Kim YE, et al. Ann Lab Med. 2019 Sep;39(5):421-429. https://doi.org/10.3343/alm.2019.39.5.421

Species identification of nontuberculous mycobacteria (NTM) is challenging due to the increasing number of identified NTM species and the lack of standardized testing strategies. The objectives of this study were to investigate the distribution of NTM species recovered from respiratory specimens by multigene sequence-based typing and to evaluate the clinical significance of identified species. Two hundred thirty-two consecutive clinical NTM isolates were subjected to sequencing of multiple genes, including hsp65 , rpoB , and 16S-23S rRNA internal transcribed spacer (ITS) sequence. In addition, clinical data from all patients whose specimens had NTM isolates were analyzed to examine clinical virulence and treatment history. Eighteen strains from 227 isolates from 169 patients were successfully identified at the species level by multigene sequence-based typing. Mycobacterium avium complex and M. abscessus complex made up the majority of isolated NTM (88%; 199/227), followed by M. fortuitum complex (4%; 10/227). The pathogenic potential of NTM differs enormously by species, and M. avium complex and M. abscessus complex revealed especially high levels of virulence compared with findings for other NTM species. The results from our work support M. avium complex and M. abscessus complex being the most common NTM species with highly pathogenic potential isolated from clinical respiratory specimens and could be a good resource for molecular epidemiology of NTM species in South Korea.

Moyamoya disease (MMD) is a progressive steno-occlusive vasculopathy that involves large intracranial arteries accompanied by abnormal collateral vessels. Recently, RNF213 was identified as a susceptibility gene for MMD and p.Arg4810Lys (rs112735431) is the most common variant in East Asian MMD patients. Interestingly, many studies have reported that a certain proportion of the general population in Japan, Korea, and China also has this variant. In this study, we investigated the frequency of this variant and estimated an odds ratio of MMD using two different Korean populations. A total of 1,516 anonymous DNA samples, 799 from an umbilical cord blood bank and 717 from routine health-checked adults, were genotyped using targeted Sanger sequencing. The p.Arg4810Lys variant was detected at genotype frequencies of 2.25 % (18/799; 95 % confidence interval (CI), 1.43-3.53 %) in cord blood samples and 2.65 % (19/717; 95 % CI, 1.70-4.10 %) in adult samples, respectively. This variant showed a strong association with MMD (P < 0.001), giving an odds ratio of 162.7 (95 % CI, 65.5–403.9) and 137.8 (95 % CI, 55.8–339.9) based on the cord blood and adults samples, respectively. These results confirm that the RNF213 p.Arg4810Lys variant is not uncommon in the general Korean population and provide reference data for the association of this variant and MMD.

Recent studies on the urine microbiome have highlighted the importance of the gut–vagina–bladder axis in recurrent urinary tract infection (rUTI). In particular, the role of Gardnerella as a covert pathogen that activates E. coli in animal experiments has been reported. Herein, we conducted a human bladder microbiome study to investigate the effect of Gardnerella on rUTI. Urine 16S ribosomal RNA gene sequencing via transurethral catheterization was conducted in the normal control group (NC) (n = 18) and rUTI group (n = 78). The positive detection rate of Gardnerella species did not differ between the NC and rUTI groups (22.2% vs. 18.0%, p = 0.677). In addition, the Gardnerella-positive NC and Gardnerella-positive rUTI groups showed similar levels of microbiome diversity. The Gardnerella-positive group was categorized into three subgroups: the Escherichia-dominant group, Gardnerella-dominant group, and Lactobacillus-dominant group. All of the Escherichia-dominant groups were associated with rUTI. The Gardnerella-dominant or Lactobacillus-dominant groups expressed rUTI with symptoms when risk factors such as the degree of Gardnerella proliferation or causative agents of bacterial vaginosis were present. The presence of Gardnerella in the urine is considered to be related to rUTI depending on other risk factors. New guideline recommendations regarding antibiotic selection based on a novel method to detect the cause of rUTI may be required to reduce antibiotic resistance.