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Main research questions: Antimicrobial resistance (AR) in the food-chain is a concern due to risk of treatment failure of humans. - Do restrictions on antimicrobial (AB) usage in organic pig production lead to lower AR levels in organic pigs compared to conventional ones? - Is lower AR a quality trait of organic pork? - Does slaughtering of organic and conventional pigs together abolish this potential quality trait? - Can markers for imprudent AR use in organic pig herds be identified?

Økologiske grise indeholder færre antibiotikaresistente colibakterier end konventionelle grise, viser ny europæisk forskning. Men forskellen risikerer at bliver udlignet i slagteprocessen. Spredning af antibiotikaresistente bakterier er generelt bekymrende, fordi den i sidste ende kan betyde, at alvorlige sygdomme hos dyr og mennesker ikke kan behandles. Den årlige overvågning af resistens i danske svinebesætninger målt med E. coli som indikatorbakterie viser, at 28-42 pct. af de testede bakterier er resistente over for de fem antibiotikatyper, hvor der oftest ses resistens. Men der er brug for mere viden om spredning af de resistente bakterier. I det fælleseuropæiske forskningsprojekt SafeOrganic har vi derfor undersøgt og sammenlignet forekomsten af resistente bakterier i henholdsvis økologiske og konventionelle svinebesætninger i fire EU-lande.

Restrictive use of antibiotics in organic animal farming – a potential for safer, high quality products with less antibiotic resistant bacteria

Providing guidance on detailed rules of a food safety criterion (FSC) for fresh poultry meat (chicken and turkey) during shelf life (i.e. n and c values) with the purpose to be in accordance with the existing process hygiene criterion (PHC) on poultry carcasses (i.e. n=50, c=7) proved to be difficult given differences between both criteria in their principle concepts and methodological design. The selected approach taken was to estimate, based on certain assumptions, possible n and c values of an FSC that performs detecting a similar Salmonella prevalence to that detected by the current PHC with a given degree of certainty. Calculations presented consider both batch and carcass prevalence. Guidance was additionally provided on a possible revision of both the PHC and the FSC when the EU target (1% or less broiler flocks remaining positive for Salmonella Enteritidis or Salmonella Typhimurium) would be achieved. If a target for only these two serovars is set for flock prevalence, the impact on the prevalence of Salmonella on carcasses will depend on the relative contribution of those two serovars to all Salmonella serovars. Thus, if the current flock prevalence target is changed to a prevalence target for all serovars there may be a better relationship between the occurrence of flock infection and the prevalence of Salmonella in carcasses. Advice is given on possible changes in both the PHC and the FSC under such low Salmonella flock prevalence scenario. A series of recommendations are made on data needs in case future related analysis would be needed.

A specific PCR assay was used to detect Salmonella in enriched broths of 48 natural samples of minced pork and 48 natural samples of minced beef. By comparison with a routine culture method, the sensitivity of the PCR method was estimated to be 92% and the specificity of the PCR method was estimated to be 99%. The sensitivity of the culture method was estimated to be 50% in this study.

Synthetic oligonucleotides have been deduced and synthesized based on the sequence of a salmonella‐specific polynucleotide probe. Two oligonucleotide probes, ST4 and ST15rev hybridized to 93 and 92 strains respectively out of 93 strains of Salmonella analysed. ST4, however, cross hybridized to one of the 28 strains of 16 genera of Enterobacteriaceae tested. Based on sequence alignment, in 16 strains of Salmonella, of a 114 base pair region, a Salm. typhimurium specific oligonucleotide probe, ST22, was identified. In colony hybridization, this probe detected all 47 strains of Salm. typhimurium analysed without hybridization to 94 strains of other Salmonella serotypes and to 26 strains of non‐Salmonella bacteria.

DNA-hybridization and the polymerase chain reaction (PCR) are techniques commonly used to detect pathogenic bacteria. In this paper, the use of these techniques for detection of Salmonella, E. coli, V. cholerae, non-O1 Vibrio, Yersinia enterocolitica, Campylobacter, Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, and C. botulinum is reviewed with emphasis on application in food microbiology. In food control, DNA-techniques have most often been used in a 'culture confirmation' fashion, i.e. bacteria are enriched and sometimes even purified by traditional culture procedures and thereafter identified by the use of DNA-based methods. The most desirable approach is, however, to detect organisms directly in the food, but major problems remain to be solved before this can be routinely performed.

Polymerase chain reaction (PCR) primers for genus specific detection of Salmonella have been selected from a Salmonella-specific fragment of 2·3 kilobases (kb). Due to interserovar sequence diversity within this fragment, primer selection was based on DNA sequence alignment of sequences from 20 different Salmonella serovars. The specific PCR product of 429 base pairs (bp) was formed from 144 of 146 salmonella strains tested (116 of 118 serovars). The two false-negative strains belonged to two different serovars of the rarely isolated subspecies IIIa (monophasic S. arizonae). No product was produced in any of 86 non-Salmonella Enterobacteriacea strains tested, covering 41 species from 21 genera.

A 2.3 kilobase (kb) Salmonella probe, JEO402‐1, and two subfragments, F1214 (1.3 kb) and F1217 (0.8 kb), have been evaluated by colony hybridization using pure cultures of Salmonella serovars and non‐salmonella bacteria. JEO402‐1, and its subfragments, F1214 and F1217, hybridized to all of 156 different Salmonella serovars tested, while there was no reaction to 112 non‐salmonella strains belonging to 19 genera and 37 species of Enterobacteriaceae. Together with previously published results, the JEO402‐1 probe has now been shown to detect a total of 396 Salmonella strains belonging to 214 serovars of Slamonella subspecies I‐VI. A total of 178 non‐salmonella strains representing 23 genera and 51 species of Enterobacteriaceae have all tested negative with JEO402‐1. The hybridization results obtained using a digoxigenin‐labeled probe were similar to those obtained with 35S isotopic labeling when complete colony lysis was ensured.