Early line-probe assay using DNA specimens in patients with pulmonary TB

BACKGROUND: We investigated the feasibility of early line-probe assay (LPA) using remnant DNA of Mycobacterium tuberculosis from polymerase chain reaction (PCR) test.METHODS: M. tuberculosis DNA specimens with cycle threshold (Ct) values reported and collected from patients with known results for both LPA with culture isolates and phenotype drug susceptibility testing (pDST) were selected. The diagnostic performance of DNA-based LPA according to the Ct value was investigated.RESULTS: A total of 143 respiratory specimens were included. For isoniazid resistance, the accuracy in subgroups with Ct value <25, 25-29 and ≥29 was respectively 96.8%, 65.7% and 13.3%. For rifampicin resistance, accuracy in subgroups with Ct values <29 and ≥29 was respectively 87.8% and 13.3%. When compared to the pDST results, sensitivity, specificity, positive predictive value and negative predictive value in specimens with Ct values <25 was respectively 1.00 (95% CI 0.69-1.00), 0.95 (95% CI 0.76-1.00), 0.91 (95% CI 0.59-1.00) and 1.00 (95% CI 0.83-1.00) for isoniazid resistance. For rifampicin resistance, corresponding values in subgroups with Ct values <29 were respectively 0.89 (95% CI 0.52-1.00), 0.98 (95% CI 0.91-1.00), 0.80 (95% CI 0.50-0.94) and 0.99 (95% CI 0.92-1.00).CONCLUSIONS: DNA-based early LPA with remnant DNA from respiratory samples was feasible and accurate when the Ct values were low.

Blood group antigen and phenotype prevalence in the Korean population compared to other ethnic populations and its association with RBC alloantibody frequency

OBJECTIVES

This study aimed to analyse the allele frequency of blood group antigens in the Korean population and other ethnic populations and the association of blood group antigens with red blood cell (RBC) alloantibodies.

BACKGROUND

Blood group antigen genotyping can support patients undergoing frequent transfusions who have alloantibodies and antibodies against high-prevalence blood group antigens.

METHODS

Twenty-nine single nucleotide variations and 37 blood group antigens were tested. Samples requested for routine blood typing were collected from Jan to Apr 2016. Genotyping was performed on 145 Korean samples and was confirmed by bidirectional sequencing and serologic tests. The allele frequency data were compared with previous genotyping datasets (three datasets from Korea and one each from China, Europe, Asia, and the USA). Alloantibody frequencies and blood group antigens from the electronic medical record of 1772 cases were examined.

RESULTS

E antigen was higher in the Korean population compared to that of Asian and European populations. K, Kp^a , Fy^b and Do^a allele frequencies were lower compared to other ethnic populations. RBC alloantibodies with frequencies (%) greater than 1% from the 1772 cases were as follows: anti-E, 36·7%, anti-C, 17·7%; anti-c 7·39%; anti-M, 5·9%; anti-e, 5·2%; anti-Jk^a , 2·9%; and anti-Fy^a , 1·1%. Blood group antigens and alloantibody frequencies revealed inverse trends that did not reach statistical significance.

CONCLUSION

The allele frequency of blood group antigens assessed by high-throughput methods provided reliable and valuable information that could be used for maintaining donor pools and providing compatible blood for genotyped patients.