of Veterans Affairs in Boise, Idaho. Another pathologist, Carl Weigert, later discovered that gram-negative bacteria retained stain from safranin. Gram-positive bacteria retained the color of Gentian violet gram-negative bacteria bleached. In 1884, Gram published his findings that bacterial cells would “take up” and retain specific stains. Gram was a pharmacologist and pathologist fascinated by botany, which led him to the microscope and the beginnings of pharmacology. The Gram stain stems from the work of Danish physician Hans C.J. In the lab, it is possible to distinguish between gram-negative and gram-positive bacteria by use of gram staining. As normal flora in their indigenous locales, they are benign, assisting in digestion and producing nutrients, but if the host is immunocompromised or the bacteria make their way to new territory, chaos can result. ![]() , a one-celled organism without a true nucleus or cell organelles, belonging to the kingdom Procaryotae (Monera)īacteria can be classified as normal flora or as pathogens. Gram-negative and gram-positive bacteria both make up a significant part of the body’s defense system when they reside in the appropriate settings taken out of their comfort zones, they can be fatal. Gram-negative and Gram-positive Bacteria Can’t Live With ‘Em, Can’t Live Without ‘Em By Kathy Dix
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