Optimized Electrophoretic Deposition of Chitosan/Mesoporous Glass Nanoparticles with Gentamicin on Titanium Implants: Enhancing Hemocompatibility and Antibacterial Activity.

Titanium-based implants have long been studied and used for applications in bone tissue engineering, thanks to their outstanding mechanical properties and appropriate biocompatibility. However, many implants struggle with osseointegration and attachment and can be vulnerable to the development of infections. In this work, we have developed a composite coating via electrophoretic deposition, which is both bioactive and antibacterial. Mesoporous bioactive glass particles with gentamicin were electrophoretically deposited onto a titanium substrate. In order to validate the hypothesis that the quantity of particles in the coatings is sufficiently high and uniform in each deposition process, an easy-to-use image processing algorithm was designed to minimize human dependence and ensure reproducible results. The addition of loaded mesoporous particles did not affect the good adhesion of the coating to the substrate although roughness was clearly enhanced. After 7 days of immersion, the composite coatings were almost dissolved and released, but phosphate-related compounds started to nucleate at the surface. With a simple and low-cost technique like electrophoretic deposition, and optimized stir and suspension times, we were able to synthesize a hemocompatible coating that significantly improves the antibacterial activity when compared to the bare substrate for both Gram-positive and Gram-negative bacteria.

Quantification of early biofilm growth in microtiter plates through a novel image analysis software.

Given the significant impact of biofilms on human health and material corrosion, research in this field urgently needs more accessible techniques to facilitate the testing of new control agents and general understanding of biofilm biology. Microtiter plates offer a convenient format for standardized evaluations, including high-throughput assays of alternative treatments and molecular modulators. This study introduces a novel Biofilm Analysis Software (BAS) for quantifying biofilms from microtiter plate images. We focused on early biofilm growth stages and compared BAS quantification to common techniques: direct turbidity measurement, intrinsic fluorescence detection linked to pyoverdine production, and standard crystal violet staining which enables image analysis and optical density measurement. We also assessed their sensitivity for detecting subtle growth effects caused by cyclic AMP and gentamicin. Our results show that BAS image analysis is at least as sensitive as the standard method of spectrophotometrically quantifying the crystal violet retained by biofilms. Furthermore, we demonstrated that bacteria adhered after short incubations (from 10 min to 4 h), isolated from planktonic populations by a simple rinse, can be monitored until their growth is detectable by intrinsic fluorescence, BAS analysis, or resolubilized crystal violet. These procedures are widely accessible for many laboratories, including those with limited resources, as they do not require a spectrophotometer or other specialized equipment.

Mesenchymal Stromal Cells Nanovesicles Carry microRNA with Nephroprotective Proprieties Regardless of Aging.

Containing information molecules from their parent cells and inclining to fuse with targeted cells, bone marrow mesenchymal stromal cells-derived extracellular vesicles (MSCs- EV) are valuable in nanomedicine. BACKGROUND: The effects of aging on the paracrine mechanism and in the production and action of MSCs-EV and their cargos of miR-26a and siRNA-26a for the treatment of tubular renal cells under nephrotoxicity injury remain unelucidated. OBJECTIVE: The purpose of this study was to evaluate MSCs-EV of different ages and their ability to deliver the cargos of miR-26a and siRNA-26a to target renal tubular cells affected by nephrotoxicity injury. METHODS: In a model of gentamicin-induced nephrotoxicity, renal tubular cells treated with MSCs-EV expressing or not expressing microRNA-26a were analyzed. Western blotting was utilized to evaluate cell cycle markers, and MTT assay was utilized to evaluate auto-renovation capacity. RESULTS: Tubular cells under nephrotoxicity injury showed decreased proliferative capacity, but the treatment in the tubular renal cells under nephrotoxicity injury with MSCs-EV expressing microRNA-26a showed nephroprotective effects, regardless of EV age. While the treatment with EV-mediated siRNA-26a failed to preserve the nephroprotective effects equally, regardless of age. CONCLUSION: Mesenchymal stromal cell nanovesicles carry microRNA with nephroprotective proprieties regardless of aging.

Sulfato de gentamicina combinado à doxiciclina para o tratamento da brucelose humana / Gentamicin sulfate combined with doxycycline for the treatment of human brucellosis

INTRODUÇÃO: A brucelose humana é uma doença bacteriana de evolução geralmente insidiosa, caracterizada por febre com padrão variável, mal-estar e sudorese noturna. Manifestações comuns incluem perda de peso, artralgia, cefaleia, dor lombar, fadiga, anorexia, mialgia, tosse e alterações emocionais com padrão depressivo. O tratamento é realizado com antibióticos e tem como objetivo a melhora dos sinais e sintomas e evitar a ocorrência de complicações em sistemasórgãos. A melhor evidência disponível aponta que a combinação de aminoglicosídeos com a doxiciclina apresenta as menores taxas de insucesso da terapia. Apenas um antimicrobiano da classe dos aminoglicosídeos está disponível no SUS, o sulfato de estreptomicina, fabricado por um único laboratório oficial e utilizado principalmente no tratamento da tuberculose. Considerando a necessidade de ampliar o arsenal terapêutico para o tratamento da brucelose, a incorporação da gentamicina é uma opção a ser avaliada. PERGUNTA: Qual a eficácia e a segurança da combinação de sulfato de gentamicina e doxiciclina no tratamento da brucelose humana, comparada com a combinação de sulfato de estreptomicina e doxiciclina? EVIDÊNCIAS CLÍNICAS: Foram buscados ensaios clínicos randomizados (ECRs) avaliando desfechos clínicos representativos de sucesso terapêutico com o uso de sulfato de gentamicina combinado à doxiciclina em comparação com sulfato de estreptomicina + doxiciclina, terapia atualmente disponível para mesma indicação no SUS. A busca na literatura foi estruturada através do acrônico PICOS. Foram identificados 2 ECRs que atenderam aos objetivos deste relatório. Não foram observadas diferenças nas taxas de sucesso terapêutico entre a combinação sulfato de gentamicina + doxiciclina vs. sulfato de estreptomicina + doxiciclina (RR: 0,58, IC95%: 0,29 a 1,14). O perfil de segurança avaliado pela taxa de eventos adversos (EA) também foi similar na comparação entre as duas combinações (RR: 1,22; IC95%: 0,83 a 1,80). AVALIAÇÃO ECONÔMICA: Uma análise de custo-efetividade foi realizada utilizando uma modelagem do tipo árvore de decisão. As razões de custo-efetividade para sulfato de estreptomicina e para sulfato de gentamicina, ambos combinados com doxiciclina, foram de, respectivamente, R$ 50,82 e R$ 77,21. A razão de custo-efetividade incremental (ICER) foi de R$ 535,09/por cura. A análise de sensibilidade univariada indicou que a incerteza quanto aos custos do esquema doxiciclina + estreptomicina foi o parâmetro com maior impacto no resultado do ICER. A análise probabilística corrobora com os resultados iniciais, mostrando que o sulfato de gentamicina apresenta maior custo total de tratamento e um benefício clínico levemente superior, cujo efeito é considerado semelhante ao sulfato de estreptomicina. ANÁLISE DE IMPACTO ORÇAMENTÁRIO: Observa-se que a incorporação do sulfato de gentamicina no SUS tem como resultado um incremento de R$59.000,00 em 5 anos, em um cenário conservador. Nos quatro cenários projetados, o impacto orçamentário variou entre uma economia de R$314.000,00 (cenário de baixa incidência) até o incremento de R$454.000,00 (cenário de alta incidência) em 5 anos. Análise de sensibilidade apontou que os parâmetros epidemiológicos (incidência da doença) e populacionais (cobertura no SUS), respectivamente, são os que mais impactam nos valores desta análise. EVIDÊNCIAS INTERNACIONAIS: Até o momento, a incorporação do sulfato de gentamicina para o tratamento de pacientes com brucelose humana ainda não foi avaliada por agências internacionais de ATS pesquisadas. Ressalta-se que nenhuma outra tecnologia foi identificada como já incorporada para tratamento de brucelose por estas agências. MONITORAMENTO DO HORIZONTE TECNOLÓGICO: Não foram detectadas tecnologias no MHT para pacientes com diagnóstico de brucelose humana na forma não localizada. CONSIDERAÇÕES FINAIS: A incorporação de mais um antimicrobiano da classe dos aminoglicosídeos representa ampliação de opções terapêuticas para brucelose humana no Brasil, com o diferencial de oferecer a via de administração endovenosa, em comparação com a via intramuscular, que pode ser uma alternativa mais cômoda para alguns usuários. PERSPECTIVA DO PACIENTE: Foi aberta a Chamada Pública nº 10/2024 para inscrição de participantes para a Perspectiva do Paciente, durante o período de 09/02/2024 a 18/02/2024. Entretanto, não houve inscrições. RECOMENDAÇÃO PRELIMINAR DA CONITEC: Diante do exposto, os membros do Comitê de Medicamentos presentes na 127ª Reunião Extraordinária da Conitec, no dia 07 de março de 2024, recomendaram, por unanimidade, disponibilizar a matéria em consulta pública com parecer preliminar favorável à incorporação ao SUS de sulfato de gentamicina combinado a doxiciclina para o tratamento da brucelose humana. O Comitê considerou para esta recomendação que a possibilidade de mais um medicamento para o tratamento da brucelose humana amplia o arsenal terapêutico e preenche lacunas para o manejo da doença que dispõe atualmente de um antimicrobiano da classe dos aminoglicosídeos, representando vantagens inerentes para este programa estratégico. A implementação da tecnologia foi um ponto destacado para discussão no contexto do PCDT em elaboração, assim como a notificação compulsória dos casos, tema a ser discutido em breve pela área técnica do Ministério da Saúde, no contexto do programa da brucelose humana. CONSULTA PÚBLICA: A consulta pública nº 14 foi realizada entre os dias 09/04/2024 e 29/04/2024 e recebeu uma contribuição de experiência e opinião. A contribuição foi a favor à incorporação, destacando a experiência do profissional com esta tecnologia e outras para o tratamento da brucelose humana. Foi citado como ponto positivo a segurança e conhecimento amplo dos efeitos colaterais do medicamento e como pontos negativos o difícil acesso a esta tecnologia para o tratamento da brucelose humana. A experiência com os medicamentos já padronizados no SUS destaca a eficácia das terapias, mas pontua a existência de recidiva da doença. RECOMENDAÇÃO FINAL DA CONITEC: Após apreciação da contribuição recebida na Consulta Pública, os membros do Comitê de Medicamentos presentes na 129ª Reunião Ordinária da Conitec deliberaram, por unanimidade, recomendar a incorporação do sulfato de gentamicina combinado à doxiciclina para o tratamento da brucelose humana. Foi assinado o Registro de Deliberação nº 898/2024. DECISÃO: Incorporar, no âmbito do Sistema Único de Saúde - SUS, o sulfato de gentamicina combinado à doxiciclina para o tratamento da brucelose humana, publicada no Diário Oficial da União, nº 118, seção 1, página 210, em 21 de junho de 2024.

In vitro effects of alginate lyase SG4 + produced by Paenibacillus lautus alone and combined with antibiotics on biofilm formation by mucoid Pseudomonas aeruginosa.

Alginate is a major extra polymeric substance in the biofilm formed by mucoid Pseudomonas aeruginosa. It is the main proven perpetrator of lung infections in patients suffering from cystic fibrosis. Alginate lyases are very important in the treatment of cystic fibrosis. This study evaluated the role of standalone and in conjugation, effect of alginate lyase of SG4 + isolated from Paenibacillus lautus in enhancing in vitro bactericidal activity of gentamicin and amikacin on mucoid P. aeruginosa. Using Response Surface Methodology (RSM) alginate lyase SG4 + production was optimized in shake flask and there 8.49-fold enhancement in enzyme production. In fermenter, maximum growth (10.15 mg/ml) and alginate lyase (1.46 International Units) production, 1.71-fold was increased using Central Composite Design (CCD). Further, fermentation time was reduced from 48 to 20 h. To the best of our knowledge this is the first report in which CCD was used for fermenter studies to optimize alginate lyase production. The Km and Vmax of purified enzyme were found to be 2.7 mg/ml and 0.84 mol/ml-min, respectively. The half-life (t 1/2) of purified alginate lyase SG4 + at 37 °C was 180 min. Alginate lyase SG4 + in combination with gentamicin and amikacin eradiated 48.4- 52.3% and 58- 64.6%, alginate biofilm formed by P. aeruginosa strains, respectively. The study proves that alginate lyase SG4 + has excellent exopolysaccharide disintegrating ability and may be useful in development of potent therapeutic agent to treat P. aeruginosa biofilms.

Influence of systemic antibiotic therapy on the development and progression of induced apical periodontitis in Wistar rats.

The aim of this study was to investigate the influence of systemic antibiotic therapy on the development and progression of induced apical periodontitis (AP) in Wistar rats. Fifty-six rats were submitted to pulp exposure of the lower left first molar for the induction of AP. On the same day, intraperitoneal antibiotic therapy was administered once a day, for 15 days, until euthanasia. The groups were formed according to the different treatments (n = 8): C-control; GEN-treated with gentamicin (10 mg/Kg); AC-treated with amoxicillin (100 mg/Kg); MZ-treated with metronidazole (40 mg/Kg); AMP-treated with ampicillin (100 mg/Kg); AMC group-treated with amoxicillin + clavulanic acid (100 mg/kg); CLI-treated with clindamycin (60 mg/kg). After euthanasia, the jaws were collected and processed for (1) histological and histometric analysis using hematoxylin and eosin staining, (2) analysis of collagen fibers using Picrosirius Red staining and (3) bacteriological analysis using Brown-Brenn staining. The data were analyzed statistically (p < 0.05). AP induction was confirmed in all groups. The AMC group had the lower intensity of inflammatory infiltrate (p = 0.028) and less periapical bone resorption compared to control (p = 0.006). Regarding collagen maturation, PSR staining revealed a predominance of mature collagen fibers in all groups. The AC and AMC groups had the lower amount of mature fibers and the highest amount of immature fibers, compared to all other groups (p < 0.001). All groups showed bacterial contamination; however, the AC and AMC groups showed a lower extent of bacterial contamination compared to the control (p < 0.001). It can be concluded that systemic antibiotic therapy influences the development and progression of induced AP.

Antibacterial effectiveness of trans-cinnamaldehyde against foodborne Enterobacteriaceae and its adjuvant effect with gentamicin.

The Enterobacteriaceae family is recognized as a primary group of Gram-negative pathogens responsible for foodborne illnesses and is frequently associated with antibiotic resistance. The present study explores the natural-based compound trans-cinnamaldehyde (TC) against drug-resistant Enterobacteriaceae and its synergism with gentamicin (GEN) to address this issue. The research employs three strains of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae, previously isolated from shrimp. The antibacterial activity was evaluated by the disk diffusion method, microdilution test, kinetics of growth, and time-kill curve. In addition, the synergistic effect between TC/GEN was investigated by checkerboard assay. All strains showed sensitivity to TC with an inhibition zone diameter > 35 mm. The TC showed inhibitory and bactericidal action in the most tested bacteria around 625 µg/mL. Sub-inhibitory amounts (1/2 and 1/4 MIC) of TC interfered with the growth kinetics by lag phase extension and decreased the log phase. Time-kill curves show a reduction of viable cells after the first hour of TC treatment at bactericidal concentrations. The synergistic effect between TC/GEN was observed for E. coli and E. cloacae strains with FICi ranging from 0.15 to 0.50. These findings, therefore, suggest TC as a promising alternative in the fight against drug-resistant Enterobacteriaceae that can cause foodborne illnesses.

Sub-inhibitory concentrations of ceftriaxone induce morphological alterations and PIA-independent biofilm formation in Staphylococcus aureus.

The exposure of bacteria to sub-inhibitory concentrations of antibiotics is of biological significance since it can occur in vivo under many circumstances, including low-dose treatment, poor adherence to a regimen, poor drug penetration, drug-drug interactions, and antibiotic resistance of the pathogen. In this study, we investigated the effects of subinhibitory concentrations of four antibiotics: ampicillin, ceftriaxone, gentamicin, and norfloxacin, which are commonly used in clinical settings and on cell morphology and biofilm formation in Staphylococcus aureus as one of the leading causes of nosocomial and biofilm-associated infections. Nine clinical S. aureus biofilm-producing isolates and two known biofilm-producing reference strains, S. aureus ATCC 29213 and S. aureus ATCC 6538, were used in this study. Sub-MICs of beta-lactam antibiotics (ampicillin and ceftriaxone) significantly induced biofilm formation in S. aureus ATCC 29213 and S. aureus ATCC 6538 and in six clinical isolates out of the nine selected isolates when compared with the antibiotic-free control group (P < 0.05), with an approximately 2- to 2.5-fold increase. Gentamicin and norfloxacin induced biofilms in S. aureus ATCC 29213 and S. aureus ATCC 6538, while gentamicin and norfloxacin induced biofilms only in three and two of the nine tested isolates, respectively (P < 0.05). The chemical nature of the biofilm matrix produced by half the MIC of ceftriaxone in the six isolates that showed increased biofilm was all non-polysaccharide in composition (PIA-independent). Gene expression of biofilm-encoding genes atl and sarA in biofilms of the two tested strains (S. aureus ATCC 6538) and clinical strain (S. aureus 16) showed a significant upregulation after exposure to half MIC of ceftriaxone. Additionally, the bacterial cell morphological changes in planktonic cells caused by half MIC of ceftriaxone were evaluated by scanning electron microscopy, which demonstrated a significant cell enlargement when compared with the antibiotic-free control (P < 0.05), and some deformed cells were also noticed. In S. aureus clinical isolates, sub-MICs of ampicillin, ceftriaxone, gentamicin, and norfloxacin may stimulate substantial production of biofilm, which could have important clinical significance and make infection treatment challenges. Further, in vivo research is needed to fully comprehend how sub-MIC of antibiotics can affect biofilm formation in clinical settings. Additionally, more research is required to reveal the clinical implications of the morphological alterations in S. aureus brought on by exposure to ceftriaxone at concentrations below its MIC.

Methicillin-Resistant Staphylococcus aureus and Coagulase-Negative Staphylococcus from School Dining Rooms in Argentina.

Methicillin-resistant Staphylococcus aureus (MRSA) constitutes an important cause for concern in the field of public health, and the role of the food chain in the transmission of this pathogen and in antimicrobial resistance (AMR) has not yet been defined. The objectives of this work were to isolate and characterize coagulase-positive Staphylococcus (CoPS) and coagulase-negative Staphylococcus (CoNS), particularly S. aureus, from school dining rooms located in Argentina. From 95 samples that were obtained from handlers, inert surfaces, food, and air in 10 establishments, 30 Staphylococcus strains were isolated. Four isolates were S. aureus, and the remaining ones (N = 26) belonged to 11 coagulase-negative species (CoNS). The isolates were tested for susceptibility to nine antibiotics. The presence of genes encoding toxins (luk-PV, sea, seb, sec, sed, and see), adhesins (icaA, icaD), and genes that confer resistance to methicillin (mecA) and vancomycin (vanA) was investigated. The resistance rates measured for penicillin, cefoxitin, gentamicin, vancomycin, erythromycin, clindamycin, levofloxacin, trimethoprim-sulfamethoxazole, and tetracycline were 73%, 30%, 13%, 3%, 33%, 17%, 13%, 7%, and 7% of the isolates, respectively. Seventeen AMR profiles were detected, and 11 isolates were multidrug resistant (MDR). Seven methicillin-resistant Staphylococcus isolates were detected in the hands of handlers from four establishments, two of them were MRSA. Two S. aureus isolates presented icaA and icaD, another one, only icaD. The gene vanA was found in two isolates. In relation to S. aureus, resistance to vancomycin but not to gentamicin was detected. School feeding plays a key role in the nutrition of children, and the consumption of food contaminated with MRSA and vancomycin-resistant S. aureus (VRSA) can be a serious threat to health. In particular, it was detected that the handlers were the source of MRSA, VRSA, MR-CoNS (methicillin-resistant coagulase-negative Staphylococcus), and MDR isolates. The results obtained indicate that the vigilance of this pathogen in school dining rooms should be extreme.

High prevalence of Panton-Valentine Leucocidin among Staphylococcus coagulans isolated from dogs in Rio de Janeiro.

AIMS: The purpose of this study was to characterize the capacity for biofilm formation, antimicrobial resistance rates, and search for genetic determinants of resistance and virulence in the species. METHODS AND RESULTS: Strains were collected from asymptomatic and infected dogs. Identification was conducted using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF), antimicrobial susceptibility using disk diffusion and PCR targeting mecA. Biofilm formation was evaluated on a microtiter plate assay. A total of 27 strains were selected for whole-genome sequencing. We identified 111 Staphylococcus coagulans. The highest number was obtained from infected dogs. The highest resistance rates were observed for penicillin, gentamicin, and ciprofloxacin/erythromycin. Twelve strains were characterized as resistant to methicillin. All isolates had the ability to form biofilm and were strong producers. Among Methicillin Resistant Staphylococcus coagulans (MRSC), SCCmec types IIIA, and Vc were identified. Acquired resistance genes, such as aac(6')-aph(2''), tet(K), blaZ, qacG, qacJ, and erm(C) were found. Different virulence genes were identified. Of note, Panton-Valentine Leucocidin was highly prevalent among the isolates. CONCLUSION: Staphylococcus coagulans had a high isolation rate among infected dogs and demonstrated significant resistance to commonly used antibiotics such as penicillin and gentamicin.

Recovering the susceptibility of antibiotic-resistant bacteria using photooxidative damage.

Multidrug-resistant bacteria are one of the most serious threats to infection control. Few new antibiotics have been developed; however, the lack of an effective new mechanism of their action has worsened the situation. Photodynamic inactivation (PDI) can break antimicrobial resistance, since it potentiates the effect of antibiotics, and induces oxidative stress in microorganisms through the interaction of light with a photosensitizer. This paper addresses the application of PDI for increasing bacterial susceptibility to antibiotics and helping in bacterial persistence and virulence. The effect of photodynamic action on resistant bacteria collected from patients and bacteria cells with induced resistance in the laboratory was investigated. Staphylococcus aureus resistance breakdown levels for each antibiotic (amoxicillin, erythromycin, and gentamicin) from the photodynamic effect (10 µM curcumin, 10 J/cm2) and its maintenance in descendant microorganisms were demonstrated within five cycles after PDI application. PDI showed an innovative feature for modifying the degree of bacterial sensitivity to antibiotics according to dosages, thus reducing resistance and persistence of microorganisms from standard and clinical strains. We hypothesize a reduction in the degree of antimicrobial resistance through photooxidative action combats antibiotic failures.

Prescription of off-label and unlicensed medication for newborns hospitalized in the Intensive Care Unit.

OBJECTIVE: To analyze the prevalence of off-label and unlicensed prescriptions for a population of neonates admitted to the Neonatal Intensive Care Unit in a hospital in southern Santa Catarina. METHODS: Observational study with a cross-sectional design. All neonates admitted to the Intensive Care Unit during the period from March 2020 to March 2021 were included. Data collection was performed through a questionnaire made by the authors and the classification of drugs based on the Electronic Drug Description (Bulário Eletrônico) of the Brazilian Health Regulatory Agency and Drug Dex-Micromedex. RESULTS: Data from 296 neonates were evaluated. The prevalence was 50,7% for prescribing off-label medications and 37,2% for unlicensed medications. The use of drugs was higher in preterm neonates, with low birth weight, 1st minute Apgar between 6-8, 5th minute Apgar between 7-8, and in need of invasive procedures. The most used off-label drugs were ampicillin, gentamicin and fentanyl (92.6, 92.0 and 26.6%, respectively), whereas the most used unlicensed drugs were caffeine, phenobarbital and bromopride (78.1, 16.3 and 10.9%, respectively). CONCLUSIONS: This study showed a large percentage of prescriptions made in the off-label (50.7%) and unlicensed (37.2%) form in the Neonatal Intensive Care Unit, corroborating the worrying world scenario. The most exposed neonates were precisely the most vulnerable ones and, among the most commonly prescribed medications, ampicillin and gentamicin stood out in off-label form and caffeine in unlicensed form.

Reversing the biofilm-inducing effect of two xanthones from Garcinia mangostana by 3-methyl-2(5H)-furanone and N-butyryl-D-L homoserine lactone.

BACKGROUND: According to the WHO, 12 bacteria cause numerous human infections, including Enterobacteriaceae Klebsiella pneumoniae, and thus represent a public health problem. Microbial resistance is associated with biofilm formation; therefore, it is critical to know the biofilm-inducing potential of various compounds of everyday life. Likewise, the reversibility of biofilms and the modulation of persister cells are important for controlling microbial pathogens. In this work, we investigated the biofilm-inducing effects of xanthones from Garcinia mangostana on Klebsiella pneumoniae. Furthermore, we investigated the reversal effect of 3-methyl-2(5H)-furanone and the formation of persister cells induced by xanthones and their role in modulating the biofilm to the antibiotic gentamicin. METHODS: To analyze the biofilm-inducing role of xanthones from Garcinia mangostana, cultures of K. pneumoniae containing duodenal probe pieces were treated with 0.1-0.001 µM α- and γ-mangostin, and the biofilm levels were measured using spectrophotometry. To determine biofilm reversion, cultures treated with xanthones, or gentamicin were mixed with 3-methyl-2(5H)-furanone or N-butyryl-DL-homoserine lactone. The presence of K. pneumoniae persister cells was determined by applying the compounds to the mature biofilm, and the number of colony-forming units was counted. RESULTS: The xanthones α- and γ-mangostin increased K. pneumoniae biofilm production by 40% with duodenal probes. However, 3-methyl-2(5H)-furanone at 0.001 µΜ reversed biofilm formation by up to 60%. Moreover, adding the same to a culture treated with gentamicin reduced the biofilm by 80.5%. This effect was highlighted when 3-methyl-2(5H)-furanone was administered 6 h later than xanthones. At high concentrations of α-mangostin, persister K. pneumoniae cells in the biofilm were about 5 - 10 times more abundant than cells, whereas, with γ-mangostin, they were about 100 times more. CONCLUSION: Two xanthones, α- and γ-mangostin from G. mangostana, induced biofilm formation in K. pneumoniae and promoted persister cells. However, the biofilm formation was reversed by adding 3-methyl-2(5H)-furanone, and even this effect was achieved with gentamicin. In addition, this compound controlled the persister K. pneumoniae cells promoted by α-mangostin. Thus, synthetic, and natural biofilm-inducing compounds could harm human health. Therefore, avoiding these substances and looking for biofilm inhibitors would be a strategy to overcome microbial resistance and recover antibiotics that are no longer used.

Eugenia uniflora: a promising natural alternative against multidrug-resistant bacteria.

This work aimed to evaluate the chemical composition, antioxidant and antimicrobial activities from crude extract and fractions from leaves of Eugenia uniflora Linn. The crude extract was obtained by turbo extraction and their fractions by partitioning. Chromatographic analysis were performed, and the antioxidant capacity was verified by two methods (DPPH• and ABTS•+). The Minimal Inhibitory/Bactericidal Concentration were conducted against twenty-two bacteria, selecting five strains susceptible to extract/fractions and resistant to the antibiotics tested. Ampicillin, azithromycin, ciprofloxacin, and gentamicin were associated with Ethyl Acetate Fraction (EAF) against multidrug-resistant strains in modulatory and checkerboard tests. The chromatographic data showed gallic acid, ellagic acid, and myricitrin in crude extract, with enrichment in the EAF. The electron transfer activity demonstrated in the antioxidant tests is related to the presence of flavonoids. The Gram-positive strains were more susceptible to EAF, and their action spectra were improved by association, comprising Gram-negative bacilli. Synergisms were observed to ciprofloxacin and gentamicin against Pseudomonas aeruginosa colistin-resistant. The results demonstrate that the extract and enriched fraction obtained from the leaves of E. uniflora act as a promising natural alternative against multidrug-resistant bacteria.

Exploring porcine kidney explants as a model for the study of nephrotoxins and the therapeutic potential of phytic acid.

The use of in vivo models to assess nephrotoxicity has faced ethical limitations. A viable alternative is the ex vivo model that combines the 3 R principles with the preservation of tissue histology. Here, we established a gentamicin nephrotoxicity model using pigs` kidney explants and investigated the effect of phytic acid (IP6) against gentamicin- induced nephrotoxicity. A total of 360 kidney explants were divided into control, gentamicin (10 mM), IP6 (5 mM), and gentamicin+IP6 groups. The activity of gammaglutamyltransferase (GGT), creatinine levels, histological assessment, oxidative stress, and inflammatory cytokine expression were analyzed. Exposure to gentamicin induced an increase in GGT activity, creatinine levels, lesion score, lipoperoxidation and IL-8 expression. Explants exposed to IP6 remained like the control. The addition of IP6 to gentamicin prevented tissue damage, increasing the antioxidant status and gene expression of IL-10. This model proved to be an adequate experimental approach for identifying nephrotoxins and potential products to modulate the toxicity.

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.

Topical gentamicin for the prevention of tunneled hemodialysis catheter-related infections: a randomized double-blind study.

INTRODUCTION: Infection is the second leading cause of death in dialysis patients, with catheter-related bloodstream infection being the most serious. Exit Site Infection and Tunnel Infection are also related to the catheter. OBJECTIVE: To compare the infection rates achieved with the application of either topical gentamicin or placebo to the exit-site of tunneled catheters filled with locking solution in chronic hemodialysis patients. METHODS: This randomized double-blind clinical trial compared the application of 0.1% gentamicin versus placebo to the exit site of tunneled hemodialysis catheters filled with a prophylactic locking solution. A total of 91 patients were randomly allocated to 2 groups: placebo or 0.1% gentamicin. RESULTS: Mean patient age was 60.4 (+ 15.3) years, with predominance of males (60.4%). The main cause of chronic kidney disease was diabetes (40.7%). The rates of exit site infection (placebo = 30% vs. gentamicin = 34.1%, p = 0.821), and bloodstream infection (placebo = 22% vs. gentamicin = 17.1%, p = 0.60), as well as both exit site infection and bloodstream infection incidence density per 1000 catheter-days (p = 1) did not differ between groups. The infection-free curve was also similar in both groups. CONCLUSION: The application of topical 0.1% gentamicin to the exit site of tunneled catheters filled with lock solution did not reduce infectious complications when compared to topical placebo in patients on chronic hemodialysis.

Molecular identification and antimicrobial resistance pattern of Nocardia isolated from 14 diseased dogs and cats.

Nocardia are ubiquitous, saprophytic and opportunistic bacteria. They cause a set of pyogenic clinical infections in animals and humans, particularly immunocompromised patients, mostly affecting the skin and respiratory tract, with refractoriness to conventional therapy. The most descriptions of nocardial infections in companion animals involve case reports, and there are scarce case series studies focused on canine and feline nocardiosis in which diagnosis has been based on molecular techniques. We investigated epidemiological aspects, clinical findings, in vitro susceptibility profile, and molecular identification of Nocardia using PCR-based method targeted 16S rRNA gene in twelve dogs and two cats. Among dogs were observed cutaneous lesions (8/12 = 67%), pneumonia (3/12 = 25%), and encephalitis (2/12 = 17%), whereas cats developed cutaneous lesions and osteomyelitis. Nocardia and canine morbillivirus coinfection was described in six dogs (6/12 = 50%). A high mortality rate (6/8 = 75%) was seen among dogs. Three dogs (3/4 = 75%) and one cat (1/2 = 50%) with systemic signs (pneumonia, encephalitis, osteomyelitis), and 83% (5/6) of dogs with a history of concomitant morbillivirus infection died. N. nova (5/12 = 42%), N. cyriacigeorgica (3/12 = 25%), N. farcinica (2/12 = 17%), N. veterana (1/12 = 8%), and N. asteroides (1/12 = 8%) species were identified in dogs, whereas N. africana and N. veterana in cats. Among the isolates from dogs, cefuroxime (12/12 = 100%), amikacin (10/12 = 83%), gentamycin (10/12 = 83%), and imipenem (10/12 = 83%) were the most effective antimicrobials, whereas cefuroxime, cephalexin, amoxicillin/clavulanic acid, imipenem, and gentamycin were efficient against isolates from cats. Multidrug resistance was observed in 36% (5/14) of isolates. We describe a variety of Nocardia species infecting dogs and cats, multidrug-resistant ones, and a high mortality rate, highlighting a poor prognosis of nocardiosis in companion animals, particularly among animals systemically compromised or coinfected by canine morbillivirus. Our study contributes to species identification, in vitro antimicrobial susceptibility profile, clinical-epidemiological aspects, and outcome of natural Nocardia-acquired infections in dogs and cats.

Endocarditis de la válvula aórtica causada por Brucella melitensis / Aortic valve endocarditis caused by Brucella melitensis

La endocarditis bacteriana secundaria a la infección por Brucella spp., en este caso B. melitensis, como complicación de la brucelosis humana tiene una incidencia baja y, aunque es la presentación clínica con la que se asocia más frecuentemente la mortalidad, no todos los casos son letales, si son tratados oportunamente. Se describe el caso clínico de una endocarditis bacteriana por B. melitensis, diagnosticada en un adulto por el aislamiento del microorganismo en el hemocultivo. Paciente del sexo masculino, de 40 años, con antecedentes de realizar partos en el ganado bovino y consumir leche no pasteurizada. Acudió al médico por presentar durante siete días de evolución de las siguientes manifestaciones clínicas: fiebre, mialgias, artralgias, tos seca y pérdida de peso (15 kg). El hemograma informa: leucopenia, trombocitopenia y anemia; mientras que en un ecocardiograma transesofágico se observó vegetación en la válvula aórtica con una disminución de la función sistólica y en el hemocultivo se aisló B. melitensis. Debido a estos antecedentes, se inició el tratamiento antibacteriano con rifampicina, doxiciclina y gentamicina. El paciente se recuperó y tuvo una evolución clínica satisfactoria. La brucelosis es una enfermedad infrecuente. Debe considerarse en toda persona con fiebre de foco desconocido que resida en zonas endémicas o esté expuesto al cuidado de animales de granja. En esta enfermedad se impone un diagnóstico y tratamiento preciso, por ser una complicación con alta letalidad.

Bacterial endocarditis, secondary to Brucella spp. infection, in this case by B. melitensis, as a complication of human brucellosis has a low incidence. Although it is the clinical presentation most frequently associated with mortality, not all cases are lethal if timely treatment is provided. We describe a clinical case of bacterial endocarditis due to B. melitensis in a 40-year-old male patient with a history of conducting cattle deliveries and consuming unpasteurized milk, diagnosed after isolating the microorganism in blood culture. He presented with the following clinical manifestations after seven days of evolution: fever, myalgias, arthralgias, dry cough and weight loss (15 kg). The hemogram revealed leukopenia, thrombocytopenia, and anemia; while a transesophageal echocardiogram showed vegetation on the aortic valve with decreased systolic function, and B. melitensis was isolated in a blood culture. Considering this medical history, antibacterial treatment was initiated with rifampicin, doxycycline and gentamicin. The patient recovered and had satisfactory clinical evolution. Brucellosis is a rare disease. It should be considered in any person with a fever of unknown origin who lives in endemic areas or is exposed to the care of farm animals. Endocarditis is a highly lethal complication of human brucellosis; therefore, it requires a precise diagnosis and treatment.

Evaluation of the antimicrobial effect of the Origanum vulgare L essential oil on strains of Klebsiella pneumoniae.

Bacteria may be the initial cause of certain pathologies as well as a secondary agent responsible for the development of complications such as pressure ulcer infections. Pressure ulcers are a persistent health problem, especially in immunocompromised patients, and associated with infection by opportunistic microorganisms with antimicrobial resistance, such as Klebsiella pneumoniae, highlight the need for the development of new antimicrobial approaches. Thus, the aim of this study was to evaluate the antibacterial and anti-adherent activity of Origanum vulgare L. (oregano) essential oil against Klebsiella pneumoniae strains, as well as the effect of its association with synthetic antimicrobials. To this end, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) analyses were performed on microdilution plates. The assay of the Minimum Inhibitory Adherence Concentration (MIAC), with test tubes. As well as, the association study through the infusion disc method containing ampicillin (AMP), gentamicin (GEN), ciprofloxacin (CIP) and ceftriaxone (CEF). Therefore, it was possible to obtain that the essential oil of oregano presents antimicrobial and bactericidal activity, with MIC ranging between 128µg/mL and 256 µg/mL and MBC between 256 µg/mL and 512 µg/mL, on the tested K. pneumoniae strains. When used in association with ampicillin and gentamicin, oregano essential oil showed synergistic effect for some strains. Therefore, it is observed that the tested essential oil can act as a promising antibacterial in the treatment of diseases caused by K. pneumoniae.