Okpa BO1, Gberikon1, Ogbonna1, Aguoru1
Isolation and molecular characterization of Salmonella serovars in Benue State was undertaken. Conventional cultural characterization and biochemical results showed that eighteen [18]positive samples of Salmonella species were obtained out of the four hundred and twenty [420] samples collected from Patients across the three [3] senatorial districts sampled. The organisms possessed characteristic pinkish colonies and black dots at the center on the XLD agar and whitish-green colonies on BGA. The API tests result showed the difference in the utilization of various substrates that distinguished between Salmonella species and other members of Enterobacteriaceae. Four [4] distinct serovars of S.enterica and one from S.bongori, totaling eight different groups of Salmonella were observed. S.enterica Typhimurium was the highest with 6 [33.33%] and prevalence of 1.43% followed by S.enterica Enteritidis with 4 [22.22%] and prevalence of 0.95%. Other serovars had <0.5% prevalence. S.entericaTyphi and S.enterica Heidelberg had 2 cases each while the remaining four [S.enterica Agona, S.enterica Paratyphi B, S.enterica Huaian and S.bongori] had a lone case each. Significant association was established between occurrence of Salmonella infection and causative serovars [χ2= 57.93, P<0.05]. Molecular characterization results obtained showed that the dendrogram formed 2 main clusters [numbered 36 and 81] with two divergent Salmonella strains. The first sub cluster of main cluster [numbered 57] has four strains isolated from different locations: S.entericaHeidelberg- MG663473.1 from Gboko; S.entericaTyphimurium- JQ228518.1 from Katsina-Ala; S.enterica Typhimurium- CP014981 from Makurdi and S.enterica Typhimurium- CP023166.1 from Kwande. Seventy five percent [75%] of strains in this group were Typhimurium serovars. In this group, S.entericaTyphimurium-CP023166.1 sourced from Kwande was a unique strain that showed wider genetic variability but closely related to the check strain [S.bongori strain KU060291.1]. The second sub cluster of a main [numbered 98] also consisted of 3 strains all of different serovars of S.enterica and one strain of another species. They are: S.entericaParatyphi B-JQ694526.1; S.enterica Heidelberg-CP019176.1; S.enterica Typhimurium- CP024619.1 and S.bongori-FR877557.1. The latter belongs to the same group with Paratyphi serovar and even closely related with Paratyphi B strain MF772492.1 used as a check. The second main cluster [numbered 81] comprised 8 strains belonging to 4 Enteritidis, 2 Typhi, 1 Huaian and 1 Typhimurium cutting across all locations except Gboko. Within this group, 4 strains showed wider relationships with other members and they were all of different serovars while Typhimurium strains were either closely clustered to themselves or to the Typhi strain. S.entericaTyphimurium- Mh496335.1 is divergent from the source of the main clusters [88] bearing no close relationship with any existing check strain. The most unique of all the 18 strains identified was the S.enterica serovar Agona strain 392869-2 and is closely related with a known check Enteritidis strain.
