A Facile and Green Approach for the Preparation of Silver Nanoparticles on Graphene Oxide with Favorable Antibacterial Activity.

Herein, we introduce a simple precipitation method for preparing graphene oxide-silver nanoparticle (GO/AgNP) composites, utilizing Calendula officinalis (C. officinalis) seed extract as both a reducing and stabilizing agent. Our research combines the sustainable preparation of graphene oxide (GO) with the green synthesis of silver nanoparticles (AgNPs), aiming to explore the potential of the obtained composite as a novel antibacterial material. To establish a benchmark, the synthesis was also performed using sodium citrate, a conventional reducing agent. The resultant GO/AgNP composites were characterized through several analytical techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, X-ray diffraction (XRD), infrared (IR) spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy, confirming the successful functionalization of GO with AgNPs. The antibacterial effectiveness of the composites was systematically assessed against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with nanoparticle concentrations spanning from 0 to 250 µg/mL, utilizing mostly disk diffusion and colony-forming unit (CFU) count assays. The AgNPs were characterized by a size range of 15-50 nm. Notably, the GO/AgNP composite prepared using C. officinalis seed extract demonstrated superior antibacterial activity at all tested concentrations, outperforming both pure GO and the GO/AgNP composite prepared with sodium citrate. The most pronounced antibacterial effect was observed at a concentration of 32.0 µg/mL. Therefore, this innovative synthesis approach may offer a valuable contribution to the development of new therapeutic agents to combat bacterial infections, suggesting further exploration into antibacterial coatings or potential drug development.

Cefadroxil photodegradation processes sensitized by natural pigments: mechanistic aspects and impact on the antimicrobial function.

Cefadroxil is a widely used antibiotic with a low elimination efficiency in wastewater treatments plants, so it represents a contaminants of emerging concern that should be removed. The photosensitization process that involves natural pigments and visible sunlight can be offered as an environmentally friendly alternative to be considered for Cefadroxil degradation. In this investigation, we carried out a mechanistic and kinetic approach to Cefadroxil photodegradation sensitized by Riboflavin and Humic Acid, in individual and combined processes. Our experiments indicate that Cefadroxil is able to interact with the excited states of Riboflavin as well as with the photogenerated reactive oxygen species, with an important contribution of singlet oxygen. The antibiotic was less sensitive to the photodegradation in the presence of Humic Acids and in the mixture of Riboflavin and Humic Acids. Self-sensitization processes and internal filter effects are proposed as possible explanations for the observed phenomenon. The reaction between Cefadroxil and singlet oxygen showed a dependence with the pH of the medium, the photodegradation kinetic constants are greater at alkaline pH compared to neutral pH. The reaction is favored when the anionic species of the antibiotic is present. Microbiological tests on S. aureus indicated that the antibiotic reduce its antimicrobial activity as a consequence of the photooxidative process mediated by singlet oxygen. We believe that the results are relevant since, the sensitized photodegradation process could lead to the oxidation of Cefadroxil and to the progressive loss of its antimicrobial function, this fact could contribute to the decrease in the generation of bacterial multi-resistance to antibiotics in the environment.

Peptide derived from plant defensins: A promising 68Ga radiolabelled agent for diagnostic of infection foci in PET.

The development of new radiopharmaceuticals for the detection of hidden infection foci has great relevance for early detection and the selection of the correct treatment, particularly in immunosuppressed patients. In that sense, the labelling of antimicrobial peptides (AMPs) that are capable of binding specifically to the pathogenic microorganism which causes the infection, should provide a sufficiently specific agent, able to distinguish an infection from a sterile inflammation. Defensins are particularly interesting molecules with antimicrobial activity, the EcgDf1 defensin was identified from the genome of a Uruguayan native plant, Erythrina crista-galli, the 'Ceibo' tree. Our group has previously reported a synthetic biologically active short analogue EcgDf21 (ERFTGGHCRGFRRRCFCTKHC) successfully labelled with 99mTc. Herein we present a shorter analogue which also preserves the γ-core domain, as a pharmacophore for a potential infection detection agent. This peptide was derivatized with the bifunctional chelating agent 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) through a lysine linker in the amino-terminal group (NOTA-KGHCRGFRRRC) and radiolabelled with 68Ga ([68Ga]Ga-NOTA-K-EcgDf1(10)). The [68Ga]Ga-NOTA-K-EcgDf1(10) labelling procedure rendered a product with high radiochemical purity and stability in the labelling milieu. The Log P value indicated that the complex has a hydrophilic behaviour, confirmed by the biodistribution profile. The [68Ga]Ga-NOTA-K-EcgDf1(10) complex demonstrated specific binding to cultures of Candida albicans and Aspergillus niger. Its biodistribution showed renal elimination and low accumulation in the rest of the body. It was possible to successfully differentiate sterile inflammation from infection by PET images in nude mice with a target/non-target ratio of 3.3 for C. albicans and 3.7 for A. niger, respectively.

Staphylococcus aureus: changes in antimicrobial sensitivity profile and its relationship with SCCmec among clinical isolates / Staphylococcus aureus: alterações no perfil de sensibilidade antimicrobiana e sua relação com SCCmec entre isolados clínicos / Staphylococcus aureus: cambios en el perfil de sensibilidad antimicrobiana y su relación con SCCmec entre aislados clínicos

Background and Objectives: Staphylococcus aureus is a pathogen of great clinical relevance, especially those resistant to methicillin, called MRSA. Over the years, S. aureus antimicrobial resistance patterns have changed. Understanding such changes is essential to update protocols and propose efficient therapeutic approaches. This study aimed to characterize the temporal distribution of S. aureus antimicrobial resistance in patients admitted to the hospital as well as to assess its relationship with SCCmec typing. Methods: a total of 9,949 cultures of clinical materials were analyzed, between January 2000 and October 2019, from patients admitted to a university hospital in southern Brazil. All isolates had their identification and antimicrobial sensitivity profile analyzed using manual and automated techniques. Furthermore, 86 isolates were selected for mecA gene research and SCCmec typing using conventional and multiplex PCR techniques, respectively. Results: when assessing the temporal distribution of S. aureus over 20 years, it was possible to observe a drop in the proportion of MRSA compared to methicillin-sensitive S. aureus (MSSA). Between 2000 and 2002, the frequency of MRSA was 58.5%, whereas that of MSSA was 36.7%. However, from 2003 onwards, there was a reversal of these percentages. At the end of the analyzed period, 55.2% of infections were caused by MSSA, whereas 36.2% contained MRSA isolates. Furthermore, in the period analyzed, the highest prevalence was of SCCmec type II. Conclusion: these data suggest an epidemiological change in S. aureus from clinical materials, with a change in the prevalent type of SCCmec and changes in the antimicrobial sensitivity profile exhibited by the isolates. Such facts must be considered by the clinical staff with a focus on effective patient management, the choice of appropriate antimicrobial therapy so that effective infection control measures are implemented.(AU)

Justificativa e Objetivos: Staphylococcus aureus é um patógeno de grande relevância clínica, especialmente aqueles resistentes à meticilina, denominados MRSA. Ao longo dos anos, os padrões de resistência antimicrobiana dos S. aureus têm apresentado modificações. Compreender tais mudanças é fundamental para atualizar protocolos e propor abordagens terapêuticas eficientes. O objetivo do estudo foi caracterizar a distribuição temporal da resistência antimicrobiana de S. aureus proveniente de pacientes internados no hospital, bem como avaliar sua relação com a tipagem SCCmec. Métodos: foram analisadas 9.949 culturas de materiais clínicos, entre janeiro de 2000 e outubro de 2019, de pacientes internados em um hospital universitário no sul do Brasil. Todos os isolados tiveram sua identificação e perfil de sensibilidade aos antimicrobianos analisados por técnicas manuais e automatizadas. Ainda, 86 isolados foram selecionados para a realização da pesquisa do gene mecA e tipagem SCCmec, utilizando a técnica de PCR convencional e multiplex, respectivamente. Resultados: avaliando a distribuição temporal dos S. aureus ao longo de 20 anos, foi possível observar queda na proporção de MRSA em comparação com o S. aureus sensível à meticilina (MSSA). Entre 2000 e 2002, a frequência de MRSA foi de 58,5%, enquanto que a de MSSA foi de 36,7%. No entanto, a partir de 2003, houve uma inversão desses percentuais. Ao final do período analisado, 55,2% das infecções foram ocasionadas por MSSA, enquanto que 36,2% continham isolados de MRSA. Ainda, no período analisado, a prevalência maior foi do SCCmec tipo II. Conclusão: esses dados sugerem uma alteração epidemiológica em S. aureus provenientes de materiais clínicos, com alteração do tipo SCCmec prevalente e modificações do perfil de sensibilidade aos antimicrobianos exibidos pelos isolados. Tais fatos devem ser considerados pelo corpo clínico, focando para que haja um manejo efetivo dos pacientes, escolha da terapia antimicrobiana adequada e para que medidas de efetivas de controle de infecção sejam implementadas.(AU)

Justificación y Objetivos: Staphylococcus aureus es un patógeno de gran relevancia clínica, especialmente los resistentes a meticilina, denominado MRSA. Con el paso de los años, los patrones de resistencia a los antimicrobianos de S. aureus han cambiado. Comprender tales cambios es esencial para actualizar los protocolos y proponer enfoques terapéuticos eficientes. El objetivo del estudio fue caracterizar la distribución temporal de la resistencia antimicrobiana de S. aureus en pacientes ingresados en el hospital, así como evaluar su relación con la tipificación de SCCmec. Métodos: se analizaron 9.949 cultivos de materiales clínicos, entre enero de 2000 y octubre de 2019, de pacientes ingresados en un hospital universitario del sur de Brasil. Se analizó la identificación y el perfil de sensibilidad antimicrobiana de todos los aislados mediante técnicas manuales y automatizadas. Además, se seleccionaron 86 aislados para la investigación del gen mecA y la tipificación de SCCmec, utilizando técnicas de PCR convencional y múltiple, respectivamente. Resultados: al evaluar la distribución temporal de S. aureus durante 20 años, fue posible observar una caída en la proporción de MRSA en comparación con S. aureus sensible a meticilina (MSSA). Entre 2000 y 2002, la frecuencia de MRSA fue del 58,5%, mientras que la de MSSA fue del 36,7%. Sin embargo, a partir de 2003, se produjo una reversión de estos porcentajes. Al final del período analizado, el 55,2% de las infecciones fueron causadas por MSSA, mientras que el 36,2% contenía aislados de MRSA. Además, en el período analizado, la mayor prevalencia fue de SCCmec tipo II. Conclusión: estos datos sugieren un cambio epidemiológico en S. aureus a partir de materiales clínicos, con un cambio en el tipo prevalente de SCCmec y cambios en el perfil de sensibilidad antimicrobiana exhibido por los aislados. El personal clínico debe considerar estos hechos, centrándose en el tratamiento eficaz del paciente, la elección del tratamiento antimicrobiano adecuado y la implementación de medidas eficaces de control de infecciones.(AU)

Epidemiological and microbiological characteristics of S. aureus pediatric infections in Colombia 2018-2021, a national multicenter study (Staphylored Colombia).

Background: Staphylococcus aureus infections are a significant cause of morbidity and mortality in pediatric populations worldwide. The Staphylo Research Network conducted an extensive study on pediatric patients across Colombia from 2018 to 2021. The aim of this study was to describe the epidemiological and microbiological characteristics of S. aureus in this patient group. Methods: We analyzed S. aureus isolates from WHONET-reporting centers. An "event" was a positive culture isolation in a previously negative individual after 2 weeks. We studied center characteristics, age distribution, infection type, and antibiotic susceptibilities, comparing methicillin sensitive (MSSA) and resistant S. aureus (MRSA) isolates. Results: Isolates from 20 centers across 7 Colombian cities were included. Most centers (80%) served both adults and children, with 55% offering oncology services and 85% having a PICU. We registered 8,157 S. aureus culture isolations from 5,384 events (3,345 MSSA and 1,961 MRSA) in 4,821 patients, with a median age of 5 years. Blood (26.2%) and skin/soft tissue (18.6%) were the most common infection sources. Most isolates per event remained susceptible to oxacillin (63.2%), clindamycin (94.3%), and TMP-SMX (98.3%). MRSA prevalence varied by city (<0.001), with slightly higher rates observed in exclusively pediatric hospitals. In contrast, the MRSA rate was somewhat lower in centers with Antimicrobial Stewardship Program (ASP). MRSA was predominantly isolated from osteoarticular infections and multiple foci, while MSSA was more frequently associated with recurrent infections compared to MRSA. Conclusions: This is the largest study of pediatric S. aureus infections in Colombia. We found MSSA predominance, but resistance have important regional variations. S. aureus remains susceptible to other commonly used antibiotics such as TMP-SMX and clindamycin. Ongoing monitoring of S. aureus infections is vital for understanding their behavior in children. Prospective studies within the Staphylored LATAM are underway for a more comprehensive clinical and genetic characterization.

Genetic and Phenotypic Changes Related to the Development of mec-Independent Oxacillin Non-Susceptibility in ST8 Staphylococcus aureus Recovered after Antibiotic Therapy in a Patient with Bacteremia.

The mec-independent oxacillin non-susceptible S. aureus (MIONSA) strains represent a great clinical challenge, as they are not easily detected and can lead to treatment failure. However, the responsible molecular mechanisms are still very little understood. Here, we studied four clinical ST8-MSSA-t024 isolates recovered during the course of antibiotic treatment from a patient suffering successive episodes of bacteremia. The first isolates (SAMS1, SAMS2, and SAMS3) were susceptible to cefoxitin and oxacillin. The last one (SA2) was susceptible to cefoxitin, resistant to oxacillin, lacked mec genes, and had reduced susceptibility to teicoplanin. SA2 showed higher ß-lactamase activity than SAMS1. However, ß-lactamase hyperproduction could not be linked to oxacillin resistance as it was not inhibited by clavulanic acid, and no genetic changes that could account for its hyperproduction were found. Importantly, we hereby report the in vivo acquisition and coexistence of different adaptive mutations in genes associated with peptidoglycan synthesis (pbp2, rodA, stp1, yjbH, and yvqF/vraT), which is possibly related with the development of oxacillin resistance and reduced susceptibility to teicoplanin in SA2. Using three-dimensional models and PBP binding assays, we demonstrated the high contribution of the SA2 PBP2 Ala450Asp mutation to the observed oxacillin resistance phenotype. Our results should be considered as a warning for physicians and microbiologists in the region, as MIONSA detection and treatment represent an important clinical challenge.

Antimicrobial and Antibiofilm Potential of Flourensia retinophylla against Staphylococcus aureus.

Staphylococcus aureus is a Gram-positive bacteria with the greatest impact in the clinical area, due to the high rate of infections and deaths reaching every year. A previous scenario is associated with the bacteria's ability to develop resistance against conventional antibiotic therapies as well as biofilm formation. The above situation exhibits the necessity to reach new effective strategies against this pathogen. Flourensia retinophylla is a medicinal plant commonly used for bacterial infections treatments and has demonstrated antimicrobial effect, although its effect against S. aureus and bacterial biofilms has not been investigated. The purpose of this work was to analyze the antimicrobial and antibiofilm potential of F. retinophylla against S. aureus. The antimicrobial effect was determined using an ethanolic extract of F. retinophylla. The surface charge of the bacterial membrane, the K+ leakage and the effect on motility were determined. The ability to prevent and remove bacterial biofilms was analyzed in terms of bacterial biomass, metabolic activity and viability. The results showed that F. retinophylla presents inhibitory (MIC: 250 µg/mL) and bactericidal (MBC: 500 µg/mL) activity against S. aureus. The MIC extract increased the bacterial surface charge by 1.4 times and the K+ concentration in the extracellular medium by 60%. The MIC extract inhibited the motility process by 100%, 61% and 40% after 24, 48 and 72 h, respectively. The MIC extract prevented the formation of biofilms by more than 80% in terms of biomass production and metabolic activity. An extract at 10 × MIC reduced the metabolic activity by 82% and the viability by ≈50% in preformed biofilms. The results suggest that F. retinophylla affects S. areus membrane and the process of biofilm formation and removal. This effect could set a precedent to use this plant as alternative for antimicrobial and disinfectant therapies to control infections caused by this pathogen. In addition, this shrub could be considered for carrying out a purification process in order to identify the compounds responsible for the antimicrobial and antibiofilm effect.

Genomic insights of S. aureus associated with bovine mastitis in a high livestock activity region of Mexico.

IMPORTANCE: Bovine mastitis, predominantly associated with gram-positive Staphylococcus aureus, poses a significant threat to dairy cows, leading to a decline in milk quality and volume with substantial economic implications. OBJECTIVE: This study investigated the incidence, virulence, and antibiotic resistance of S. aureus associated with mastitis in dairy cows. METHODS: Fifty milk-productive cows underwent a subclinical mastitis diagnosis, and the S. aureus strains were isolated. Genomic DNA extraction, sequencing, and bioinformatic analysis were performed, supplemented by including 124 S. aureus genomes from cows with subclinical mastitis to enhance the overall analysis. RESULTS: The results revealed a 42% prevalence of subclinical mastitis among the cows tested. Genomic analysis identified 26 sequence types (STs) for all isolates, with Mexican STs belonging primarily to CC1 and CC97. The analyzed genomes exhibited multidrug resistance to phenicol, fluoroquinolone, tetracycline, and cephalosporine, which are commonly used as the first line of treatment. Furthermore, a similar genomic virulence repertoire was observed across the genomes, encompassing the genes related to invasion, survival, pathogenesis, and iron uptake. In particular, the toxic shock syndrome toxin (tss-1) was found predominantly in the genomes isolated in this study, posing potential health risks, particularly in children. CONCLUSION AND RELEVANCE: These findings underscore the broad capacity for antibiotic resistance and pathogenicity by S. aureus, compromising the integrity of milk and dairy products. The study emphasizes the need to evaluate the effectiveness of antibiotics in combating S. aureus infections.

Screening of essential oils against oxacillin - resistant Staphylococcus aureus strains isolated from bovine mastitis / Screening de aceites esenciales frente a Staphylococcus aureus oxacilino - resistentes extraidos de aislados de mastitis bovina

Bovine mastitis is a disease wi th far - reaching consequences for the dairy industry. Staphylococcus aureus is a pathogen that is especially resistant to antibiotics. The objective of this study was to evaluate the antimicrobial activity of the essential oils Lippia citriodora (Lam.), Thy mus vulgaris (L), and a mixture of the essential oils Lippia citriodora and Thymus vulgaris (50/50 v/v), against isolates of oxacillin - resistant Staphylococcus aureus (n=15) of positive cases of bovine mastitis. For the statistical analysis, the IBM SPSS s tatistical package was used. The mixture of essential oils ( Lippia citriodora and Thymus vulgaris (50/50 v/v)) obtained the most significant antimicrobial activity in relation to pure essential oils. It is therefore concluded that the mixture of these oils boosts their antimicrobial activity ( p <0.05). The minimum inhibitory and bactericidal concentration of this mixture for the total isolations was 12 µL/L and 25 µL/mL, respectively.

La mastitis bovina es una enfermedad de gran impacto para la industria lechera. El Staphylococcus aureus es uno de los principales patógenos, especialmente aquellos resistentes a los antibióticos. El objetivo de este estudio fue evaluar la actividad antimicrobiana de los aceites esenciales de Lippia citriodora (Lam.), Thymus vulgaris (L), y una mezcla de aceites esenciales de Lippia citriodora y Thymus vulgaris (50/50 v/v), frente a aislamientos clínicos de Staph ylococcus aureus oxacilino - resistentes (n=15) de mastitis bovina. Se utilizó p rograma estadístico IBM SPSS y se concluyó la diferencia significativa a un p <0.05. La mezcla de aceites esenciales ( Lippia citriodora y Thymus vulgaris (50/50 v/v)), obtuvo la m ayor actividad antimicrobiana en relación a los aceites esenciales puros, se concluye que la mezcla de estos aceites potencia su actividad antimicrobiana ( p <0.019). La concentración mínima inhibitoria y bactericida de esta mezcla fue del 12 µL/mL y 25 µL/m L, respectivamente, y puede ser una alternativa terapéutica.

Detection of Vancomycin Resistance among Methicillin-Resistant Staphylococcus aureus Strains Recovered from Children with Invasive Diseases in a Reference Pediatric Hospital.

Vancomycin is the cornerstone in treating methicillin-resistant Staphylococcus aureus (MRSA) infections. However, therapeutic failures can occur when MRSA strains with decreased susceptibility to glycopeptides (DSG) are involved. The aim of this study was to detect and characterize DSG in MRSA recovered from children with invasive diseases at a reference pediatric hospital between 2009 and 2019. Fifty-two MRSA strains were screened using agar plates with vancomycin 3 and 4 mg/L (BHI-3 and BHI-4); the VITEK2 system; and standard and macro E-tests. Suspicious hVISA were studied by population analysis profiling-area under the curve (PAP-AUC), and wall thickness was analyzed by transmission electron microscopy. Neither VRSA nor VISA were detected in this set. As only three strains met the hVISA criteria, the PAP-AUC study included 12 additional MRSA strains that grew one colony on BHI-4 plates or showed minimum inhibitory concentrations of vancomycin and/or teicoplanin ≥ 1.5 mg/L. One strain was confirmed as hVISA by PAP-AUC. The wall thickness was greater than the vancomycin-susceptible control strain; it belonged to ST30 and carried SCCmec IV. As expected, a low frequency of hVISA was found (1.9%). The only hVISA confirmed by PAP-AUC was not detected by the screening methods, highlighting the challenge that its detection represents for microbiology laboratories.

Different evolution of S. aureus methicillin-resistant and methicillin-susceptible infections, Argentina.

Staphylococcus aureus-(SA) is widespread among healthcare-associated-(HA) and the community-associated-(CA) infections. However, the contributions of MRSA and MSSA to the SA overall burden remain unclear. In a nationally-representative-survey conducted in Argentina, 668 SA clinical isolates from 61 hospitals were examined in a prospective, cross-sectional, multicenter study in April 2015. The study aimed to analyze MRSA molecular epidemiology, estimate overall SA infection incidence (MSSA, MRSA, and genotypes) in community-onset (CO: HACO, Healthcare-Associated-CO and CACO, Community-Associated-CO) and healthcare-onset (HO: HAHO, Healthcare-associated-HO) infections, stratified by age groups. Additionally temporal evolution was estimated by comparing this study's (2015) incidence values with a previous study (2009) in the same region. Erythromycin-resistant-MSSA and all MRSA strains were genetically typed. The SA total-infections (TI) overall-incidence was 49.1/100,000 monthly-visits, 25.1 and 24.0 for MRSA and MSSA respectively (P = 0.5889), in April 2015. In adults with invasive-infections (INVI), MSSA was 15.7 and MRSA was 11.8 (P = 0.0288), 1.3-fold higher. HA SA infections, both MSSA and MRSA, surpassed CA infections by over threefold. During 2009-2015, there was a significant 23.4 % increase in the SA infections overall-incidence, mainly driven by MSSA, notably a 54.2 % increase in INVI among adults, while MRSA infection rates remained stable. The MSSA rise was accompanied by increased antimicrobial resistance, particularly to erythromycin, linked to MSSA-CC398-t1451-ermT + -IEC+-pvl- emergence. The SA-infections rise was primarily attributed to community-onset-infections (37.3 % and 62.4 % increase for TI and INVI, respectively), particularly HACO-MSSA and HACO-MRSA in adults, as well as CACO-MSSA. The main CA-MRSA-PFGE-typeN-ST30-SCCmecIVc-PVL+/- clone along with other clones (USA300-ST8-IV-LV-PVL+/-, PFGE-typeDD-ST97-IV- PVL-) added to rather than replaced CA-MRSA-PFGE-typeI-ST5-SCCmecIVa-PVL+/- clone in HA invasive-infections. They also displaced clone HA-MRSA-PFGE-typeA-ST5-SCCmecI, mainly in HAHO infections. The overall-burden of SA infections is rising in Argentina, driven primarily by community-onset MSSA, particularly in adults, linked to increased erythromycin-resistance and MSSA-CC398-t1451-ermT + -IEC+-pvl- emergence. Novel knowledge and transmission-control strategies are required for MSSA.

Clinical and microbiological profile of health care-associated infections in a tertiary hospital: Comparison between a cohort of hospitalized patients during prepandemic and COVID-19 pandemic periods.

BACKGROUND: During the COVID-19 pandemic, health service practices underwent significant changes, impacting the occurrence of health care-associated infections (HAIs). This study presents the epidemiology of bacterial infections and compares clinical data on nosocomial infections in hospitalized patients before and during the pandemic. METHODS: A unicentric, observational, retrospective cohort study was conducted with descriptive analyses on the microorganism identification and resistance profile. Patient's clinical data who had hospital-acquired infection (HAI), during their hospitalization in a tertiary hospital before and during the COVID-19 pandemic was compared by descriptive and inferential analyses. RESULTS: A total of 1,581 bacteria were isolated from 1,183 hospitalized patients. Among patients coinfected with COVID-19, there was a statistically significant increase in HAI-related deaths (P < .001) and HAI caused by multidrug-resistant organisms (P < .001), mainly by Acinetobacter baumannii and Staphylococcus aureus. A higher odds ratio of HAI-related deaths compared to the prepandemic period was observed (odds ratio 6.98 [95% confidence interval 3.97-12.64]). CONCLUSIONS: The higher incidence of multidrug-resistant bacteria and increased deaths due to HAI, especially in patients with COVID-19 coinfection, might be related to various factors such as increased workload, broad-spectrum antibiotic use, and limited resources. The pandemic has changed the profile of circulating bacteria and antimicrobial resistance. Prevention strategies should be considered to reduce the impact of these infections.

A photochemical route in the synthesis and characterization of La2Ti2O7 and La2Ti2O7/AgO films and its evaluation in Congo red degradation and as antibacterial control to Staphylococcus aureus.

In this article, we propose a simple photochemical method to synthesize pure La2Ti2O7 films and La2Ti2O7 films doped with silver at 1.0, 3.0, and 5.0 mol%. After annealing the photo-deposited films at 900 °C, XRD, SEM, and XPS analyses showed the formation of a monoclinic La2Ti2O7 phase and the presence of Ag and AgO in doped samples. Photocatalytic tests for Congo red degradation demonstrated that pure La2Ti2O7 achieved 25.4% degradation, while doped samples reached a maximum of 92.7% degradation. Moreover, increasing silver doping on La2Ti2O7 films significantly reduced the growth of Staphylococcus aureus, indicating potential antibacterial properties. The enhanced photoactivity was attributed to the formation of a type I heterojunction between La2Ti2O7 and AgO, and a degradation mechanism was proposed based on Congo red degradation.

Fluoroquinolone Analogs, SAR Analysis, and the Antimicrobial Evaluation of 7-Benzimidazol-1-yl-fluoroquinolone in In Vitro, In Silico, and In Vivo Models.

Structure-activity relationship (SAR) studies allow the evaluation of the relationship between structural chemical changes and biological activity. Fluoroquinolones have chemical characteristics that allow their structure to be modified and new analogs with different therapeutic properties to be generated. The objective of this research is to identify and select the C-7 heterocycle fluoroquinolone analog (FQH 1-5) with antibacterial activity similar to the reference fluoroquinolone through in vitro, in silico, and in vivo evaluations. First, SAR analysis was conducted on the FQH 1-5, using an in vitro antimicrobial sensibility model in order to select the best compound. Then, an in silico model mechanism of action analysis was carried out by molecular docking. The non-bacterial cell cytotoxicity was evaluated, and finally, the antimicrobial potential was determined by an in vivo model of topical infection in mice. The results showed antimicrobial differences between the FQH 1-5 and Gram-positive and Gram-negative bacteria, identifying the 7-benzimidazol-1-yl-fluoroquinolone (FQH-2) as the most active against S. aureus. Suggesting the same mechanism of action as the other fluoroquinolones; no cytotoxic effects on non-bacterial cells were found. FQH-2 was demonstrated to decrease the amount of bacteria in infected wound tissue.

Calidad microbiológica y actividad antibacteriana de miel producida por Melipona beecheii en Yucatán, México

RESUMEN Objetivo. Analizar la calidad microbiológica y actividad antibacteriana en 43 muestras de miel producida por Melipona beecheii, extraída durante las épocas de cosecha (enero a mayo del 2020 y 2021) y poscosecha (junio a octubre 2020) de meliponarios ubicados en selva baja caducifolia del Sureste de México. Materiales y métodos. La calidad microbiológica se determinó evaluando el contenido de mesófilos aerobios totales, coliformes, hongos, levaduras y anaerobios formadores de esporas. Para la actividad antibacteriana, se utilizó el ensayo de difusión en agar con pocillos utilizando concentraciones de miel al 5, 10, 20, 40 y 80%. Resultados. Se observó la presencia de mesófilos aerobios (83.7% de las muestras), coliformes (4.6%), mohos (20.9%) y levaduras (39.5%), con un máximo de 4.5x102, 2.5x10, 9.5x10 y 3.2x103 UFC/g, respectivamente. En ninguna muestra se observó la presencia de formas esporuladas de clostridios sulfito reductores. Con respecto a la actividad antibacteriana las mayores zonas de inhibición se registraron contra Staphylococcus aureus a una concentración de la miel al 80 y 40%, contrario a lo observado con Salmonella var. Typhimurium, Pseudomonas aureginosa y Escherichia coli, en donde la interferencia en el crecimiento bacteriano no fue tan evidente. Conclusiones. No obstante, el crecimiento de mesófilos y levaduras en la mayoría de las muestras, éstas presentaron actividad antibacteriana contra los patógenos referidos, lo cual puede ser atribuido a las interacciones entre microbioma, plantas, abejas y características fisicoquímicas de la miel.

ABSTRACT Objective. To analyze the microbiological quality and antibacterial activity in 43 samples of honey produced by Melipona beecheii, extracted during the years 2020 and 2021 in the harvest (January to May) and post-harvest (June to October) seasons from meliponaries located in the low deciduous forest of southeast of Mexico. Materials and methods. Microbiological quality was determined by evaluating the content of total aerobic mesophiles, coliforms, molds, yeasts, and spore-forming anaerobes. For antibacterial activity, the agar well diffusion assay was used using 5, 10, 20, 40 and 80% honey concentrations. Results. The presence of aerobic mesophiles (83.7% of the samples), coliforms (4.6%), molds (20.9%) and yeasts (39.5%) was observed, with a maximum of 4.5x102, 2.5x10, 9.5x10 and 3.2x103 CFU/g, respectively. The presence of sporulated forms of sulfite-reducing clostridia was not observed in any sample. With respect to the antibacterial activity, the highest zones of inhibition were recorded against Staphylococcus aureus at a honey concentration of 80 and 40%, contrary to what was observed with Salmonella var. Typhimurium, Pseudomonas aureginosa and Escherichia coli, where the interference in bacterial growth was not so evident. Conclusions. However, the growth of mesophiles and yeasts in most of the samples showed antibacterial activity against the pathogens mentioned above, which can be attributed to the interactions between microbiome, plants, bees and physicochemical characteristics of honey.

Photocatalytic Activity and Biocide Properties of Ag-TiO2 Composites on Cotton Fabrics.

Composites of Ag and TiO2 nanoparticles were synthesized in situ on cotton fabrics using sonochemical and solvothermal methods achieving the successive formation of Ag-NPs and Ti-NPs directly on the fabric. The impregnated fabrics were characterized using ATR-FTIR spectroscopy; high-resolution microscopy (HREM); scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS); Raman, photoluminescence, UV-Vis, and DRS spectroscopies; and by tensile tension tests. Results showed the successful formation and impregnation of NPs on the cotton fabric, with negligible leaching of NPs after several washing cycles. The photocatalytic activity of supported NPs was assessed by the degradation of methyl blue dye (MB) under solar and UV irradiation revealing improved photocatalytic activity of the Ag-TiO2/cotton composites due to a synergy of both Ag and TiO2 nanoparticles. This behavior is attributed to a diminished electron-hole recombination effect in the Ag-TiO2/cotton samples. The biocide activity of these composites on the growth inhibition of Staphylococcus aureus (Gram+) and Escherichia coli (Gram-) was confirmed, revealing interesting possibilities for the utilization of the functionalized cotton fabric as protective cloth for medical applications.

Effects of Conjugation of Ferrocene and Gallic Acid On desCys11/Lys12/Lys13-(p-BthTX-I)2K Peptide: Structure, Permeabilization and Antibacterial Activity.

BACKGROUND: Antimicrobial resistance is an emerging global health challenge that has led researchers to study alternatives to conventional antibiotics. A promising alternative is antimicrobial peptides (AMPs), produced as the first line of defense by almost all living organisms. To improve its biological activity, the conjugation of AMPs is a promising approach. OBJECTIVE: In this study, we evaluated the N-terminal conjugation of p-Bt (a peptide derived from Bothrops Jararacuçu`s venom) with ferrocene (Fc) and gallic acid (GA). Acetylated and linear versions of p-Bt were also synthesized to evaluate the importance of N-terminal charge and dimeric structure. METHODS: The compounds were obtained using solid-phase peptide synthesis. Circular dichroism, vesicle permeabilization, antimicrobial activity, and cytotoxicity studies were conducted. RESULTS: No increase in antibacterial activity against Escherichia coli was observed by adding either Fc or GA to p-Bt. However, Fc-p-Bt and GA-p-Bt exhibited improved activity against Staphylococcus aureus. No cytotoxicity upon fibroblast was observed for GA-p-Bt. On the other hand, conjugation with Fc increased cytotoxicity. This toxicity may be related to the membrane permeabilization capacity of this bioconjugate, which showed the highest carboxyfluorescein leakage in vesicle permeabilization experiments. CONCLUSION: Considering these observations, our findings highlight the importance of adding bioactive organic compounds in the N-terminal position as a tool to modulate the activity of AMPs.

Isobolographic analysis of the ciprofloxacin-gentamicin combination against beta-lactamase-producing Staphylococcus aureus.

BACKGROUND: Bacterial multi-resistance is a serious global problem that continues to worsen over time due to multiple factors. Among these factors, it is important to highlight the clinical misuse of antibiotics and the mechanisms that microorganisms have developed to protect themselves from these drugs. In this sense, Staphylococcus aureus (S. aureus) is a pathogen that has found a way to resist many of the drugs currently in use, so infections by this bacterium represent a serious clinical problem. OBJECTIVES: The purpose of this study was to determine the type of interaction between ciprofloxacin and gentamicin against beta-lactamase-producing S. aureus using isobolographic analysis. METHODS: Ciprofloxacin (0.5-0.05 mg/mL) and gentamicin (10-1 mg/mL) were used to make concentration-dependent curves for each individual drug. Thereafter, the 50 inhibitory concentration (IC50 ) of each drug was obtained, and different proportions of the ciprofloxacin-gentamicin combination-0.5:0.5, 0.8:0.2, 0.2:0.8, 0.9:0.1, 0.1:0.9, 0.95:0.05, and 0.05:0.95-were evaluated. The isobolographic analysis and the interaction index were used to analyze the data. RESULTS: The isobolographic evaluation of the combination showed that the ratios 0.5:0.5, 0.8:0.2, 0.2:0.8, and 0.9:0.1 produced a synergistic anti-staphylococcal effect, and the 0.95:0.05 ratio induced an additive antibacterial effect. Finally, the 0.1:0.9 and 0.05:0.95 ratios of the combination presented antagonistic effects against S. aureus. On the other hand, the interaction index showed similar results to the isobolographic analysis. CONCLUSION: The isobolographic results of this in vitro assay show that the ciprofloxacin-gentamicin combination induces synergistic, additive, and antagonistic antimicrobial effects against S. aureus.

Proteomics and Genetic Approaches Elucidate the Circulation of Low Variability Staphylococcus aureus Strains on Colombian Dairy Farms.

Staphylococcus aureus is one of the most prevalent pathogens causing bovine mastitis in the world, in part because of its ease of adaptation to various hosts and the environment. This study aimed to determine the prevalence of S. aureus in Colombian dairy farms and its relationship with the causal network of subclinical mastitis. From thirteen dairy farms enrolled, 1288 quarter milk samples (QMS) and 330 teat samples were taken from cows with positive (70.1%) and negative California Mastitis Test (CMT). In addition, 126 samples from the milking parlor environment and 40 from workers (nasal) were collected. On each dairy farm, a survey was conducted, and the milking process was monitored on the day of sampling. S. aureus was identified in 176 samples, i.e., 138 QMS, 20 from teats, 8 from the milking parlor environment, and 10 from workers' nasal swabs. Isolates identified as S. aureus underwent proteomics (clustering of mass spectrum) and molecular (tuf, coa, spa Ig, clfA, and eno genes) analysis. Regarding proteomics results, isolates were distributed into three clusters, each with members from all sources and all farms. Concerning molecular analysis, the virulence-related genes clfA and eno were identified in 41.3% and 37.8% of S. aureus isolates, respectively. We provide evidence on the circulation of S. aureus strains with limited variability among animals, humans, and the environment. The parameters with the lowest compliance in the farms which may be implicated in the transmission of S. aureus are the lack of handwashing and abnormal milk handling.

Effect of Essential Oil from Lippia origanoides on the Transcriptional Expression of Genes Related to Quorum Sensing, Biofilm Formation, and Virulence of Escherichia coli and Staphylococcus aureus.

Microbial infections resistant to conventional antibiotics constitute one of the most important causes of mortality in the world. In some bacterial species, such as Escherichia coli and Staphylococcus aureus pathogens, biofilm formation can favor their antimicrobial resistance. These biofilm-forming bacteria produce a compact and protective matrix, allowing their adherence and colonization to different surfaces, and contributing to resistance, recurrence, and chronicity of the infections. Therefore, different therapeutic alternatives have been investigated to interrupt both cellular communication routes and biofilm formation. Among these, essential oils (EO) from Lippia origanoides thymol-carvacrol II chemotype (LOTC II) plants have demonstrated biological activity against different biofilm-forming pathogenic bacteria. In this work, we determined the effect of LOTC II EO on the expression of genes associated with quorum sensing (QS) communication, biofilm formation, and virulence of E. coli ATCC 25922 and S. aureus ATCC 29213. This EO was found to have high efficacy against biofilm formation, decreasing-by negative regulation-the expression of genes involved in motility (fimH), adherence and cellular aggregation (csgD), and exopolysaccharide production (pgaC) in E. coli. In addition, this effect was also determined in S. aureus where the L. origanoides EO diminished the expression of genes involved in QS communication (agrA), production of exopolysaccharides by PIA/PNG (icaA), synthesis of alpha hemolysin (hla), transcriptional regulators of the production of extracellular toxins (RNA III), QS and biofilm formation transcriptional regulators (sarA) and global regulators of biofilm formation (rbf and aur). Positive regulation was observed on the expression of genes encoding inhibitors of biofilm formation (e.g., sdiA and ariR). These findings suggest that LOTCII EO can affect biological pathways associated with QS communication, biofilm formation, and virulence of E. coli and S. aureus at subinhibitory concentrations and could be a promising candidate as a natural antibacterial alternative to conventional antibiotics.