The spoilage flora of vacuum-packaged, sodium nitrite or potassium nitrate treated, cold-smoked rainbow trout stored at 4°C or 8°C

http://www.elsevier.nl/locate/01681605The spoilage flora of vacuum-packaged, salted, cold-smoked rainbow trout fillets, with or without the addition of nitrate or nitrite, stored at 4°C and 8°C, was studied. Of 620 isolates, lactic acid bacteria were the major fraction (76%), predominating in all samples of spoiled product. However, the phenotypical tests used were insufficient to identify the lactic acid bacteria to the species level. Gram-positive, catalase-positive cocci, Gram-negative, oxidase-negative rods and Gram-negative, oxidase-positive rods were found in 6%, 16% and 2% of the samples, respectively. Of 39 Gram-positive, catalase-positive cocci, 29 were identified as staphylococci and 10 as micrococci. Eighty-five isolates were found to belong to the family Enterobacteriaceae, with 45 of those being Serratia plymuthica. Eleven isolates from the nitrate treated samples stored at 8°C were identified as Pseudomonas aeruginosa. The occurrence of P. aeruginosa and staphylococci in the nitrate-containing samples, stored at 8°C, may cause problems with respect to the safety of the product. The types of lactic acid and other bacteria in the spoilage flora were generally reduced by the addition of nitrate or nitrite to fillets

Characterisation of ropy slime-producing Lactobacillus sakei using repetitive element sequence -based PCR

http://www.elsevier.nl/locate/01681605Eighteen earlier well characterised Lactobacillus sake strains representing different slime production capabilities in vacuum-packaged meat products were analysed using repetitive element sequence-based PCR (rep-PCR). The single primers BOXA1R and RW3A and the primer pair REP1R-Dt & REP2R-Dt were evaluated for their applicability in L. sake genotyping. The five different patterns produced by RW3A were least revealing, with the discriminatory power equalling to ribotyping. BOXA1R and REP-primer pair both produced six different banding patterns and the combination of these results yielded seven different rep-types. Rep-PCR was concluded to have approximately the same discriminatory power as randomly amplified polymorphic DNA (RAPD) analysis, but it was inferior to pulsed-field gel electrophoresis (PFGE). How-ever, if the results of rep-PCR and RAPD were combined, the discrimination was comparable PFGE, with the exception that within Ribogroup I the non-slime-producing strains were not distinguished from weak slime producers. It was concluded that the combination of the two PCR-based typing techniques, rep-PCR and RAPD, would be a valuable tool in large scale contamination studies at the meat processing plants, since results can be obtained rapidly and fewer isolates need further analysis by PFGE

Safety evaluation of sous vide-processed products with respect to nonproteolytic Clostridium botulinum by use of challenge studies and predictive microbiological models.

Sixteen different types of sous vide-processed products were evaluated for safety with respect to nonproteolytic group II Clostridium botulinum by using challenge tests with low (2.0-log-CFU/kg) and high (5.3-log-CFU/kg) inocula and two currently available predictive microbiological models, Food MicroModel (FMM) and Pathogen Modeling Program (PMP). After thermal processing, the products were stored at 4 and 8°C and examined for the presence of botulinal spores and neurotoxin on the sell-by date and 7 days after the sell-by date. Most of the thermal processes were found to be inadequate for eliminating spores, even in low-inoculum samples. Only 2 of the 16 products were found to be negative for botulinal spores and neurotoxin at both sampling times. Two products at the high inoculum level showed toxigenesis during storage at 8°C, one of them at the sell-by date. The predictions generated by both the FMM thermal death model and the FMM and PMP growth models were found to be inconsistent with the observed results in a majority of the challenges. The inaccurate predictions were caused by the limited number and range of the controlling factors in the models. Based on this study, it was concluded that the safety of sous vide products needs to be carefully evaluated product by product. Time-temperature combinations used in thermal treatments should be reevaluated to increase the efficiency of processing, and the use of additional antibotulinal hurdles, such as biopreservatives, should be assessed

Raudan vaikutus koiran interdigitaaliseen furunkoloosiin

Tutkielma jakaantuu kahteen osaan: kirjallisuuskatsaukseen ja kokeelliseen osuuteen. Kirjallisuuskatsauksen alkuosassa käsitellään koiran interdigitaalista furunkuloosia eli pododermatiittia. Siinä esitellään furunkuloosin erilaiset ilmenemismuodot ja kliiniset piirteet. Pododermatiitin etiologisiin tekijöihin paneudutaan tarkasti. Lisäksi käsitellään diagnostiikkaa, sekä kuvataan yksityiskohtaisesti idiopaattisen, bakteriaalisen pododermatiitin hoito. Kirjallisuuskatsauksen jälkimmäisessä osassa käsitellään koiran normaalia rautametaboliaa ja sen laboratoriodiagnostiikkaa. Tärkeimmät rautametabolian häiriötilat kuvataan yksityiskohtaisesti sekä pohditaan raudan vaikutusta immuunijärjestelmään ja infektioiden vastustuskykyyn. Kokeellisessa osuudessa kartoitettiin interdigitaalista furunkuloosia sairastavien koirien rautametaboliaa kuvaavia parametreja. Lisäksi tutkittiin peroraalisen rautaterapian vaikutusta furunkuloosiin. Tutkimusaineistona oli 60 kroonista, idiopaattista interdigitaalista urunkuloosia sairastavaa koiraa, jotka jaettiin sattumanvaraisesti rautaterapia- ja plaseboryhmiin. Ennen terapiaa potilaista otettiin O-verinäytteet, joista määritettiin hematologiset perusparametrit, punasoluindeksit sekä seerumin rauta- ja TIBC (total ironbinding capacity)-pitoisuus. Lisäksi tassujen leesiot merkittiin tarkasti muistiin. Kolmenviikon terapian jälkeen potilaat tulivat kontrolliin, jolloin otettiin uusintaverinäytteet ja tarkastettiin tassujen leesioissa tapahtuneet muutokset. Rautaterapiaa jatkettiin vielä seuraavat kolme viikkoa. Myös plaseboryhmälle ryhdyttiin tässä vaiheessa antamaan rautaa. Viimeinen kontrolli oli kuuden viikon kuluttua kokeen alusta, jolloin tehtiin samat toimenpiteet kuin edellisellä kontrollikerralla. Furunkuloosi-potilailla todettiin esiintyvän lievää hypoferremiaa. Ero viitevälin keskiarvoon oli tilastollisesti merkitsevä. Samoin punasolujen MCH (punasolun keskimääräinen hemoglobiinimäärä) ja MCHC (punasolun keskimääräinen hemoglobiinipitoisuus) olivat viitearvoja alemmat. Kuudenkaan viikon rautaterapia ei nostanut seerumin rautapitoisuutta normaalitasolle. Sen sijaan punasoluindekseihin rautaterapialla oli selvä vaikutus: kolmen viikon terapian jälkeen MCV (punasolun keskimääräinen tilavuus) oli kasvanut viitearvoja korkeammaksi. Vastaavasti MCH ja MCHC laskivat edelleen. Furunkuloosileesioiden paranemisessa ei ollut tilastollisesti merkitsevää eroa rauta- ja plaseboryhmien välillä kolmen viikon terapian jälkeen. Eroa ei myöskään esiintynyt verrattaessa kuusi viikkoa rautaa saaneiden potilaiden paranemista kolme viikkoa plaseboa syöneiden paranemiseen

Phylogenetic Analysis of Enterohemorrhagic Escherichia coli O157, Germany, 1987–2008

Multilocus variable number tandem repeat analysis (MLVA) is a subtyping technique for characterizing human pathogenic bacteria such as enterohemorrhagic Escherichia coli (EHEC) O157. We determined the phylogeny of 202 epidemiologically unrelated EHEC O157:H7/H– clinical isolates through 8 MLVA loci obtained in Germany during 1987–2008. Biodiversity in the loci ranged from 0.66 to 0.90. Four of 8 loci showed null alleles and a frequency <44.1%. These loci were distributed among 48.5% of all strains. Overall, 141 MLVA profiles were identified. Phylogenetic analysis assigned 67.3% of the strains to 19 MLVA clusters. Specific MLVA profiles with an evolutionary persistence were identified, particularly within sorbitol-fermenting EHEC O157:H–.These pathogens belonged to the same MLVA cluster. Our findings indicate successful persistence of this clone