Bacteria are single-celled microorganisms which can exist either as independent (free-living) organisms or as parasites (dependent upon another organism for life). They are about 0.5 to 2 micrometres in size. A grain of sand is 2 millimetres in size. This means you could fit 1000 bacterial cells into a single grain of sand. This means we can only see bacterial cells through the microscope.
Campylobacter jejuni bacteria inhabits the intestinal tract of warm-blooded animals such as poultry and are frequently detected within these farmed birds, especially chicken. It is a gram-negative (like E.coli ) spiral-shaped bacterium. It’s ideal growth temperature is directly within the temperature danger zone, most optimally at 37°C (99 °F).