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How do neutrophils help fight bacteria at an injured area?

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Collagenous fibers — connective tissue Randomly oriented collagenous fibers of varying size in a thin spread of loose areolar connective tissue (magnified about 370 ×).

Neutrophils are essential components of the immune system that defend the body against bacterial infection at sites of injury. Their response involves several coordinated steps:

Migration: When tissue is injured or infected, substances released at the site trigger chemotaxis, a process that directs neutrophils to move from the blood vessels into the affected connective tissue.12
Phagocytosis: Once at the site, neutrophils act as voracious phagocytes. They engulf bacteria, enclosing them within a membrane-bound structure called a phagosome.12
Destruction: Neutrophils contain granules filled with potent enzymes that discharge into the phagosome to digest the bacteria. Additionally, a metabolic process within these granules generates hydrogen peroxide and superoxide, which are highly active forms of oxygen that destroy the ingested microorganisms.1

Because neutrophils have a short lifespan, they die in large numbers after completing their mission. The accumulation of these dead and dying cells at the site of inflammation is known as pus.3