分子与遗传医学

Identification of Single-nucleotide Polymorphisms (SNPs) of Enterococcus faecal Isolated from HIV Seropositive Nigerian Patients with CD4⁺ Cells of<200 Cells/μl: A Possible Vaccine Target

Abstract

Ehiaghe Friday Alfred1*, Ehiaghe Imuetinya Joy2, Rebecca Chinyelu Chukwuanukwu1, Onah Ejike Christian1, Ihim Augustine Chinedu1, Ochiabuto Mary-Theodora Ogochukwu1, Unaeze Chukwuebuka Bright1, Obi Chioma Maureen1, Ukibe Rose Nkiruka1, Osakue Omoyemen Nosahkare1, Onyenekwe Charlse Chinedum1, Meludu Chukwuemeka Samuel1,Manafa Patrick Onochie1 and Emeje Paul Isaac3

Enterococci have gained significance as the cause of nosocomial infections. They occur as food contaminants and have also been linked to dental diseases. Currently, infective endocarditis (IE) caused by Enterococcus faecalis represents 10% of all IE and is marked by its difficult management and the frequency of relapses. Although the precise reasons for that remain to be elucidated, the evolution of the culprit strain based on single nucleotide polymorphism (SNP) could be, at least in part, involved. The cross sectional study randomly selected 40 consented (25 male and 15 female) HIV seropositive patients and body mass index of 16.7 ± 1.0 (Kg/m2 ) with CD4+ cells<200 cells/µl. Urine and feces samples were collected used for testing. Chrom agar was used for bacterial isolation. DNA isolations from the 24-hour growth cultures of possible Enterococcus faecalis were carried out using Zymo Research Bacterial DNA isolation kit. The twenty-nine (29) clinical isolates that showed black-colored colonies and were further subjected to polymerase chain reaction identification using Enterococcus faecalis gene specific primers. Only two (2) out of twenty-nine (29) suspected Enterococcus spp were PCR confirmed Enterococcus faecalis. We observed that about 85.36313% sites of the accessions are polymorphic among the two isolates. Considering the Enterococcus faecalis gene the polymorphic sites are 76.4% and 23.6% biallelic and triallelic respectively with a corresponding number of such sites as 447 and 331, respectively. The coding regions (CDs) for the Enterococcus faecalis genome displayed the majority of SNP loci at codon position C2 and C3 with 34.5% and 31.3% of their respective total SNP loci, respectively. The observed variability between the two sequences from Nigeria may be due to increased genetic diversity over time and could be a possible vaccine target in the prevention of infective endocarditis (IE) caused by Enterococcus faecalis.