Characterization of Campylobacter jejuni strains from different hosts and modelling the survival of C. jejuni in chicken meat and in water

Manuel González

Tutkimustuotos: OpinnäyteVäitöskirjaArtikkelikokoelma

Abstrakti

Campylobacter spp. are recognized as a major cause of bacterial food-borne gastroenteritis worldwide, with Campylobacter jejuni and Campylobacter coli being the most common species isolated in human infections (WHO, 2011). The number of registered cases of human campylobacteriosis in Finland has ranged from 3,796 cases in 2001 to 4,231 cases in 2011. The reported incidence in Finland in the last 10 years is higher than the European Union average.

In order to compare human, chicken and cattle C. jejuni isolates, the presence or absence of four nonubiquitous genes were determined so that they could be associated with the source of the isolate. First, we tested the presence of dmsA, which encodes a subunit of the putative tripartite anaerobic dimethyl sulfoxide oxidoreductase (DMSO/trimethylamine N-oxide reductase). Second, we detected cj1585c, which encodes another oxidoreductase. Third, the serine protease gene cjj81176-1367/1371 was isolated. Fourth, γ-glutamyl-transpeptidase gene ggt was detected. We ascertained that ggt and dmsA are present more frequently in isolates obtained from humans and chickens, whereas cjj81176-1367/1371 and cj1585c are the most common in bovine isolates.

Campylobacter jejuni is able to survive in different environments and in a wide range of temperatures. The study of C. jejuni inactivation in minced chicken meat and dug well water ascertain that the Weibull model could be applied optimally to the data to build a reliable prediction model for the survival of this microorganism as a function of temperature. The longest survival time found for C. jejuni in minced meat chicken was at the storage temperature of -20°C, and that of dug well water was at 4°C.

We analyzed the effect of different seasoning as dry marinade combinations on accelerating the reduction of C. jejuni counts on chicken drumsticks and observed a decrease of more than 1 log CFU/g. In addition, our results showed that using some fractions of potato protein in combination with food additives and sodium lactate obtained inactivation levels in excess than 1.66 log CFU/g. The most important C. jejuni counts reductions were always obtained within the first hours after the application of the seasoning combinations onto the chicken meat.

Alkuperäiskielienglanti
JulkaisupaikkaHelsinki
Kustantaja
Painoksen ISBN978-952-10-8165-1
Sähköinen ISBN978-952-10-8166-8
TilaJulkaistu - 2012
OKM-julkaisutyyppiG5 Tohtorinväitöskirja (artikkeli)

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