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How are bacteria identified in bacterial infections?

Bacteria are microscopic organisms that are identified by their shape, cell wall, and need for oxygen. Bacteria shaped like rods (bacilli) include salmonella and tuberculosis-causing organisms. Bacteria shaped like spheres (cocci) include pneumonia, staph, and strep-causing bacteria. Bacteria are also shaped like spirals (spirochetes). Bacterial cell walls can be identified using staining methods. Bacteria that stains blue are labeled gram-positive, like Streptococcus bacteria. Bacteria that stains pink are labeled as gram-negative, like E. coli. Bacteria also are classified as needing oxygen to survive. Particular bacteria are identified by growing the urine, blood or pus specimen in a laboratory culture. If bacteria do grow in the culture, they can be identified by staining them and viewing them under a microscope. They may also be identified by molecular techniques such as DNA sequencing, which directly analyzes the nucleotide sequences in the 16S ribosomal RNA gene.
Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)

One way to identify the type of bacteria causing the infection is to check their ability to absorb or resist a colored stain in a laboratory setting. Gram-positive bacteria possess certain unique characteristics in their membranes that cause them to take up a purple stain, while Gram-negative bacteria don't, but they do turn pink when a counterstain is applied.


This content originally appeared on doctoroz.com

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