First detection and characterization ofSalmonellaspp. in poultry and swine raised in backyard production systems in central Chile

Abstract

SUMMARYLittle is known aboutSalmonellaserovars circulating in backyard poultry and swine populations worldwide. Backyard production systems (BPS) that raise swine and/or poultry are distributed across Chile, but are more heavily concentrated in central Chile, where industrialized systems are in close contact with BPS. This study aims to detect and identify circulatingSalmonellaserovars in poultry and swine raised in BPS. BacteriologicalSalmonellaisolation was carried out for 1744 samples collected from 329 BPS in central Chile. Faecal samples were taken from swine, poultry, geese, ducks, turkeys and peacocks, as well as environmental faecal samples. Confirmation ofSalmonellaspp. was performed usinginvA-polymerase chain reaction (PCR). Identification of serovars was carried out using a molecular serotyping approach, where serogroups were confirmed by a multiplex PCR ofSalmonellaserogroup genes for fiveSalmonellaO antigens (i.e., D, B, C1, C2-C3, and E1), along with two PCR amplifications, followed by sequencing offliCandfljBgenes. A total of 25 samples (1·4% of total samples) from 15 BPS (4·6 % of total sampled BPS) were found positive forSalmonella. Positive samples were found in poultry (chickens and ducks), swine and environmental sources. Molecular prediction of serovars onSalmonellaisolated showed 52·0% ofS.Typhimurium, 16·0% ofS.Infantis, 16·0%S.Enteritidis, 8·0%S.Hadar, 4·0%S.Tennessee and 4·0%S.Kentucky. Poor biosecurity measures were found on sampled BPS, where a high percentage of mixed confinement systems (72·8%); and almost half of the sampled BPS with improper management of infected mortalities (e.g. selling the carcasses of infected animals for consumption). Number of birds other than chickens (P= 0·014; OR = 1·04; IC (95%) = 1·01–1·07), mixed productive objective (P= 0·030; OR = 5·35; IC (95%) = 1·24–27·59) and mixed animal replacement origin (P= 0017; OR = 5·19; IC (95%) = 1·35–20·47) were detected as risk factors for BPS positivity toSalmonellaspp. This is the first evidence of serovars ofSalmonellaspp. circulating in BPS from central Chile. Detected serovars have been linked to human and animal clinical outbreaks worldwide and in Chile, highlighting the importance of BPS on the control and dissemination ofSalmonellaserovars potentially hazardous to public health.