Multiple analysis of a foodborne outbreak caused by XXXX formula contaminated by an atypical Salmonella virchow strain.

@entity1 @entity1132 @entity4968
An outbreak of food @entity4968 involving most autonomous Spanish communities was detected in the first half of 1994. The causative food was @entity1 formula milk contaminated by @entity1132 -fermenting Salmonella virchow. It was not possible to isolate the causative strain from the manufacturer's facilities. During the same period of time, there was a significant increase in @entity1132 -non-fermenting Salmonella virchow strains compared with the same period in previous years. Simultaneously, @entity1132 -non-fermenting strains were recovered from clinical samples from @entity1 and from some milk samples that were involved in the outbreak. Therefore, it was speculated that the outbreak might be more extensive than initially thought. The following epidemiological markers were used for typing the Salmonella virchow strains involved in the outbreak: (i) phage typing: (ii) ribotyping, using a set of 20 different endonucleases: and (iii) pulsed-field gel electrophoresis, using three different endonucleases. The most useful markers for this serotype were phage typing and pulsed-field gel electrophoresis, since ribotyping was not able to distinguish all strains tested. The results obtained revealed that the outbreak was caused by at least two strains: one presenting phage type 4-4a and pulsed-field patterns A1 or A2 and L+ or L-, and another presenting phage type 2 and pulsed-field patterns A1 or A2 and L+ or L-. The results indicate that the outbreak was more extensive than initially thought and that the Virchow serotype is very clonal in Spain.
