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Geographic divergence of methicillin-resistant Staphylococcus aureus ST5-SCCmecI in the aftermath of a major earthquake and tsunami: impact of a plasmid harboring heavy metal resistance genes
(American Society for Microbiology, 2025-04-09)
Jose R. W. Martínez
;
Manuel Alcalde-Rico
;
Estefanía Jara-Videla
;
Jinnethe Reyes
;
Lina P. Carvajal
(MRSA) is a major public health menace. The global spread of MRSA is characterized by successive waves of epidemic clones dominating specific geographical regions. The acquisition of genes encoding resistance to heavy metals (HMRGs) is thought to be a key feature in the geographic divergence of MRSA. However, the cause-effect relationship between the presence of HMRGs and the divergence of MRSA clones remains to be clarified. In this study, we assessed the role that HMRGs may have played in the evolutionary divergence of the MRSA ST5-SCC <jats:italic>mec</jats:italic> I lineage in Latin America. We conducted a genomic characterization of 113 MRSA clinical isolates from six Latin American healthcare centers, including 53 isolates collected from two cities in Chile (Santiago and Concepción). We found a plasmid (pSCL4752) harboring arsenic, cadmium, and mercury resistance genes in 65% ( <jats:italic>n</jats:italic> = 71) of the ST5-SCC <jats:italic>mec</jats:italic> I isolates. We also observed a geographic divergence associated with the presence of pSCL4752 in Chilean isolates, with a higher frequency in isolates from Concepción (88%) compared to Santiago (29%). Interestingly, a molecular clock analysis revealed that this divergence occurred in the aftermath of an 8.8 Mw earthquake and tsunami that struck the Concepción area in 2010. Moreover, our results demonstrate that the carriage of pSCL4752 can be beneficial or detrimental for ST5-SCC <jats:italic>mec</jats:italic> I isolates, depending on the environmental availability of these heavy metals. Our results suggest that the divergence of the ST5-SCC <jats:italic>mec</jats:italic> I MRSA lineage in Latin America could have been fostered by environmental disasters and influenced by the presence/absence of HMRGs harbored in a plasmid. </jats:p> <jats:sec> <jats:title>IMPORTANCE</jats:title> <jats:p> Methicillin-resistant <jats:italic>Staphylococcus aureus</jats:italic> (MRSA) is a major cause of life-threatening infections worldwide and a growing public health concern. The rise of antibiotic-resistant bacteria, such as MRSA, is often linked to genetic adaptations that enhance their survival. Our research sheds light on how environmental changes, such as those triggered by a natural disaster, can influence the evolution and geographic spread of a highly resistant MRSA lineage in Latin America. We identified a plasmid carrying genes for resistance to arsenic, cadmium, and mercury, which was associated with the geographic divergence of the ST5-SCC <jats:italic>mec</jats:italic> I MRSA lineage, with striking differences in its prevalence between regions affected by a major earthquake and tsunami. By linking environmental events to pathogen evolution, our study highlights the role of ecological pressures in the spread of MRSA. These findings emphasize the need to integrate environmental monitoring into public health strategies to better understand the global challenge of antimicrobial resistance.
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Fighting resistance with redundancy: a path forward for treating antimicrobial-resistant infections?
(American Society for Microbiology, 2025-04-02)
MUNITA SEPULVEDA, JOSE MANUEL
;
Pranita D. Tamma
;
Cesar A. Arias
Acinetobacter baumannii</jats:italic> (CRAB) remains a major threat, with high mortality and limited effective treatments. Sulbactam-durlobactam has emerged as a promising therapy against CRAB. Sulbactam-durlobactam was combined with imipenem-cilastatin in a clinical trial that led to its United States Food and Drug Administration approval. However, the additive benefit of imipenem remains uncertain. In a recent study (Antimicrob Agents Chemother 69:e01627-24, 2025, <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://doi.org/10.1128/aac.01627-24" xlink:type="simple">https://doi.org/10.1128/aac.01627-24</jats:ext-link> ), Veeraraghavan and colleagues provide convincing mechanistic evidence that adding imipenem to sulbactam-durlobactam enhances bacterial killing, likely through complementary inhibition of penicillin binding proteins, leveraging the concept of target redundancy.
Scopus© Citations 2 2
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Multispecies emergence of dual blaKPC/NDM carbapenemase-producing Enterobacterales recovered from invasive infections in Chile
(American Society for Microbiology, 2025-01-31)
QUESILLE VILLALOBOS, ANA MARIA
;
Camila Solar
;
Jose R. W. Martínez
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RIVAS JIMENEZ, LINA MARIA
;
Valeria Quiroz
Carbapenemase-producing carbapenem-resistant Enterobacterales (CP-CRE) represent a significant global threat. The emergence of dual CP-CRE is particularly alarming, as they can potentially compromise the efficacy of newer antibiotics, further decreasing therapeutic alternatives. Herein, we report the emergence of multiple species of CP-CRE recovered from invasive infections in Chile that simultaneously harbor and provide an in-depth genomic characterization of these worrisome pathogens. We collected carbapenem-resistant Enterobacterales (CRE) isolates from invasive infections over a 4-year period, across 11 healthcare centers in Chile. Bacterial species and the presence of carbapenemase genes were confirmed using MALDI-TOF and PCR assays, respectively. Antimicrobial susceptibility testing was conducted through disk diffusion and broth microdilution methods. Dual CP-CRE isolates were subjected to short- and long-read whole genome sequencing to perform a detailed genomic characterization of the isolates and of the mobile genetic elements harboring the enzymes. From a total of 1,335 CRE isolates, we observed an increase in the prevalence of CP-CRE, from 11% in 2019 to 38% in 2022. A total of 11 dual CP-CRE isolates were recovered, all of them harboring
Scopus© Citations 10 15
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Copper-Modified Cellulose Paper: A Comparative Study of How Antimicrobial Activity Is Affected by Particle Size and Testing Standards
(MDPI AG, 2025-01-08)
Sara Ramírez
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Fabian Zúñiga
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Alejandra Amenábar
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CONTRERAS CORREA, PAULINA DEL PILAR
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Viviana Benavides
This study aims to provide evidence that when testing cellulose paper modified with copper particles (CuPs), the particle size and the analysis method influence the antimicrobial activity observed by this material. Commercial CuPs of nanometric size (2.7 nm, CuNPs) and micrometric size (2.5 µm, CuMPs) were used to modify cellulose paper sheets. CuPs were incorporated during the pulp disintegration phase (stage 1) of the sheet formation process, according to the ISO 5269-1:2005 standard. Modified paper sheets retained 16% and 14% of CuNPs and CuMPs, respectively. Additionally, CuPs were distributed randomly on the fiber surfaces, often forming aggregates. Finally, the antimicrobial activity of the modified paper sheets was evaluated using ISO 20645:2004 and ISO 20743:2013. The results showed that the antimicrobial activity assessed using each standard method is conditioned by the mechanism of action of the CuPs and, therefore, by their size. It was concluded that ISO 20645:2004 is suitable for evaluating the antibacterial effect of paper/CuNPs, as nanoparticles diffuse from the paper and are released into the culture medium. In contrast, ISO 20743:2013 can be used for both CuNP- and CuMP-based paper, as it evaluates the antibacterial effect based on the direct interaction between the copper particle and the bacteria.
Scopus© Citations 2 14
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Increased mortality in hospital- compared to community-onset carbapenem-resistant enterobacterales infections
(2024)
Angelique E Boutzoukas
;
Natalie Mackow
;
Abhigya Giri
;
Lauren Komarow
;
Carol Hill
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>The CDC reported a 35% increase in hospital-onset (HO) carbapenem-resistant Enterobacterales (CRE) infections during the COVID-19 pandemic. We evaluated patient outcomes following HO and community-onset (CO) CRE bloodstream infections (BSI).</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Patients prospectively enrolled in CRACKLE-2 from 56 hospitals in 10 countries between 30 April 2016 and 30 November 2019 with a CRE BSI were eligible. Infections were defined as CO or HO by CDC guidelines, and clinical characteristics and outcomes were compared. The primary outcome was desirability of outcome ranking (DOOR) 30 days after index culture. Difference in 30-day mortality was calculated with 95% CI.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Among 891 patients with CRE BSI, 65% were HO (582/891). Compared to those with CO CRE, patients with HO CRE were younger [median 60 (Q1 42, Q3 70) years versus 65 (52, 74); P &lt; 0.001], had fewer comorbidities [median Charlson comorbidity index 2 (1, 4) versus 3 (1, 5); P = 0.002] and were more acutely ill (Pitt bacteraemia score ≥4: 47% versus 32%; P &lt; 0.001). The probability of a better DOOR outcome in a randomly selected patient with CO BSI compared to a patient with HO BSI was 60.6% (95% CI: 56.8%–64.3%). Mortality at 30-days was 12% higher in HO BSI (192/582; 33%) than CO BSI [66/309 (21%); P &lt; 0.001].</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusion</jats:title> <jats:p>We found a disproportionately greater impact on patient outcomes with HO compared to CO CRE BSIs; thus, the recently reported increases in HO CRE infections by CDC requires rigorous surveillance and infection prevention methods to prevent added mortality.</jats:p> </jats:sec>
Scopus© Citations 1 3
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Porcentaje de éxito de erradicación de Helicobacter pylori con tratamiento antibiótico empírico en pacientes pediátricos de un Hospital Terciario
(2023)
Sofía Darritchon Lama
;
Diego Díaz García
;
Marcela Toledo Cumplido
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LUCERO ALVAREZ, YALDA CECILIA
<jats:p>La infección por Helicobacter pylori es una condición frecuente, que a largo plazo se asocia con desarrollo de enfermedad ulceropéptica y eventualmente cáncer gástrico, que se podrían prevenir con un tratamiento oportuno. Lo óptimo sería lograr un éxito de erradicación mayor al 90%, pero los tratamientos empíricos recomendados no logran esas tasas en condiciones reales.Objetivo: Determinar el porcentaje de éxito del tratamiento empírico de erradicación de primera línea contra H. pylori en pacientes pediátricos atendidos en un hospital terciario.Pacientes y Método: Estudio descriptivo retrospectivo en pacientes con infección por H. pylori detectado en biopsias gástricas y que hubieran recibido tratamiento antibiótico de primera línea durante el periodo 2017-2021. Se consideró erradicación exitosa el resultado negativo de test de antígeno en deposiciones o nuevas biopsias luego de ≥ 1 mes de finalizado el tratamiento.Resultados: Se identificaron 82 pacientes con infección por H. pylori, de los cuales 53 recibieron tratamiento de erradicación. De éstos, 26 (49%) fueron controlados con test de erradicación luego del tratamiento y en ellos el porcentaje de éxito fue de solo 38% (10/26).Conclusiones: La tasa de erradicación con los esquemas empíricos utilizados fue menor a la esperada, lo que evidencia el desafío de buscar estrategias más efectivas de tratamiento incluyendo el estudio de susceptibilidad a antimicrobianos. La adherencia de los pacientes al protocolo de seguimiento también fue baja, lo que deberá reforzarse en el futuro para poder realizar un manejo clínico más adecuado. </jats:p>
Scopus© Citations 4 2
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Priorities and Progress in Gram-positive Bacterial Infection Research by the Antibacterial Resistance Leadership Group: A Narrative Review
(2023)
Sarah B Doernberg
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Cesar A Arias
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Deena R Altman
;
Ahmed Babiker
;
Helen W Boucher
<jats:title>Abstract</jats:title><jats:p>The Antibacterial Resistance Leadership Group (ARLG) has prioritized infections caused by gram-positive bacteria as one of its core areas of emphasis. The ARLG Gram-positive Committee has focused on studies responding to 3 main identified research priorities: (1) investigation of strategies or therapies for infections predominantly caused by gram-positive bacteria, (2) evaluation of the efficacy of novel agents for infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci, and (3) optimization of dosing and duration of antimicrobial agents for gram-positive infections. Herein, we summarize ARLG accomplishments in gram-positive bacterial infection research, including studies aiming to (1) inform optimal vancomycin dosing, (2) determine the role of dalbavancin in MRSA bloodstream infection, (3) characterize enterococcal bloodstream infections, (4) demonstrate the benefits of short-course therapy for pediatric community-acquired pneumonia, (5) develop quality of life measures for use in clinical trials, and (6) advance understanding of the microbiome. Future studies will incorporate innovative methodologies with a focus on interventional clinical trials that have the potential to change clinical practice for difficult-to-treat infections, such as MRSA bloodstream infections.</jats:p>
8Scopus© Citations 7
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Spent coffee grounds extract: antimicrobial activity against Paenibacillus larvae and its effect on the expression of antimicrobial peptides in Apis mellifera
(2023)
Pablo Giménez-Martínez
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Fabián Zúñiga
;
Sandra Medici
;
Sandra Fuselli
;
Jessica Martínez
1Scopus© Citations 4
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High Burden of Intestinal Colonization With Antimicrobial-Resistant Bacteria in Chile: An Antibiotic Resistance in Communities and Hospitals (ARCH) Study
(2023)
ARAOS BRALIC, RAFAEL IGNACIO
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Rachel M Smith
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Ashley Styczynski
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Felipe Sánchez
;
Lea Maureira
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>Antimicrobial resistance is a global threat, heavily impacting low- and middle-income countries. This study estimated antimicrobial-resistant gram-negative bacteria (GNB) fecal colonization prevalence in hospitalized and community-dwelling adults in Chile before the coronavirus disease 2019 pandemic.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>From December 2018 to May 2019, we enrolled hospitalized adults in 4 public hospitals and community dwellers from central Chile, who provided fecal specimens and epidemiological information. Samples were plated onto MacConkey agar with ciprofloxacin or ceftazidime added. All recovered morphotypes were identified and characterized according to the following phenotypes: fluoroquinolone-resistant (FQR), extended-spectrum cephalosporin-resistant (ESCR), carbapenem-resistant (CR), or multidrug-resistant (MDR; as per Centers for Disease Control and Prevention criteria) GNB. Categories were not mutually exclusive.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>A total of 775 hospitalized adults and 357 community dwellers were enrolled. Among hospitalized subjects, the prevalence of colonization with FQR, ESCR, CR, or MDR-GNB was 46.4% (95% confidence interval [CI], 42.9–50.0), 41.2% (95% CI, 37.7–44.6), 14.5% (95% CI, 12.0–16.9), and 26.3% (95% CI, 23.2–29.4). In the community, the prevalence of FQR, ESCR, CR, and MDR-GNB colonization was 39.5% (95% CI, 34.4–44.6), 28.9% (95% CI, 24.2–33.6), 5.6% (95% CI, 3.2–8.0), and 4.8% (95% CI, 2.6–7.0), respectively.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>A high burden of antimicrobial-resistant GNB colonization was observed in this sample of hospitalized and community-dwelling adults, suggesting that the community is a relevant source of antibiotic resistance. Efforts are needed to understand the relatedness between resistant strains circulating in the community and hospitals.</jats:p> </jats:sec>
Scopus© Citations 10 2
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Head-to-head comparison of CAMPYAIR aerobic culture medium versus standard microaerophilic culture for Campylobacter isolation from clinical samples
(2023)
Arturo Levican
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Carmen Varela
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Lorena Porte
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WEITZEL, THOMAS
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Isabel Briceño
<jats:p><jats:italic>Campylobacter</jats:italic> spp. are considered the most frequent cause of acute gastroenteritis worldwide. However, outside high-income countries, its burden is poorly understood. Limited published data suggest that <jats:italic>Campylobacter</jats:italic> prevalence in low- and middle-income countries is high, but their reservoirs and age distribution are different. Culturing <jats:italic>Campylobacter</jats:italic> is expensive due to laboratory equipment and supplies needed to grow the bacterium (e.g., selective culture media, microaerophilic atmosphere, and a 42°C incubator). These requirements limit the diagnostic capacity of clinical laboratories in many resource-poor regions, leading to significant underdiagnosis and underreporting of isolation of the pathogen. CAMPYAIR, a newly developed selective differential medium, permits <jats:italic>Campylobacter</jats:italic> isolation without the need for microaerophilic incubation. The medium is supplemented with antibiotics to allow <jats:italic>Campylobacter</jats:italic> isolation in complex matrices such as human feces. The present study aims to evaluate the ability of the medium to recover <jats:italic>Campylobacter</jats:italic> from routine clinical samples. A total of 191 human stool samples were used to compare the ability of CAMPYAIR (aerobic incubation) and a commercial <jats:italic>Campylobacter</jats:italic> medium (CASA, microaerophilic incubation) to recover <jats:italic>Campylobacter</jats:italic>. All <jats:italic>Campylobacter</jats:italic> isolates were then identified by MALDI-TOF MS. CAMPYAIR showed sensitivity and specificity values of 87.5% (95% CI 47.4%–99.7%) and 100% (95% CI 98%–100%), respectively. The positive predictive value of CAMPYAIR was 100% and its negative predictive value was 99.5% (95% CI 96.7%–99.9%); Kappa Cohen coefficient was 0.93 (95% CI 0.79–1.0). The high diagnostic performance and low technical requirements of the CAMPYAIR medium could permit <jats:italic>Campylobacter</jats:italic> culture in countries with limited resources.</jats:p>
Scopus© Citations 3 1

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