Browsing by Autor "Carla Calderon Toledo"

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Antibiotic resistance genes and class 1 integron: Evidence of fecal pollution as a major driver for their abundance in water and sediments impacted by metal contamination and wastewater in the Andean region of Bolivia
(2020) Jorge Agramont; Sergio Gutiérrez-Cortez; Enrique Joffré; Åsa Sjöling; Carla Calderon Toledo
Abstract Water and sediment samples affected by mining activities were collected from three lakes in Bolivia, the pristine Andean lake Pata Khota, the Milluni Chico lake directly impacted by acid mine drainage, and the Uru-Uru lake located close to Oruro city and highly polluted by mining activities and human wastewater discharges. Physicochemical parameters, including metal compositions, were analyzed in water and sediment samples. Antibiotic resistance genes (ARGs), were screened for, and verified by quantitative PCR together with the mobile element class 1 integron ( intl1 ) as well as crAssphage, a marker of human fecal pollution. The gene intl1 showed a positive correlation with sul1, sul2, tetA and blaOXA-2 . CrAssphage was only detected in Uru-Uru lake and its tributaries and significantly higher abundance of ARGs were found in these sites. Multivariate analysis showed that crAssphage abundance, electrical conductivity and pH were positively correlated with higher levels of intl1 and ARGs. Taken together our results suggest that fecal pollution is the major driver of higher ARGs and intl1 in wastewater and mining contaminated environments.
Circulation of enterotoxigenic Escherichia coli (ETEC) isolates expressing CS23 from the environment to clinical settings
(American Society for Microbiology, 2023) Carla Calderon Toledo; Astrid von Mentzer; Jorge Agramont; Kaisa Thorell; Yingshun Zhou; Miklós Szabó; Patricia Colque; Inger Kühn; Sergio Gutiérrez-Cortez; Enrique Joffré
The importance of clean water cannot be overstated. It is a vital resource for maintaining health and well-being. Unfortunately, water sources contaminated with fecal discharges from animal and human origin due to a lack of wastewater management pose a significant risk to communities, as they can become a means of transmission of pathogenic bacteria like enterotoxigenic E. coli (ETEC). ETEC is frequently found in polluted water in countries with a high prevalence of diarrheal diseases, such as Bolivia. This study provides novel insights into the circulation of ETEC between diarrheal cases and polluted water sources in areas with high rates of diarrheal disease. These findings highlight the Choqueyapu River as a potential reservoir for emerging pathogens carrying antibiotic-resistance genes, making it a crucial area for monitoring and intervention. Furthermore, the results demonstrate the feasibility of a low-cost, high-throughput method for tracking bacterial pathogens in low- and middle-income countries, making it a valuable tool for One Health monitoring efforts.
Circulation of enterotoxigenic Escherichia coli (ETEC) isolates expressing CS23 from the environment to clinical settings
(2023) Carla Calderon Toledo; Astrid von Mentzer; Jorge Agramont; Kaisa Thorell; Yingshun Zhou; Miklós Szabó; Patricia Colque; Inger Kühn; Sergio Gutiérrez-Cortez; Enrique Joffré
Abstract Enterotoxigenic Escherichia coli (ETEC) is one of the leading causes of infant diarrhea in low- and middle-income countries (LMICs). Diarrheal pathogens are transmitted through environmental reservoirs; however, the bacterial clones that spread across the human-environment interphases remind unexplored. We aimed to determine the relationship and clonal dissemination of ETEC between children with diarrhea (> 5 years of age) and polluted water samples from local river in La Paz, Bolivia. Our study used whole genome sequencing and phenotypic fingerprinting system (PhenePlates) to analyze ETEC strains. We showed that ST218 and ST410 LT+STh CS23 ETEC were found with high frequency in both samples. The CS23 ETEC isolates were found within several STs, E. coli phylogroups A, B1, C, and D, and across ETEC lineages. Our comparative genomic analysis and PhenePlate screening of globally distributed clinical ETEC strains suggested that virulent CS23 plasmids acquisition occurs independently of the bacterial chromosomal background. Environmental strains were more often multidrug-resistant (MDR) than clinical isolates and harbored the class 1 integron-integrase gene intI1 next to the MDR cassettes. Retrospective analysis of antibiotic resistance in ETEC revealed a high frequency of MDR in clinical isolates. The LT+STh CS23 ETEC isolates showed an increased biofilm ability at environmental temperature, equal cytotoxicity, and significantly lower adherence to human epithelial cells compared to ETEC expressing other CFs. Together, our findings suggest that CS23 is more prevalent in ETEC than previously estimated, and the Choqueyapu River is a reservoir for LT+STh CS23 ETEC containing strains capable of causing diarrheal cases in children. Importance The importance of clean water cannot be overstated. It is a vital resource for maintaining health and well-being. Unfortunately, water sources contaminated with fecal discharges from animal and human origin due to a lack of wastewater management poses a significant risk to communities, as they can become a means of transmission pathogenic bacteria like enterotoxigenic E. coli (ETEC). ETEC is frequently found in polluted water in countries with a high prevalence of diarrheal diseases, such as Bolivia. This study provides novel insights into the circulation of ETEC between diarrheal cases and polluted water sources in areas with high rates of diarrheal disease. The findings highlight the Choqueyapu River as a potential reservoir for emerging pathogens carrying antibiotic-resistance genes, making it a crucial area for monitoring and intervention. Furthermore, the results demonstrate the feasibility of a low-cost, high-throughput method for tracking bacterial pathogens in low- and middle-income countries, making it a valuable tool for One Health monitoring efforts.
Cross-Reactive Protection against Enterohemorrhagic Escherichia coli Infection by Enteropathogenic E. coli in a Mouse Model
(American Society for Microbiology, 2011) Carla Calderon Toledo; Ida Arvidsson; Diana Karpman
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) are related attaching and effacing (A/E) pathogens. The genes responsible for the A/E pathology are carried on a chromosomal pathogenicity island termed the locus of enterocyte effacement (LEE). Both pathogens share a high degree of homology in the LEE and additional O islands. EHEC prevalence is much lower in areas where EPEC is endemic. This may be due to the development of antibodies against common EPEC and EHEC antigens. This study investigated the hypothesis that EPEC infections may protect against EHEC infections. We used a mouse model to inoculate BALB/c mice intragastrically, first with EPEC and then with EHEC (E. coli O157:H7). Four control groups received either a nonpathogenic E. coli (NPEC) strain followed by EHEC (NPEC/EHEC), phosphate-buffered saline (PBS) followed by EHEC (PBS/EHEC), EPEC/PBS, or PBS/PBS. Mice were monitored for weight loss and symptoms. EPEC colonized the intestine after challenge, and mice developed serum antibodies to intimin and E. coli secreted protein B (encoded in the LEE). Prechallenge with an EPEC strain had a protective effect after EHEC infection, as only a few mice developed mild symptoms, from which they recovered. These mice had an increase in body weight similar to that in control animals, and tissue morphology exhibited mild intestinal changes and normal renal histology. All mice that were not prechallenged with the EPEC strain developed mild to severe symptoms after EHEC infection, with weight loss as well as intestinal and renal histopathological changes. These data suggest that EPEC may protect against EHEC infection in this mouse model.
Fecal Pollution Drives Antibiotic Resistance and Class 1 Integron Abundance in Aquatic Environments of the Bolivian Andes Impacted by Mining and Wastewater
(Multidisciplinary Digital Publishing Institute, 2020) Jorge Agramont; Sergio Gutiérrez-Cortez; Enrique Joffré; Åsa Sjöling; Carla Calderon Toledo
An increased abundance of antibiotic resistance genes (ARGs) in aquatic environments has been linked to environmental pollution. Mining polluted sites with high concentration of metals could favor the in situ coselection of ARGs, whereas wastewater discharges release fecal antibiotic resistant bacteria in the environment. To study the effect of human fecal contamination and mining pollution, water and sediment samples affected by mining activities and sewage discharges were collected from three lakes in Bolivia, the pristine Andean lake Pata Khota, the Milluni Chico lake directly impacted by acid mine drainage, and the Uru-Uru lake located close to Oruro city and highly polluted by mining activities and human wastewater discharges. Physicochemical parameters, including metal composition, were analyzed in water and sediment samples. ARGs were screened for and verified by quantitative polymerase chain reaction (PCR) together with the mobile element class 1 integron (intl1), as well as crAssphage, a marker of human fecal pollution. The gene intl1 was positively correlated with sul1, sul2, tetA, and blaOXA-2. CrAssphage was only detected in the Uru-Uru lake, and its tributaries and significantly higher abundance of ARGs were found in these sites. Multivariate analysis showed that crAssphage abundance, electrical conductivity, and pH were positively correlated with higher levels of intl1 and ARGs. Taken together, our results suggest that fecal pollution is the major driver of higher levels of ARGs and intl1 in environments contaminated by wastewater and mining activities.
Identifying and quantifying ESKAPEE pathogens in and around sinks in high burden hospitals
(2026) Lindsay B. Saber; Melani Rojas; Ivory C Blakley; Shan Sun; Melissa Lott; Anthony A. Fodor; Carla Calderon Toledo; Joe Brown
Hospital-acquired infections driven by ESKAPEE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli) are highly prevalent. Premise plumbing, sinks and drains, seeds these organisms into patient environments via aerosolization and subsequent surface contamination. We measured viable ESKAPEE pathogens and overall microbial communities in and around sinks in two high-burden hospitals in La Paz, Bolivia, using culture and 16S rDNA sequencing. In a prospective observational study (May–August 2025), we collected 233 surface swabs and 39 air samples across four sink- related surface categories and in room air. Samples were plated on selective media for ESKAPEE identification and quantified as colony-forming units (CFU) normalized to 100 cm 2 or 6000 L. DNA was extracted, and the full 16S rDNA gene was sequenced on PacBio Revio, analyzed via DADA2/QIIME2 and R. We detected viable presumptive ESKAPEE pathogens in 74.7% surface swabs and 74.4% air samples. Sink basins were most contaminated (mean 31CFU/100 cm 2 , 95 % CI16– 46); concentrations declined with distance from the drain. Klebsiella/Enterobacter spp. showed the highest mean concentration across samples; S. aureus was most frequently detected (54.4% of samples). Hospital-specific differences were evident in culture positivity (Hospital A 85% vs. Hospital B 66.9%) and community composition (PERMANOVA P = 0.001; sample location explained 21.9% vs. 11.7% of variation). 16S profiling confirmed elevated relative abundances of Klebsiella, Enterococcus, and Enterobacter in basins relative to distant surfaces and air. The hospitals studied had high levels of ESKAPEE pathogens, underscoring the need for control measures.
Impaired maternal central hemodynamics precede the onset of vascular disorders of pregnancy at high altitude
(American Physical Society, 2024) Rosalieke E. Wiegel; Kori Baker; Carla Calderon Toledo; Richard B. Gomez; Sergio Gutiérrez-Cortez; Julie A. Houck; Andima Larrea; Litzi Lazo‐Vega; Lorna G. Moore; Julia A. Pisc
Hypertensive disorders of pregnancy represent an escalating global health concern with increasing incidence in low- to middle-income countries and high-income countries alike. The current lack of methods to detect the subclinical stages of preeclampsia (PE) and fetal growth restriction (FGR), two common vascular disorders of pregnancy, limits treatment options to minimize acute- and long-term adverse outcomes for both mother and child. To determine whether impaired maternal cardiovascular or uteroplacental vascular function precedes the onset of PE and/or FGR (PE-FGR), we used noninvasive techniques to obtain serial measurements of maternal cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR), and uterine and fetal arterial resistance at gestational weeks 10-16, 20-24, and 30-34 for 79 maternal-infant pairs in La Paz-El Alto, Bolivia (3,850 m), where the chronic hypoxia of high altitude increases the incidence of PE and FGR. Compared with controls (n = 55), PE-FGR cases (n = 24) had lower SV, higher SVR, and greater uterine artery resistance at 10-16 wk. In addition, fetuses of women with lower SV and higher SVR at 10-16 wk showed evidence of brain sparing at 30-34 wk and had lower birth weights, respectively. Although the trajectory of SV and SVR across pregnancy was similar between groups, PE-FGR cases had a comparatively blunted rise in CO from the first to the third visit. Impaired maternal central hemodynamics and increased uteroplacental resistance precede PE-FGR onset, highlighting the potential use of such measures for identifying high-risk pregnancies at high altitudes.NEW & NOTEWORTHY In this prospective study of maternal central hemodynamics at high altitude, pregnancies later affected by preeclampsia (PE) and/or fetal growth restriction (FGR) show elevated systemic and uterine vascular resistance and reduced stroke volume as early as 10-16 wk gestation. Maternal hemodynamic assessments could facilitate early detection of high-risk pregnancies, improving resource allocation and reducing adverse outcomes. We propose an integrated model linking maternal cardiovascular performance to placental insufficiency, enhancing the understanding of PE-FGR in high-altitude settings.
MIL-53 MOF on Sustainable Biomaterial for Antimicrobial Evaluation Against E. coli and S. aureus Bacteria by Efficient Release of Penicillin G
(Multidisciplinary Digital Publishing Institute, 2025) Delia Monserrat Ávila-Márquez; Alien Blanco-Flores; Helen Paola Toledo-Jaldín; Mateo Burke Irazoque; Miguel Torres-Rodríguez; Alfredo R. Vilchis-Néstor; Carla Calderon Toledo; Sergio Gutiérrez-Cortez; Juan M. Rodrı́guez; Alejandro Dorazco‐González
The development of efficient antibiotic-releasing materials derived from sustainable and recyclable compounds represents a key area within biomedical materials science, particularly in the treatment of antibacterial infections. Herein, a Fe3+/terephthalate-based metal-organic framework (MIL-53) and a novel advanced material made of MIL-53 with biogenic hydroxyapatite (1) were prepared by solvothermal reactions, and these were studied in detail as a Penicillin-G-releasing material. After loading Penicillin G on 1 and MIL-53, the antibiotic percentage release was studied, and the antimicrobial effectiveness of each material was evaluated against two bacterial ATCC strains (E. coli and S. aureus) and various Penicillin-G-resistant uropathogenic strains such as E. coli isolates (HHM 25, ERV 6, and FGI 4). Functional, structural, and morphological characteristics of these materials were thoroughly studied by analytical tools (FTIR, XRD, BET, SEM-EDS, and XPS). The Penicillin G load did not exceed 50% in both materials. The Penicillin G adsorption mechanism involves several types of interactions with the materials. The release of the antibiotic was more efficient from MIL-53, where the load did not exceed 20%. The release was analyzed using mathematical models. They indicated that when Penicillin G is released from MIL-53, the process follows diffusion through a uniform matrix; however, 1 is more porous, which helps with the release by diffusion of Penicillin G, and 1 exhibits more than a 90% inhibition of the growth of bacteria and strains like MIL-53. This suggests a valuable approach to antibiotic activity against resistant pathogens. The use of composite materials derived from the Fe-MOF with a sustainable matrix of hydroxyapatite as antibiotic-releasing materials has been unexplored until now.
Recent Progress on Enterotoxigenic E. coli (ETEC) and Antibiotic Resistance in Pathogenic E. coli
(2023) Enrique Joffré; Jeannete Zurita; Carla Calderon Toledo; Sergio Gutiérrez-Cortez