DSpace Community: INEI

Impact of Cefiderocol on Klebsiella pneumoniae: A Population-based Longitudinal Analysis of Phenotypic and Genotypic Responses at Subinhibitory and Inhibitory Concentrations

2026-05-27T20:17:09Z

Title: Impact of Cefiderocol on Klebsiella pneumoniae: A Population-based Longitudinal Analysis of Phenotypic and Genotypic Responses at Subinhibitory and Inhibitory Concentrations Authors: Traglia, German M; Moheb, Samyar; Akhar, Usman; Quiroga, Cecilia; Tuttobene, Marisel R; Mase, Hamza; Pasteran, Fernando; Rao, Gauri G.; Tolmasky, Marcelo E.; Bonomo, Robert A; Ramirez, Maria Soledad Abstract: Background: Cefiderocol (FDC) is a siderophore cephalosporin active against carbapenem-resistant Klebsiella pneumoniae (CRKP), but resistance has emerged, often involving iron-uptake pathways and β-lactamases. We investigated how an NDM-producing clinical isolate adapts to FDC under stepwise selective pressure. Methods: A ST147 K. pneumoniae isolate (Kp-1) carrying blaNDM-5 and blaOXA-181, susceptible to FDC but resistant to other agents, was propagated in iron-depleted Mueller-Hinton broth with progressive FDC exposure. Population-based whole-genome sequencing (WGS) tracked mutation dynamics, and RT-qPCR profiled 17 genes related to FDC resistance, iron acquisition, and virulence, comparing the parental population (G0) to the first exposed generation (G1 + FDC). Results: The mean number of mutations detected in generation G1 under FDC exposure was 24.3 ± 12.2, and in generation G2, it increased to 31.7 ± 6.4. Two nonsynonymous substitutions in baeS (V295G and T299P) were recurrently selected, with V295G reaching ≥ 70% frequency in independent lineages, indicating convergent evolution. RT-qPCR revealed downregulation of iron-uptake and porin genes (iroN, cirA, fepA, kfu, ompK35), and upregulation of entB, ompK36, blaNDM-5, and capsule-related genes (wzm, wbbM); baeS/baeR transcript levels were unchanged. Early FDC exposure enhanced biofilm formation without significantly affecting capsule production. Conclusions: Short-term FDC exposure reproducibly selects baeS variants and triggers a transcriptional program reducing siderophore-receptor entry and remodeling the outer membrane. These adaptations-together with increased blaNDM-5 expression and biofilm formation-contribute to reduced FDC susceptibility. The recurrent baeS mutations (V295G/T299P) and decreased cirA/fepA expression may serve as early surveillance markers of FDC adaptation in K. pneumoniae.

Manual de interpretación de resultados para la identificación de levaduras de interés médico por MALDI-TOF

2026-05-22T19:17:49Z

Title: Manual de interpretación de resultados para la identificación de levaduras de interés médico por MALDI-TOF Authors: Arias, Barbara; Canteros, Cristina Elena; Gómez, Yanina; Taverna, Constanza Giselle; Vivot, Matias Ezequiel Abstract: [RESUMEN]: El objetivo de este manual es presentar la validación o verificación de las bases de datos para la identificación de levaduras de importancia clínica utilizando los Equipos comerciales Bruker y VITEK MS. Así como dar recomendaciones para la identificación de levaduras utilizando estos equipos basadas fundamentalmente en los resultados obtenidos de estos procesos de validación y verificación. En algunos casos, donde nuestra evidencia es escasa o ninguna, se incluyó información obtenida de búsquedas bibliográficas. Description: Fil: Arias, Bárbara. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Ciudad Autónoma de Buenos Aires, Argentina; Fil: Canteros, Cristina. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Ciudad Autónoma de Buenos Aires, Argentina; Fil: Gómez, Yanina. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Ciudad Autónoma de Buenos Aires, Argentina; Fil: Taverna, Costanza. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Ciudad Autónoma de Buenos Aires, Argentina; Fil: Vivot, Matías. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Ciudad Autónoma de Buenos Aires, Argentina

Establishment of epidemiological cutoff values for clinically relevant Sporothrix species using CLSI-broth microdilution

2026-05-18T19:25:52Z

Title: Establishment of epidemiological cutoff values for clinically relevant Sporothrix species using CLSI-broth microdilution Authors: dos Santos, Amanda R; Bonifaz, Alexandro; Bombassaro, Amanda; Sá Machado, Ana Caroline de; Rodrigues. Anderson; Borman, Andrew M.; Chakrabarti, A; Chowdary, Anuradha; Rediguieri, Bruno; Johnson, E M; Hagen, Ferry; Queiroz-Telles, Flavio; Gonzalez, Gloria M.; Garcia-Effron, Guillermo; Ferreira Gremião, Isabella Dib; Meis, Jacques F; Possato Fernandes Takahas, Juliana; Pereira Borba dos Santos, Luana; Melhem, Marcia C.; Cappellano, Paola; Nogueira Brilhante, Raimunda Sâmia; Pereira, Sandro Antonio; Santos Gonçalvez, Sarah; Kidd, Sarah; Zhang, Sean X.; Rudramurthy, Shivaprakash; Rozental, Sonia; Córdoba, Susana; De Groot, Theun; Liu, Wei; Wiederhold, Nathan P.; Meijer, Eelco F. J.; Lockhart, Shawn R.; Dufresne, Philippe J. Abstract: Sporotrichosis is a globally distributed subcutaneous mycosis caused mainly by Sporothrix brasiliensis, S. schenckii, and S. globosa. Cat-transmitted sporotrichosis, primarily caused by S. brasiliensis in South America and to a lesser extent by S. schenckii in Southeast Asia, is emerging as a substantial public health concern due to its outbreak potential. Itraconazole is the first-line drug for the treatment of humans and cats, but reduced susceptibility has been reported based on previously proposed epidemiologi cal cut-off values (ECVs). To support resistance surveillance, we aimed to establish the Clinical and Laboratory Standards Institute (CLSI)-endorsed ECVs for these clinically relevant Sporothrix species. A total of 3,504 minimum inhibitory concentration (MIC) values for six antifungal agents (amphotericin B, itraconazole, posaconazole, voricona zole, isavuconazole, and terbinafine) were obtained from 19 international laboratories. Four of seven antifungals met the CLSI M57 guidelines criteria to determine the ECV. Established ECVs for amphotericin B were found to be high, with 8 μg/mL for S. brasiliensis and S. globosa, and 4 μg/mL for S. schenckii. Itraconazole ECVs were 4 μg/mL for S. brasiliensis and S. schenckii. Posaconazole ECVs were 4 μg/mL for all three species (tentative for S. globosa), while the terbinafine ECV for S. brasiliensis was 0.12 μg/mL. Overall, this study establishes validated ECVs for key antifungals against Sporothrix species and identifies a low prevalence of non-wild-type (NWT) isolates (<10% except for S. schenckii and posaconazole), supporting ongoing antifungal resistance monitoring.

Global trends in norovirus genotype distribution among medically attended children with acute gastroenteritis, 2020-2025

2026-05-18T19:25:26Z

Title: Global trends in norovirus genotype distribution among medically attended children with acute gastroenteritis, 2020-2025 Authors: Cannon, Jennifer L; Bonifacio, Joseph; Fumian, Tulio M; Pabbaraju, Kanti; Pietsch, Corinna; Gonzalez, Mark D; Hossain, Mohammad Enayet; Selvarangan, Rangaraj; Buesa, Javier; Pan, Chao-Yang; Sakon, Naomi; Chang, Jen-Hung; Hewitt, Joanne; Croucher, Dawn; White, Peter A; Mercer, Lewis K; Chuchaona, Watchaporn; Duarte Martinez, Francisco Javier; López Moya, Mariel; Vân Trang, Nguyên; Hatyoka, Luiza Miyanda; Mans, Janet; Gomes, K. A.; Degiuseppe, Juan Ignacio; Ingunza, Alejandra; Varghese, Tintu; Lay, Margarita K; Santiago, Fabian Gómez; Bartlett, Eddie; Relja, Boris; Barclay, Leslie; Simuyandi, Michelo; Lanata, Claudio F; Rahman, Mustafizur; Poovorawan, Yong; Wu, Fang-Tzy; Pang, Xiao-Li; Vinjé, Jan Abstract: Norovirus is a leading cause of acute gastroenteritis, with a broad diversity of genotypes infecting children. NoroSurv is an established global network for norovirus strain surveillance among medically attended children < 5 years of age.