1.The oral microbiome community variations associated with normal, potentially malignant disorders and malignant lesions of the oral cavity
MOK Shao Feng ; YAP Sook Fan ; Alan ONG Han Kiat
The Malaysian Journal of Pathology 2017;39(1):1-15
The human oral microbiome has been known to show strong association with various oral diseases
including oral cancer. This study attempts to characterize the community variations between
normal, oral potentially malignant disorders (OPMD) and cancer associated microbiota using 16S
rDNA sequencing. Swab samples were collected from three groups (normal, OPMD and oral
cancer) with nine subjects from each group. Bacteria genomic DNA was isolated in which full
length 16S rDNA were amplified and used for cloned library sequencing. 16S rDNA sequences
were processed and analysed with MOTHUR. A core oral microbiome was identified consisting
of Firmicutes, Proteobacteria, Fusobacteria, Bacteroidetes and Actinobacteria at the phylum level
while Streptococcus, Veillonella, Gemella, Granulicatella, Neisseria, Haemophilus, Selenomonas,
Fusobacterium, Leptotrichia, Prevotella, Porphyromonas and Lachnoanaerobaculum were detected at
the genus level. Firmicutes and Streptococcus were the predominant phylum and genus respectively.
Potential oral microbiome memberships unique to normal, OPMD and oral cancer oral cavities were
also identified. Analysis of Molecular Variance (AMOVA) showed a significant difference between
the normal and the cancer associated oral microbiota but not between the OPMD and the other two
groups. However, 2D NMDS showed an overlapping of the OPMD associated oral microbiome
between the normal and cancer groups. These findings indicated that oral microbes could be potential
biomarkers to distinguish between normal, OPMD and cancer subjects.
2. Comparative analysis of current diagnostic PCR assays in detecting pathogenic Leptospira isolates from environmental samples
May-Ling YAP ; Zamberi SEKAWI ; Hui-Yee CHEE ; Vasantha NEELA ; Han Alan ONG
Asian Pacific Journal of Tropical Medicine 2019;12(10):472-478
Objective: To compare the efficiency of routine diagnostic PCR assays in detecting pathogenic Leptospira isolated from water and soils. Methods: Seven routine assays targeting six genes (lipL32, flaB, gyrB, lfb1, secY and ligB) were evaluated and compared on the cultures of two groups of pathogenic Leptospira from different sources. One group included 19 described reference strains recovered from infected human or animals, and another group included 22 environmental isolates from recreational and residential sites in Malaysia. The latter have been confirmed for presence of pathogenic Leptospira DNA. PCR positivity or detection sensitivity of each assay was determined and compared between the two groups. Results: Validation on reference strains showed 100.0% PCR sensitivity for all assays except ligB-PCR (95.0%) that failed to amplify Leptospira interrogans serovar Pomona. In marked contrast, there was a notable decline in sensitivity in the environmental isolates (lipL32-PCR, 95.5%;flaB-PCR, 90.9%; gyrB-PCR, 77.3%; lfb1-PCR, 59.1%; secY-PCRs, 40.9% G1/G2-PCR, 36.4%; ligB-PCR, 13.6%), implying a large genetic distance between the two groups, as well as nucleotide polymorphism among environmental isolates. Conclusions: High proportion of false-negative PCR results suggests a need of prudent selection of primers in detecting environmental pathogenic Leptospira. These findings offer valuable insights on the extensive biodiversity of genus Leptospira and its impact on the efficacy and development of molecular detection tool.