In the present study, almost all Finnish retail poultry meat products were found to be contaminated with E. coli. Twenty-two per cent of the products contained E. coli strains that could be classified as ExPEC. The analysis of these poultry meat samples was focused to the virulence genes that are most typical of avian pathogenic ExPEC, and thus most likely to prevail in poultry products. Inclusion of all kpsMT II group genes, instead of only that for K1 capsule, and some other ExPEC associated virulence factor genes, could have increased the observed prevalence of ExPEC. The findings from the Finnish poultry products are consistent with studies made in other countries on poultry meat at the retail level. Johnson et al.
 found 21% of 110 E. coli isolates from chicken products to satisfy the criteria for ExPEC. Johnson et al.
 reported a contamination rate of 46% for ExPEC in 189 retail poultry products. Xia et al.
 found among different retail meats the highest rate of ExPEC strains in ground turkey (23.5%) and chicken breasts (20.2%). Kobayashi et al.
 isolated 80 strains from 57 retail chicken carcasses, and grouped 21.25% of the strains into group B2 and 28.75% into group D. It has been recently shown that B2 strains positive for svg belong to a subset of ExPEC strains that contain avian pathogenic, uropathogenic as well as neonatal meningitis causing E. coli. These strains often belong to serogroups O1, O2 or O18, and contain a high number of virulence genes. In this study, such ExPEC bacteria were found in 1% of Finnish poultry meat products. The isolates belonged to serogroup O1, and contained seven of the ten virulence genes studied.
Fecal contamination of carcasses at slaughter is presumed to be the source of contamination of meat with potential ExPEC bacteria
[24–26]. However, our previous studies (unpublished) detected E. coli fulfilling ExPEC criteria only in 2.3% of fecal samples from healthy broilers. All these isolates belonged to phylogroup D, and none to B2. Our studies have shown that colibacillosis caused by avian pathogenic E. coli is not an uncommon disease in Finnish broiler houses. The study shows that such ExPEC bacteria can efficiently contaminate poultry meat and enter the food chain. In Finland, poultry meat is usually cut into pieces or very thin slices. It can be speculated that cutting may provide favorable or even selective conditions for the survival of ExPEC bacteria in the product consisting of meat and meat juice. The conditions may mimic those in the host tissue, thus supporting the survival of bacteria possessing protective virulence mechanisms. Meat processing may favor the survival of other types of E. coli as well, such ESBL-producing strains, in the meat products.
Marinades and especially their spices may potentially serve as sources of food pathogens, and furthermore promote pathogen survival. This has been a matter of concern in Finland, where most of the poultry meat is sold in marinades. In this study, we did not observe any differences between E. coli strains from marinated and non-marinated products with regard to prevalence of potential ExPEC and other virulence factor genes and phylogenetic groups. The studies on survival of E. coli in marinated meat products have focused on verocytotoxigenic strains. It has been stated that acidification of a traditional marinade resulted in greater lethality of E. coli O157:H7 compared with otherwise similar marinades that were not further acidified
[27, 28]. The pH of commercial marinades used in Finnish retail poultry meat products ranges from pH 4.16 ± 0.03
 to pH 4.5
. It has been speculated that the buffering capacity of meat might neutralize the acidic components in marinades, leading to a decreased antimicrobial effect
. Although this study did not indicate that marinades are a risk factor for ExPEC contamination of the product, it is necessary to study the effect of marinades on survival of zoonotic E. coli, such as ESBL-producing strains.
In the present study, all potential ExPEC isolates (n = 48) were susceptible to ciprofloxacin and cephalosporins, and only one isolate exhibited resistance to nalidixic acid. These results illustrate the very low level of antimicrobials used in poultry production in Finland. Meat producing flocks, in particular, are usually reared without any antimicrobial treatment. The percentage of flocks treated has varied between 0.0 and 0.37% in broiler flocks and 3.79–4.97% in turkey flocks during 2007–2010 (
http://www.ett.fi). No fluoroquinolones or cephalosporins are used for poultry. Cephalosporin resistant E. coli isolates have emerged in numerous locations around the world after the sampling time of this study. This study, covering the Finnish retail market in 2006–2007, serves as a starting point for further studies. It is essential to gain more information about the antibiotic resistance and the genetic properties of the E. coli isolates present in retail poultry meat in Finland.