Assignment of serotype to Salmonella enterica isolates obtained from poultry and their environment in southern Brazil

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 (406%), Enteritidis (342%), Hadar (84%), Typhimurium (39%), Gallinarum (32%), Agona (13%), Cerro (13%), Livingstone (13%), Infantis (06%), Isangi (06%), Mbandaka (06%), Montevideo (06%) and Senftenberg (06%). 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 852%, 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.