Research Seminar 30.9.2008 Coli Bacteria in Poultry – A possible Zoonosis

29.9.2008

<div>Escherichia coli bacteria pathogenic to poultry are called avian pathogenic Escherichia coli (APEC). APEC bacteria belong to a diverse group of extraintestinal pathogenic E. coli (ExPEC). As the expression suggests, these E. coli bacteria cause infections external to the intestines, e.g., in the urinary tract, abdominal cavity and meninges. </div>

VML Tarja Pohjanvirta
Research Department, Veterinary Bacteriology, Evira, Kuopio
Evira/Helsinki Viikki, Auditorium C111 Kalevi
Tu 30 September 2008 at 3:00 - 4:00 pm

ExPEC bacteria are also often found in blood cultures. Unlike E. coli causing intestinal infections, ExPEC bacteria have no distinct virulence factor profiles. Their pathogenic ability is based on various combinations of iadherence factors, protectins, ironbinding factors and toxins. Based on the developmental origin, E. coli bacteria can be divided in phylogeny groups. Most ExPEC bacteria belong to phylogeny group B2, while also group D bacteria occur.

A major part of ExPEC bacteria in group B2 belong to sero-groups O1, O2 and O18, and they have a K1 capsule. Several studies using various molecular methods as well as experiments exposing chicks have shown ExPEC bacteria in group B2svg to be very similar and even identical regardless of from which species they originally were isoalted. Hence, most studies have brought up the ques-tion regarding the possible zoonotic potential of APEC strains.

In Finland, no extensive studies have been carried out on pathogenic E. coli among poultry. Since beginning of the 2000s, various problems involving E. coli in Finnish production of meat from poultry have increased. In order to study the characteristics of pathogenic E. coli strains, Evira collected E. coli strains from birds delivered for analysing the causes of deaths, and which had become diseased through coli infections. As reference material was used E. coli isolated from faeces of healthy birds.

E. coli bacteria were also studied in raw poultry products in retail stores, as also were the charac-teristics of ExPEC strains among humans in Finland through analysis of E. coli bacteria from blood cultures stored in 2006 at Kuopio University Hospital. These strains were analyzed for various virulence factors using PCR, and for distribution over phylogenic groups. Pulsed Field Gel Electropho-resis (PFGE) was used to establish uniformity among strains. A representative variety of coli bacteria in poultry was selected to establish sensitivity to antimicrobial agents.

Based on the study it was possible to show that a significant portion of strains infecting poultry in Finland belongs to the possibly zoonotic group B2svg (sero type O1:K1). This type is also present in 1 % of products in retail stores. The PFGE study shows that strains in this group are genetically very similar and that strains isolated from retail products were identical to the strains present in sick birds. Resistance to antibiotic agents was rarely found among bacteria in this group. The distribu-tion of virulence factors in human blood culture isolates of group B2svg differed from those of poul-try.

The zoonotic potential of the O1:K1 clone found in poultry will be subsequently studied, for exam-ple, applying more precise molecular genetic analyses.

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