Le Centre national de référence (CNR) des Salmonella (Institut Pasteur) said the 25 cases identified retrospectively occurred between 2006 and 2016 with no grouping over time or in a specific region.
Institut Pasteur said it could not say if these cases had drunk infant formula produced at Craon like those infected last year.
The institute found the profile of 2017 cases is the same as that of strains isolated during the 2004-2005 outbreak linked to infant milk produced in the same plant.
A Salmonella Agona outbreak affected 141 confirmed cases in France in 2005 and was associated with two different products manufactured within the same facility as the 2017 outbreak.
The Craon site was owned by Célia in 2005 and bought by Lactalis in 2006.
During the 2005 outbreak, only one of 176 and four of 27 samples from the two implicated food products and six of 420 environmental samples tested positive for S. Agona, suggesting a low level contamination.
Same strain in 2017 and 2005
Lactalis also confirmed the Salmonella Agona strain that caused contamination in 2017 was the same as in 2005.
The firm said it is not withdrawing from the infant nutrition market and is working on a project to build a new facility.
Isolates from the 2005 outbreak did produce hydrogen sulfide (H2S) and gas after 18 hours of incubation Kligler-Hajna media unlike isolates from the outbreak in 2017.
Lactalis said contaminated infant milks and nutritional products were manufactured in the Craon Tower number 1. It has made the decision to stop activity of the tower.
Contamination was identified at the foot of the tower before spreading to the whole of it. It was sporadic but spread enough over several months to present risks at several places of the tower.
Construction work from the start of 2017 freed the bacteria which then spread in the tower.
Plan to restart
Lactalis said reinforced controls since December mean its control plan needs to be improved and it will present a plan to authorities to restart the second tower and packaging lines.
The firm added it will look at sensitivity of analyzes by its external laboratory after nearly 16,000 tests came back clear and did not identify S. Agona presence.
Lactalis said if analyzes of finished products had revealed the pathogen it would not have commercialized the products and would have avoided the crisis.
The outbreak affected 39 children under one year of age: 37 in France, one in Spain confirmed by whole genome sequencing (WGS) and one in Greece.
However, this weekend the Department of Health of the Basque Government said it had confirmed a second case of a baby affected by Salmonella who had consumed formula milk prepared by Lactalis.
Osakidetza said the baby's health is good and was treated at the Hospital Universitario Basurto.
Pepti Junior de Picot, Picot SL, Picot anti-colique, Picot riz and Milumel Bio 1 sans huile de palme are affected brands.
L’Association des Familles Victimes du Lait Contaminé aux Salmonelles (AFVLCS) said it was aware of 10 additional cases of babies diagnosed with salmonellosis that were not recorded by Santé Publique France.