Some Arcobacter species can cause diarrhoea in humans and animals. This infection involves as a rule stomach pains and nausea as well as aqueous diarrhoea but can also have an asymptomatic course. In general, a rather mild course of disease is observed in humans.
Main sources of infection
Arcobacters have an extremely diverse natural habitat. There are plant and animal associated species as well as some free-living environmental germs. Consequently Arcobacter spp. can be found, amongst others, in waters, such as surface and river waters, waste water and sea water. Furthermore, species have been isolated from several foods, mainly of animal origin, such as beef, pork, sheep and poultry meat.
The Arcobacter genus constitutes together with the genuses Campylobacter and Sulfurospirillum the family of Campylobacteraceae within the order of Campylobacterales of the epsilon proteobacteria.
The gram-negative Arcobacters were originally classified as Campylobacters and currently include six different species: A. butzleri, A. cryaerophilus, A. skirrowii, A. nitrofigilis, A. halophilus and A. cibarius. They are, however, significantly different from Campylobacters in terms of their growth even at low temperatures and because of their aerotolerance. They are between 0.5 and 3 μm long, 0.2 – 0.9 μm wide and basically grow in a temperature range of 15°C to 42°C with a growth optimum at approximately 30°C. Because of their monotrichous flagellation they constitute mobile rods which are partly spirally shaped. Under unfavourable conditions the bacteria are transformed into cocci which are similar to those of Campylobacter and probably represent a survival form.