Clostridioides difficile is an opportunistic spore-forming pathogen responsible for antibiotic-associated diarrhea in humans. C. difficile produces two main toxins: TcdA and TcdB as well as a third toxin named binary toxin (CDT) that is also involved in virulence. The present study aimed at characterizing the C. difficile isolate ALCD3 involved in a relapse episode of nosocomial infection. Molecular characterization showed that isolate ALCD3 belongs to toxinotype 0/v and the MLST analysis demonstrated allelic profile adk:91, atpA:1, dxr:2, glyA: 1, recA:27, sodA: 1 and tpi:1 which corresponds to ST293 (MLST clade: 1). During growth, isolate ALCD3 showed an early increase in the sporulation ratio as well as maximal values of heat resistant forms after 2 days of incubation. Both sporulation kinetics and production of heat resistant forms were faster for isolate ALCD3 than for the reference strain VPI 10463. Germination in the presence of the natural germinant taurocholate was faster for isolate ALCD3 than for strain VPI 10463, which indicates that isolate ALCD3 starts cortex hydrolysis earlier than strain VPI 10463. Furthermore, the co-germinant glycine, induces rapid release of dipicolinic acid (DPA) in isolate ALCD3. These findings indicate that isolate ALCD3 is particularly efficient in both sporulation and germination. The present work represents the first report of the circulation of C. difficile ST293 in Argentina. The ability of isolate ALCD3 to produce toxins and its high sporulation/germination capacity are key features compatible with a microorganism with high dissemination potential and the possibility of inducing recurrent infections.

艰难梭菌是一种机会性孢子形成病原体，导致人类抗生素相关性腹泻。艰难梭菌产生两种主要毒素：TcdA 和 TcdB，以及第三种名为二元毒素 (CDT) 的毒素，该毒素也具有毒力。本研究旨在表征与医院感染复发有关的艰难梭菌分离株 ALCD3。分子表征表明分离株 ALCD3 属于毒素型 0/v，MLST 分析显示等位基因谱adk:91、atpA:1、dxr:2、glyA: 1、recA:27、sodA: 1和tpi:1对应于 ST293（MLST 进化枝：1）。在生长过程中，分离株 ALCD3 显示出孢子形成率的早期增加，以及在培养 2 天后耐热形式的最大值。分离株 ALCD3 的孢子形成动力学和耐热形式的产生都比参考菌株 VPI 10463 更快。在天然萌发牛磺胆酸盐存在的情况下，分离株 ALCD3 的发芽速度比菌株 VPI 10463 更快，这表明分离株 ALCD3 开始皮层水解早于菌株 VPI 10463。此外，共萌发甘氨酸可诱导分离株 ALCD3 中吡啶二羧酸 (DPA) 的快速释放。这些发现表明分离株 ALCD3 在孢子形成和萌发方面特别有效。本作品代表了第一份流通报告阿根廷的艰难梭菌ST293。分离的 ALCD3 产生毒素的能力及其高孢子形成/发芽能力是与具有高传播潜力和诱导反复感染的可能性的微生物相容的关键特征。