Serogenotyping and emergence of extended-spectrum β-lactamase genes in non-typhoidal Salmonella: first report from Saudi Arabia

Salmonella are Gram-negative bacteria with >50 serogroups and >2500 serotypes. Ubiquitous non-typhoidal Salmonella (NTS) serotypes are associated with high morbidity and mortality. The classical approach for Salmonella classification into O-groups based on the O-antigen has been replaced by the Kauffmann–White– Le Minor scheme in which antigenic formulae of the serovars based on the Oantigen, H1-antigen and H2-antigen are denoted (Grimont & Weill, 2007; Guibourdenche et al., 2010). The Kauffmann–White–Le Minor scheme is now the internationally accepted gold standard for Salmonella nomenclature to facilitate international comparability of Salmonella surveillance data and for outbreak investigations (Tindall et al., 2005; Guibourdenche et al., 2010). Available data on the distribution of Salmonella serotypes in Saudi Arabia have been based on classical O-antigen detection method (Kambal, 1996; Somily et al., 2012; Elhadi et al., 2013). In recent years, resistant NTS including those harbouring extended-spectrum blactamase (ESBL) and carbapenemase genes have emerged (S aanchez-Vargas et al., 2011; Somily et al., 2012; Huang et al., 2013). This study was carried out to characterize NTS isolates from Saudi Arabia using serogenotyping and to determine carriage of ESBL and carbapenemase genes.