Tea Tree Oil Nanoemulsion Potentiates Antibiotics against Multidrug-Resistant Escherichia coli

Eucalyptus oil: A promising anticoccidial agent with multifaceted protective effects

In-feed preventive coccidiostat additives are regarded as the primary choice of coccidiosis control, whereas the lasting appearance of drug resistance seriously hampered its application. Eucalyptus oil (EUC) has been evidenced to possess anti-malaria and anti-helminth efficacy. Confronting the urgent requirements for novel anticoccidial remedies, EUC was picked to scrutinize its anticoccidial efficacy with the in vivo coccidiosis model. Birds were orally administrated with 8 × 104 sporulated oocysts and treated with 20 mg/kg EUC in feed during the whole experimental period, diclazuril (DIC) was selected as a positive control. The results manifested that EUC supplementation lessened cecal damage, oocyst shedding and mortality, and recovering body weight gain, so the anticoccidial index (ACI) was up to 160, indicating moderate anticoccidial activity. Additionally, the safeguarding effects of EUC on E. tenella-evoked cecal damage were respectively evidenced on macroscopic, histopathological, and ultrastructural levels. Meanwhile, EUC also exerted an inhibitory effect on redox imbalance and inflammatory response caused by E. tenella. Moreover, EUC treatment remarkably suppressed the invasion-related gene transcriptional level and enhanced the apoptosis mRNA expression level of coccidia. Besides, EUC noticeably decreased the Clostridium perfringens (C. perfringens) proliferation in vivo and in vitro. In conclusion, the EUC additive presented a moderate anticoccidial effect which is associated with the remission activity on E. tenella-induced cecal injury, redox imbalance, and inflammatory response which may be associated with inhibitory effect on Eimeria invasion and C. perfringens proliferation, and activating influence on coccidial apoptosis.

Sustainable nanophytosome-based therapies against multidrug-resistant Escherichia coli in urinary tract infections: an in Vitro and in vivo study

BACKGROUND

Urinary tract infection (UTI) is a prevalent bacterial infection impacting a significant number of individuals globally. The rise in multidrug-resistant (MDR) E. coli strains as the predominant cause of UTIs presents a substantial public health concern and poses a challenge to existing antibiotic treatments. This study introduces an innovative and sustainable therapeutic approach utilizing rosemary oil nanophytosomes as a targeted drug delivery system to address biofilms in UTIs induced by MDR E. coli.

METHOD

Seventy clinically identified E. coli isolates from UTI patients were used for this study. Nanophytosomes were formulated with chitosan (CS) and nanostructured lipid carriers. CS-nanophytosomes were lyophilized to evaluate the storage stability. In vivo study included 40 female Wistar rats with daily treatment over seven days. For all the statistical tests, differences were considered significant at p < 0.01 and highly significant at p < 0.001.

RESULTS

CS-nanophytosomes demonstrated a particle size of 176.70 ± 12.30 nm with a substantial antibiofilm efficacy against MDR E. coli. High entrapment efficiency was ascertained with 93.12 ± 1.05%. The drug release study showed that the pure rosemary oil exhibited a notably lower release of 35.4 ± 2.36% over 48 h. In contrast, the CS-nanophytosomes and lyophilized CS-nanophytosomes displayed significantly higher release percentages of 58.6 ± 3.69% and 56.9 ± 5.01%, respectively, compared to the pure rosemary oil of 35.4 ± 2.36% over 48 h. The in vivo study indicated that nanophytosomes successfully reduced the bacterial load in the urine, bladder, and kidney tissues of mice infected with MDR E. coli, while also lowering the levels of inflammatory cytokines and oxidative stress markers in serum and urine samples. Additionally, the nanophytosomes improved histopathological changes in bladder and kidney tissues caused by UTI without causing any toxicity or adverse effects on kidney function or hematological parameters.

CONCLUSION

Our research introduces a cost-effective and innovative approach to addressing UTIs caused by MDR E. coli by the use of rosemary oil, a natural antimicrobial agent encapsulated in nanophytosomes. This strategy not only demonstrates proven therapeutic efficacy in UTI animal models but also promotes the adoption of sustainable medical approaches. CS-nanophytosomes provides a sustainable alternative therapeutic option to combat MDR UTIs.

Tea tree oil nanoemulsion targets AgrA protein potentiates amoxicillin efficacy against methicillin-resistant Staphylococcus aureus

The excessive utilization of antibiotics gives rise to the development of bacterial resistance, the deterioration of animal immune functions, the increase in mortality rates, and the undermining of human immunity. Therefore, there is an urgent necessity to explore new antimicrobial agents or alternatives to tackle bacterial resistance. We investigated tea tree oil (TTO), a pure natural plant essential oil extracted from Melaleuca leaves, which exerted efficient antibacterial activities. However, the poor solubility and high volatility of TTO limited the clinical application. Therefore, tea tree oil and Tween 80 were formulated into a stable nanoemulsion (Nano TTO). We attested that Nano TTO, as an antibiotic adjuvant, enhanced the antibacterial activity of amoxicillin (AMX) against methicillin-resistant Staphylococcus aureus (MRSA) and inhibited the formation of biofilms. Mechanistic studies proved that the Nano TTO potentiation effect on AMX was primarily the result of inhibition of the Agr expression by targeting the accessory regulator AgrA. Furthermore, Nano TTO effectively boosts the efficacy of amoxicillin in the mouse septicaemia model and mouse skin wound infection model. Overall, these results revealed the potential of Nano TTO as an adjuvant to evade multidrug-resistant bacterial pathogens and improve treatment outcomes for drug-resistant infections.

Natural agents derived Pickering emulsion enabled by silica nanoparticles with enhanced antibacterial activity against drug-resistant bacteria

The emergence of antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) has become a global health challenge due to the overuse of antibiotics. Natural substances including enzymes and essential oils have shown great potential as alternative treatment options. However, the combinational use of these natural agents remains challenging due to the denaturation of enzymes upon direct contact with oil. In this study, we report the design of a Pickering emulsion containing two natural antibacterial agents, lysozyme and tea tree oil, stabilized by fractal silica nanoparticles. In this design, the enzyme activity is kept and the volatility problem of tea tree oil is mitigated. Due to synergistic bacterial cell wall digestion and membrane disruption functions, potent bactericidal efficacy in vitro against drug-resistant bacteria is achieved. The therapeutic potential is further demonstrated in a wound healing model with drug-resistant bacteria infection, better than a synthetic antibiotic, Ampicillin. This study opens new avenues for the development of natural product-based antimicrobial treatments with promising application potential.

Synergistic effect of acetic acid and chitosan against Aspergillus flavus

The mycotoxin-producing fungi contamination of foodstuffs and agricultural commodities is a serious problem. In this study, the efficacy of acetic acid (AcA), chitosan (CS), and CS with extra AcA (CS/extra AcA) against Aspergillus flavus (A. flavus) in vitro and in vivo were investigated. Results showed that CS/extra AcA strongly inhibited the mycelial growth and aflatoxins production of A. flavus at lower concentrations than CS (MIC > 16.0 mg/mL) or AcA (MIC: 0.31 %). Significant inhibition was achieved in the presence of 4.0/0.12 and 8.0/0.08 CS (mg/mL)/extra AcA (%). CS/extra AcA exhibited remarkable antifungal activities based on the results of spore germination inhibition, abnormalities of spore morphology, disruption of cell membrane, mitochondrial dysfunction, and induction of apoptosis of hyphae. Moreover, pathogenicity test in peanut kernels showed that 8.0/0.16 CS (mg/mL)/extra AcA (%) could effectively inhibit the fungal infection and aflatoxin B1 production. The efficacy of CS/extra AcA is possibly due to the synergy of the antifungal property of CS, and undissociated AcA. The findings referred that CS/extra AcA is safe, efficient, and economical, and it could be used as a promising way to control A. flavus contamination in agro-foods preservation.

Investigating topical delivery of erythromycin laden into lipid nanocarrier for enhancing the anti-bacterial activity

Skin infections considered as one of the predominant disorders that could greatly influence humans. Topical drug delivery is believed to be an effective substitute to systemically delivered medication for skin disorders management. Erythromycin has been proven to retain anti-bacterial activity. Based on that, the aim of existent study is to develop a proper nanocarrier, namely; nanoemulsion using tea tree oil including Erythromycin. Applying quality by design approach, the optimized nanoemulsion was selected based on number of independent variables namely; particle size and in vitro release study. Yet, in order to get appropriate topical application, the optimized nanoemulsion was combined with previously prepared hydrogel base to provide Erythromycin based nanoemulgel. The developed nanoemulgel was assessed for its organoleptic and physical characters to ensure its suitability for topical application. Stability study was implemented over three months after being kept in two distinct environments. Eventually, the antibacterial behavior of the preparation was investigated on MRSA to verify the expected antibacterial improvement and validate the effectiveness of the developed nanocarrier. The formulation showed consistent appearance, with pH (6.11 ± 0.19), viscosity (10400 ± 1275 cP), spreadability (54.03 ± 2.3 mm), extrudability (80.36 ± 3.15 g/cm2) and drug content (99.3 ± 0.46 %) that seemed to be satisfied for topical application. It could provide 48.1 ± 4.2 % releases over 6 h in addition to be stable at room temperature and at refrigerator. Ultimately, the formula showed a significant antibacterial activity against MRSA proving the combination and the nanocarrier effectiveness.

Nanotechnology-driven strategies to enhance the treatment of drug-resistant bacterial infections

The misuse of antibiotics has led to increased bacterial resistance, posing a global public health crisis and seriously endangering lives. Currently, antibiotic therapy remains the most common approach for treating bacterial infections, but its effectiveness against multidrug-resistant bacteria is diminishing due to the slow development of new antibiotics and the increase of bacterial drug resistance. Consequently, developing new a\ntimicrobial strategies and improving antibiotic efficacy to combat bacterial infection has become an urgent priority. The emergence of nanotechnology has revolutionized the traditional antibiotic treatment, presenting new opportunities for refractory bacterial infection. Here we comprehensively review the research progress in nanotechnology-based antimicrobial drug delivery and highlight diverse platforms designed to target different bacterial resistance mechanisms. We also outline the use of nanotechnology in combining antibiotic therapy with other therapeutic modalities to enhance the therapeutic effectiveness of drug-resistant bacterial infections. These innovative therapeutic strategies have the potential to enhance bacterial susceptibility and overcome bacterial resistance. Finally, the challenges and prospects for the application of nanomaterial-based antimicrobial strategies in combating bacterial resistance are discussed. This article is categorized under: Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Characterization and Determination of the Antibacterial Activity of Baccharis dracunculifolia Essential-Oil Nanoemulsions

The aim of this study was to evaluate the antibacterial activity of nanoemulsions of Baccharis dracunculifolia essential oil. The volatile compounds of the essential oil were identified using gas chromatography-mass spectrometry. The properties of the nanoemulsions (droplet size, polydispersity index, pH, and electrical conductivity) were determined. The antibacterial activities of the essential oil and its nanoemulsions were evaluated using MIC, MBC, and disk diffusion. The microorganisms used were: Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 14579, Streptococcus mutans ATCC 25175, and Enterococcus faecalis ATCC 29212) and Gram-negative bacteria (Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC BAA-1706, Salmonella enterica ATCC 14028, and Escherichia coli ATCC 25922). The major volatile compounds of the B. dracunculifolia essential oil were limonene (19.36%), (E)-nerolidol (12.75%), bicyclogermacrene (10.76%), and β-pinene (9.60%). The nanoemulsions had a mean droplet size between 13.14 and 56.84 nm. The nanoemulsions presented lower and statistically significant MIC values compared to the essential oil, indicating enhancement of the bacteriostatic action. The disk diffusion method showed that both the nanoemulsions and the essential oil presented inhibition zones only for Gram-positive bacteria, while there were no results against Gram-negative bacteria, indicating that B. dracunculifolia essential oil has a better antimicrobial effect on Gram-positive microorganisms.

Natural Antimicrobial Mixtures Disrupt Attachment and Survival of E. coli and C. jejuni to Non-Organic and Organic Surfaces

The contact and adherence of bacteria to various surfaces has significant consequences on biofilm formation through changes in bacterial surface structures or gene expression with potential ramifications on plant and animal health. Therefore, this study aimed to investigate the effect of organic acid-based mixtures (Ac) on the ability Campylobacter jejuni and Escherichia coli to attach and form biofilm on various surfaces, including plastic, chicken carcass skins, straw bedding, and eggshells. Moreover, we aimed to explore the effect of Ac on the expression of E. coli (luxS, fimC, csgD) and C. jejuni (luxS, flaA, flaB) bacterial genes involved in the attachment and biofilm formation via changes in bacterial surface polysaccharidic structures. Our results show that Ac had a significant effect on the expression of these genes in bacteria either attached to these surfaces or in planktonic cells. Moreover, the significant decrease in bacterial adhesion was coupled with structural changes in bacterial surface polysaccharide profiles, impacting their adhesion and biofilm-forming ability. Essentially, our findings accentuate the potential of natural antimicrobials, such as Ac, in reducing bacterial attachment and biofilm formation across various environments, suggesting promising potential applications in sectors like poultry production and healthcare.

The synergy of tea tree oil nano-emulsion and antibiotics against multidrug-resistant bacteria

AIMS

We determined the synergistic effects of tea tree essential oil nano-emulsion (nanoTTO) and antibiotics against multidrug-resistant (MDR) bacteria in vitro and in vivo. Then, the underlying mechanism of action of nanoTTO was investigated.

METHODS AND RESULTS

Minimum inhibitory concentrations and fractional inhibitory concentration index (FICI) were determined. The transepithelial electrical resistance (TEER) and the expression of tight junction (TJ) protein of IPEC-J2 cells were measured to determine the in vitro efficacy of nanoTTO in combination with antibiotics. A mouse intestinal infection model evaluated the in vivo synergistic efficacy. Proteome, adhesion assays, quantitative real-time PCR, and scanning electron microscopy were used to explore the underlying mechanisms. Results showed that nanoTTO was synergistic (FICI ≤ 0.5) or partial synergistic (0.5 < FICI < 1) with antibiotics against MDR Gram-positive and Gram-negative bacteria strains. Moreover, combinations increased the TEER values and the TJ protein expression of IPEC-J2 cells infected with MDR Escherichia coli. The in vivo study showed that the combination of nanoTTO and amoxicillin improved the relative weight gain and maintained the structural integrity of intestinal barriers. Proteome showed that type 1 fimbriae d-mannose specific adhesin of E. coli was downregulated by nanoTTO. Then, nanoTTO reduced bacterial adhesion and invasion and inhibited the mRNA expression of fimC, fimG, and fliC, and disrupted bacterial membranes.