Carboxydobacteria are a group of bacteria which are able to grow chemolithotrophically on carbon monoxide (CO) as the sole carbon and energy source under aerobic conditions (22,30 Microbiol. 1965Microbiol. , abstr. P108, 1965, and Actinoplanes, Microbispora, and Mycobacterium (4), have also been described.The facultatively chemolithotrophic bacterium Mycobacterium sp. strain JC1 (originally Acinetobacter sp. strain JC1 DSM 3803; reclassified by Song et al. [41]), is capable of growing aerobically not only on CO but also on methanol as a sole source of carbon and energy (8,39). This means that the bacterium is able to employ three distinct types of nutrition, chemoheterotrophy, chemolithotrophy, and methylotrophy, depending on substrate availability.Combined with these results, the facts that many mycobacterial species including Mycobacterium tuberculosis (10; GenBank accession no. AL123456), Mycobacterium avium (NCBI reference sequence [RefSeq] NC-002943), Mycobacterium bovis (NCBI RefSeq NC-002945), Mycobacterium leprae (9; GenBank accession no. AL450380), and Mycobacterium smegmatis (NCBI RefSeq NC-002974) have genes encoding amino acid sequences similar to those of Mycobacterium sp. strain JC1 CO dehydrogenase (CO-DH) (T. Song and Y. M. Kim, unpublished data), that Mycobacterium phlei is able to oxidize CO (4), and that Mycobacterium cuneatum (40), Mycobaterium gastri (18), and Mycobacterium ID-Y (36) are capable of growing on methanol raise the possibility that all known mycobacteria have an intrinsic ability to grow on CO and/or methanol as the sole carbon and energy source.In order to address this question, we examined several wellknown mycobacteria for the ability to grow on CO and/or methanol, and we found that all the mycobacteria tested grew well on each of these substrates as the sole source of carbon and energy, except that M. tuberculosis did not grow on methanol. We also present several enzymological backgrounds for the growth of the mycobacteria on CO and methanol. MATERIALS AND METHODSStrains and cultivation conditions. Mycobacterium sp. strain JC1 (DSM 3803) (3, 41), Mycobacterium flavescens (ATCC 14474), M. gastri (ATCC 15754), Mycobacterium neoaurum (ATCC 25795), Mycobacterium parafortuitum (ATCC 19686), Mycobacterium peregrinum (ATCC 14467), M. phlei (ATCC 11758), M. smegmatis mc 2 (ATCC 700084), M. tuberculosis H37Ra (ATCC 35835), and Mycobacterium vaccae (ATCC 15483) were used throughout this study. Cells were cultivated at 37°C under CO chemolithoautotrophy with a gas mixture of 30% CO-70% air in either standard mineral base (SMB) medium (SMB-CO) (21) or 0.47% (wt/vol) Middlebrook 7H9 medium (7H9-CO; Becton Dickinson, Cockeysville, Md.). For methylotrophic growth, cells were grown at 37°C in SMB medium supplemented with 1% (vol/vol) methanol (SMB-MeOH). For the methanol assimilation enzyme assay, Methylobacterium extorquens AM1 (NCIB 9133) and Methylobacillus sp. strain SK1 (DSM 8269) grown at 30°C in SMBMeOH were used as controls. Growth was measured with a spectrophotometer by determi...

The clinical guidelines for acquired immunodeficiency syndrome (AIDS) in HIV-infected Koreans recommend routine HIV drug resistance testing for patients undergoing their first highly active antiretroviral therapy or considering a change in medication after 2018. Herein, the trends in HIV-1 subtypes and drug resistance were assessed from 2017 to 2022 by retrospectively analyzing 2,107 HIV-1-infected patients’ data. The Stanford HIV Drug Resistance Database was used to analyze each patient’s HIV-1 polymerase ( pol) gene sequences. Subtype B infections were predominant in the study population (75.7%). Meanwhile, CRF01_AE was the most prevalent non-B subtype and increased from 58.4% to 73.7% during the study period. Overall, all types of drug resistance mutations (DRM) were detected in 34.7% of the HIV-1 pol sequences. The prevalence of DRMs and high-level resistance mutations decreased from 39.4% to 31.6% and 16.7% to 7.7%, respectively. The prevalence of DRM was higher in patients treated with antiretroviral therapy (ART). These findings indicate that the prevalence of non-B subtype HIV infection has increased rapidly in South Korea, and the overall prevalence of DRMs decreased between 2017 and 2022. Additionally, since DRM is high in ART-treated patients, routine standard genotypic resistance testing surveillance is important before and after the treatment.

Liquid biopsy using circulating tumor DNA helps overcome the limitations of conventional tissue testing. Non-invasive molecular profiling using circulating tumor DNA is increasingly being used to diagnose cancer, stratify risk, and select targeted treatments. By understanding the biological characteristics of circulating tumor DNA and patient factors that can affect concentrations of circulating tumor DNA as well as optimizing the techniques, the clinical utilization of circulating tumor DNA tests can be improved. It is also necessary to formulate guidelines for the administration and reporting of circulating tumor DNA tests.