Induction of biofilm in extended-spectrum beta-lactamase Staphylococcus aureus with drugs commonly used in pharmacotherapy.

Staphylococcus aureus is a bacterial pathogen that causes bloodstream infections, pneumonia, and skin abscesses and is the primary pathogen responsible for medical devices associated with biofilm infections, accounting for approximately 70 % of cases. Therefore, the World Health Organization (WHO) has designated this microorganism as a top priority due to its role in causing over 20,000 bacteremia-related deaths in the US each year. The issue of pathogen resistance to antibiotics, mainly by a biofilm, further complicates these infections since biofilms render the bacterial colony impervious to antibiotics. However, many natural and synthetic substances also induce bacterial biofilm formation. Therefore, we investigated whether the most common active pharmaceutical ingredients (APIs) could induce biofilm formation in two clinical isolates of extended-spectrum beta-lactamase Staphylococcus aureus, one of them also methicillin-resistant (A2M) and two medical devices. We detected biofilm inducers, inhibitors, and destabilizers. Microbial strain, medical devices, API structure, and concentration influenced the modulatory effects of biofilm. In all devices tested, including microplates, FR18 duodenal probe, and respiratory probe, the clinic isolate methicillin-resistant S. aureus A2M exhibited lower susceptibility to biofilm formation than S. aureus A1. The anti-inflammatory acetaminophen, the hypocholesterolemic lovastatin, and the diuretic hydrochlorothiazide all induced biofilm. However, verapamil, an antihypertensive, and cetirizine, an antihistamine, inhibited biofilm on S. aureus A2M, while propranolol, another antihypertensive, inhibited biofilm on S. aureus A1. Additionally, diclofenac, an analgesic, and cetirizine destabilized the biofilm, resulting in more free bacteria and possibly making them more susceptible to external agents such as antibiotics. Nonetheless, further epidemiologic analyses and in vivo assays are needed to confirm these findings and to establish a correlation between drug use, the onset of bacterial infections in patients, and the use of medical devices. This work provides information about the probable clinical implications of drugs in patients using medical devices or undergoing surgical procedures. Inhibitory APIs could also be used as drug repurposing or templates to design new, more potent biofilm inhibitors.

Staphylococcus spp. as part of the microbiota and as opportunistic pathogen in free-ranging black-tuffed marmosets (Callithrix penicillata) from urban areas: Epidemiology, antimicrobial resistance, and pathology.

BACKGROUND: Marmosets (Callithrix sp.), including black-tuffed marmosets (C. penicillata), are neotropical primates that can be highly adapted to urban environments, especially parks and forested areas near cities. Staphylococcus spp. are part of the microbiota of many different hosts and lead to opportunistic severe infection. Isolates from wild animals can be resistant to antimicrobial drugs. However, there are a few studies that evaluated Staphylococcus spp. in neotropical primates. The goal of this study was to evaluate Staphylococcus spp. isolated from free-ranging black-tuffed marmosets. METHODS: Marmosets were captured in six urban parks. After sedation, skin and rectal swabs and feces were sampled. Staphylococcus spp. isolates were identified by MALDI-ToF and their antimicrobial susceptibility was determined. RESULTS: Over 30% of captured individuals were positive for Staphylococcus spp., and S. aureus was the most isolated species followed by Mammaliicoccus (Staphylococcus) sciuri. With the exception of the marmoset subjected to necropsy, none of the other had lesions, which supports that notion that Staphylococcus spp. are members of the microbiota, but also opportunistic pathogens. Most isolates were susceptible to all antimicrobials tested; however, one isolate of S. epidermidis was resistant to multiple antimicrobials (penicillin, cefoxitin, ciprofloxacin, clindamycin, and erythromycin). We considered S. aureus as the main staphylococci to colonize black-tuffed marmosets. CONCLUSIONS: Black-tuffed marmosets can be colonized by several Staphylococcus species, most frequently by S. aureus, and the majority of isolates were sensible to the antimicrobials tested. One S. epidermidis isolate was considered multidrug resistant.

Desafío Diagnóstico

Niña 6 años, originaria de Darién, sin antecedentes personales de interés. Inicia cuadro de dolor y cojera de miembro inferior izquierdo con edema en región posterior de tobillo izquierdo. Los familiares lo relacionan con haber estado de excursión en un río de Darién días previos. Consultan en varias ocasiones en centros de salud de la zona, donde pautan tratamiento ambulatorio y colocación de férula. (provisto por Infomedic International)

6-year-old girl, originally from Darien, with no personal history of interest. She begins with pain and lameness of the left lower limb with edema in the posterior region of the left ankle. Family members relate it to having been hiking in a river in Darien the previous days. They consulted several times in health centers in the area, where they prescribed outpatient treatment and splinting. (provided by Infomedic International)

Synthesis and Superficial Modification "In Situ" of Copper Selenide (Cu2-x Se) Nanoparticles and Their Antibacterial Activity.

Copper selenide nanoparticles (Cu2-x Se NPs) have received a lot of attention in recent decades due to their interesting properties and potential applications in various areas such as electronics, health, solar cells, etc. In this study, details of the synthesis and characterization of copper selenide nanoparticles modified with gum arabic (GA) are reported. Also, through transmission electronic microscopy (TEM) analysis, the transformation of the morphology and particle size of copper selenide nanoparticles in aqueous solution was studied. In addition, we present an antimicrobial study with different microorganisms such as Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Candida albiacans (C. albicans). Copper selenide nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry analysis (DSC) and TEM. XRD confirmed the crystal-line structure of the nanoparticles such as cubic berzelanite with a particle size of 6 nm ± 0.5. FTIR and TGA corroborated the surface modification of copper selenide nanoparticles with gum arabic, and DSC suggested a change in the structural phase from cubic to hexagonal. TEM analysis demonstrated that the surface modification of the Cu2-x Se NPs stabilized the nanostructure of the particles, preventing changes in the morphology and particle size. The antimicrobial susceptibility analysis of copper selenide nanoparticles indicated that they have the ability to inhibit the microbial growth of Staphylococcus aureus, Escherichia coli and Candida albicans.

Melaleuca alternifolia essential oil in a natural product-based formulation: Antimicrobial and healing effects in Staphylococcus aureus-infected wounds.

Owing to its exposed nature, the skin can be injured by various factors, including by Staphylococcus aureus, which inhabits its innate microbiota. Treatment of infected wounds presents an important challenge, making it imperative to develop new treatment options. Plant-derived formulations, such as those containing Melaleuca alternifolia essential oil (MaEO), are used for wound treatment because of their healing, anti-inflammatory, and antimicrobial properties. This study presents a cream containing 2% MaEO (2% CMa) and evaluates its effects in an S. aureus-infected wound murine model. The 2% CMa was subjected to quality control testing and pH and analysis of density, organoleptic characteristics, and microbiological effects. The quality control parameters all revealed the good stability of the 2% CMa. The formulation strongly reduced the S. aureus ATCC 6538 colony-forming unit (CFU) count in an ex vivo porcine skin model. In the murine model, daily topical application of 2% CMa reduced the severity and size of S. aureus-infected wounds and the bacterial load. These effects may be due to the presence of terpinen-4-ol, which exhibits anti-inflammatory activity. Based on these findings, the formulation exhibits good quality and safety. We suggest the topical application of this formulation, which exhibited an antimicrobial effect, as an interesting treatment strategy for wound healing.

Enhancing the efficacy of antimicrobial photodynamic therapy through curcumin modifications.

Curcumin serves as a photosensitizer (PS) in the context of microbial inactivation when subjected to light exposure, to produce reactive oxygen species, which exhibit efficacy in eradicating microorganisms. This remarkable property underscores the growing potential of antimicrobial photodynamic therapy (aPDT) in the ongoing fight against bacterial infections. Considering this, we investigate the efficacy of various in vitro curcumin formulations within a PDT protocol designed to target Staphylococcus aureus. Specifically, we conduct a comparative analysis involving synthetic curcumin (Cur-Syn) and curcumin derivatives modified with chlorine (Cl), selenium (Se), and iodine (I) (Cur-Cl, Cur-Se, Cur-I). To assess the impact of aPDT, we subject S. aureus to incubation with curcumin, followed by irradiation at 450 nm with energy doses of 3.75, 7.5, and 15 J/cm2. Our investigation encompasses an evaluation of PS uptake and photobleaching across the various curcumin variants. Notably, all three modifications (Cur-Cl, Cur-Se, Cur-I) induce a significant reduction in bacterial viability, approximately achieving a 3-log reduction. Interestingly, the uptake kinetics of Cur-Syn and Cur-Se exhibit similarities, reaching saturation after 20 min. Our findings suggest that modifications to curcumin have a discernible impact on the photodynamic properties of the PS molecule.

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.

Biosurfactant complexed with arginine has antibiofilm activity against methicillin-resistant Staphylococcus aureus.

Aim: The present study investigated the antimicrobial effectiveness of a rhamnolipid complexed with arginine (RLMIX_Arg) against planktonic cells and biofilms of methicillin-resistant Staphylococcus aureus (MRSA). Methodology: Susceptibility testing was performed using the Clinical & Laboratory Standards Institute protocol: M07-A10, checkerboard test, biofilm in plates and catheters and flow cytometry were used. Result: RLMIX_Arg has bactericidal and synergistic activity with oxacillin. RLMIX_Arg inhibits the formation of MRSA biofilms on plates at sub-inhibitory concentrations and has antibiofilm action against MRSA in peripheral venous catheters. Catheters impregnated with RLMIX_Arg reduce the formation of MRSA biofilms. Conclusion: RLMIX_Arg exhibits potential for application in preventing infections related to methicillin-resistant S. aureus biofilms.

[Box: see text].

Enhanced Antibacterial Properties of Titanium Surfaces through Diversified Ion Plating with Silver Atom Deposition.

In this study, we investigate the antibacterial effect of silver atoms implanted into a thin surface layer of titanium at low energies using an alternative ion plating technology called Diversified Ion Plating. Silver atoms were incorporated into titanium samples using reactive low-voltage ion plating at 2 keV and 4 keV. Surface modifications and morphology were evaluated using wettability, profilometry measurements, and energy-dispersive spectroscopy. For a precise determination of the quantity and depth of implanted silver atoms on titanium surfaces, a combination of experimental techniques such as Rutherford Backscattering Spectrometry along with Monte Carlo simulations were utilized. To assess the antibacterial effects of the silver atoms incorporated into pure titanium surfaces, bacterial suspension immersion tests were performed with a standard strain of Staphylococcus aureus (ATCC 12600). The outcomes indicate that titanium surfaces implanted with silver atoms were more effective in inhibiting the growth of Staphylococcus aureus than pure titanium surfaces. Better results were found when the deposition was performed at 4 keV, indicating that a deeper implantation of silver, spanning a few nanometers, can result in a longer and more effective release of silver atoms. These findings suggest the potential for the development of new, cost-effective biomaterials, paving the way for improved implant materials in various health-related applications.

New Synergistic Combination Therapy of Mupirocin and α-Pinene Against Multidrug-Resistant Clinical Strains of Methicillin-Resistant Staphylococcus aureus.

OBJECTIVE: Increased mupirocin use leads to mupirocin resistance and is associated with persistence of methicillin-resistant Staphylococcus aureus (MRSA) carriers, prolonged hospitalization, and significant economic burdens for health systems. The study aimed to investigate the antimicrobial activity of compounds of Salvia rosmarinus L. ("rosemary", formerly Rosmarinus officinalis), alone or in combination with mupirocin, against multidrug resistant MRSA using isolates obtained from pediatric patients. METHODS: The in vitro antibacterial activity of the monoterpene α-pinene (α-Pi), a rosemary essential oil constituent, alone and in combination with mupirocin, was evaluated by determining the minimum inhibitory concentrations and minimum bactericidal concentrations (MBCs) and the fractional inhibitory concentration indices (FICIs) and fractional bactericidal concentration indices against multidrug-resistant clinical MRSA strains. The in vivo efficacy of α-Pi, alone and in combination with mupirocin, to eradicate MRSA infection was determined using an optimized mouse model of MRSA-infected wounds. Mouse skin samples (obtained via biopsy) were assessed for toxicity, and rabbit skin samples for irritation. RESULTS: Both in vitro and in vivo, α-Pi was active against MRSA strains and acted synergistically with mupirocin against MRSA strains. Mupirocin-monoterpene combinations exhibited FICI values of 0.2 to 0.4, reducing the MBC of topical mupirocin 33-fold. A topical formulation containing α-Pi and mupirocin enhanced the efficacy of mupirocin in an in vivo MRSA-infected mouse skin model without significantly harming the skin of mice and rabbits. CONCLUSIONS: A topical formulation combining mupirocin and α-Pi may aid in the development of innovative agents for treating MRSA infections.

Skin care for toxic shock syndrome: case report / Cuidados com a pele na síndrome do choque tóxico: relato de caso / Cuidado de la piel en el síndrome de shock tóxico: reporte de caso

Objetivo: A síndrome do choque tóxico (SCT) é uma condição multissistêmica grave, causada por Staphylococcus aureus ou Streptococcus pyogenes,e o manejo inicial e contínuo das lesões de pele é essencial para o controle da infecção. Este relato teve o objetivo de descrever os cuidados com a pele nessa síndrome. Relato do caso: Paciente do sexo masculino com abscesso no quadril que evoluiu com febre e hipotensão e consequente transferência para a Unidade de Terapia Intensiva (UTI). Foi diagnosticado com choque séptico de provável foco no quadril, imediatamente abordado cirurgicamente para tratamento local da infecção. Apresentou insuficiência renal, além de disfunção multissistêmica (hepática e cardíaca), instabilidade hemodinâmnica e lesões disseminadas de pele. Com o isolamento do Staphylococcus aureus, iniciou-se clindamicina e o diagnóstico foi de SCT, uma vez que apresentou lesões epidermolíticas desde o início do quadro. Foram iniciadas medidas de recuperação cutânea com a sulfadiazina de prata e, posteriormente, com hidrofibra com prata com restauração do epitélio em 8 dias. Após 10 dias da pele restaurada, o paciente recebeu alta da UTI para enfermaria com manutenção do tratamento proposto. Conclusão: Neste caso, o uso da hidrofibra obteve uma performancesatisfatória, contudo ainda há necessidade de estudos robustos que comprovem tal eficácia. (AU)

Objective: Toxic shock syndrome (TSS) is a severe multisystemic condition caused by Staphylococcus aureus or Streptococcus pyogenes, and initial management of skin lesions is essential for infection control. This article aimed to describe skin care for TSS. Case report: We report a man with a hip abscess who developed fever and hypotension and was subsequently transferred to an intensive care unit (ICU). He was diagnosed with septic shock, probably of hip origin, and was immediately treated surgically for local infection control. He presented with renal failure besides multiple organ dysfunction (hepatic and cardiac), hemodynamic instability, and disseminated skin lesions. With the isolation of Staphylococcus aureus, clindamycin was initiated, and the diagnosis was TSS due to epidermolytic lesions since the onset of the condition. Cutaneous recovery measures were initiated with silver sulfadiazine, followed by silver hydrofiber with skin recovery in 8 days. After 10 days of skin recovery, the patient was discharged from the ICU to the ward with maintenance of the proposed treatment. Conclusion: In this case, the use of hydrofiber showed satisfactory performance; however, robust studies are needed to confirm such efficacy. (AU)

Objetivo: El síndrome de shock tóxico (SST) es una afección multisistémica grave causada por Staphylococcus aureuso Streptococcus pyogenes, y el tratamiento inicial y continuo de las lesiones cutáneas es esencial para controlar la infección. Este informe tuvo como objetivo describir los cuidado de la piel en este síndrome. Reporte del caso:Paciente masculino con absceso en la cadera que desarrolló fiebre e hipotensión y fue tranferido a la Unidad de Cuidados Intensivos (UCI). Se diagnosticó shock séptico, probablemente focalizado en la cadera, por lo que fue inmediatamente abordado quirúrgicamente para tratamiento local de la infección. Presentó insuficiencia renal además de disfunción multisistémica (hepática y cardiaca), inestabilidad hemodinámica y lesiones cutáneas diseminadas. Con el aislamiento de Staphylococcus aureus, se inició clindamicina y el diagnóstico fue SST, ya que presentaba lesiones epidermolíticas desde el inicio del cuadro. Se iniciaron medidas de recuperación cutánea con sulfadiazina de plata y, posteriormente, se optó por hidrofibra con plata, con restauración del epitelio en 8 días. Después de 10 días de piel restaurada, el paciente fue dado de alta de la UCI a planta con mantenimiento del tratamiento propuesto. Conclusión: Alcen este caso, el uso de hidrofibra obtuvo un desempeño satisfactorio, sin embargo, aún se necesitan estudios robustos para probar tal eficacia. (AU)

Bacteriological characteristics of primary breast abscesses in patients from the community in the era of microbial resistance.

Objective: The aim of this study is to evaluate the etiological profile and antimicrobial resistance in breast abscess cultures from patients from the community, treated at a public hospital located in Porto Alegre, Brazil. Methods: This is an retrospective cross-sectional study that evaluated the medical records of patients with bacterial isolates in breast abscess secretion cultures and their antibiograms, from January 2010 to August 2022. Results: Based on 129 positive cultures from women from the community diagnosed with breast abscesses and treated at Fêmina Hospital, 99 (76.7%) of the patients had positive cultures for Staphylococcus sp, 91 (92%) of which were cases of Staphylococcus aureus. Regarding the resistance profile of S. aureus, 32% of the strains were resistant to clindamycin, 26% to oxacillin and 5% to trimethoprim-sulfamethoxazole. The antimicrobials vancomycin, linezolid and tigecycline did not show resistance for S. aureus. Conclusion: Staphylococcus aureus was the most common pathogen found in the breast abscess isolates during the study period. Oxacillin remains a good option for hospitalized patients. The use of sulfamethoxazole plus trimethoprim should be considered as a good option for use at home, due to its low bacterial resistance, effectiveness and low cost.

Flavonoids isolated from Vismia macrophylla Kunth against resistant bacteria.

The antimicrobial activity of Vismia macrophylla extract is reported in the literature; however, little is known about the presence of phenolic compounds and their antimicrobial activity in this species. This study aimed to isolate phenolic compounds with antimicrobial action from the leaves of V. macrophylla. The ethanolic extract (VmL-Et) was submitted to sephadex column separation, and some fractions were submitted to derivatization with BSTFA and analysed by GC-MS. This study indicated the presence of the catechin, osajaxanthone, quercetin, quercitrin, and glucodistylin. Of these, osajaxanthone, quercetin, quercitrin, and glucodistylin were isolated and identified by spectroscopic techniques. VmL-Et, quercetin, quercitrin, glucodistylin, and maslinic acid, were tested against the Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis. The results showed broad spectrum action of the extract Vm-Et, glucodistylin and quercitrin. The species V. macrophylla occurring in the Brazilian biome showed potential for obtaining phenolic compounds that can help combat microbial resistance.

Correlation between the results of cultures and the molecular BIOFIRE® joint infection panel in a cohort of pediatric patients with bone and joint infections in Bogotá, Colombia.

Introduction: Bone and Joint Infections (BJI) have high morbidity. Methicillin resistant Staphylococcus aureus (MRSA) has increased. Culture-based diagnosis has difficult to recovering fastidious bacteria and detecting polymicrobial infections, molecular methods offer a promising improvement for the diagnosis of BJI with reduced time to result. The aim of the study was to determine the correlation between culture results and the Biofire joint infection panel (BJIP) in a cohort of pediatric patients with BJI. Materials and methods: Descriptive study. Patients admitted with probable o confirmed BJI between July 1, 2019 and February 28, 2021 at HOMI. Blood cultures, synovial and bone fluid samples were taken. Samples were kept at -70 °C. On September 2022, the panel was performed. Results: 32 patients were included. The average age was 83m (RIQ: 32-145). 23 (71.8%) patients had a positive culture. The most frequent microorganism were S. aureus 19 (83%), 11/19 (57.9%) Staphylococci isolates were MRSA. 24/32 (75%) were positive by panel, 20 positive detections were concordant with culture, there were 6 additional isolates by panel (2 S. aureus, 2 S. pyogenes, 1 K. kingae and 1 C. albicans), three microorganisms were isolated in culture but not in the panel. (2 S. aureus and 1 S. agalactiae). Two patients with coinfection were detected. All MRSA were detected by culture and panel. In 26 (81.3%) patients the etiology was documented by any method. Conclusion: These results showed a moderate level of agreement between BJIP and culture (κ = 0.47). The panel allowed the detection of fastidious bacteria including K. kingae and polymicrobial samples. There was a very good level of agreement between the panel and culture for the MRSA detection (κ = 1).

Inhibition of Shikimate Kinase from Methicillin-Resistant Staphylococcus aureus by Benzimidazole Derivatives. Kinetic, Computational, Toxicological, and Biological Activity Studies.

Antimicrobial resistance (AMR) is one of the biggest threats in modern times. It was estimated that in 2019, 1.27 million deaths occurred around the globe due to AMR. Methicillin-resistant Staphylococcus aureus (MRSA) strains, a pathogen considered of high priority by the World Health Organization, have proven to be resistant to most of the actual antimicrobial treatments. Therefore, new treatments are required to be able to manage this increasing threat. Under this perspective, an important metabolic pathway for MRSA survival, and absent in mammals, is the shikimate pathway, which is involved in the biosynthesis of chorismate, an intermediate for the synthesis of aromatic amino acids, folates, and ubiquinone. Therefore, the enzymes of this route have been considered good targets to design novel antibiotics. The fifth step of the route is performed by shikimate kinase (SK). In this study, an in-house chemical library of 170 benzimidazole derivatives was screened against MRSA shikimate kinase (SaSK). This effort led to the identification of the first SaSK inhibitors, and the two inhibitors with the greatest inhibition activity (C1 and C2) were characterized. Kinetic studies showed that both compounds were competitive inhibitors with respect to ATP and non-competitive for shikimate. Structural analysis through molecular docking and molecular dynamics simulations indicated that both inhibitors interacted with ARG113, an important residue involved in ATP binding, and formed stable complexes during the simulation period. Biological activity evaluation showed that both compounds were able to inhibit the growth of a MRSA strain. Mitochondrial assays showed that both compounds modify the activity of electron transport chain complexes. Finally, ADMETox predictions suggested that, in general, C1 and C2 can be considered as potential drug candidates. Therefore, the benzimidazole derivatives reported here are the first SaSK inhibitors, representing a promising scaffold and a guide to design new drugs against MRSA.

MSDeepAMR: antimicrobial resistance prediction based on deep neural networks and transfer learning.

Introduction: Antimicrobial resistance (AMR) is a global health problem that requires early and effective treatments to prevent the indiscriminate use of antimicrobial drugs and the outcome of infections. Mass Spectrometry (MS), and more particularly MALDI-TOF, have been widely adopted by routine clinical microbiology laboratories to identify bacterial species and detect AMR. The analysis of AMR with deep learning is still recent, and most models depend on filters and preprocessing techniques manually applied on spectra. Methods: This study propose a deep neural network, MSDeepAMR, to learn from raw mass spectra to predict AMR. MSDeepAMR model was implemented for Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus under different antibiotic resistance profiles. Additionally, a transfer learning test was performed to study the benefits of adapting the previously trained models to external data. Results: MSDeepAMR models showed a good classification performance to detect antibiotic resistance. The AUROC of the model was above 0.83 in most cases studied, improving the results of previous investigations by over 10%. The adapted models improved the AUROC by up to 20% when compared to a model trained only with external data. Discussion: This study demonstrate the potential of the MSDeepAMR model to predict antibiotic resistance and their use on external MS data. This allow the extrapolation of the MSDeepAMR model to de used in different laboratories that need to study AMR and do not have the capacity for an extensive sample collection.

Potential Anti-Infectious Activity of Essential Oil Chemotypes of Lippia origanoides Kunth on Antibiotic-Resistant Staphylococcus aureus Strains.

Staphylococcus aureus infections are prevalent in healthcare and community environments. Methicillin-resistant S. aureus is catalogued as a superbug of high priority among the pathogens. This Gram-positive coccus can form biofilms and produce toxins, leading to persistent infection and antibiotic resistance. Limited effective antibiotics have encouraged the development of innovative strategies, with a particular emphasis on resistance mechanisms and/or virulence factors. Medicinal aromatic plants have emerged as promising alternative sources. This study investigated the antimicrobial, antibiofilm, and antihemolysis properties of three different chemotypes of Lippia origanoides essential oil (EO) against susceptible and drug-resistant S. aureus strains. The chemical composition of the EO was analyzed using GC-MS, revealing high monoterpene concentrations, with carvacrol and thymol as the major components in two of the chemotypes. The third chemotype consisted mainly of the sesquiterpene ß-caryophyllene. The MIC values for the two monoterpene chemotypes ranged from 62.5 to 500 µg/mL for all strains, whereas the sesquiterpene chemotype showed activity against seven strains at concentrations of 125-500 µg/mL, which is the first report of its anti-S. aureus activity. The phenolic chemotypes inhibited biofilm formation in seven S. aureus strains, whereas the sesquiterpene chemotype only inhibited biofilm formation in four strains. In addition, phenolic chemotypes displayed antihemolysis activity, with IC50 values ranging from 58.9 ± 3.8 to 128.3 ± 9.2 µg/mL. Our study highlights the importance of L. origanoides EO from the Yucatan Peninsula, which has the potential for the development of anti-S. aureus agents.

Substrate Analogues Entering the Lipoic Acid Salvage Pathway via Lipoate-Protein Ligase 2 Interfere with Staphylococcus aureus Virulence.

Lipoic acid (LA) is an essential cofactor in prokaryotic and eukaryotic organisms, required for the function of several multienzyme complexes such as oxoacid dehydrogenases. Prokaryotes either synthesize LA or salvage it from the environment. The salvage pathway in Staphylococcus aureus includes two lipoate-protein ligases, LplA1 and LplA2, as well as the amidotransferase LipL. In this study, we intended to hijack the salvage pathway by LA analogues that are transferred via LplA2 and LipL to the E2 subunits of various dehydrogenases, thereby resulting in nonfunctional enzymes that eventually impair viability of the bacterium. Initially, a virtual screening campaign was carried out to identify potential LA analogues that bind to LplA2. Three selected compounds affected S. aureus USA300 growth in minimal medium at concentrations ranging from 2.5 to 10 µg/mL. Further analysis of the most potent compound (Lpl-004) revealed its transfer to E2 subunits of dehydrogenase complexes and a negative impact on its functionality. Growth impairment caused by Lpl-004 treatment was restored by adding products of the lipoate-dependent enzyme complexes. In addition, Caenorhabditis elegans infected with LpL-004-treated USA300 demonstrated a significantly expanded lifespan compared to worms infected with untreated bacteria. Our results provide evidence that LA analogues exploiting the LA salvage pathway represent an innovative strategy for the development of novel antimicrobial substances.

Methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus produce antimicrobial substances against members of the skin microbiota in children with atopic dermatitis.

Coagulase-negative Staphylococcus (CoNS) species inhibiting Staphylococcus aureus has been described in the skin of atopic dermatitis (AD) patients. This study evaluated whether Staphylococcus spp. from the skin and nares of AD and non-AD children produced antimicrobial substances (AMS). AMS production was screened by an overlay method and tested against NaOH, proteases and 30 indicator strains. Clonality was assessed by pulsed-field gel electrophoresis. Proteinaceous AMS-producers were investigated for autoimmunity by the overlay method and presence of bacteriocin genes by polymerase chain reaction. Two AMS-producers had their genome screened for AMS genes. A methicillin-resistant S. aureus (MRSA) produced proteinaceous AMS that inhibited 51.7% of the staphylococcal indicator strains, and it was active against 60% of the colonies selected from the AD child where it was isolated. On the other hand, 57 (8.8%) CoNS from the nares and skin of AD and non-AD children, most of them S. epidermidis (45.6%), reduced the growth of S. aureus and other CoNS species. Bacteriocin-related genes were detected in the genomes of AMS-producers. AMS production by CoNS inhibited S. aureus and other skin microbiota species from children with AD. Furthermore, an MRSA colonizing a child with AD produced AMS, reinforcing its contribution to dysbiosis and disease severity.

Point-of-Care Electrochemical Immunosensor Applied against Nosocomial Infection: Staphylococcus aureus Detection in Human Hand Skin.

Staphylococcus aureus is an important pathogen that causes nosocomial infections, resulting in unacceptable morbidity and mortality rates. In this work, we proposed the construction of a nanostructured ZnO-based electrochemical immunosensor for qualitative and semiquantitative detection of S. aureus using simple methods for growing zinc oxide nanorods (ZnO NRs) on a sensor board and immobilizing the anti-S. aureus antibody on ZnO NRs through cystamine and glutaraldehyde. The immunosensor detected S. aureus in the 103-107 colony-forming unit (CFU) mL-1 range and showed a limit of detection (LoD) around 0.792 × 103 CFU mL-1. Beyond a satisfactory LoD, the developed immunosensor presented other advantages, such as high versatility for point-of-care assays and a suitable selective factor that admits the detection of the S. aureus concentration range in human hand skin after washing. Moreover, the immunosensor showed the potential to be an excellent device to control nosocomial infection by detecting the presence of S. aureus in human hand skin.