Ramón Pérez-Tanoira

Background: Antimicrobial resistance represents a major global health threat, particularly due to the increasing prevalence of multidrug-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA). Snake venoms have emerged as promising sources of bioactive molecules with potential antimicrobial applications. However, their activity against clinical MRSA isolates and bacterial biofilms remains insufficiently characterized. This study evaluated the antibacterial, biofilm formation inhibitory, and hemocompatibility properties of venom obtained from a captive-bred Bitis rhinoceros specimen against S. aureus strains and clinical MRSA isolates. Methods: Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), minimum biofilm eradication concentration (MBEC), and biofilm formation inhibition assays were performed. In addition, direct and indirect hemolytic and hemagglutinating activities were evaluated to assess venom selectivity and biocompatibility. Results: Proteomic characterization revealed that the venom proteome is dominated by C-type lectin-like proteins (46.7%), with minor contributions from PIII snake venom metalloproteinase, phospholipase A₂, and L-amino acid oxidase toxin families. B. rhinoceros venom exhibited potent bactericidal activity against planktonic S. aureus cells, with minimum inhibitory and bactericidal concentration values ranging from 4 to 16 mg/L. Notably, the two clinical MRSA isolates showed lower values than the reference strain, although this observation should be interpreted with caution given the limited number of isolates tested. The venom also strongly inhibited biofilm formation at the concentrations tested, with inhibition exceeding 97% and remaining statistically significant across all three strains and MIC multiples when analyzed at the level of the independent experiment (n = 3; paired t-test, Benjamini–Hochberg-adjusted p < 0.001), although limited activity was observed against preformed mature biofilms. Hemocompatibility assays demonstrated low direct and indirect hemolytic activity together with favorable selectivity indices against bacterial cells. Conclusions: These findings suggest that captive-bred B. rhinoceros venom may represent a promising source of antimicrobial compounds against planktonic MRSA infections and early-stage biofilm development. The favorable hemocompatibility profile supports its potential applicability as a topical antimicrobial candidate. Nevertheless, this study is a proof of concept and, therefore, further assays are required to isolate and functionally characterize the specific venom fractions responsible for the antimicrobial activity.

The rising prevalence of multidrug-resistant (MDR) Enterobacterales poses a major challenge for the empirical treatment of urinary tract infections (UTIs). We evaluated the in vitro activity of mecillinam against urinary Escherichia coli and Klebsiella pneumoniae isolates, including extended-spectrum β-lactamase (ESBL)-producing and non-ESBL-producing isolates. In this prospective, single-center study conducted in Spain (December 2020–March 2021), urinary isolates of E. coli and K. pneumoniae from patients with suspected UTIs were tested for susceptibility to mecillinam and other commonly used antibiotics. A total of 503 isolates were analyzed, including 285 non-ESBL-producing and 218 ESBL-producing isolates. Overall susceptibility was 96.2% (95% CI, 94.2–97.7%) for mecillinam and 98.2% for ertapenem. Mecillinam susceptibility was 96.5% (95% CI, 93.6–98.3%) among non-ESBL-producing isolates and 95.9% (95% CI, 92.3–98.1%) among ESBL-producing isolates, with MIC₅₀ values of 0.5 mg/L and 1 mg/L, respectively. Among ESBL-producing isolates, susceptibility to fosfomycin and trimethoprim–sulfamethoxazole was 72.9% and 44.0%, respectively. These findings demonstrate high in vitro activity of mecillinam against urinary E. coli and K. pneumoniae isolates, including both ESBL-producing and non-ESBL-producing isolates, and provide microbiological evidence supporting further clinical evaluation of pivmecillinam as an oral treatment option for UTIs.

Introducción: La simulación clínica se ha consolidado como un recurso clave en la educación médica, pero su integración sistemática en asignaturas básicas como Microbiología Médica sigue siendo escasa en el contexto español, lo que facilitaría que el estudiantado conectara los contenidos microbiológicos con el razonamiento clínico y la solicitud razonada de estudios microbiológicos. Objetivo: Analizar los resultados académicos y la utilidad percibida de las prácticas de simulación clínica realizadas en dicha asignatura. Método: Se realizó un estudio descriptivo observacional de las calificaciones de la parte de la asignatura vinculada a unas prácticas de simulación basadas en entrevistas clínicas sobre síndromes infecciosos en Microbiología Médica de tercer curso de Medicina (cursos 2012-2013 a 2025-2026). Las prácticas se estructuraron en torno a entrevistas clínicas simuladas sobre síndromes frecuentes y se evaluaron mediante tres formatos sucesivos (preguntas abiertas en cuaderno de prácticas, test online domiciliario y test online presencial), aplicando estadística descriptiva y un ANOVA de medidas repetidas. De forma complementaria, se revisaron comentarios abiertos del estudiantado sobre la utilidad formativa de la experiencia. Resultados: Las calificaciones medias oscilaron entre 7,54 y 9,67 sobre 10, con medianas altas y desviaciones estándar bajas o moderadas. El ANOVA mostró diferencias significativas entre formatos (F = 466,92; p < 0,001), con puntuaciones más altas en el test online domiciliario y estabilidad posterior en el test online presencial. Estos hallazgos aconsejan interpretar los resultados académicos con cautela, ya que parte de la variación observada puede estar relacionada con el formato de evaluación y no exclusivamente con la intervención docente. El estudiantado valoró muy positivamente las prácticas, destacando su utilidad para comprender la relevancia clínica de la Microbiología, organizar el estudio en torno a síndromes infecciosos y prepararse para ECOE y rotaciones clínicas. Conclusiones: La simulación de entrevistas clínicas en Microbiología Médica constituye una innovación docente sostenible, asociada a resultados académicos elevados y consistentes, y a una utilidad formativa claramente percibida por el estudiantado, que favorece la integración básico-clínica en el grado de Medicina y ofrece un modelo transferible a otras facultades de diferentes sistemas educativos interesadas en incorporar la simulación en materias básicas.

Coinfections in COVID-19 patients can worsen disease severity by enhancing SARS-CoV-2 replication and proinflammatory cytokine levels. This study analyzes the characteristics of coinfected COVID-19 patients across the pandemic and their association with in-hospital mortality. We retrospectively examined data from 351 COVID-19 patients hospitalized in a Spanish secondary hospital between March 2020 and February–March 2021. Nasopharyngeal swabs from 340 patients were analyzed using multiplex RT-PCR to identify 26 respiratory pathogens. A total of 136 patients were coinfected with 191 bacteria (100 Gram-negative and 91 Gram-positive), 20 viruses, 18 fungi, and 1 protist. In 2021, empirical cephalosporin use increased (p = 0.009). The incidence of enterococcal coinfections tripled from 2020 to 2021 (p < 0.001). In 2021, a greater proportion of patients experienced urine (p = 0.001) and bloodstream (p = 0.010) coinfections. In 2020, there was one bloodstream infection, while in 2021, there were seven, with half of them being fatal. Coinfected patients experienced longer hospital stays and higher odds of long COVID (p < 0.001; p = 0.014; p = 0.045). Non-respiratory coinfections in 2021 correlated with increased mortality (p = 0.002). Antimicrobial resistance remained stable (p = 0.149). The rise in cephalosporin use correlated with increased Enterococcus infections, notably bloodstream infections, which were linked to mortality (p = 0.016). In 2021, coinfections were linked to prolonged hospital stays and an increased risk of mortality in our patient cohort.

Background/Objectives: Multidrug-resistant (MDR) bacterial colonization poses a significant risk for subsequent infections, especially within hospital environments. Healthcare workers can inadvertently transmit these MDR bacteria to vulnerable patients, exacerbating the problem. This study aimed to determine the colonization rates of MDR bacteria among patients and healthcare workers in a rural Ethiopian hospital with limited resources. Methods: Between 26 May and 6 June 2024, nasal, rectal, vagino-rectal exudate, and stool samples were collected from patients (n = 78) and healthcare workers (n = 11) at Gambo General Hospital (Oromia Region, Ethiopia). Samples were cultured on chromogenic media selective for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), and carbapenemase-producing Enterobacteriaceae (CPE). Bacterial identification was performed using MALDI-TOF mass spectrometry (Bruker), antimicrobial susceptibility testing using the MicroScan WalkAway system (Beckman Coulter), and genotypic characterization with the MDR Direct Flow Chip kit (Vitro). Results: MRSA nasal colonization was detected in 43.3% of patients (13/30; 95% CI: 27.4–60.8%) and 27.3% of healthcare workers (3/11; 95% CI: 6.0–61.0%) (p = 0.73). Rectal (or stool) colonization by MDR bacteria was significantly higher in pediatric patients (85.0%, 17/20; 95% CI: 62.1–96.8%) than in adults (14.3%, 4/28; 95% CI: 5.7–31.5%) (p < 0.001). Notably, a high proportion of pediatric patients harbored Escherichia coli strains co-producing NDM carbapenemase and CTX-M ESBL, and VRE strains were also predominantly isolated in this group. Conclusions: This study reveals a concerningly high prevalence of MRSA and MDR Enterobacteriaceae, especially among children at Gambo Hospital. The VRE prevalence was also substantially elevated compared to other studies. These findings underscore the urgent need for strengthened infection control measures and antimicrobial stewardship programs within the hospital setting.

Purpose: Accurate and rapid diagnosis of gastrointestinal infections is essential for effective patient management. This study compared the diagnostic performance of two multiplex PCR panels— the Seegene Allplex™ Gastrointestinal Panels (Seegene, Seoul, Korea) and the Luminex NxTAG ^® Gastrointestinal Pathogen Panel (Luminex Corporation, Austin, Texas, a Diasorin Company)—in detecting gastrointestinal pathogens from clinical stool samples. Methods: A total of 196 stool samples, collected from patients at a Spanish hospital during 2023, were analyzed using both assays through prospective and retrospective approaches. The performance of each test was assessed based on Positive Percentage Agreement (PPA), Negative Percentage Agreement (NPA), and overall agreement. Discrepancies between methods were resolved with a third confirmatory technique when available. Results: Both assays demonstrated high overall concordance, with NPA values consistently above 95% and overall Kappa values exceeding 0.8 for most pathogens. The average PPA was greater than 89% for nearly all targets; however, lower agreement was observed for Cryptosporidium spp. (86.6%). Notably, discrepancies were primarily observed for certain pathogens, such as Salmonella spp. and Cryptosporidium spp., highlighting the diagnostic challenges associated with these targets. Conclusion: To our knowledge, this is the first study to compare the novel Luminex NxTAG^® panels from Diasorin with the Seegene Allplex™. Both multiplex assays provide rapid and reliable detection of gastrointestinal pathogens, making them valuable tools in clinical diagnostics. Future research should focus on improving detection accuracy for challenging pathogens and expanding target panels to further enhance patient management and reduce disease burden.

Purpose: Malaria remains a major global health challenge, particularly in sub-Saharan Africa and low- and middle-income countries (LMICs), contributing substantially to mortality and morbidity rates. In resource-limited settings, access to specialized diagnostic tests is often restricted, making basic blood analysis a valuable diagnostic tool. This study investigated the correlation between malaria infection and full blood count values in a rural region of Ghana during the 2022 rainy season, aiming to highlight diagnostic insights available from routine blood analyses. Methods: A retrospective case-control analysis was conducted on 544 confirmed malaria cases, comparing their blood values with those of matched malaria-negative controls. Results: Parasitaemia levels peaked during the rainy season, with July showing the highest values. Malaria-positive patients exhibited lower levels of haemoglobin, white blood cells, lymphocytes, and platelets, but higher neutrophil counts compared to controls. Middle-aged women had significantly lower haemoglobin levels than men, and younger individuals showed higher parasitaemia levels. A negative correlation was found between Plasmodium density and haemoglobin and platelet counts, while positive correlations were observed with white blood cell and neutrophil counts. Conclusion: This study highlights the significant burden of malaria in rural Ghana during the rainy season and underscores the impact of infection on blood values. Routine full blood count analysis provides a practical and accessible diagnostic tool in resource-limited settings. The findings emphasise the importance of targeted interventions for high-risk groups, particularly children and women, to improve patient management and reduce malaria-related morbidity. Graphical

Gastrointestinal microorganism resistance and dissemination are increasing, partly due to international travel. This study investigated gastrointestinal colonisations and the acquisition of antimicrobial resistance (AMR) genes among international travellers moving between Spain and low- and middle-income countries (Peru and Ethiopia). We analysed 102 stool samples from 51 volunteers collected before and after travel, revealing significantly higher rates of colonisation by both bacteria and protists upon return. Diarrhoeagenic strains of E. coli were the most notable microorganism detected using RT-PCR with the Seegene Allplex™ Gastrointestinal Panel Assays. A striking prevalence of β-lactamase resistance genes, particularly the TEM gene, was observed both before and after travel. No significant differences in AMR genes were found between the different locations. These findings highlight the need for rigorous surveillance and preventive strategies, as travel does not significantly impact AMR gene acquisition but does affect microbial colonisations. This study provides valuable insights into the intersection of gastrointestinal microorganism acquisition and AMR in international travellers, underscoring the need for targeted interventions and increased awareness.

The guanidine core has been one of the most studied functional groups in medicinal chemistry, and guanylation reactions are powerful tools for synthesizing this kind of compound. In this study, a series of five guanidine-core small molecules were obtained through guanylation reactions. These compounds were then evaluated against three different strains of Escherichia coli, one collection strain from the American Type Culture Collection (ATCC) of E. coli ATCC 35218, and two clinical extended-spectrum beta-lactamase (ESBL)-producing E. coli isolates (ESBL1 and ESBL2). Moreover, three different strains of Pseudomonas aeruginosa were studied, one collection strain of P. aeruginosa ATCC 27853, and two clinical multidrug-resistant isolates (PA24 and PA35). Among Gram-positive strains, three different strains of Staphylococcus aureus, one collection strain of S. aureus ATCC 29213, and two clinical methicillin-resistant S. aureus (MRSA1 and MRSA2) were evaluated. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) experiments were reported, and the drop plate (DP) method was used to determine the number of viable suspended bacteria in a known beaker volume. The results from this assessment suggest that guanidine-core small molecules hold promise as therapeutic alternatives for treating infections caused by clinical Gram-negative and Gram-positive bacteria, highlighting the need for further studies to explore their potential. The results from this assessment suggest that the chemical structure of CAPP4 might serve as the basis for designing more active guanidine-based antimicrobial compounds, highlighting the need for further studies to explore their potential.