Clinical features of NAAT-positive, toxin-negative <i>Clostridioides difficile</i> infections in South Korea

Choi, In Hyoung; Oh, Chang Kyo; Cho, Young Wook; Cho, Young-Seok

doi:2026.41.2.255

Korean J Intern Med > Volume 41(2); 2026 > Article

ORIGINAL ARTICLE

Gastroenterology

Korean J Intern Med. 2026;41(2):255-264. doi: https://doi.org/10.3904/kjim.2025.207

Clinical features of NAAT-positive, toxin-negative Clostridioides difficile infections in South Korea

In Hyoung Choi¹, Chang Kyo Oh², Young Wook Cho³, and Young-Seok Cho¹

¹Division of Gastroenterology, Department of Internal Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
²Division of Gastroenterology, Department of Internal Medicine, Kangnam Sacred Heart Hospital, Hallym University of Korea, Seoul, Korea
³Department of Internal Medicine, Dongshin Hospital, Seoul, Korea

Corresponding Author: Young-Seok Cho , Tel: +82-2-2258-6021, Fax: +82-2-2258-2038, Email: yscho@catholic.ac.kr

Received: June 30, 2025; Revised: August 17, 2025; Accepted: August 31, 2025.

Abstract

Background/Aims: The clinical characteristics of Clostridioides difficile infection (CDI) in patients within the Asia-Pacific region who test positive on the nucleic acid amplification test (NAAT) and negative on the toxin enzyme immunoassay (EIA, hereafter referred to as “Toxin”) are unclear. We evaluated the clinical significance and associated factors of NAAT+/Toxinpatients whose diagnosis of CDI was confirmed by toxigenic C. difficile culture.
Methods: This retrospective cohort study enrolled adult patients admitted to Seoul St. Mary’s Hospital between January 2015 and December 2015 with a diagnosis of active CDI.
Results: In total, 3,311 stool samples were subjected to C. difficile culture, NAAT, and toxin EIA. Among them, 298 culture- positive patients fulfilled the criteria for CDI, and 3 NAAT-/Toxin- patients were excluded. The risk factors for a negative EIA and positive NAAT and culture results were evaluated in 295 patients. Among them, 128 patients were Toxin- and 167 were Toxin+. No clinical or laboratory parameters (fever, white blood cell count of < 1,000/mm³, eosinophils, C-reactive protein, creatinine, or albumin) differed significantly between NAAT+/Toxin+ and NAAT+/Toxin- patients. In addition, the clinical outcomes did not differ between the two groups. In the multivariable analysis, previous use of antibiotics was inversely associated with negative EIA results, whereas high-dose corticosteroid use was positively associated.
Conclusions: Clinical outcomes related to CDI are not different between NAAT+/Toxin+ and NAAT+/Toxin- patients, emphasizing the need for individual clinical evaluation.

Keywords: Clostridioides difficile ; Nucleic acid amplification techniques ; Immunoenzyme techniques ; Republic of Korea