Stability Assessment of The Human Oral Microbiota

Objective: To evaluate the stability of the human oral microbiota in temporal variations that could be critical in obtaining the microbiological baseline which was used to detect differences associated with HIV infection. Method: Whole stimulated saliva samples were collected from 36 HIV-infected subjects at two different time points prior to antiretroviral therapy, and 59 HIV-negative controls. Each sample was cultured on an enriched media to obtain an optimum assessment of colony forming units (CFU) and to estimate the level of total cultivable bacteria in the oral cavity.  Two culture-independent survey methods, quantitative real time PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE) were conducted to compare the DNA levels and similarities of microbial composition between the two sample sets, visit-1 vs. visit-2. Result: The average time difference between two visits was 10.9 days. Culture-based quantitative assessment showed no significant difference in bacterial CFU log values for S. mutans, S .sobrinus, Lactobacilli, Candida, total mutans streptococci or total cultivable microbiota between the two visits amongst both HIV positive and negative subjects. The qPCR results showed no significant differences  between the two visits in bacterial DNA levels for P. gingivalis, T. forsythensis, T. denticola, and A. actinomycetemcomitans. Conclusion: The composition of oral microbiota remains constant with no significant variations in both HIV-positive and HIV-negative subjects, therefore, one baseline sampling would be reliable for clinical oral microbial studies. We also observed that the two-visit-correlation was higher in HIV-positive as compared to HIV-negative individuals, suggesting that the host immune response may play an important role in regulating the overall microbial variability in saliva. Supported by research grants U19 DE018385 from the NIDCR/NIH and NYUCD Student Summary Research Program.