Volume 9, Issue 1 (Winter 2023)
Abstract
Backgrounds: 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.
Materials & Methods: 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.
Findings: 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.
Conclusion: 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.
Volume 10, Issue 3 (Summer 2024)
Abstract
Background: Typhoid fever is endemic in Nigeria, and there are no high-quality routine diagnostic tests. Immunodiagnostic assays, blood culture, and quantitative real-time polymerase chain reaction (qPCR) were used to study typhoid fever co-infection with malaria.
Materials & Methods: Blood samples of 125 patients were taken from April to August 2021. The samples were analyzed using standard microbiological methods such as immunodiagnostic assays and qPCR, whereas malaria parasitemia was examined using microscopy.
Findings: In the study, the Widal test (WT) showed that 28.8 and 32.8% of the patients had antibodies against O-antigen and H-antigen at a cut-off titre of 1:160, respectively. The immunochromatographic test (ICT) indicated that 16% had IgM antibodies, and 18.4% had both IgM and IgG antibodies, suggesting a recent typhoid infection. Various bacterial pathogens were identified in patients with positive WT and ICT results, including Salmonella species, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus species, and Proteus mirabilis. Eight Salmonella strains were confirmed through invA gene detection using qPCR, none of which were S. Typhi and S. Paratyphi A. Both WT and ICT exhibited low sensitivity but high specificity ranging from 73.6 to 81.6% with negative predictive values of 100%. Additionally, the results showed a prevalence rate of 65.5% for malaria parasitemia and 9.8% for non-typhoidal Salmonella-associated bacteraemia co-infection with malaria.
Conclusion: This research once again highlighted the limited diagnostic accuracy of both immunochromatographic and Widal tests. The presence of concurrent infections involving malaria and other bacterial pathogens further exacerbates the inadequacies of these diagnostic methods.
