What Are Bacteria?
Bacteria are microscopic, single-celled organisms found in air, water, soil, and food. They live on plants, insects, animals, pets, and even in the human digestive system and upper respiratory tract. There are thousands of kinds of bacteria, but only a few actually cause disease in humans.
Bacteria are frequently identified by their shape, the makeup of their cell walls, and their ability to grow in air. They can be round (such as staphylococci or streptococci), rod-shaped (such as bacillus or E. coli), or corkscrew-shaped (Borrelia species). In most cases, bacteria have cell walls that provide a target for many antibiotics (antibiotics easily identify bacteria) (Gold 2000).
They are also classified by their color after a Gram stain is applied. Gram-positive bacteria stain blue, while Gram-negative bacteria stain pink.
Gram-negative bacterial cell walls contain a substance known as lipopolysaccharide (LPS), a highly inflammatory chemical that provokes an immune response in the human body. LPS is responsible for triggering the overreaction of the host immune system, which results in the release of oxygen and nitrogen species, cytokines, and other pro-inflammatory mediators.