This is the first nationwide study on the toxin status, including PCR ribotyping and antimicrobial resistance, of C. difficile isolates in Korea. The prevalence of A-B+ strains was 25.7%, much higher than that reported from other countries. Binary toxin-producing strains accounted for 7.1% of all strains, which was not rare in Korea. The most prevalent ribotype was ribotype 017, and all A-B+ strains showed this pattern. We did not isolate strains with decreased susceptibility to metronidazole or vancomycin.
The Prototheca species is achlorophyllic algae and rarely causes human infection. Human protothecosis presents clinically as a cutaneous infection, olecranon bursitis, and disseminated systemic disease. We report a case of human cutaneous protothecosis involving the left wrist. A 68-year-old man presented with an ill-defined erythematous lesion with crust at the dorsal aspect of his left wrist. A punch biopsy was performed to reveal the histologic features of granulomatous inflammation with necrosis at the upper dermis, containing Prototheca organisms, of which, the characteristic features were highlighted by special staining. Through a molecular study, the Prototheca zopfii species was identified.
The sensitivity of molecular diagnostics could be affected by nucleotide variants in pathogen genes, and the sites affected by such variants should be monitored. We report a single-nucleotide variant (SNV) in the nucleocapsid (N) gene of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), i.e., G29179T, which impairs the diagnostic sensitivity of the Xpert Xpress SARS-CoV-2 assay (Cepheid, Sunnyvale, CA, USA). We observed significant differences between the threshold cycle (Ct) values for envelope (E) and N genes and confirmed the SNV as the cause of the differences using Sanger sequencing. This SNV, G29179T, is the most prevalent in Korea and is associated with the B.1.497 virus lineage, which is dominant in Korea. Clinical laboratories should be aware of the various SNVs in the SARS-CoV-2 genome and consider their potential effects on the diagnosis of coronavirus disease 2019.
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