Salmonella Infection in Mesenteric Lymph Nodes of Breeding Sows

Abstract

Salmonellosis is one of the main foodborne diseases worldwide. Breeding sows asymptomatically infected with Salmonella can transmit the pathogen to piglets and humans. The isolation of Salmonella from mesenteric lymph nodes (MLNs) is considered a demonstration of asymptomatic infection in swine. As previous breeding sow studies have been performed using feces, the aim of this work was to study the occurrence of Salmonella infections by sampling MLNs, in comparison to their serological status. First, Salmonella fecal shedding was studied in 12/16 large breeding farms to establish the framework of study. Then, MLN (n = 264) and blood (n = 237) samples were obtained at an abattoir from sows of 15 of these 16 breeding farms. Additionally, risk factors associated with Salmonella MLN infection were analyzed. A total of 6.1% (16/264) sows, distributed in 40% (6/15) of the farms, had the pathogen in MLN. Salmonella Typhimurium was the most frequent serovar isolated. Interestingly, 43.8% (7/16) of MLN isolates were susceptible to all the antimicrobials tested and were found distributed throughout all farms with at least one sow positive. As well, one isolate of the emerging DT195 clone was detected and found to be resistant to six antibiotic families (ASSuTNx-Cfx). The serovars and the resistance profiles of the Salmonella isolates from feces were completely different to those obtained from MLNs. The seroprevalence (41.8% of sows and 100% of farms) was higher than that of MLN infections, showing no concordance (k = 0.15) between these two diagnostic tests in sows. Strategies directed to correct two risk factors (i.e., administration of dry food and old premises) would most likely help to reduce Salmonella infections in breeding sows.

A Preliminary Study on the Presence of Salmonella in Lymph Nodes of Sows at Processing Plants in the United States

“…There were four MDR isolates from cervical LN and two from mandibular LN. These results are similar to Salmonella prevalence of 6.1% in mediastinal LN from sows at slaughter in Spain [ 19 ]. In that study, serotypes of isolates were: Typhimurium (43.7%), Derby (18.7%), Enteritidis (12.5%), and Montevideo (12.5%) with 9/16 of isolates showing multi-resistance to three or more antimicrobial classes (SSuT, ACSSut, and ASSut-Nx-Cfx).…”

“…The decreased Salmonella isolation rates (0.73%) of Plant B in the present study mirror those of 0% reported for superficial cervical LN [ 17 ] and 0.06% for subiliac LN [ 18 ] of market hogs in U.S. plants. Although not peripheral LN, similar Salmonella prevalence results (6.1%) were reported for mesenteric LN from breeder sows in Spain [ 19 ].…”

Prevalence of Salmonella in Free-Range Pigs: Risk Factors and Intestinal Microbiota Composition

“…For this reason, detecting risk factors associated with the presence of Salmonella in the primary sector is essential for designing mitigation strategies. Additionally, it is interesting that only the monophasic variant was recovered herein, while Salmonella Typhimurium (4,5:12:i:1,2) was the most prevalent serovar detected in fattening pigs and sows within intensive systems [ 11 , 12 , 29 ]. Furthermore, the most common serovars reported in Iberian pigs were Anatum and Typhimurium with resistance to streptomycin and tetracycline [ 25 ], differing from those described in our study.…”

“…Salmonella isolation procedures were performed according to ISO 6579:2002/Amd 1:2007 (ISO) rules [ 10 ], as previously described [ 11 , 12 , 13 ]. All culture media and reagents used were purchased from Laboratorios Conda S.A., Spain.…”

Clinical Breakpoint of Apramycin to Swine Salmonella and Its Effect on Ileum Flora

“…Salmonellosis is one of the most frequent foodborne zoonotic diseases, characterised by abdominal cramps, diarrhoea, fever and vomiting, constituting a worldwide major public health concern [1]. Breeding sows asymptomatically infected with Salmonella can be naturally transmitted directly or indirectly between animals and humans, for example through the consumption of contaminated animal derived food or through contact with infected animals [2].…”