Arcobacter spp: Culture; Molecular diagnosis (PCR and sequencing) 

Information 03-12-2017.

The genus Arcobacter is composed of curved Gramnegative bacilli, S-shaped when in young cultures, and coccoid or spherical in old cultures. This genus was created in 1991 as a second genus within the family Campylobacteraceae to include bacteria that differed from those of the genus Campylobacter for its ability to grow at temperatures below 30°C and its aerotolerance. Since then, the genus Arcobacter has evolved rapidly, and currently (2017), it is composed of 26 species. In recent years, bacteria of the genus Arcobacter have become increasingly important because they have been identified as emerging enteropathogens and potential zoonotic agents.

The species of the genus Arcobacter are found in a great diversity of hosts and ecological niches all over the world. Species of this genus have been isolated from cattle, swine, chicken and other poultry, in fetuses of porcine and bovine abortions, meat products, milk, molluscs, and vegetables. Also, some species of the genus have been recovered from drinking water treatment plants, sewers, river water, coastal seawater, saltwater lakes, groundwater, and various types of mud.

The role of Arcobacter species as causes of human and animal pathology has not been fully established. In animals, Arcobacter species have been implicated in abortions, mastitis, and gastrointestinal disorders, but also, they have recovered from asymptomatic animals. In humans, the severity of the clinical picture of infections is very varied. Bacteria of the genus Arcobacter can cause from asymptomatic infections, mild diarrhea, chronic and abundant diarrhea, to severe enteric cases that require hospitalization. Occasionally, infection with Arcobacter has also been associated with bacteremia, endocarditis and peritonitis. Specifically, four species of the genus have been identified as causing disease in humans: Arcobacter butzleri, Arcobacter cryaerophilus, Arcobacter skirrowii and Arcobacter thereius. According to existing studies, A. butzleri has the highest prevalence in humans, followed by A. cryaerophilus, and A. skirrowii. Finally, A. thereius has recently been isolated from two hospitalized patients with symptoms of enterocolitis.

The mechanism of pathogenicity of bacteria of this genus has not yet been elucidated. In addition, the routes of infection are not completely known. Infection with Arcobacter can occur through cross contamination in food handling, the consumption of contaminated animal foods, and the consumption of contaminated water. For this reason, the genus Arcobacter has been classified by the International Commission of Microbiological Specifications for Foods (ICMSF) as emerging pathogens. In addition, infection can occur through direct contamination with fecal matter, both animal and human, and contact with infected persons has been postulated as another possible source of infection.

The increases and studies and research carried out after their discovery as alimentary enteropathogens seem to indicate that the incidence of the genus Arcobacter in humans and animals has probably been underestimated. The lack of a standardized reference procedure for the isolation of Arcobacter, together with the fact that the culture media used for its isolation are not used daily in clinical and food laboratories, has made it difficult to find and identify this bacterium.

Tests carried out in IVAMI:

• Diagnosis of Arcobacter spp. by isolation by cultivation in selective media

• Molecular identification of the Arcobacter species (PCR and sequencing).

Recommended sample:

• Sample of suspect or controlled food. A minimum of about 100 g is recommended.

• Sample of the water suspected or controlled. A minimum of 200 ml is recommended.

• Stool sample. A minimum of 10g is recommended.

Conservation and shipment of the sample:

• Refrigerated (preferred) for less than 2 days.

• Frozen: more than 2 days.

Delivery of results:

• Isolation detection in culture: 5 days.

• Detection by isolation in culture and molecular identification: 3 to 4 days.

Cost of the test:

• Cost of the culture test and molecular identification: Consult to ivami@ivami.com.