Antibiotic-eluting scaffolds with responsive dual-release kinetics facilitate bone healing and eliminate S. aureus infection.

Osteomyelitis (OM) is a progressive, inflammatory infection of bone caused predominately by Staphylococcus aureus. Herein, we engineered an antibiotic-eluting collagen-hydroxyapatite scaffold capable of eliminating infection and facilitating bone healing. An iterative freeze-drying and chemical crosslinking approach was leveraged to modify antibiotic release kinetics, resulting in a layered dual-release system whereby an initial rapid release of antibiotic to clear infection was followed by a sustained controlled release to prevent reoccurrence of infection. We observed that the presence of microbial collagenase accelerated antibiotic release from the crosslinked layer of the scaffold, indicating that the material is responsive to microbial activity. As exemplar drugs, vancomycin and gentamicin-eluting scaffolds were demonstrated to be bactericidal, and supported osteogenesis in vitro. In a pilot murine model of OM, vancomycin-eluting scaffolds were observed to reduce S. aureus infection within the tibia. Finally, in a rabbit model of chronic OM, gentamicin-eluting scaffolds both facilitated radial bone defect healing and eliminated S. aureus infection. These results show that antibiotic-eluting collagen-hydroxyapatite scaffolds are a one-stage therapy for OM, which when implanted into infected bone defects simultaneously eradicate infection and facilitate bone tissue healing.

Effect of mitochondrial coenzyme-Q10 precursor solanesol in gentamicin-induced experimental nephrotoxicity: Evidence from restoration of ETC-complexes and histopathological alterations.

Nephrotoxicity occurs when the body is exposed to certain drugs or toxins. When kidney damage occurs, the kidney fails to eliminate excess urine and waste. Solanesol (C45H74O) is a tri-sesquiterpenoid alcohol first isolated from tobacco, and it is widely distributed in plants of the Solanaceae family. Solanesol (SNL) is an intermediate in the synthesis of coenzyme Q10 (CoQ10), an antioxidant which protects nerve cells. This study investigated the protective effect of SNL at doses of 30 and 60 mg/kg in gentamicin-induced nephrotoxicity in Wistar albino rats. Animals were distributed into six groups and administered 100 mg/kg gentamicin-intraperitoneal injection for 14 days. Biochemical assessments were performed on kidney homogenate, blood, and serum. Treatment with SNL was shown as lower serum levels of creatinine, blood urea nitrogen (BUN), thiobarbituric acid reactive substances (TBARS), and Tumor necrosis factor alpha)TNF-α ((p < .001). It also restored reduced glutathione (GSH) and mitochondrial complex enzymatic activity as protective measures against gentamicin-induced nephrotoxicity. SNL were shown to reduce inflammation and oxidative stress markers (p < .001). Histological findings furtherly augmented the protective effects of SNL. Long-term SNL therapy also restored mitochondrial electron transport chain complex enzymes, such as complex-I (p < .001). In conclusion, these findings suggest that SNL can represent a protective therapeutic option for drug-induced nephrotoxicity, a long-term adverse effect of aminoglycoside antibiotics such as gentamicin.

Profile of antimicrobial use and potential use of the defined daily dose in neonatology.

One of the measures for monitoring microbial resistance is the calculation of the defined daily dose of antimicrobial agents. For this calculation, the weight of an adult of 70 kg is used as a standard, so that application in neonatology is not possible. The aim of this study is to describe the use profile and calculate the defined daily dose (DDD) of antimicrobials in a neonatal intensive care unit (NICU) of a public hospital in the interior of Bahia, Brazil. From March 2020 to December 2021, the medical records of 712 newborns admitted to a NICU between September 2018 and June 2020 were analyzed. A total of 410 newborns diagnosed with neonatal sepsis were included. The most used antimicrobials per patient were gentamicin (408/410; 99.5%), ampicillin (407; 99.3%), amikacin (29; 7.1%) and oxacillin (21; 5.1%), with a mean (SD) treatment duration of 9.8 (3.9) days. The most commonly used combination of antimicrobials was ampicillin with gentamicin, which was used in 406 patients (99.0%). The values for neonatal DDDs were on average 26 times lower than those for adult DDDs. The neonatal DDDs were similar to those observed in other studies. Ampicilin and cefepime were the antimicrobials for which the greatest differences were observed in neonatal DDDs compared with adult DDDs, which differed mainly between maintenance doses, reflecting the lack of international standards in neonatology. Standardization of DDDs as a surveillance measure has the potential to clarify the pattern of antimicrobial use in neonatal patients worldwide and, in particular, to prevent indiscriminate use and bacterial resistance.

Antibiotics stimulates the development of persistent cells in biofilms of Candida albicans bloodstream isolates.

Candida albicans invasive candidiasis is considered a global health problem. In such cases, biofilm formation on implanted devices represents a therapeutic challenge and the presence of metabolically inactive persistent cells (PCs) in these communities increases their tolerance to fungicidal drugs. This study investigated the influence of amoxicillin, AMX; cefepime, CEF; gentamicin, GEN; amikacin, AMK; vancomycin, VAN; and ciprofloxacin, CIP; on the production of PCs in biofilms of C. albicans bloodstream isolates. 48 h-mature biofilms (n = 6) grown in RPMI-1640 supplemented with antibiotics were treated with 100 µg ml-1 amphotericin B and then evaluated for PCs. Biofilms grown in the presence of antibiotics produced more PCs, up to 10×, when exposed to AMX and CIP; 5 × to CEF; and 6 × to GEN and VAN. The results indicate that antibiotics can modulate PC production in C. albicans biofilms. This scenario may have clinical repercussions in immunocompromised patients under broad-spectrum antibiotic therapy.

Biofilms are microbial communities tolerant to antifungals. Our research showed that antibiotics stimulate the formation of persistent cells within Candida albicans biofilms. These are dormant, metabolically silent cells that resist to therapy and can be related to metastatic and recalcitrant infections.

Antimicrobial Sub-MIC induces Staphylococcus aureus biofilm formation without affecting the bacterial count.

BACKGROUND: Biofilm formation is an essential virulence factor that creates a highly protected growth mode for Staphylococcus aureus (S. aureus) to survive in any hostile environment. Antibiotic sub-minimal inhibitory concentration (sub-MIC) may modulate the biofilm formation ability of bacterial pathogens, thereby affecting bacterial pathogenesis and infection outcomes. Intense antimicrobial therapy to treat biofilm-associated infections can control the pathogenic infection aggravation but cannot guarantee its complete eradication. OBJECTIVE: This study aimed to assess the sub-MICs effect of 5 different antimicrobial classes on biofilm-forming capacity among Staphylococcus aureus clinical isolates using three different biofilm quantitation techniques. METHODS: In this study, the effects of 5 different antimicrobial agents, namely, azithromycin, gentamicin, ciprofloxacin, doxycycline, and imipenem, at sub-MICs of 12.5%, 25%, and 50% were tested on 5 different clinical isolates of S. aureus. The biofilms formed in the absence and presence of different antimicrobial sub-MICs were then assessed using the following three different techniques: the crystal violet (CV) staining method, the quantitative PCR (qPCR) method, and the spread plate method (SPM). RESULTS: Biofilm formation was significantly induced in 64% of the tested conditions using the CV technique. On the other hand, the qPCR quantifying the total bacterial count and the SPM quantifying the viable bacterial count showed significant induction only in 24% and 17.3%, respectively (Fig. 1). The difference between CV and the other techniques indicates an increase in biofilm biomass without an increase in bacterial growth. As expected, sub-MICs did not reduce the viable cell count, as shown by the SPM. The CV staining method revealed that sub-MICs of imipenem and ciprofloxacin had the highest significance rate (80%) showing an inductive effect on the biofilm development. On the other hand, doxycycline, azithromycin, and gentamicin displayed lower significance rates of 73%, 53%, and 47%, respectively. CONCLUSION: Exposure to sub-MIC doses of antimicrobial agents induces the biofilm-forming capacity of S. aureus via increasing the total biomass without significantly affecting the bacterial growth of viable count.

Microbiome-derived antimicrobial peptides show therapeutic activity against the critically important priority pathogen, Acinetobacter baumannii.

Acinetobacter baumannii is designated by the World Health Organisation as a critical priority pathogen. Previously we discovered antimicrobial peptides (AMPs), namely Lynronne-1, -2 and -3, with efficacy against bacterial pathogens, such as Staphylococcus aureus and Pseudomonas aeruginosa. Here we assessed Lynronne-1, -2 and -3 structure by circular dichroism and efficacy against clinical strains of A. baumannii. All Lynronne AMPs demonstrated alpha-helical secondary structures and had antimicrobial activity towards all tested strains of A. baumannii (Minimum Inhibitory Concentrations 2-128 µg/ml), whilst also having anti-biofilm activity. Lynronne-2 and -3 demonstrated additive effects with amoxicillin and erythromycin, and synergy with gentamicin. The AMPs demonstrated little toxicity towards mammalian cell lines or Galleria mellonella. Fluorescence-based assay data demonstrated that Lynronne-1 and -3 had higher membrane-destabilising action against A. baumannii in comparison with Lynronne-2, which was corroborated by transcriptomic analysis. For the first time, we demonstrate the therapeutic activity of Lynronne AMPs against A. baumannii.

Microbial community interactions on a chip.

Multispecies microbial communities drive most ecosystems on Earth. Chemical and biological interactions within these communities can affect the survival of individual members and the entire community. However, the prohibitively high number of possible interactions within a microbial community has made the characterization of factors that influence community development challenging. Here, we report a Microbial Community Interaction (µCI) device to advance the systematic study of chemical and biological interactions within a microbial community. The µCI creates a combinatorial landscape made up of an array of triangular wells interconnected with circular wells, which each contains either a different chemical or microbial strain, generating chemical gradients and revealing biological interactions. Bacillus cereus UW85 containing green fluorescent protein provided the "target" readout in the triangular wells, and antibiotics or microorganisms in adjacent circular wells are designated the "variables." The µCI device revealed that gentamicin and vancomycin are antagonistic to each other in inhibiting the target B. cereus UW85, displaying weaker inhibitory activity when used in combination than alone. We identified three-member communities constructed with isolates from the plant rhizosphere that increased or decreased the growth of B. cereus. The µCI device enables both strain-level and community-level insight. The scalable geometric design of the µCI device enables experiments with high combinatorial efficiency, thereby providing a simple, scalable platform for systematic interrogation of three-factor interactions that influence microorganisms in solitary or community life.

Comparative Metabolomics Reveals Changes in the Metabolic Pathways of Ampicillin- and Gentamicin-Resistant Staphylococcus aureus.

Antibiotic resistance is a major global challenge requiring new treatments and a better understanding of the bacterial resistance mechanisms. In this study, we compared ampicillin-resistant (R-AMP) and gentamicin-resistant (R-GEN) Staphylococcus aureus strains with a sensitive strain (ATCC6538) using metabolomics. We identified 109 metabolites; 28 or 31 metabolites in R-AMP or R-GEN differed from those in ATCC6538. Moreover, R-AMP and R-GEN were enriched in five and four pathways, respectively. R-AMP showed significantly up-regulated amino acid metabolism and down-regulated energy metabolism, whereas R-GEN exhibited an overall decrease in metabolism, including carbohydrate, energy, and amino acid metabolism. Furthermore, the activities of the metabolism-related enzymes pyruvate dehydrogenase and TCA cycle dehydrogenases were inhibited in antibiotic-resistant bacteria. Significant decreases in NADH and ATP levels were also observed. In addition, the arginine biosynthesis pathway, which is related to nitric oxide (NO) production, was enriched in both antibiotic-resistant strains. Enhanced NO synthase activity in S. aureus promoted NO production, which further reduced reactive oxygen species, mediating the development of bacterial resistance to ampicillin and gentamicin. This study reveals that bacterial resistance affects metabolic profile, and changes in energy metabolism and arginine biosynthesis are important factors leading to drug resistance in S. aureus.

The effect of combinations of a glyphosate-based herbicide with various clinically used antibiotics on phenotypic traits of Gram-negative species from the ESKAPEE group.

The emission of glyphosate and antibiotic residues from human activities threatens the diversity and functioning of the microbial community. This study examines the impact of a glyphosate-based herbicide (GBH) and common antibiotics on Gram-negative bacteria within the ESKAPEE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli). Ten strains, including type and multidrug-resistant strains for each species were analysed and eight antibiotics (cefotaxime, meropenem, aztreonam, ciprofloxacin, gentamicin, tigecycline, sulfamethoxazole-trimethoprim, and colistin) were combined with the GBH. While most combinations yielded additive or indifferent effects in 70 associations, antagonistic effects were observed with ciprofloxacin and gentamicin in five strains. GBH notably decreased the minimum inhibitory concentration of colistin in eight strains and displayed synergistic activity with meropenem against metallo-ß-lactamase (MBL)-producing strains. Investigation into the effect of GBH properties on outer membrane permeability involved exposing strains to a combination of this GBH and vancomycin. Results indicated that GBH rendered strains sensitive to vancomycin, which is typically ineffective against Gram-negative bacteria. Furthermore, we examined the impact of GBH in combination with three carbapenem agents on 14 strains exhibiting varying carbapenem-resistance mechanisms to assess its effect on carbapenemase activity. The GBH efficiently inhibited MBL activity, demonstrating similar effects to EDTA (ethylenediaminetetraacetic acid). Chelating effect of GBH may have multifaceted impacts on bacterial cells, potentially by increasing outer membrane permeability and inactivating metalloenzyme activity.

Protective Effects of Gastrodin Against Gentamicin-Induced Vestibular Damage by the Notch Signaling Pathway.

PURPOSE: Gentamicin is a broad-spectrum antibiotic commonly used in clinical practice. However, the drug causes side effects of ototoxicity, leading to disruption in balance functionality. This study investigated the effect of gastrodin, a prominent compound present in Gastrodia, and the underlying mechanism on the development of gentamicin-induced vestibular dysfunction. METHODS: Wild-type C57BL/6 mice were randomly assigned to three groups: control, gentamicin, and gentamicin + gastrodin groups. The extent of gentamicin-induced vestibular impairment was assessed through a series of tests including the swimming test, contact righting reflex test, and air-righting reflex. Alterations in vestibular hair cells were monitored through immunofluorescence assay, and cellular apoptosis was observed using TUNEL staining. The mRNA and protein expression of Notch1, Jagged1, and Hes1 was quantified through qRT-PCR, immunofluorescence, and western blot analyses. RESULTS: Gentamicin treatment led to pronounced deficits in vestibular function and otolith organ hair cells in mice. Nevertheless, pretreatment with gastrodin significantly alleviated these impairments. Additionally, the Notch signaling pathway was activated by gentamicin in the utricle, contributing to a notable increase in the expression levels of apoptosis-associated proteins. By contrast, gastrodin treatment effectively suppressed the Notch signaling pathway, thereby mitigating the occurrence of apoptosis. CONCLUSION: Collectively, these findings underscore the crucial role of gastrodin in safeguarding against gentamicin-induced vestibular dysfunction through the modulation of the Notch signaling pathway. This study suggests the potential of gastrodin as a promising therapeutic agent for preventing vestibular injuries.