Clonal spread of pESI-positive multidrug-resistant ST32 Salmonella enterica serovar Infantis isolates among broilers and humans in Slovenia

Papić, Bojan (author), Kušar, Darja (author), Mićunović, Jasna (author), Pirš, Mateja (author), Ocepek, Matjaž (author), Avberšek, Jana (author)

Salmonella enterica subsp. enterica serovar Infantis is the most prevalent serovar found in broilers and broiler meat and is among the top five serovars responsible for human infections in Europe. In 2008, a multidrug-resistant S. Infantis isolate emerged in Israel with a mosaic megaplasmid named pESI, associated with increased virulence, biofilm formation, and multidrug resistance. Since then, S. Infantis clones with pESI-like plasmids have been reported worldwide, replacing pESI-free clones. Here, we typed 161 S. Infantis isolates of poultry (n = 133) and human clinical (n = 28) origin using whole-genome sequencing. The isolates were collected between 2007 and 2021. In addition, we performed PacBio/Illumina sequencing for two representative pESI-like plasmids and compared them with publicly available sequences. All isolates belonged to sequence type 32 (ST32), except for one isolate that represented a novel single-locus variant of ST32. Core genome MLST (cgMLST) analysis revealed 14 clusters of genetically closely related isolates, of which four suggested broiler-to-human transmission of S. Infantis. pESI-like plasmids were present in 148/161 (91.9%) isolates; all were highly similar to the publicly available pESI-like sequences but lacked extended-spectrum beta-lactamase (ESBL) genes. PacBio/Illumina hybrid assembly allowed the reconstruction of two novel complete pESI variants. The present study revealed that the multidrug-resistant, pESI-positive S. Infantis clone became the predominant S. Infantis clone in Slovenian broilers and humans during the last decade. Continued surveillance of resistant S. Infantis clones along the food chain is needed to guide public health efforts.

• Language: English
• Keywords: Salmonella Infantis, ST32, pESI, multidrug resistance, broilers, humans
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: VF - Veterinary Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2022
• Number of pages: 9 str.
• Numbering: Vol. 10, no. 6, [article no.] e02481-22
• PID: 20.500.12556/RUL-145025
• UDC: 636.09:579
• ISSN on article: 2165-0497
• DOI: 10.1128/spectrum.02481-22
• COBISS.SI-ID: 130438147
• Publication date in RUL: 30.03.2023

Record is a part of a journal

• Title: Microbiology spectrum
• Shortened title: Microbiol. spectr.
• Publisher: ASM Press
• ISSN: 2165-0497
• COBISS.SI-ID: 4526968

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 30.03.2023