Molecular epidemiological survey of Listeria monocytogenes in broilers and poultry products.

Aims: To investigate the prevalence of Listeria monocytogenes in poultry products, and to elucidate whether poultry products may be linked to listeriosis cases. A further goal was to identify contamination routes for L. monocytogenes to broiler carcasses.

Occurrence of and a possible mechanism for resistance to a quaternary ammonium compound in Listeria monocytogenes.

In a study of 200 Listeria monocytogenes isolates, 10% were determined to be resistant to benzalkonium chloride (BC). Serial subcultivation of initially BC sensitive (BC(S)) and BC resistant (BC(R)) isolates in sublethal concentrations of BC resulted in enhanced and approximately equal resistance of all strains to the compound. Fifty per cent of the BC(R) isolates showed resistance to ethidium bromide (EB) as well.

Molecular epidemiological survey of Listeria monocytogenes in seafoods and seafood-processing plants.

To evaluate the role of seafoods in the epidemiology of human listeriosis and the role of the processing environment as a source of Listeria monocytogenes in seafood products, 305 L. monocytogenes isolates were characterized by multilocus enzyme electrophoresis using 21 genetic loci and restriction enzyme analysis of total DNA. Forty-four isolates were recovered from patients in Norway; 93 were isolated from seafoods, seafood-processing environments, and seawater from 55 different producers; and the remaining 168 isolates originated from six seafood-processing plants and one transport terminal examined in detail for L.

Optimization of sample cleanup procedure for determination of diarrhoeic shellfish poisoning toxins by use of experimental design.

In routine monitoring of diarrhoeic shellfish poison (dinophysistoxin-1 and okadaic acid) there appeared to be an inconsistency between the mouse bioassay and existing chemical analysis based on liquid chromatography. The sample cleanup procedure has been subject to minor modifications in an effort to overcome the problem. However, further studies have appeared necessary and in this study all experimental factors that can influence the sample cleanup using solid-phase extraction columns prior to the LC analysis have been evaluated by use of experimental statistical design in order to understand the effect of the various factors and to optimize the conditions for recovery of the toxins.

Lipids of heliobacteria are characterised by a high proportion of monoenoic fatty acids with variable double bond positions.

The fatty acid composition and lipid pattern of six strains of heliobacteria have been analysed. The results were fairly uniform for all strains. Phosphatidyl ethanolamine and phosphatidyl glycerol were the dominating lipids found, with the former as the major one.