Brazilian red propolis in combination with ß-lactams exerts an efficient antibacterial action over methicillin-resistant Staphylococcus aureus (MRSA) strains.

AIMS: The antibacterial activity of red propolis extract (RPE) and brown propolis extracts (BPE) and the synergistic effect of RPE with cefoxitin (CEFO), imipenem (IMI), and ertapenem (ERTA) was evaluated in vitro against methicillin-resistant Staphylococcus aureus (MRSA) strains. METHODS AND RESULTS: MRSA ATCC 33591, community-associated (CA-MRSA) USA300, and four clinical isolates were used. A broth microdilution assay was performed to obtain inhibitory and bactericidal concentrations of BPE, RPE, CEFO, IMI, and ERTA. RPE in combination with CEFO, IMI, and ERTA was evaluated on the formation or eradication of biofilm. The bacterial relative membrane conductivity of the strains was assessed after RPE and combinations exposition. Surface/binding computational analyzes between RPE compounds and penicillin binding protein 2a (PBP2a) were performed. BPE samples had no activity against MRSA (MICs 3.2-5 g l-1; MBCs 10-15 g l-1), so the subsequent assays were carried out only with RPE and antimicrobials. RPE exerted a bacteriostatic action (MICs 0.0156-0.125 g l-1; MBCs 0.5-2 g l-1) but the combinations with IMI and ERTA showed the highest inhibition, as observed in the time-kill curve. However, the FICI index showed synergism (≥0.5) only to RPE + IMI. This combination was the most effective in inhibiting the biofilm and showed the highest values of membrane conductivity. Computational predictions indicated that RPE constituents may interact with PBP2a. CONCLUSION: RPE and RPE + IMI exerted an antibacterial and antibiofilm activity on MRSA strains probably due to membrane/wall damage and interactions with PBP2a.

Antibacterial and anti-biofilm activities of cinnamaldehyde against S. epidermidis.

The search for new antimicrobial drugs has been necessary due to the increased bacterial resistance to antibiotics currently in use, and natural products play an important role in this field. The aim of this study was to evaluate the in vitro effect of cinnamaldehyde on S. epidermidis strains, biofilm set-up prevention, as well as its effect on pre-established biofilms. The minimum inhibitory concentration (MIC) ranged from 300 to 500 µg/mL, and the minimum bactericidal concentration (MBC) from 400 to 600 µg/mL. The biofilm inhibitory concentration and biofilm eradication concentration values were four-fold (clinical isolate) and eight-fold (ATCC strain) greater than the concentration required to inhibit planktonic growth. Sub-inhibitory concentrations of cinnamaldehyde attenuated biofilm formation of S. epidermidis strains on polystyrene microtiter plates. The combination of cinnamaldehyde and linezolid was able to inhibit S. epidermidis with a bactericidal effect. Further investigation of the mechanism of action of cinnamaldehyde revealed its effect on the cell membrane permeability, and confocal laser scanning microscopy (CLSM) images illustrated the impact of cinnamaldehyde in the detachment and killing of existing biofilms. Thereby, our data confirmed the ability of cinnamaldehyde to reduce bacterial planktonic growth of S. epidermidis, inhibiting biofilm formation and eradicating pre-formed biofilm.

Clinical complications in envenoming by Apis honeybee stings: insights into mechanisms, diagnosis, and pharmacological interventions.

Envenoming resulting from Apis honeybee stings pose a neglected public health concern, with clinical complications ranging from mild local reactions to severe systemic manifestations. This review explores the mechanisms underlying envenoming by honeybee sting, discusses diagnostic approaches, and reviews current pharmacological interventions. This section explores the diverse clinical presentations of honeybee envenoming, including allergic and non-allergic reactions, emphasizing the need for accurate diagnosis to guide appropriate medical management. Mechanistic insights into the honeybee venom's impact on physiological systems, including the immune and cardiovascular systems, are provided to enhance understanding of the complexities of honeybee sting envenoming. Additionally, the article evaluates emerging diagnostic technologies and therapeutic strategies, providing a critical analysis of their potential contributions to improved patient outcomes. This article aims to provide current knowledge for healthcare professionals to effectively manage honeybee sting envenoming, thereby improving patient care and treatment outcomes.

Unveiling the Pain Relief Potential: Harnessing Analgesic Peptides from Animal Venoms.

The concept of pain encompasses a complex interplay of sensory and emotional experiences associated with actual or potential tissue damage. Accurately describing and localizing pain, whether acute or chronic, mild or severe, poses a challenge due to its diverse manifestations. Understanding the underlying origins and mechanisms of these pain variations is crucial for effective management and pharmacological interventions. Derived from a wide spectrum of species, including snakes, arthropods, mollusks, and vertebrates, animal venoms have emerged as abundant repositories of potential biomolecules exhibiting analgesic properties across a broad spectrum of pain models. This review focuses on highlighting the most promising venom-derived toxins investigated as potential prototypes for analgesic drugs. The discussion further encompasses research prospects, challenges in advancing analgesics, and the practical application of venom-derived toxins. As the field continues its evolution, tapping into the latent potential of these natural bioactive compounds holds the key to pioneering approaches in pain management and treatment. Therefore, animal toxins present countless possibilities for treating pain caused by different diseases. The development of new analgesic drugs from toxins is one of the directions that therapy must follow, and it seems to be moving forward by recommending the composition of multimodal therapy to combat pain.

Potential in vitro action of an adenosine analog and synergism with penicillin against Corynebacterium pseudotuberculosis.

Caseous lymphadenitis is a well-known disease caused by Corynebacterium pseudotuberculosis affecting small ruminants with small significance to human health because of its minor zoonotic potential. In both cases, few treatment options are available and conventional antimicrobial therapy is commonly refractory due to development of pyogranulomatous reactions, bringing great interest in discovering novel therapeutics for more suitable approaches. Dideoxynucleotides presented antibacterial action against various bacteria but were never described for C. pseudotuberculosis. Hypothesizing the antimicrobial action of 2',3'-dideoxiadenosine (ddATP) against C. pseudotuberculosis, we performed for the first time an investigation of its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in the ATCC® 19,410 strain and a well-characterized clinical isolate of C. pseudotuberculosis. We also assessed potential synergism with penicillin. ddATP showed a growth delay effect for C. pseudotuberculosis at 2 µmol/mL and a MIC and MBC of 4 µmol/mL against the ATCC® 19,410 strain, but not for the clinical strain. An antimicrobial effect was observed when using concentrations lower than the MIC of ddATP associated with penicillin for both strains tested. Our data suggest the potential of nucleotide analogs, especially adenosine, and its combination with penicillin, as a possible novel treatment for C. pseudotuberculosis-induced infections, and contributes with knowledge regarding alternative drugs to treat C. pseudotuberculosis infections.

Synergistic Antibacterial Efficacy of Melittin in Combination with Oxacillin against Methicillin-Resistant Staphylococcus aureus (MRSA).

Methicillin-resistant Staphylococcus aureus (MRSA) often cause infections with high mortality rates. Antimicrobial peptides are a source of molecules for developing antimicrobials; one such peptide is melittin, a fraction from the venom of the Apis mellifera bee. This study aimed to evaluate the antibacterial and antibiofilm activities of melittin and its association with oxacillin (mel+oxa) against MRSA isolates, and to investigate the mechanisms of action of the treatments on MRSA. Minimum inhibitory concentrations (MICs) were determined, and synergistic effects of melittin with oxacillin and cephalothin were assessed. Antibiofilm and cytotoxic activities, as well as their impact on the cell membrane, were evaluated for melittin, oxacillin, and mel+oxa. Proteomics evaluated the effects of the treatments on MRSA. Melittin mean MICs for MRSA was 4.7 µg/mL and 12 µg/mL for oxacillin. Mel+oxa exhibited synergistic effects, reducing biofilm formation, and causing leakage of proteins, nucleic acids, potassium, and phosphate ions, indicating action on cell membrane. Melittin and mel+oxa, at MIC values, did not induce hemolysis and apoptosis in HaCaT cells. The treatments resulted in differential expression of proteins associated with protein synthesis and energy metabolism. Mel+oxa demonstrated antibacterial activity against MRSA, suggesting a potential as a candidate for the development of new antibacterial agents against MRSA.

Inhibitory activities of propolis, nisin, melittin and essential oil compounds on Paenibacillus alvei and Bacillus subtilis.

Background: Natural products represent important sources of antimicrobial compounds. Propolis and compounds from essential oils comprise good examples of such substances because of their inhibitory effects on bacterial spores, including bee pathogens. Methods: Ethanol extracts of propolis (EEP) from Apis mellifera were prepared using different methods: double ultrasonication, double maceration and maceration associated with ultrasonication. Together with the antimicrobial peptides nisin and melittin, and compounds present in the essential oils of clove (Syzygium aromaticum) and cinnamon (Cinnamomum zeylanicum), assays were carried out on one Bacillus subtilis isolate and Paenibacillus alvei (ATCC 6344) against vegetative and sporulated forms, using the resazurin microtiter assay. Synergism with all the antimicrobials in association with tetracycline was verified by the time-kill curve method. Potassium and phosphate efflux, release of proteins and nucleic acids were investigated. Results: EEPs showed the same MIC, 156.25 µg/mL against B. subtilis and 78.12 µg/mL against P. alvei. The peptides showed better activities against B. subtilis (MIC of 12 µg/mL for melittin and 37.50 µg/mL for nisin). Antimicrobials showed similar inhibitory effects, but cinnamaldehyde (39.06 µg/mL) showed the best action against P. alvei. Melittin and nisin showed the greatest capacity to reduce spores, regarding B. subtilis there was a 100% reduction at 6.25 and 0.78 µg/mL, respectively. Concerning P. alvei, the reduction was 93 and 98% at concentrations of 80 µg/mL of melittin and 15 µg/mL of nisin. EEPs showed the highest effects on the protein release against B. subtilis and P. alvei. Nucleic acid release, phosphate and potassium efflux assays indicated bacterial cell membrane damage. Synergism between antimicrobials and tetracycline was demonstrated against both bacteria. Conclusion: All antimicrobials tested showed antibacterial activities against vegetative and sporulated forms of P. alvei and B. subtilis, especially nisin and melittin. Synergism with tetracycline and damage on bacterial cell membrane also occurred.

Comparative Proteomics of Methicillin-Resistant Staphylococcus aureus Subjected to Synergistic Effects of the Lantibiotic Nisin and Oxacillin.

We investigated the responses and mechanisms of action of methicillin-resistant Staphylococcus aureus (MRSA) metabolism when exposed under sublethal concentrations of the synergistic antibacterial combination of nisin + oxacillin (» of maximum sublethal concentration) and sublethal concentrations of oxacillin only and nisin only. A total of 135 proteins were identified, showing an alteration in the expression of 85 proteins when treatment was compared with untreated bacteria (control). When the bacteria were treated using the combination, there was an increase in the expression of proteins related to resistance (e.g., beta-lactamase) and also in the ones involved in protein synthesis, and there was a decrease in the expression of proteins related to stress and alterations in proteins related to bacterial energy metabolism. Bacterial oxidative stress showed that the combination was able to induce oxidative stress (p < 0.05) and increase enzyme activities and lipid hydroperoxide levels compared with individual treatments. The analysis of cell ultrastructure showed damage in MRSA, especially on the bacterial wall and the plasma membrane, with cell lysis and death. Thus, the changes caused by these treatments affected different proteins related to the bacterial biological processes and signaling pathways such as cell division, structure, stress, regulation, bacterial resistance, protein synthesis, gene expression, energetic metabolism, and virulence. It was observed that synergism among antimicrobials has high potential in therapeutic use and may reduce the required amounts of antibacterial substances in addition to being effective on different targets in bacterial cells.