Antimicrobial activities of graphene oxide against biofilm and intracellular Staphylococcus aureus isolated from bovine mastitis

Effects of Graphene Derivatives and Near-Infrared Laser Irradiation on E. coli Biofilms and Stress Response Gene Expression

Photothermal therapy combines the effects of near-infrared laser (NIR laser) and strong light-absorbing materials to combat pathogens and unwanted biofilms. Graphene derivatives have a negative effect on microorganisms, and the combination of NIR laser irradiation and carbon nanomaterials (CNMs) can enhance their antibacterial effect. This investigation is devoted to the determination of the expression level of bacterial stress response genes (soxS and rpoS) under graphene oxide (GO), reduced graphene oxide (rGO), and NIR laser irradiation (1270 nm). GO, rGO and NIR laser irradiation separately and irradiation in the presence of graphene derivatives cause an increase in the expression level of rpoS associated with the general stress response of bacteria. GO and rGO do not change the expression level of soxS associated with the cell response to oxidative stress, and decrease it in the presence of a strong oxidizing agent paraquat (PQ). The expression of soxS increases under laser irradiation, but decreases under NIR laser irradiation in combination with graphene derivatives. The effect of GO, rGO, and NIR laser irradiation on the formation and eradication of E. coli biofilms was studied. NIR laser with GO and rGO suppresses the metabolic rate and decreases the intracellular ATP content by 94 and 99.6%, respectively. CNMs are shown to reduce biofilm biomass and the content of extracellular polymeric substances (EPSs), both exopolysaccharides and protein in the biofilm matrix. Graphene derivatives in combination with NIR laser irradiation may be an effective means of combating emerging and mature biofilms of Gram-negative bacteria.

A Review on Bioengineering the Bovine Mammary Gland: The Role of the Extracellular Matrix and Reconstruction Prospects

The mammary gland is a modified sweat gland responsible for milk production. It is affected by diseases that reduce animals' quality of life, consequently leading to economic losses in livestock. With advancements in tissue bioengineering and regenerative medicine, studying the extracellular matrix (ECM) of the bovine mammary gland can improve our understanding of its physiology and the processes that affect it. This knowledge could also enable the development of sustainable therapeutic alternatives for both the dairy production chain and human oncology research. A common approach in regenerative medicine is decellularization, a process that removes all cells from tissue while preserving its architecture and ECM components for subsequent recellularization. The success of recellularization depends on obtaining immunologically compatible scaffolds and using appropriate cell culture sources and methods to ensure tissue functionality. However, tissue culture technology still faces challenges due to specific requirements and high costs. Here, we review the literature on biomaterials and tissue engineering, providing an overview of the ECM of the bovine mammary gland and advances in its bioengineering, with a focus on regenerative medicine for bovine species. The methodology employed consists of a structured search of scientific databases, including PubMed, Google Scholar, and SciELO, using specific keywords related to tissue engineering and the bovine mammary gland. The selection criteria prioritized peer-reviewed articles published between 2002 and 2025 that demonstrated scientific relevance and contributed to the understanding of bovine mammary gland bioengineering. Although research on this topic has advanced, vascularization, tissue maturation, and scalability remain key barriers to widespread application and economic viability.

Green Nanotechnology: Naturally Sourced Nanoparticles as Antibiofilm and Antivirulence Agents Against Infectious Diseases

The escalating threat of infectious diseases, exacerbated by antimicrobial resistance (AMR) and biofilm formation, necessitates innovative therapeutic strategies. This review presents a comprehensive exploration of the potential of nanoparticles synthesized from natural sources, including plant extracts, microbial products, and marine compounds, as antimicrobial agents. These naturally derived nanoparticles demonstrated significant antibiofilm and antivirulence effects, with specific examples revealing their capacity to reduce biofilm mass by up to 78% and inhibit bacterial quorum sensing by 65%. The integration of bioactive compounds, such as polyphenols and chitosan, facilitates nanoparticle stability and enhances antimicrobial efficacy, while green synthesis protocols reduce environmental risks. Notably, the review identifies the potential of silver nanoparticles synthesized using green tea extracts, achieving 85% inhibition of polymicrobial growth in vitro. Despite these promising results, challenges such as standardization of synthesis protocols and scalability persist. This study underscores the transformative potential of leveraging naturally sourced nanoparticles as sustainable alternatives to conventional antimicrobials, offering quantitative insights for their future application in combating mono- and polymicrobial infections.

Role of lactoferrin in the treatment of E. coli-induced bovine mastitis

Background

Bovine mastitis (BM) is a costly disease in the dairy industry. It is associated with reduced milk production and changes in milk composition and quality. Escherichia coli is the most important pathogen causing BM.

Aim

This study aimed to assess the efficacy of lactoferrin (LF) as an enhanced agent when combined with marbofloxacin for the treatment of E. coli BM.

Methods

Eighty lactating cattle and buffaloes, 40 each, aged 4-6 years suffering from BM underwent clinical examination. Milk samples were collected for bacteriological examination. The recovered E. coli isolates were subjected to serological, and polymerase chain reaction (PCR) analysis. BM cases were allocated into two groups: group (A) was treated with marbofloxacin combined with LF, and group (B) was treated with marbofloxacin alone.

Results

Fifty E. coli isolates were recovered. Six serogroup were identified: O55, O103, O26, O11, O44, and O124. All isolates were sensitive to marbofloxacin, while there was resistance to gentamycin and ampicillin (26% each), cefquinome (14%), cefixime (10%), and SuLFamethoxazole and trimethoprim (4%). The molecular identification of E. coli strains revealed that the 16S rRNA gene was present in all identified E. coli strains (100%). All isolates resistant to antibiotics encoded BlaTEM, aadB, and Sul1, whereas the qnrS gene was not detected in any E. coli isolate. The broth dilution method did not detect growth when the marbofloxacin (6 μg/ml) was combined with LF (2 mg/ml). Group (A) showed significant improvements compared with group (B), with no recurrence rate.

Conclusion

LF can serve as a significant cotreatment agent for treating BM. As antibiotic resistance increases, LF-based drugs could play an important role in providing sustainable, effective alternatives for dairy animals.

Structural, Morphological, and Antibacterial Attributes of Graphene Oxide Prepared by Hummers' and Brodie's Methods

Graphite oxidation to graphene oxide (GO) is carried out using methods developed by Brodie (GO-B) and Hummers (GO-H). However, a comparison of the antibacterial properties based on the physicochemical properties has not been performed. Therefore, this paper outlines a comparative analysis of GO-H and GO-B on antibacterial efficacy against Gram-positive and Gram-negative bacterial cultures and biofilms in an aqueous environment and discusses which of the properties of these GO nanomaterials have the most significant impact on the antibacterial activity of these materials. Synthesis of GO with Brodie's and modified Hummers' methods was followed by an evaluation of their structural, morphological, and physicochemical properties by Raman, FTIR, UV-vis spectroscopy, and X-ray diffraction (XRD). The GO-B surface appeared more oxidized than that of GO-H, which could be crucial for interactions with bacteria. According to our results, GO-B demonstrated notably superior anti-biofilm efficacy. Despite its higher production cost, GO-B exhibits more excellent capabilities in combating bacterial biofilms than GO-H.

Recent progress in antibiofilm strategies in the dairy industry

Biofilm formation allows microorganisms including bacteria to persist on abiotic or biotic surfaces, to resist treatments with biocides (disinfectants and antibiotics) and to evade the immune response in animal hosts much more than they do in the planktonic form. Bacteria able to form biofilm can be troublesome in the dairy industry, both by causing clinical symptoms in livestock and by colonizing milking devices and milk processing equipment, resulting in dairy products of lower quality and sometimes raising serious food safety issues. In fact, most of the bacterial species isolated frequently in the dairy chain have the ability to form biofilm. Common examples include Staphylococcus aureus and other staphylococci that frequently infect mammary glands, but also Bacillus spp., Listeria monocytogenes and Pseudomonas spp. which cause spoilage of dairy products and sometimes foodborne illnesses. The economic losses due to biofilm formation in the dairy industry are considerable, and scientists are constantly solicited to develop new antibiofilm strategies, especially using biocides of natural origin. Although the number of studies in this subject area has exploded in recent years, the in vivo efficacy of most novel approaches remains to be explored. Used alone or to increase the efficacy of disinfectants or antibiotics, they could allow the implementation of strategies having less impact on the environment. Their use is expected to lead to less reliance on antibiotics to treat intramammary infections in dairy farms and to the use of lower concentrations of chemical disinfectants in dairy processing plants.

Confronting the complexities of antimicrobial management for Staphyloccous aureus causing bovine mastitis: an innovative paradigm

Globally, Mastitis is a disease commonly affecting dairy cattle which leads to the use of antimicrobials. The majority of mastitis etiological agents are bacterial pathogens and Staphylococcus aureus is the predominant causative agent. Antimicrobial treatment is administered mainly via intramammary and intramuscular routes. Due to increasing antimicrobial resistance (AMR) often associated with antimicrobial misuse, the treatment of mastitis is becoming challenging with less alternative treatment options. Besides, biofilms formation and ability of mastitis-causing bacteria to enter and adhere within the cells of the mammary epithelium complicate the treatment of bovine mastitis. In this review article, we address the challenges in treating mastitis through conventional antibiotic treatment because of the rising AMR, biofilms formation, and the intracellular survival of bacteria. This review article describes different alternative treatments including phytochemical compounds, antimicrobial peptides (AMPs), phage therapy, and Graphene Nanomaterial-Based Therapy that can potentially be further developed to complement existing antimicrobial therapy and overcome the growing threat of AMR in etiologies of mastitis.

SMR peptide antagonizes Staphylococcus aureus biofilm formation

The emergence and international dissemination of multi-drug resistant Staphylococcus aureus (S. aureus) strains challenge current antibiotic-based therapies, representing an urgent threat to public health worldwide. In the U.S. alone, S. aureus infections are responsible for 11,000 deaths and 500,000 hospitalizations annually. Biofilm formation is a major contributor to antibiotic tolerance and resistance-induced delays in empirical therapy with increased infection severity, frequency, treatment failure, and mortality. Developing novel treatment strategies to prevent and disrupt biofilm formation is imperative. In this article, we test the Secretion Modification Region (SMR) peptides for inhibitory effects on resistant S. aureus biofilm-forming capacity by targeting the molecular chaperone DnaK. The dose effect of SMR peptides on biofilm formation was assessed using microtiter plate methods and confocal microscopy. Interaction between the antagonist and DnaK was determined by immune precipitation with anti-Flag M2 Affinity and Western blot analysis. Increasing SMR peptide concentrations exhibited increasing blockade of S. aureus biofilm formation with significant inhibition found at 18 µM, 36 µM, and 72 µM. This work supports the potential therapeutic benefit of SMR peptides in reducing biofilm viability and could improve the susceptibility to antimicrobial agents.IMPORTANCEThe development of anti-biofilm agents is critical to restoring bacterial sensitivity, directly combating the evolution of resistance, and overall reducing the clinical burden related to pervasive biofilm-mediated infections. Thus, in this study, the SMR peptide, a novel small molecule derived from the HIV Nef protein, was preliminarily explored for anti-biofilm properties. The SMR peptide was shown to effectively target the molecular chaperone DnaK and inhibit biofilm formation in a dose-dependent manner. These results support further investigation into the mechanism of SMR peptide-mediated biofilm formation and inhibition to benefit rational drug design and the identification of therapeutic targets.

Intramammary preparation of enrofloxacin hydrochloride-dihydrate for bovine mastitis (biofilm-forming Staphylococcus aureus)

BACKGROUND

Chronic bovine mastitis is linked to biofilm-producing Staphylococcus aureus (bp-Sa) or Staphylococcus coagulase-negative (bp-Scn).

OBJECTIVES

Bp-Sa and bp-Scn were treated with intramammary preparations of either enrofloxacin HCl·2H2O-dimethyl-sulfoxide-chitosan (enro-C/DMSO/chitosan) or enro-C alone. Their potential to inhibit and degrade biofilm formation in vitro was also assessed.

METHODS

Milk samples were obtained from the affected quarters in a herd. Phenotypical and genotypical identifications as biofilm-producing Staphylococcus species were carried out. Enro-C/DMSO/chitosan and enro-C alone were assessed to determine their in vitro efficacy in interfering with biofilm formation and their bactericidal effects. A prolonged eight-day treatment with a twice-daily intramammary insertion of 10 mL of enro-C/DMSO/chitosan or enro-C alone was set to evaluate the clinical and bacteriological cures on day 10 in 15 cows per group and the biofilm-inhibiting ability.

RESULTS

Fifty-seven percent of the isolates were identified as Staphylococcus spp., of which 50% were bp-Sa, 46% bp-Scn, and 4% Staphylococcus pseudintermedius. One hundred percent of the S. aureus isolated and 77% of Staphylococcus coagulase-negative were biofilm producers. In both groups, the icaA and icaD biofilm-producing genes were identified. The experimental preparation could inhibit biofilm formation, degrade mature biofilms, and have well-defined microbicidal effects on planktonic and biofilm bacteria. The respective clinical and bacteriological cure rates were 100% and 80% for enro-C/DMSO/chitosan and 41.7% and 25% for enro-C alone.

CONCLUSIONS

Enro-C/DMSO/chitosan eliminates bp-Sa and bp-Scn from cases of chronic bovine mastitis.

Bovine mastitis, a worldwide impact disease: Prevalence, antimicrobial resistance, and viable alternative approaches

Bovine mastitis is globally considered one of the most important diseases within dairy herds, mainly due to the associated economic losses. The most prevalent etiology are bacteria, classified into contagious and environmental, with Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, Escherichia coli and Klebsiella pneumoniae being the most common pathogens associated with mastitis cases. To date these pathogens are resistant to the most common active ingredients used for mastitis treatment. According to recent studies resistance to new antimicrobials has increased, which is why developing of alternative treatments is imperative. Therefore the present review aims to summarize the reports about bovine mastitis along 10 years, emphasizing bacterial etiology, its epidemiology, and the current situation of antimicrobial resistance, as well as the development of alternative treatments for this pathology. Analyzed data showed that the prevalence of major pathogens associated with bovine mastitis varied according to geographical region. Moreover, these pathogens are classified as multidrug-resistant, since the effectiveness of antimicrobials on them has decreased. To date, several studies have focused on the research of alternative treatments, among them vegetal extracts, essential oils, or peptides. Some other works have reported the application of nanotechnology and polymers against bacteria associated with bovine mastitis. Results demonstrated that these alternatives may be effective on bacteria associated with bovine mastitis.

Bactericidal Activity of Graphene Oxide Tests for Selected Microorganisms

The aim of this study was to determine the bactericidal potential of graphene oxide (GO) in contact with four species of bacteria: E. coli, S. mutans, S. aureus and E. faecalis. Bacterial cell suspensions of each species were incubated in a medium containing GO, with incubation times of 5, 10, 30 and 60 min, at final concentrations of 50, 100, 200, 300 and 500 μg/mL. The cytotoxicity of GO was evaluated using live/dead staining. The results were recorded using a BD Accuri C6 flow cytofluorimeter. Obtained data were analyzed using BD CSampler software. A significant bacteria viability reduction was noted in all GO-containing samples. The antibacterial properties of GO were strongly influenced by GO concentration and incubation time. The highest bactericidal activity was observed at concentrations of 300 and 500 μg/mL for all incubation times (5, 10, 30 and 60 min). The highest antimicrobial potential was observed for E. coli: after 60 min, the mortality rate was 94% at 300 µg/mL GO and 96% at 500 µg/mL GO; the lowest was found for S. aureus-49% (300 µg/mL) and 55% (500 µg/mL).