Microorganisms (Sep 2023)

Occurrence of a New Variant of <i>Salmonella</i> Infantis Lacking Somatic Antigen

  • Alessandra Alessiani,
  • Gianfranco La Bella,
  • Adelia Donatiello,
  • Gilda Occhiochiuso,
  • Simona Faleo,
  • Antonella Didonna,
  • Luigi D’Attoli,
  • Patrizia Selicato,
  • Carmine Pedarra,
  • Giovanna La Salandra,
  • Maria Emanuela Mancini,
  • Pietro Di Taranto,
  • Elisa Goffredo

DOI
https://doi.org/10.3390/microorganisms11092274
Journal volume & issue
Vol. 11, no. 9
p. 2274

Abstract

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Salmonella Infantis is one of the most frequent serovars reported in broilers and is also regularly identified in human salmonellosis cases, representing a relevant public health problem. In the laboratories of the Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata (IZSPB), six Salmonella Infantis strains with antigenic formula -:r:1,5 have been isolated from the litter and carcass of broilers between 2018 and 2022. The strains were investigated to evaluate their phenotype, antibiotic resistance and genomic profiles. Genomic analysis confirmed that the isolates belonged to the Infantis serotype and to the sequence type ST32. Moreover, all strains showed a multidrug-resistant (MDR) profile and were characterised by the presence of the IncFIB plasmid incompatibility group. Three strains had the blaCTX-M-1 gene, and one of them carried IncX1. The presence of this new variant of S. Infantis is particularly relevant because it could expand the landscape of the S. Infantis population. The absence of the somatic antigen could pose a problem in both isolation and serotyping and a consequent public health concern due to the spread of Salmonella infection.

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