Campylobacter jejuni bacteria. Coloured trans- mission electron micrograph (TEM) of a section through two Campylobacter jejuni bacteria. These bacteria can grow in areas where little oxygen is present and cause food poisoning in humans. They are Gram-negative bacteria which have two hair- like flagella (yellow) for locomotion. They are a common cause of gastroenteritis in humans, especially children and young adults. Contaminated poultry, meat and milk are sources of infection. Symptoms include fever and acute abdominal pain, followed by watery and often bloody diarrhoea. Recovery is usually rapid. Magnification: x16,000 at 6x7cm size.