Salmonella in breeding pigs: Shedding pattern, transmission of infection and the role of environmental contamination in Irish commercial farrow‐to‐finish herds

Abstract

SummaryThis study aimed to provide new insights into the epidemiology of Salmonella in pig production, focusing on potential shedding patterns in breeding pigs throughout a full production cycle and the risk of transmission of infection from the sow to her offspring. A longitudinal study was conducted on five farrow-to-finish commercial pig farms. In each herd, shedding of Salmonella in faeces was monitored in breeders through service, gestation and lactation. Swabs of the farrowing room floor and pools of faeces from piglets were collected on two occasions during lactation. Environmental pen swabs were also taken in the weaning and finisher houses. Salmonella isolates were serotyped, tested for antimicrobial resistance (AMR) and typed by Multiple-Locus Variable number tandem repeat Analysis (MLVA). Shedding by breeding pigs was low in all stages of the production cycle; 5% of sows shed at service, the production stage with highest risk of shedding (p < .01), 1.6% shed during gestation and 2.5% after farrowing. Salmonella was detected in 4% of piglet faecal pools in the second week postfarrowing and 5% in the fourth week. Serotyping and AMR profiles of Salmonella isolates revealed that strains in sows and gilts were mostly different from strains isolated in weaner and finisher facilities. MLVA typing confirmed that the source of infection in piglets was in most instances the contaminated environment rather than their dam. Based on the typing results, it appears that sows do not pose a major risk in the maintenance and transmission of Salmonella to their progeny but instead the contaminated pen environment is more significant in the perpetuation of the organism on farm. K E Y W O R D SBreeding sows, Environmental contamination, Pigs, Salmonella

Weaned piglets: another factor to be considered for the control of Salmonella infection in breeding pig farms

“…Both the prevalence of shedding in weaned sows and the serotypes found were variable between farms (Tables 2 and 4). Overall prevalence of Salmonella shedding was higher (21.9%) than that reported in other studies with levels of seroprevalence similar to those found here [4, 17, 21, 50, 51]. This difference may be attributed to methodological differences between studies, such as including sows of different parities, animal management and immune status.…”

“…Due to the stress associated with weaning, the post-weaning period seems to present higher risk for Salmonella shedding in sows [21, 50]. For this reason, recently weaned sows were sampled to determine the most prevalent on-farm circulating serotypes.…”

“…With regard to suckling piglets in intensive-reared pig farms, a few published studies suggest that the prevalence of Salmonella shedding is, in general, low (< 10%) [3, 17–20]. Even when pools of fresh feces were used, the mean prevalence of shedding in these piglets was < 5% [21]. However, results from all these studies are based mostly on the analysis of a small amount of feces, in many occasions collected through rectal swabs.…”

Characterization of Antimicrobial Resistance Determinants and Class 1 and Class 2 Integrons in Salmonella enterica spp., Multidrug-Resistant Isolates from Pigs

“…Theoretically, limiting or even removing the use of antibiotics will decrease the presence of antimicrobial resistance (AMR) in microorganisms, such as Salmonella , either by losing the AMR determinants that are located in mobile elements such as plasmids, or by the replacement of the strains that are circulating on farms by others that adapt better to a new antibiotic-free scenario. The large number of studies that are focused on phenotypic characterization of AMR in Salmonella isolates recovered from swine [ 9 , 16 , 17 , 18 ], contrast to the scarce information about the genetic determinants that confer resistance to these antimicrobial compounds [ 19 , 20 ]. While considering the forthcoming scenario, more information about the genetic determinants in Salmonella is required to better understanding the mechanisms which confer these AMR, their potential spread and how an antibiotic-free animal production system would impact in the reduction of MDR bacteria in farm animals.…”

Salmonella shedding status of the sow affects the microbiota of their piglets at weaning

“…; Lynch et al . ). It has been hypothesized that piglets are protected against vertical transmission of Salmonella colonization by the antibodies transferred by the sows (Matiasovic et al .…”