The Gram stain test, developed in the 1800s by Hans Christian Gram, is a method for classifying different types of bacteria using a chemical stain and viewing through a microscope the results on the bacteria’s protective cell wall. Most bacteria are classified into two groups—Gram-positive or Gram-negative—depending on whether they retain a specific stain color. Gram-positive bacteria retain a purple-colored stain, while Gram-negative bacteria appear pinkish or red.
Gram-negative bacteria can cause many types of infections and are spread to humans in a variety of ways. Several species, including Escherichia coli, are common causes of foodborne disease. Vibrio cholerae—the bacteria responsible for cholera—is a waterborne pathogen. Gram-negative bacteria can also cause respiratory infections, such as certain types of pneumonia, and sexually transmitted diseases, including gonorrhea. Yersinia pestis, the Gram-negative bacterium responsible for plague, is transmitted to people through the bite of an infected insect or handling an infected animal.
Increasing Concern About Drug ResistanceCertain types of Gram-negative bacteria have become increasingly resistant to available antibiotic drugs. Some strains are now resistant to many, most, or all available treatments resulting in increased illness and death from bacterial infections, and contributing to escalating healthcare costs. Examples of Gram-negative bacteria that have demonstrated drug resistance include
E. coli, which causes the majority of urinary tract infections
Acinetobacter baumanii, which causes disease mainly in healthcare settings. In addition, wound infections caused by Acinetobacter have been found in U.S. military personnel who were deployed to Iraq and Afghanistan.
Pseudomonas aeruginosa, which causes bloodstream infections and pneumonia in hospitalized patients. It is a common cause of pneumonia in patients with cystic fibrosis.
Klebsiella pneumoniae, which causes many types of healthcare-associated infections, including pneumonia, urinary tract infections, and bloodstream infections. #healthy #healthylifestyle #healthcare