Molecular Characterization of Salmonella from Human and Animal Origins in Uganda

Sporadic Salmonella outbreaks with varying clinical presentations have been on the rise in various parts of Uganda. The sources of outbreaks and factors underlying the different clinical manifestation are curtailed by paucity of information on Salmonella genotypes and the associated virulence genes. This study reports molecular diversity of Salmonella enterica and their genetic virulence profiles among human and animal isolates. Characterization was done using Kauffman-White classification scheme and virulence genes analysis using multiplex PCR. Overall, 52% of the isolates belonged to serogroup D, 16% to serogroup E, 15% to poly F, H-S, and 12% to serogroup B. Serogroups A, C1, and C2 each consisted of only one isolate representing 5%. Virulence genes located on SPI-1 [spaN and sipB] and on SPI-2 [spiA] in addition to pagC and msgA were equally distributed in isolates obtained from all sources. Plasmid encoded virulence gene spvB was found in <5% of isolates from both human epidemic and animal origins whereas it occurred in 80% of clinical isolates. This study reveals that serogroup D is the predominant Salmonella serogroup in circulation and it is widely shared among animals and humans and calls for joint and coordinated surveillance for one health implementation in Uganda.