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Emerging resistance to novel β-lactam β-lactamase inhibitor combinations in Klebsiella pneumoniae bearing KPC variants

2025-10-28T18:45:34Z

Title: Emerging resistance to novel β-lactam β-lactamase inhibitor combinations in Klebsiella pneumoniae bearing KPC variants Authors: Mase, Hamza; Traglia, German M; Maccari, Lucia; Gómez, Sonia Alejandra; Sanz, María Belén; Akhtar, Usman; Mezcord, Vyanka; Escalante, Jenny; Corso, Alejandra; Rodriguez, Cecilia; Bethel, Christopher R.; Rao, Gauri G.; Tolmasky, Marcelo E.; Paterson, David; Bonomo, Robert A; Pasteran, Fernando; Ramirez, Maria Soledad Abstract: Objective: Klebsiella pneumoniae carbapenemase (KPC) variants, predominantly KPC-2 and KPC-3, are sig- nificant global resistance mechanisms, conferring resistance to many β-lactams, including carbapenems, while remaining susceptible to ceftazidime-avibactam (CZA). Recently, new KPC variants have developed resistance to CZA through mutations, insertions, or deletions in regions such as the -loop, 240-loop (237–243 aa), and 270-loop (266–275 aa). This study investigated collateral resistance to cefiderocol (FDC) and cefepime/zidebactam (FPZ) in isolates with these mutations. Methods: Fifteen clinical KPC-producing Klebsiella spp. isolates representing 15 distinct variants were analysed. Antimicrobial susceptibility testing determined the MICs for CZA, carbapenems, FDC, FPZ, and other antibiotics. Synergy between CZA and FDC was assessed. Whole-genome sequencing (WGS) was used to identify resistance-related mutations. Results: CZA resistance was confirmed in 12/15 variants. Collateral resistance to FDC occurred in eight isolates, with five exhibiting spontaneous resistant subpopulations. Six FDC-resistant strains had muta- tions in the 270-loop (266–275 aa). FPZ resistance was seen in three KPC variants, especially those with mutations in the 270-loop, though many -loop and 240-loop (237–243 aa) mutants remained suscepti- ble. WGS of FDC-resistant subpopulations revealed additional mutations in ompC, rpoC, dksA , and cirA . Conclusions: Emerging CZA-resistant KPC variants often exhibit collateral FDC resistance, with FPZ seen less frequently. Mutations in blaKPC , cirA , and other genes contribute to resistance. Understanding these emerging resistant patterns linked with new KPC variants is crucial to inform therapeutic decisions, as emerging resistance may limit last-line treatment options in clinical settings.

Intestinal Parasites in a Vulnerable Population in the Province of Buenos Aires, Argentina

2025-09-10T15:10:52Z

Title: Intestinal Parasites in a Vulnerable Population in the Province of Buenos Aires, Argentina Authors: Gamboa, María Inés; Osen, Beatriz; Corbalán, Valeria; Butti, Marcos Javier; Lagala, Fiamma; Radman, Nilda Abstract: Socio-environmental factors are frequently related to health/illness, in parasitism and other communicable diseases. The objective of this research was to determine the presence of enteroparasites in a vulnerable population living in an area at risk of health and to analyze the possible risk factors for infection. Serial fecal samples were taken and analyzed using the Sheather and Telemann techniques. Serial anal brushes were also made to search for Enterobius vermicularis. Semi-structured surveys were completed to find out the risk factors. For the statistical analysis, the EPI INFO 3.5.1 was used. A total of 866 people were analyzed, of which 566 (65.3%) were positive. Of these, anal swabs were performed on 656, the results of which showed that 250 (38.1%) had E. vermicularis. This was the species with the highest frequency, followed by Blastocystis spp. (35.1%) and Giardia spp. (20.0%). The specific richness was 14 species, coexisting up to 6 species per host. 51.1% of the positives were monoparasitized and 48.9% polyparasitized. Intestinal parasites were more frequent in males (p < 0.01), in children from 5 to 9 years old (p < 0.01), who lived in houses with dirt floors (p < 0.01), drank water from a well or connected outside the home (p < 0.01), disposed of waste in an unsanitary manner (without municipal collection) (p < 0.01), whose parents had a low educational level (p < 0.01) and who presented some characteristic symptom of these infections (p < 0.01). People are at considerable risk of infection from intestinal parasites. The findings respond to a complex set of factors that condition the health of individuals, diminishing their abilities and restricting their chances of achieving an education that contributes to strengthening their hygienic habits. Hence, measures must be promoted to prevent people from becoming infected, such as health education, improved access to drinking water and sanitation in schools, since school-age children represent the main reservoir

Environmental Toxocara spp. presence in crowded squares and public parks from San Juan Province, Argentina: A call for a “One Health” approach

2025-08-25T16:09:29Z

Title: Environmental Toxocara spp. presence in crowded squares and public parks from San Juan Province, Argentina: A call for a “One Health” approach Authors: Avila, Héctor Gabriel; Sandon, Leonardo; Anes, Paola Emilce; Meli, Sergio Andrés; Giboin, Gustavo Adolfo; Pérez, Verónica Mirtha; Periago, Maria Victoria Abstract: Introduction: Canine soil-transmitted helminth (cSTH) parasites need specific environmental conditions to complete their life cycle. Toxocara canis and T. cati are the most important zoonotic cSTH, since they are the causal agents of human toxocariasis. Canine STHs are dispersed in feces from infected domestic and wildlife canines. In this study, the presence of STH in canine feces was evaluated in 34 crowded public parks and squares from San Juan Province (Argentina). Methods: Fecal samples were collected during different seasons in 2021–2022 and analyzed by standard coprological methods, including Sheather and Willis flotation and Telemann sedimentation. InfoStat 2020, OpenEpi V. 3.01 and R and RStudio® were used for statistical analysis and QGIS 3.16.10 for mapping. Results: From a total of 1,121 samples collected, 100 (8.9%) were positive for at least one intestinal parasite (IP) and three cSTH species were detected: Toxocara spp., Toxascaris leonina and Trichuris vulpis. The most prevalent cSTH species was T. vulpis (64/1121; 0.057%), while the least prevalent was Toxocara spp. (19/1121; 0.017%). The detection of Toxocara spp. eggs was significantly different depending on the season. The geo-spatial variation of each cSTH per season is described. Discussion: This is the first study in San Juan Province to identify environmental contamination of cSTHs in public areas. The specific localization of areas with the presence of cSTH eggs could provide information to guide strategies to reduce the cSTH infection burden in dogs and promote serological screening of the human population for Toxocara spp. Given the zoonotic nature of Toxocara spp. We hope this information will help to reinforce activities of control programs, focusing on the “One Health” approach.

Strongyloides stercoralis and Trypanosoma cruzi coinfections in a highly endemic area in Argentina

2025-08-25T15:25:32Z

Title: Strongyloides stercoralis and Trypanosoma cruzi coinfections in a highly endemic area in Argentina Authors: Fleitas, Pedro Emanuel; Floridia Yapur, Noelia; Nieves, Elvia; Echazú, Adriana; Vargas, Paola; Caro, Nicolas; Aveldaño, Ramiro; Lopez, Walter; Fernandez, Mariana; Crudo, Favio; Cimino, Rubén Oscar; Krolewiecki, Alejandro J. Abstract: Background Strongyloidiasis and Chagas disease are endemic in northern Argentina. In this study we evaluate the association between S. stercoralis and T. cruzi infections in villages with diverse prevalence levels for these parasites. Further understanding in the relationship between these Neglected Tropical Diseases of South America is relevant for the design of integrated control measures as well as exploring potential biologic interactions. Methodology Community based cross-sectional studies were carried in different villages of the Chaco and Yungas regions in Argentina. Individuals were diagnosed by serology for S. stercoralis and T. cruzi. The association between S. stercoralis and T. cruzi, and between anemia and the two parasites was evaluated using two approaches: marginal (Ma) and multilevel regression (Mu). Results A total of 706 individuals from six villages of northern Argentina were included. A total of 37% were positive for S. stercoralis, 14% were positive for T. cruzi and 5% were positive for both. No association was found between infection with S. stercoralis and T. cruzi in any of the models, but we found a negative correlation between the prevalence of these species in the different villages (r = -0.91). Adults (> 15 years) presented association with S. stercoralis (Ma OR = 2.72; Mu OR = 2.84) and T. cruzi (Ma OR = 5.12; Mu OR = 5.48). Also, 12% and