Molecular Detection of Some Virulence Genes in Salmonella Spp Isolated from Food Samples in Lagos, Nigeria

Abstract

Food-borne salmonellosis is the most prevalent disease and major source of Salmonella spp in humans and its detection particularly in developing countries is quite cumbersome and time consuming. Molecular methods for its detection as well as the genotypic diversity of some of the genes responsible for Salmonella virulence are necessary. The aim of the study was to screen for Salmonella spp using the 16S rRNA, to determine whether the invA gene is specific for Salmonella detection as well as virulence genotyping of some genes present in Salmonella spp (invA, sitC and spvA, spvB and spvC) from food samples in Lagos, Nigeria. All 76 isolates tested positive for 16S rRNA gene while 53 (69.7%) were positive for salm3 and salm4 (389 bp) gene. PCR analysis of the invA gene (284bp) showed that 73 (96.1%) were positive, 38 (50%) of the isolates were positive for sitC gene while none were positive for spvA and spvB and with the multiplex-PCR of invA/spvC gene 25 (33%) were positive for invA (244 bp) gene and none positive for spvC gene. The use of invA gene for Salmonella detection in our food samples is recommended however for most of our isolates the virulence genes were not detected.

Antimicrobial resistance and virulence genes of invasive Salmonella enterica from children with bacteremia in north-central Nigeria

“…Invasive typhoid and non-typhoidal Salmonella have been previously reported in Nigerian children. 5,8,27,67,68 Regarding the serovars found in this study, S. typhi was the highest, followed by S. choleraesuis, S. enteritidis, and S. typhimurium. Salmonella typhi is the most common serovar in invasive Salmonella infection in children, according to previous studies conducted in Nigeria and elsewhere.…”

“…Salmonella typhi is the most common serovar in invasive Salmonella infection in children, according to previous studies conducted in Nigeria and elsewhere. 5,8,67,[69][70][71] Serovars S. enteritidis and S. typhimurium are not frequently observed in invasive non-typhoidal infections in industrialized countries. Still, in sub-Saharan Africa, they are becoming a reoccurring decimal.…”

“…Salmonella strains isolated from invasive environments resist many of the most widely used antibiotics. 5,67,70,71 In particular, multidrugresistant iNTS caused life-threatening invasive disease outbreaks in children in Nigeria, Rwanda, and Malawi. 67,74,75 The antimicrobial resistance of iNTS is a big problem because it can cause bacteremia in immunocompromised people.…”

“…24,25 Although typhoidal Salmonella is a human host-adapted strain, recent literature has found typhoidal Salmonella in the food chain and water sources. [26][27][28][29][30] The worldwide rise of multi-drug resistance is a major health concern. 31 It is becoming increasingly important to routinely apply antimicrobial susceptibility testing to select the antibiotic of choice and to screen for emerging multidrug resistant (MDR) strains, 32 as several recent studies have reported the emergence of multi-drug resistant Salmonella pathogens from various origins, including humans, 33 birds, 34 cattle, 31 and fish.…”

Salmonella enterica Transmission and Antimicrobial Resistance Dynamics across One-Health Sector

“…Salmonella resistance to Meropenem is an indication to been carbapenemaseproducing [130]. Genotypic techniques are employed to confirm the phenotypic detection of an antibiotic-resistance mechanism [131]. Some of these genotypic methods for antibiotic resistance genes include whole genome sequencing and polymerase chain reaction application.…”