Repository logo

Clinical Medicine

Permanent URI for this communityhttps://hdl.handle.net/10413/7794

Browse

Browsing Clinical Medicine by Author "Abbai, Nathlee Samantha."

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Diagnostic evaluation of the BD Affirm™ VPIII assay as a point-of-care test for the diagnosis of bacterial vaginosis, trichomoniasis and candidiasis in a population of pregnant women from South Africa.
    (2020) Dessai, Fazana.; Sebitloane, Hannah Motshedisi.; Abbai, Nathlee Samantha.
    OBJECTIVE: Untreated Sexually Transmitted Infections (STIs) and Bacterial vaginosis (BV) pose a serious health risk to mother and child. Limited data exist on the use of the BD Affirm VPIII assay as a point-of-care test. This study compared the BD Affirm VPIII assay to the BD MaxTM Vaginal assay (reference test) for the detection of BV, Trichomonas vaginalis, and Candida spp. The prevalence of single and co-infections are also reported here. METHODS: The study enrolled 273 pregnant women from King Edward VIII hospital in Durban. Socio-demographic, sexual behaviour and clinical data were collected from all consenting women. The women provided two self-collected vaginal swabs for testing. The swabs were tested using the BD Affirm VPIII assay and the BD MaxTM Vaginal assay. The prevalence of BV, trichomoniasis and candidiasis was calculated as the percentage of women who tested positive for BV, T.vaginalis and Candida infection and 95% confidence intervals (CIs) were calculated for these percentages using the formulas for calculating CIs for proportions. The number of co-infections was calculated using chi-square analysis. The diagnostic accuracy of the BD AffirmTM VPIII assay compared to the BD Max assay was assessed through the calculation of sensitivity, specificity, Negative Predictive Value (NPV) and Positive Predictive Value (PPV) and their respective 95% confidence intervals. RESULTS: In this study population, 85% of the participants were unmarried; however, 84% reported having a regular partner, and 96.3% did not use a condom regularly. The prevalence of Bacterial Vaginosis, Candidiasis and Trichomoniasis was 49.4%, 57.2% and 10.3%, respectively. A large proportion of women (78.8%) in this study did not have a discharge despite being positive for one or more pathogens. The BD AffirmTM VPIII assay showed a moderate sensitivity (79.8%) and specificity (80.3%) for diagnosing BV in all participants. The assay had an excellent specificity for Candida and T. vaginalis of 97.4% and 100.0%; respectively, however, it exhibited poor sensitivities of 52.9% and 42.4%, respectively. CONCLUSION: Our findings show a higher prevalence of Bacterial Vaginosis in antenatal attendees than previously reported, while the prevalence of Candidiasis and Trichomoniasis was in keeping with previous reports. The high number of asymptomatic infections detected is of concern and indicates the need for the re-evaluation of the syndromic management approach, especially in the antenatal population. The BD AffirmTM VPIII assay was found to be unsuitable as a screening test for vaginal infections in pregnancy. The assay performed better as a confirmatory test and may serve useful if used in conjunction with other clinical parameters such as vaginal pH.
  • Thumbnail Image
    Item
    Genetic diversity of Gardnerella vaginalis in pregnant women diagnosed with intermediate and positive bacterial vaginosis.
    (2019) Nzimande, Silondiwe Philiswa.; Abbai, Nathlee Samantha.
    Bacterial vaginosis (BV) is the main cause of abnormal vaginal discharge in women of reproductive age. Gardnerella vaginalis, has been detected in almost all women with BV. However, there is limited information on the genetic diversity of G. vaginalis isolated from BV intermediate and positive cases. In this study we investigated the genetic diversity of G. vaginalis strains from South African pregnant women. Vaginal swabs were characterized by the Nugent method. A total of n= 87 samples were included in the genetic analysis, (n=50 BV positive) and (n=37 BV intermediate). The presence of G. vaginalis was detected by PCR using bacterium specific 16S rRNA primers. All PCR positive amplicons were sequenced by the Sanger method and the edited sequence data was used for the phylogenetic analysis using the PHYLIP software. The sialidase A gene was amplified by PCR using specific primers and the copy numbers of sialidase A gene was quantified by droplet digital PCR. To assess the diversity of the sialidase A gene, Sanger sequencing was performed. The 16S rRNA gene from G. vaginalis was amplified in all BV positive and BV intermediate samples. All PCR amplicons were successfully sequenced and the nucleotide BLAST results revealed 100% identify to G. vaginalis. The phylogenetic analysis revealed that there is no diversity in G. vaginalis present in BV positive and intermediate cases. The phylogenetic tree of sialidase A sequences from intermediate and positive BV cases revealed two major clades which showed differences related to sialidase A copy number. Quantification of sialidase A showed that the average number of copies per cell was much higher in the BV positive group compared to the intermediate group. Some of the intermediate cases showed high copy numbers for the virulence gene and clustered with the BV positive cases. In the present study the 16S rRNA sequences of the G. vaginalis from BV intermediate and positive women showed that there is no genetic diversity in G. vaginalis detected in BV positive and intermediate samples. The phylogenetic tree of sialidase A gene sequences of intermediate and positive BV revealed two major clades which showed differences related to sialidase A copy number. This data was previously lacking in our setting, especially in a pregnant population. We further demonstrate for the first time that the genetic information present within the sialidase A gene has a direct influence on BV status.
  • Thumbnail Image
    Item
    Genotyping of gardnerella vaginalis from pregnant women in Durban by amplified ribosomal DNA restriction analysis.
    (2020) Pillay, Kayla.; Abbai, Nathlee Samantha.; Naicker, Meleshni.
    Gardnerella vaginalis is one of the most frequently isolated microorganisms associated with bacterial vaginosis (BV). However, limited information concerning the genetic diversity of G. vaginalis isolated from BV positive and intermediate cases, has been documented. This study investigated the diversity of G. vaginalis in pregnant women, a currently under-researched area in South Africa. The study population included pregnant women recruited from a public hospital in Durban, South Africa. The women provided 2 self-collected vaginal swabs for microscopy and the genotyping assays. The BV status of the women was determined using Nugent scoring. A total sample of n=137 specimens was selected for analysis. The 16S ribosomal ribonucleic acid (rRNA) gene of G. vaginalis was used for the genotyping assays. The 16S rRNA gene polymerase chain reaction products were digested with TaqI to generate genotyping profiles and genotypic subtypes were determined by correlating BamHI and HindIII digestion profiles. Phylogenetic analysis was performed on the 16S rRNA gene sequences. The data analysis was performed in R Statistical Computing software, version 3.6.2. Restriction digestion with TaqI revealed the presence of two different genotypes i.e. GT1 and GT2. Within both BV positive and intermediate sample groups, GT1 was the most prevalent genotype (54%). Overall, 4 subtypes (1, 2B, 2AB and C) were shown to be present in the sample population. The most prevalent subtype was 2B (15/37, 40.5%), followed by subtypes 1 (11/37, 29.7%), 2C (4/37, 10.8%) and 2AB (4/37, 10.8%). The phylogenetic analysis of the 16S rRNA genes showed the presence of 5 clusters. The tree displayed clusters which contained groups of specimens from the same BV group with different genotypes and subtypes present. There were also clusters which contained specimens from across the BV groups carrying the same genotype and subtype. Finally, the study did not find a significant association (p>0.05) between reported symptoms of discharge and genotype harboured. This study provides the first report on the diversity of G. vaginalis in South African pregnant women. Diversity assessments of G. vaginalis with respect to genotypes and subtypes may aid in a greater understanding on the pathogenesis of this microorganism.