To prevent shedding in carrier animals, reduce environmental and transport-related stress. Additionally, pens and contaminated fomites must be cleaned and disinfected thoroughly to reduce Salmonella load in the environment. Producers should keep feed in rodent-proof containers to prevent contamination. Antimicrobials are not indicated for treatment of subclinical salmonellosis. Most Salmonella transmission is fecal-oral. However, direct pig-to-pig transmission, inhalation, and vertical transmission also occur.
To diagnose, culture and biochemical testing are used to identify Salmonella, but subtyping is necessary to determine serotype. Techniques used for subtyping include classical serotyping (White-Kauffman scheme), pulsed field gel electrophoresis (PFGE), multiple locus variable number of tandem repeats (MLVA), multilocus sequence typing (MLST), and whole genome sequencing (WGS).
PCR assays are not used for routine diagnosis, but several assays have been described that can differentiate S. 1,4,[5],12:i:- from S. typhimurium. ELISAs may be useful for herd-level screening, and there are several commercial assays available based on lipopolysaccharide (LPS) O-antigen that can identify Salmonella to the serogroup level. For pigs with diarrhea, pooled ileum, colon, and ileocecal lymph node are preferred for culture. Feces or tonsil scrapings can be collected from live pigs. In cases of septicemia, blood, lung, liver, and spleen are acceptable. Most ELISAs can be used with serum or meat juice. In addition, oral fluids may be useful as a surveillance tool.
Antimicrobial treatment is indicated for pigs with clinical signs and lesions suggestive of salmonellosis. Treatment regimens should be based on antibiograms, especially for emerging serotypes like S. 1,4,[5],12:i:- that often demonstrate multi-drug resistance.
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