Clinical evaluation of the cobas® MTB-RIF/INH reagent and the cobas® 6800 for the detection of isoniazid and rifampicin resistance.

We aimed to validate the performance of a newly developed real-time PCR assay using cobas® MTB-RIF/INH reagent on the cobas® 6800 system for detecting isoniazid (INH) and rifampicin (RIF) resistance, using Japanese Mycobacterium tuberculosis (MTB) isolates. In total, 119 mock sputum specimens spiked with resistant MTB were tested using the cobas® MTB-RIF/INH reagent. The whole genomes of all MTB isolates were sequenced by MiSeq and analysed for mutations/indels causing drug resistance. All isolates were tested for phenotypic drug susceptibility, then MTB negative sputa were collected and pooled to prepare mock sputum specimens for the study. The sensitivity and specificity for INH resistance at a concentration equal to 3 × the limit of detection were 77.8% and 90.0%, respectively; those for RIF resistance were 91.8% and 93.5%, respectively. The sensitivities for INH and RIF were statistically different (P = 0.014), but not the specificities (P = 0.624). Twenty-two false-susceptible and two false-resistant results were obtained in INH; meanwhile, six false-susceptible and three false-resistant results were obtained in RIF. False-resistance for INH and RIF was mainly due to disputed mutations. The cobas® MTB-RIF/INH reagent showed better performance than other rapid molecular tests.

Longitudinal study on periodontal conditions in healthy elderly people in Japan.

OBJECTIVES: A strategy for the control of periodontal disease progression is required to prevent tooth loss in older people. However, detailed epidemiological data on periodontal conditions in elderly people is limited. The purpose of the present study is to describe the natural history of periodontal disease and to evaluate the intraoral factors relating to the disease progression in systemically healthy elderly people. METHODS: In the cross-sectional study, 599 and 162 subjects aged 70 and 80 years, respectively, were examined. Of those subjects aged 70 years, 436 (73%) participated in the 2-year longitudinal study. Pocket depth (PD) and attachment level (AL) were measured for all functioning teeth at six sites per tooth. In the cross-sectional study, AL of 4 mm or greater and 7 mm or greater were defined as moderate and severe disease, respectively. In the longitudinal study, a change in AL of 3 mm or greater at each site was defined as periodontal disease progression. RESULTS: In the cross-sectional study, 97.1% of the subjects had at least one site of AL of 4 mm or greater (4+ mm). The prevalence of AL of 7 mm or greater (7+ mm) was 47.9%, with 2.8 affected teeth per person in those with AL 7+ mm. These findings reveal that periodontal disease is extremely widespread in the elderly population. However, very few had many teeth with severe periodontal conditions. In the longitudinal study, 75.1% experienced attachment loss of 3 mm or greater (3+ mm) during the 2-year study period. Of those subjects who experienced attachment loss, a mean of 4.7 teeth exhibited attachment loss. Multivariate logistic regression showed that both the highest AL in each tooth at baseline and abutment teeth for removable partial dentures were significantly related to periodontal disease progression as well as tooth loss incidence. CONCLUSIONS: These results suggest that teeth with poor periodontal conditions as well as abutment teeth for removable partial dentures were significant intraoral factors relating to periodontal disease progression as well as tooth loss.