Changes in the copy numbers of cell-free nuclear DNA (cf-nDNA) and cell-free mitochondrial DNA (cf-mtDNA) have shown promising diagnostic utilities among patients with head and neck squamous cell carcinoma (HNSCC). Considering the absence of objective prognostic tools for HNSCC surveillance, this study aimed to assess the utility of saliva-based cf-nDNA and cf-mtDNA in predicting the overall survival of patients with HNSCC. The study included ninety-four patients with a confirmed HNSCC diagnosis with a mean follow-up time of 32.04 months (±19.1). A saliva-based liquid biopsy was collected from each patient. A multiplex quantitative PCR was used to determine the absolute number of cf-nDNA and cf-mtDNA. The Kaplan–Meier estimator and Cox proportional hazards regression models were used to assess overall survival. The absolute copy numbers of cf-nDNA and cf-mtDNA were statistically significantly higher among the deceased patients than among the censored ones (p < 0.05). Individuals with elevated levels of cf-nDNA or cf-mtDNA were associated with a significantly poorer overall survival (p ≤ 0.05). A univariate analysis showed that only the absolute copy number of cf-mtDNA was the sole predictor of overall survival. However, the multivariate analysis showed that all the absolute copy numbers of cf-nDNA, the absolute copy numbers of cf-mtDNA, and the stage of HNSCC were predictors of overall survival. Our study confirms that saliva is a reliable and non-invasive source of data that can be used to predict the overall survival of patients with HNSCC, where cf-mtDNA levels act as the sole predictor.

The Beijing family of Mycobacterium tuberculosis (MTB) has been reported to have an exceptional capacity to spread tuberculosis (TB) and induce multi-drug resistance. A method has been developed to distinguish this family from the rest of the MTB families through real-time DNA amplification and subsequent analysis of the melting point of an amplicon. Two pools of multi-drug resistant (MDR) MTB samples collected at two different time periods from various regions in Syria have been selected. This preliminary screening indicated a complete absence of the Beijing family in all samples. This research presents an effective differentiation of bacterial Beijing strains, with minimal effort and cost through analysis of differential amplicon melting points.