Campylobacter jejuni. Coloured transmission electron micrograph of a thin section through the bacteria Campylobacter jejuni. These can grow in areas where little oxygen is present & cause food poisoning in humans. C. jejuni are Gram-negative and may have tail-like flagellae (not seen here). 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: x46,000 at 6x7cm size. Magnification: x160,000 at 8x10inch size.