Fig 2 - available via license: CC BY-NC-ND
Content may be subject to copyright.
The expression of hld gene in bacterial treated with 1/2MIC of melittin a: significant downregulation; b: non-significant downregulation
Source publication
Methicillin-Resistant Staphylococcus aureus (MRSA) biofilms are involved in various nosocomial infections, being in the limelight of academic research. The current study aimed to determine the antimicrobial effects of melittin on planktonic and biofilm forms of S. aureus. Following the identification of MRSA and SCCmec types (using PCR method), Min...
Contexts in source publication
Context 1
... effect of MIC/2 dose of melittin on the expression levels of the quorum-sensing gene and 16S rRNA gene were evaluated for 8 isolates of S. aureus and reference strain (S. aureus ATCC33591) and the result is shown in chart 1. As shown in Figure 2, the expression level of quorum sensing genes of clinical isolates of S. aureus significantly reduced after exposure to MIC/2 dose of melittin compared with untreated S. aureus isolates (P < 0.05, Fig. 2). ...
Context 2
... gene were evaluated for 8 isolates of S. aureus and reference strain (S. aureus ATCC33591) and the result is shown in chart 1. As shown in Figure 2, the expression level of quorum sensing genes of clinical isolates of S. aureus significantly reduced after exposure to MIC/2 dose of melittin compared with untreated S. aureus isolates (P < 0.05, Fig. ...
Citations
... Sterile TSB was used as a negative control. This experiment was repeated twice, and the values of optical densities (OD) were averaged [16]. ...
... The results showed melittin had antibacterial activities against these tested strains, particularly, melittin showed high activity against S. aureus and A. baumannii (Table 1). It is worth noting that melittin has antibacterial activity against Gram-positive and Gram-negative bacteria, which again proves that melittin has a broad spectrum of antibacterial effects as previously reported [33,34]. E. coli, S. aureus, P. aeruginosa, and A. baumannii are particularly important in human and veterinary medicine due to their pathogenicity, virulence, distribution, diversity of clinical signs, and problems related to public health. ...
... The antibacterial activity of melittin was determined by measuring their MIC using the broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines [41,42]. For MIC, a broth dilution susceptibility test was performed using Mueller-Hinton broth (MHB) [33,43,44]. Fresh bacterial colonies were incubated in MHB at 37 • C and 200 rpm overnight, a bacterial suspension with optical density (OD 600 ) between 0.9 and 1 is equal to 10 9 colony forming units (CFU)/mL, and the bacterial suspension was diluted with MHB broth to 10 6 CFU/mL. ...
The development of antibiotic-resistant microorganisms is a major global health concern. Recently, there has been an increasing interest in antimicrobial peptides as a therapeutic option. This study aimed to evaluate the triple-action (broad-spectrum antibacterial, anti-biofilm, and anti-quorum sensing activities) of melittin, a membrane-active peptide present in bee venom. The minimum inhibitory concentration and minimum bactericidal concentration of the melittin were determined using the microdilution method and agar plate counting. Growth curve analysis revealed that melittin showed a concentration-dependent antibacterial activity. Scanning electron microscope analysis revealed that melittin treatment altered the morphology. Confocal laser scanning microscope revealed that melittin increased the membrane permeability and intracellular ROS generation in bacteria, all of which contribute to bacterial cell death. In addition, the crystal violet (CV) assay was used to test the anti-biofilm activity. The CV assay demonstrated that melittin inhibited biofilm formation and eradicated mature biofilms. Biofilm formation mediated by quorum sensing (QS) plays a major role in this regard, so molecular docking and molecular dynamics analysis confirmed that melittin interacts with LasR receptors through hydrogen bonds, and further evaluates the anti-QS activity of melittin through the production of virulence factors (pyocyanin, elastase, and rhamnolipid), exopolysaccharides secretion, and bacterial motility, that may be the key to inhibiting the biofilm formation mechanism. The present findings highlight the promising role of melittin as a broad-spectrum antibacterial, anti-biofilm agent, and potential QS inhibitor, providing a new perspective and theoretical basis for the development of alternative antibiotics.
... Mirzaei et al. (2023) found that melittin was effective in inhibiting the growth of MDR-methicillin resistant Staphylococcus aureus (MRSA), with MIC values ranging from 0.625-2.5 µg/ml. Another study by Hakimi Alni et al. (2020) reported that melittin had potent bactericidal activity against planktonic S. aureus, with MBC values ranging from 4 to 16 µg/ml. ...
... Some reports noted melittin for its synergistic effect on biofilm when used with antibiotics. Hakimi Alni et al. (2020) found that synergistic growth-inhibitory effects of mupirocin with melittin could be considered as a promising approach in the treatment of MRSA and VRSA isolates. Besides, the geometric mean values of FBECi for melittin-penicillin and melittin-oxacillin concentrations against S. aureus were 5 and 2.973, respectively. ...
The emergence of multi-drug resistant bacterial strains have posed a significant challenge in community due to their ability to form biofilm and develop resistance to common antibiotics. Accordingly, we aimed to investigate the antimicrobial and antibiofilm effects of melittin AMP, both alone and in combination with penicillin and oxacillin, against biofilm-forming multidrug-resistant (MDR)- MRSA and -VRSA. We investigated the kinetics of biofilm formation and assessed various parameters including: the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Fractional Inhibitory Concentration Index (FICi), and Fractional Bactericidal Concentration Index (FBCi), and the antibiofilm activity of melittin and antibiotics indicated by the Minimum Biofilm Inhibitory Concentration (MBIC), Minimal Biofilm Eradication Concentration (MBEC), Fractional Biofilm Inhibitory Concentration Index (FBICi), and Fractional Biofilm Eradication Concentration Index (FBECi). The geometric means of the MIC values for penicillin, oxacillin, and melittin were 19.02, 16, and 1.62 µg/ml, and for MBC values were 107.63, 49.35, and 5.45 µg/ml, respectively. The melittin-penicillin and melittin-oxacillin combination indexes based on FIC values were 0.37 and 0.03, and based on FBC values were 1.145 and 0.711, respectively. Melittin inhibited the biofilm formation with MBIC values ranging from 10 to 1.25 μg/mL, and MBEC values ranging from 40 to 10 μg/mL. Melittin-penicillin and melittin-oxacillin combination indexes based on FBIC values were 0.23 and 0.177, and based on FBEC values were 5 and 2.97, respectively. In conclusion, melittin has the potential to revive beta-lactam antibiotics against MRSA and VRSA and is an innovative approach against antibiotic-resistant bacteria.
... We have shown in previous studies that melittin has a synergistic effect with mupirocin in the treatment of methicillin-resistant S. aureus (MRSA) infections by various mechanisms, such as reducing the expression of quorum sensing genes (hld) and inhibiting biofilm formation. We also examined the cytotoxic effects of melittin on the Vero cell line, and our results showed non-toxicity of melittin at MIC and sub-MIC concentrations [14]. ...
... The synergistic activity of melittin with polymyxin B or β-lactam antibiotics against multidrug-resistant (MDR) bacteria has been shown previously [41]. In another study by Alni et al., melittin in combination with antibiotics was a good choice for anti-MRSA chemotherapy and anti-biofilm activities [14]. However, no study was done on the synergistic effect of melittin with photodynamic therapy, on MDR/XDR/ strong biofilm producers. ...
... However, no study was done on the synergistic effect of melittin with photodynamic therapy, on MDR/XDR/ strong biofilm producers. Overall, it can be argued that melittin, as a plant compound without toxic effects on eukaryotic cells [14], is a good candidate to be combined with other therapies. ...
Drug-resistant biofilm producer A. baumannii isolates are a global concern that warns researchers about the development of new treatments. This study was designed to analyze the effect of photodynamic therapy (PDT) as monotherapy and associated with melittin on multidrug-resistant A. baumannii isolates. Sub-lethal doses of photosensitizer, LED, and PDT were determined. The PDT effect on the biofilm and expression of biofilm-associated genes was evaluated by scanning electron microscopy and quantitative real-time PCR (qRT-PCR) methods, respectively. The synergistic effect of PDT and melittin on the survival of MDR/XDR strong biofilm producer isolates was evaluated by checkerboard assay. Survival rates were significantly decreased at the lowest concentration of 12.5–50 μg/ml in 4 min at an energy density of 93.75 J/cm² (P < 0.05). The optimized PDT method had a bactericidal effect against all tested groups, and the mean expression levels of csu, abaI, bap, and ompA genes in the strong biofilm producers were decreased significantly compared to the control group. The combined effect of LED and melittin successfully reduced the MDR/XDR A. baumannii strong biofilm producers' growth from 3.1 logs. MB-mediated aPDT and combined treatment of PDT with melittin, which has been investigated for the first time in this study, can be an efficient strategy against MDR/XDR A. baumannii isolates with strong biofilm production capacity.
... It is well known that bacterial virulence factors such as biofilm formation are under the control of the agr quorum sensing system (Hakimi Alni et al. 2020). In our study, agr-3 (32.7%, 34/104) was predominant in the Malaysian MSSA isolates. ...
Methicillin-susceptible Staphylococcus aureus (MSSA) is an important nosocomial pathogen worldwide. This study aims to investigate the in vitro biofilm-forming ability of clinical MSSA isolated from various sources in the main public tertiary referral hospital in Terengganu, Malaysia and to detect the presence of biofilm-associated and regulatory genes among these isolates. A total of 104 MSSA isolates [pus (n = 75), blood (n = 24), respiratory secretions (n = 2), eye (n = 2), and urine (n = 1)] were investigated for slime production and biofilm formation using Congo red agar and crystal violet microtitre plate, respectively. Fifteen MSSA isolates with varying degrees of biofilm formation were selected for validation via a real-time cell analyser. All isolates were screened for microbial surface components recognising adhesive matrix molecules (MSCRAMM) and accessory gene regulator (agr) using polymerase chain reaction assay. A total of 76.0% (79/104) isolates produced slime layer, while all isolates developed biofilm as follows: 52.8% (55/104) strong biofilm producers, 40.4% (42/104) intermediate biofilm producers, and 6.7% (7/104) weak biofilm producers. A total of 98.1% (102/104) isolates carried at least one of the screened MSCRAMM gene(s) with the eno gene detected at the highest rate (87.5%, 91/104), while the sasG gene was significantly associated with strong biofilm production (p = 0.015). Three agr groups, 1, 2, and 3, were detected among the MSSA isolates with a predominance of agr-3 (32.7%, 34/104). In conclusion, biofilm formation varied greatly among clinical MSSA isolates, and the presence of sasG gene and agr-1 may play important role in initiating MSSA infections via biofilm formation.
... Other interesting approaches are the design of specifically targeted AMPs (STAMPS), where a target region improves the binding of the AMPs to a specific pathogen feature; then a killing region promotes the kill of the microorganism [123] or the employment of AMPs combined with antibiotics, which promotes a synergism between the two molecules [124] Delivery systems can be implemented with the encapsulation of SAMPs in nanoparticles, micelles, and enzymatically controlled vehicles (reviewed by [121]; Figure 3). AMPs combined with antibiotics, which promotes a synergism between the two molecules [124] Delivery systems can be implemented with the encapsulation of SAMPs in nanoparticles, micelles, and enzymatically controlled vehicles (reviewed by [121]; Figure 3). ...
... Other interesting approaches are the design of specifically targeted AMPs (STAMPS), where a target region improves the binding of the AMPs to a specific pathogen feature; then a killing region promotes the kill of the microorganism [123] or the employment of AMPs combined with antibiotics, which promotes a synergism between the two molecules [124] Delivery systems can be implemented with the encapsulation of SAMPs in nanoparticles, micelles, and enzymatically controlled vehicles (reviewed by [121]; Figure 3). AMPs combined with antibiotics, which promotes a synergism between the two molecules [124] Delivery systems can be implemented with the encapsulation of SAMPs in nanoparticles, micelles, and enzymatically controlled vehicles (reviewed by [121]; Figure 3). ...
Zoonoses have recently become the center of attention of the general population and scientific community. Notably, more than 30 new human pathogens have been identified in the last 30 years, 75% of which can be classified as zoonosis. The complete eradication of such types of infections is far out of reach, considering the limited understanding of animal determinants in zoonoses and their causes of emergence. Therefore, efforts must be doubled in examining the spread, persistence, and pathogenicity of zoonosis and studying possible clinical interventions and antimicrobial drug development. The search for antimicrobial bioactive compounds has assumed great emphasis, considering the emergence of multi-drug-resistant microorganisms. Among the biomolecules of emerging scientific interest are antimicrobial peptides (AMPs), potent biomolecules that can potentially act as important weapons against infectious diseases. Moreover, synthetic AMPs are easily tailored (bioinformatically) to target specific features of the pathogens to hijack, inducing no or very low resistance. Although very promising, previous studies on SAMPs’ efficacy are still at their early stages. Indeed, further studies and better characterization on their mechanism of action with in vitro and in vivo assays are needed so as to proceed to their clinical application on human beings.
... The levels of expression of mexB, mexD, mexY, and mexE genes were quantified using qPCR in 40 CIP-US isolates and reference strain (P. aeruginosa PAO1) based on the previously reported method (Alni et al. 2020;Dumas et al. 2006;Fey et al. 2004;Gutiérrez et al. 2007) (Table 1). Total RNA extraction and cDNA synthesis were performed using RNA Isolation Kit (MoBio, USA) and cDNA Reverse Transcription Kit (SinaClon, Iran) respectively. ...
Background
Fluoroquinolones (FQs) including ciprofloxacin (CIP) are key antibiotics for the treatment of Pseudomonas aeruginosa infections, but resistance to FQs is developing as a result of chromosomal mutations or efflux pump effects. Plasmid-mediated quinolone resistance (PMQR) has been recently reported in the Enterobacteriaceae family. This study aimed to investigate the mechanisms of CIP insusceptibility in P. aeruginosa isolates from ICU patients and to characterize their genotypes.MethodsA total of 40 ciprofloxacin unsusceptible (CIP-US) P. aeruginosa isolates from Tehran hospitals were recruited in this study. A broth microdilution assay was performed to find acquired resistance profiles of the isolates. All isolates were screened for target-site mutations (gyrA and parC), PMQR genes, and efflux pumps (mexB, D, Y, and E) expression. Clonality was determined by random amplified polymorphic DNA (RAPD)-PCR, and genotyping was performed on 5 selected isolates by analyzing 7 loci in the existing multilocus sequence typing scheme.ResultsThirty-eight out of 40 CIP-US isolates (95%) were categorized as MDR. Seven (17.5%) had gyrA mutation in codons 83, and no mutation was detected in parC; 77.5% of the isolates were positive for PMQR genes. Among PMQR genes, qnrB (30%), qnrC (35%), and qnrD (30%) predominated, while qnrA, qnrS, and aac(6)-Ib genes were harbored by 20.5%, 12.5%, and 15% of the isolates respectively. Efflux pump protein expression was observed in 35% of the isolates. After RAPD-PCR, 19 different genotypes were yielded, and 5 of them were classified into sequence types (STs): 773, 1160, 2011, 2386, and 359.Conclusion
In this first-time study on P. aeruginosa CIP-US strains from Iranian ICU patients, three main CIP unsusceptibility mechanisms were investigated. A single mutation in one CIP target enzyme could explain high CIP resistance. qnr genes in the isolates can be considered as a CIP-unsusceptibility mechanism among studied isolates. Efflux pumps have more contribution in multidrug resistance than CIP susceptibility. CIP-US isolates of this study have not spread from distinct clonal strains and probably emerged from different sources. STs identified for the first time in this study in Iran should be considered as emerging MDR strains.
... Moreover, various studies have been established to testify the ability of bee venom and propolis to control S. aureus and its biofilm formation [17,[20][21][22][23]. Many previous studies tried to evaluate the anti-biofilm activity of bee venom, melittin, and macropin peptides against S. aureus [24][25][26]. However, to date, this is the first trial to evaluate the ability of bee venom and propolis to control the biofilm formed by a cocktail of MDRSA bacteria isolated from patients. ...
Intact skin is the first physical barrier against all microbial infections. Thus, in the cases of wounds, burns, and skin damage, bacteria can infect and invade the deeper layers of skin to the bloodstream and other organs leading to severe illnesses. Thus, our study aims to investigate the potential activity of natural products, propolis and honeybee venom, to control wound infections with multi-drug resistant Staphylococcus aureus (MDRSA) and safely accelerate the wound healing. First, this study characterized the clinically isolated S. aureus using biochemical, molecular, and antibiotic sensitivity tests. Then, the hydrogel was prepared via mixing chitosan with honey, propolis, and venom at different ratios, followed by physicochemical characterization and biological examination. The in-vivo experiment results after topical application of optimum concentrations revealed that both venom and propolis have significant antibacterial activity at different temperatures. The IC50 of both propolis antioxidant and cytotoxicity assays was found to be 40.07±2.18 μg/mL and 18.3 μg/mL, respectively. The cocktail bacteria showed both minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 10 µg/mL and of 300 µg/mL with venom respectively & MIC and MBC of 100 µg/mL, 300 µg/mL with propolis respectively. The use of hydrogel was effective against wound infection and enhanced wound healing during 14 days. Before starting clinical trials, further studies can be done on large animal models.
... A study that applied the combined action of melittin/mupirocin (4.4 and 14.22 µg/mL) demonstrated the synergistic effect between the AMP-drug during treatment and highlighted its application as anti-biofilm formers against eight strains of MRSA [115]. This AMP is capable of inserting itself into the lipid membrane, forming a toroidal pore, and it also has an anti-VRE potential effect [116]. ...
Bacterial resistance has intensified in recent years due to the uncontrolled use of conventional drugs, and new bacterial strains with multiple resistance have been reported. This problem may be solved by using antimicrobial peptides (AMPs), which fulfill their bactericidal activity without developing much bacterial resistance. The rapid interaction between AMPs and the bacterial cell membrane means that the bacteria cannot easily develop resistance mechanisms. In addition, various drugs for clinical use have lost their effect as a conventional treatment; however, the synergistic effect of AMPs with these drugs would help to reactivate and enhance antimicrobial activity. Their efficiency against multi-resistant and extensively resistant bacteria has positioned them as promising molecules to replace or improve conventional drugs. In this review, we examined the importance of antimicrobial peptides and their successful activity against critical and high-priority bacteria published in the WHO list.
... We speculated that was because TCA can destroy the biofilm and cell membrane of MRSA. The results of the biofilm inhibition assay indicated that TCA can significantly inhibit the biofilm formation and the expression of the biofilm regulatory gene hld [14]. The biofilm of MRSA has serious clinical implications, making it difficult to eradicate and more tolerant to antibiotic therapy [15]. ...
Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide and has acquired multiple resistance to a wide range of antibiotics. Hence, there is a pressing need to explore novel strategies to overcome the increase in antimicrobial resistance. The present study aims to investigate the efficacy and mechanism of plant-derived antimicrobials, trans-cinnamaldehyde (TCA) in decreasing MRSA’s resistance to eight conventional antibiotics. A checkerboard dilution test and time–kill curve assay are used to determine the synergistic effects of TCA combined with the antibiotics. The results indicated that TCA increased the antibacterial activity of the antibiotics by 2-16-fold. To study the mechanism of the synergism, we analyzed the mecA transcription gene and the penicillin-binding protein 2a level of MRSA treated with TCA by quantitative RT-PCR or Western blot assay. The gene transcription and the protein level were significantly inhibited. Additionally, it was verified that TCA can significantly inhibit the biofilm, which is highly resistant to antibiotics. The expression of the biofilm regulatory gene hld of MRSA after TCA treatment was also significantly downregulated. These findings suggest that TCA maybe is an exceptionally potent modulator of antibiotics.
