Assignment of serotype to S almonella enterica isolates obtained from poultry and their environment in southern B razil

Abstract

To assess diversity of Salmonella enterica serotypes present in poultry and their environment from southern Brazil, the Kauffmann–White–Le Minor (KWL) scheme was used to serotype a total of 155 isolates. Isolates were then re-examined with nested PCR and sequencing of the dkgB-linked intergenic sequence ribotyping (ISR) region that assesses single nucleotide polymorphisms occurring around a 5S ribosomal gene. Serotypes identified were Heidelberg (40·6%), Enteritidis (34·2%), Hadar (8·4%), Typhimurium (3·9%), Gallinarum (3·2%), Agona (1·3%), Cerro (1·3%), Livingstone (1·3%), Infantis (0·6%), Isangi (0·6%), Mbandaka (0·6%), Montevideo (0·6%) and Senftenberg (0·6%). Three unique ISRs were detected from four strains. Day old chicks yielded only S. Enteritidis, whereas S. Heidelberg was most often associated with poultry carcasses. Overall agreement between KWL and ISR was 85·2%, with disagreement possibly due to the ability of ISR to detect mixtures of serotypes in culture. Overall, ISR provided more information than did KWL about the ecology of Salm. enterica on-farm. The O-antigen group D Salm. enterica serovars such as Pullorum, Gallinarum and Enteritidis appear susceptible to overgrowth by other serotypes.Significance and Impact of the StudySingle nucleotide polymorphisms found in a group of poultry-associated Salmonella isolates from southern Brazil provided evidence of mixtures of serovar group D serotypes on-farm and in single samples from birds. This finding suggests that co-infection and interserotype competition of Salmonella enterica in poultry could impact the incidence of disease in animals or humans. In addition, unique serotypes were identified on-farm that escaped characterization by antibody typing. Application of cost-efficient and highly discriminatory genomic methods for assigning serotype may alter concepts about the epidemiology of Salm. enterica on-farm and in foods.

Phenotypic and genotypic characterization of Salmonella spp. isolated from foods and clinical samples in Brazil

“…The most frequently observed serotypes in food samples are similar to those reported in other regions of Brazil and around the world (Murakami et al 2007, EFSA 2011, Pulido-Landinez et al 2013. Of 16 serotypes identified among food isolates, Salmonella Infantis was the most frequent serovar (16.0%), followed by Salmonella Enteritidis (14.0%).…”

Molecular and phylogenetic analyses of Salmonella Gallinarum trace the origin and diversification of recent outbreaks of fowl typhoid in poultry farms

“…In addition, none isolate presented positive result with the PCR procedure for SG9R detection, a strong indicative that bvGA field isolates were not originated from SG9R vaccine as described by Van Immerseel et al (2013). We further proceeded with ISR analysis to confirm the Salmonella serotype and biovars, since bvGA and bvPU have different fragment sizes and nucleotide sequences in this genome region (Pulido-Landínez et al, 2013). All bvGA and three bvPU isolates presented complete identity to bvGA and bvPU reference strains, respectively.…”

“…Genomic DNA of all isolates was extracted and submitted to molecular characterization by the following experimental approaches: i) invA real-time PCR for Salmonella generic detection (Hoorfar et al, 2000); ii) glgC conventional PCR for the detection of S. Gallinarum bvGA and bvPU (Kang et al, 2011); iii) speC conventional PCR for the detection of S. Gallinarum bvGA only (Kang et al, 2011); iv) glgC SG9R conventional PCR for detection of the vaccine strain (Kang et al, 2012); and v) operon rrnH intergenic sequence ribotyping (ISR) analysis to observe intra-serotype variation (Pulido-Landínez et al, 2013). The S. Gallinarum bvGA strain BR_RS12 has been previously sequenced, assembled and annotated by our group and a detailed explanation of the applied methodology is explained elsewhere (De Carli et al, 2016).…”

Salmonella Heidelberg reduces nitrergic neurons in the myenteric plexus of the duodenum of broilers

“…Lanzarin (2012) emphasized Salmonella Typhimurium and Salmonella Enteritidis serovars as important in poultry production. They also emphasized the increase in the indexes of Salmonella Heidelberg Brazil, 2014;Liu et al, 2017), Salmonella Agona and Salmonella Senftenberg serotypes in a few regions in Brazil. According to Pulido-Landínez et al (2013), Martins (2015), Sausen (2015), Souza (2015) and Liu et al (2017), S. Heidelberg is currently the most prevalent serotype in poultry farms. Also, the prevalence of this serotype is 20 to 33% of the positive samples for Salmonella spp.…”