Prevalence of Salmonella Bloodstream Infection and Antimicrobial Resistance in Lagos, Nigeria.

The burden of bacteremia in febrile cases is still poorly understood in Nigeria as in many sub-Saharan African countries due to diagnostic limitations. This study aimed to determine the prevalence of Salmonella bloodstream infections and antimicrobial resistance patterns of bacterial isolates recovered from febrile patients in Lagos, Nigeria.

A total of 300 blood samples were collected from febrile patients attending four medical centers in Lagos during August 2020 to July 2021. Clinical isolates were identified using API 20E kit. qPCR was used to detect Salmonella isolates in positive blood culture samples using a specific primer set. All isolates were subjected to antimicrobial susceptibility tests using standard procedures.  

  Totally, 55 bacterial isolates belonging to six bacterial genera were identified, including Salmonella (n=4, 7.27%), Klebsiella species (n=23, 41.82%), Escherichia coli (n=6, 10.91%), Proteus species (n=13, 23.64%), Serratia species (n=7, 12.73%), and Citrobacter species (n=2, 3.64%). In this study, the detection rate of Salmonella isolates in positive blood culture samples using qPCR and invA gene primer set was 100%. Salmonella isolates were 100% resistant to ceftazidime, cefotaxime, and doripenem. Multidrug resistance (MDR) was observed in Salmonella and other bacterial isolates.

  In this study, qPCR using the invA primer set was found to be highly specific for Salmonella detection. All the bloodstream bacterial pathogens in this study were MDR; thus, there is a need for continuous evaluation of antibiotics in medical settings.  Further molecular studies on these bacterial isolates is essential.