Salmonella infections in finishing pigs in The Netherlands: bacteriological herd pre-valence, serogroup and antibiotic resistance of isolates and risk factors for infection

Salmonellae are wide spread in man and animals world wide and are of increa sing significance as causative agents of foodborne diseases in man. The Eur opean Union, national authorities and the pig industry are therefore more a nd more interested in the Salmonella status of the pig population. The aim of this study was to estimate the bacteriological prevalence of Sal monella in finishing pig herds, the serogroup and the resistance to antibio tics of the isolated Salmonellae and a preliminary risk analysis of factors associated with infection. For this, 317 finishing pig herds were randomly selected from a database co ntaining 1500 herds in the southern part of the Netherlands. In each herd 2 4 samples of fresh faeces were collected from two compartments with pigs cl ose to market weight. Per compartment 12 samples of faeces were pooled into one pooled sample. Pooled samples were cultured in duplicate. Salmonella spp. were recovered from 71 out of 306 herds (23%) in which two compartments could be sampled, A total of 108 isolated Salmonella's were se rotyped: 71 serogroup B, 3 serogroup C1, 6 serogroup C2, 22 serogroup D1, a nd 6 isolates neither serogroup B, C or D1. Of a total of 115 Salmonella is olates tested, none were resistant to colistin, enrofloxacin, flumequin or gentamicin. Automated liquid feeding of by-products, and membership of an I ntegrated Quality Control (IQC) production group were associated with a dec reased risk of infection, while use of trough feeding was associated with a n increased risk of infection. It is necessary to test these presumed risk factors in intervention studies to evaluate their potency to reduce the Sal monella prevalence in finishing pigs and thereby reduce the risk of Salmone llosis in people consuming pork. (C) 1999 Elsevier Science B.V. All rights reserved.