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.

[Retrospective Study of Clinical Features and Prognosis of Pneumococcal Pneumonia Among Patients Under 65 Years of Age].

The 23-valent pneumococcal polysaccharide vaccine (PPSV23) for elderly people has been included in the National Immunization Program (NIP) of Japan since October 2014. Targets for PPSV23 were restricted to persons ≥65 years of age and persons 60 to 64 years of age with an underlying severe physical disability (expressed as 1st grade in Japan). In this study, the clinical courses of non-target persons <65 years of age were compared between those with non-severe underlying diseases (A group) and those without underlying diseases (B group), and the need to expand the targets for PPSV23 within the NIP was investigated. Persons with pneumococcal pneumonia who were diagnosed based on a positive sputum or blood culture result were enrolled between January 2004 and April 2014. As a result, the number of subjects in A group was 2.6 times larger than that in B group, and this difference was especially pronounced (4.2 times) among subjects between the age of 60 to 64 years. These findings suggest that persons with underlying disease without a 1st grade physical disability might also be susceptible to pneumococcal pneumonia. No significant differences in the severity of pneumonia, the length of treatment, or the rates of admission were seen between A group and B group. The severity of pneumonia and the rates of admission among targets of the NIP were significantly higher than those of A group. In conclusion, our study suggests that A group should also be included among the targets of the NIP and that all targets eligible to receive the pneumococcal vaccine within NIP should be inoculated.