Campylobacter

The name describes the cell under the microscope: from the Greek kampylos, curved, and baktron, rod. The cells are gram-negative, slender and curved or spiral, and they move with a fast corkscrew motion on a single polar flagellum. When they are old or exposed to air they change to a dormant spherical form. The genus sits in the family Campylobacteraceae.

These organisms were long overlooked. Theodor Escherich saw them in 1886 in the gut of infants who had died of a diarrhoeal illness, but could not culture them, and for many years they were grouped with the vibrios. The first isolation from a person was in 1938, from the blood of victims of a milk-borne outbreak. King described the enteric form in 1957, and in 1963 Sebald and Veron placed these bacteria in the new genus Campylobacter. They remained hard to study until selective culture media were developed in the 1970s, after which Campylobacter was recognised as one of the commonest causes of bacterial gastroenteritis.

For the curesmith the important point is how narrow its requirements are. Campylobacter is thermophilic, growing best at about 42 degrees C, the body temperature of a bird, and it does not grow below about 30 degrees C. It is microaerophilic: it needs a little oxygen, around five per cent, and ordinary air is harmful to it. It does not tolerate drying or salt, and it is checked by acid below about pH 5. Nothing in a curing room favours its growth, and a properly dried, fermented or cooked product is hostile to it.

**How it endangers cured meat.** It does not survive or grow in a cure, so its danger is not the product but the raw material and the workspace. It is carried on raw poultry and its drip, and it survives refrigeration well, so chilled raw chicken is a reservoir close to the meat being cured. The route to harm is cross-contamination: a board, knife or hand that has touched raw poultry and then touches the meat, casing or finished product. The species that cause most illness are Campylobacter jejuni, by a wide margin, and Campylobacter coli; the clinical detail is in the jejuni article.

Control is a matter of hygiene rather than of the cure: keep raw poultry and its juices away from curing meat and finished product, use clean equipment and hands, and cook thoroughly where a product is cooked.