Bacterial cell wall peptidoglycan is essential, maintaining both cellular integrity and morphology, in the face of internal turgor pressure. Peptidoglycan synthesis is important, as it is targeted by cell wall antibiotics, including methicillin and vancomycin. Here, we have used the major human pathogen Staphylococcus aureus to elucidate both the cell wall dynamic processes essential for growth (life) and the bactericidal effects of cell wall antibiotics (death) based on the principle of coordinated peptidoglycan synthesis and hydrolysis. The death of S. aureus due to depletion of the essential, two-component and positive regulatory system for peptidoglycan hydrolase activity (WalKR) is prevented by addition of otherwise bactericidal cell wall antibiotics, resulting in stasis. In contrast, cell wall antibiotics kill via the activity of peptidoglycan hydrolases in the absence of concomitant synthesis. Both methicillin and vancomycin treatment lead to the appearance of perforating holes throughout the cell wall due to peptidoglycan hydrolases. Methicillin alone also results in plasmolysis and misshapen septa with the involvement of the major peptidoglycan hydrolase Atl, a process that is inhibited by vancomycin. The bactericidal effect of vancomycin involves the peptidoglycan hydrolase SagB. In the presence of cell wall antibiotics, the inhibition of peptidoglycan hydrolase activity using the inhibitor complestatin results in reduced killing, while, conversely, the deregulation of hydrolase activity via loss of wall teichoic acids increases the death rate. For S. aureus, the independent regulation of cell wall synthesis and hydrolysis can lead to cell growth, death, or stasis, with implications for the development of new control regimes for this important pathogen.
- MeSH
- antibakteriální látky farmakologie MeSH
- antiinfekční látky metabolismus farmakologie MeSH
- bakteriální proteiny metabolismus MeSH
- buněčná stěna metabolismus fyziologie MeSH
- homeostáza MeSH
- kyseliny teichoové metabolismus MeSH
- methicilin farmakologie MeSH
- N-acetylmuramoyl-L-alaninamidasa metabolismus MeSH
- peptidoglykan metabolismus MeSH
- stafylokokové infekce mikrobiologie MeSH
- Staphylococcus aureus růst a vývoj metabolismus MeSH
- vankomycin farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Purpose: Nanomaterials for antimicrobial applications have gained interest in recent years due to the increasing bacteria resistance to conventional antibiotics. Wound sterilization, water treatment and surface decontamination all avail from multifunctional materials that also possess excellent antibacterial properties, eg zinc oxide (ZnO). Here, we assess and compare the effects of synthesized hedgehog-like ZnO structures and commercial ZnO particles with and without mixing on the inactivation of bacteria on surfaces and in liquid environments. Methods: Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria in microbial culture medium were added to reverse spin bioreactors that contained different concentrations of each ZnO type to enable dynamic mixing of the bacteria-ZnO suspensions. Optical density of the bacteria-ZnO suspensions was measured in real-time and the number of viable bacteria after 24 h exposure was determined using standard microbiological techniques. The concentration of zinc ion generated from ZnO dissolution in different liquid types was estimated from the dynamic interaction exposure. Static antibacterial tests without agitation in liquid media and on agar surface were performed for comparison. Results: A correlation between increasing ZnO particle concentration and reduction in viable bacteria was not monotonous. The lowest concentration tested (10 µg/mL) even stimulated bacteria growth. The hedgehog ZnO was significantly more antibacterial than commercial ZnO particles at higher concentrations (up to 1000 µg/mL tested), more against E. coli than S. aureus. Minimum inhibitory concentration in microwell plates was correlated with those results. No inhibition was detected for any ZnO type deposited on agar surface. Zinc ion release was greatly suppressed in cultivation media. Scanning electron microscopy images revealed that ZnO needles can pierce membrane of bacteria whereas the commercial ZnO nanoparticles rather agglomerate on the cell surface. Conclusion: The inhibition effects are thus mainly controlled by the interaction dynamics between bacteria and ZnO, where mixing greatly enhances antibacterial efficacy of all ZnO particles. The efficacy is modulated also by ZnO particle shapes, where hedgehog ZnO has superior effect, in particular at lower concentrations. However, at too low concentrations, ZnO can stimulate bacteria growth and must be thus used with caution.
- MeSH
- antibakteriální látky chemie farmakologie MeSH
- biomimetické materiály chemie farmakologie MeSH
- Escherichia coli účinky léků růst a vývoj MeSH
- ježkovití * MeSH
- mikrobiální testy citlivosti MeSH
- oxid zinečnatý chemie farmakologie MeSH
- Staphylococcus aureus účinky léků růst a vývoj MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The antifouling, antimicrobial, elution behavior, skin irritant, and cytotoxicity properties of water-soluble phosphate glass on stainless steel were evaluated. Water-soluble phosphate glass samples with 35% Cu (mol/mol) were prepared by altering the network modifier (Na2O, K2O) and network former (P2O5, B2O3) compositions. The materials were melted at temperatures within the range of 850-950 °C. The melt was then quenched and ground into fine particles using a twin roll mill. The resulting water-soluble glasses were prepared as glass frit (size < 100 μm) using a sieve. The amorphous phase was determined by X-ray diffraction and differential thermal analysis. Water-soluble glasses with a reduced Cu ion elution rate of 1.2 ppm per week were formed because the chemical resistances of the formulated glasses improved as the P2O5 content decreased and the B2O3 content increased. To test its antifouling properties, the glass frit was mixed with paint and coated onto a STS316L sheet. The surface roughness was increased markedly from 1.4 to 19.2 nm, increasing the specific surface area for antimicrobial activity. It was demonstrated that the proposed method was able to form noncytotoxic, nonirritant, water-soluble glasses with 99.9% antimicrobial activity against Staphylococcus aureus. These results suggest that water-soluble phosphate glass on STS316L sheets could be useful in filtration plants.
- MeSH
- antibakteriální látky chemie farmakologie MeSH
- bioznečištění prevence a kontrola MeSH
- čištění vody přístrojové vybavení MeSH
- difrakce rentgenového záření MeSH
- filtrace přístrojové vybavení MeSH
- fosfáty chemie farmakologie MeSH
- králíci MeSH
- kůže účinky léků MeSH
- sklo chemie MeSH
- Staphylococcus aureus účinky léků růst a vývoj MeSH
- teplota MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Chronic wounds and their associated bacterial infections are major issues in modern health care systems. Therefore, antimicrobial resistance (AMR), treatment costs, and number of disability-adjusted life-years have gained more interest. Recently, photodynamic therapy emerged as an effective approach against resistant and naïve bacterial strains with a low probability of creating AMR. In this study, needleless electrospinning was used to produce an indocyanine green (ICG) loaded poly(d,l-lactide) nanofibrous mesh as a photoresponsive wound dressing. The non-woven mesh had a homogeneous nanofibrous structure and showed long-term hydrolytic stability at different pH values. The antimicrobial activity was tested against several bacterial strains, namely Staphylococcus saprophyticus subsp. bovis, Escherichia coli DH5 alpha, and Staphylococcus aureus subsp. aureus. Upon irradiation with a laser of a specific wavelength (λ = 810 nm), the bacterial viability was significantly reduced by 99.978% (3.66 log10), 99.699% (2.52 log10), and 99.977% (3.64 log10), respectively. The nanofibrous mesh showed good biocompatibility, which was confirmed by the proliferation of mouse fibroblasts (L929) on the surface and into deeper parts of the mesh. Furthermore, a favorable proangiogenic effect was observed in ovo using the chorioallantoic membrane assay. In general, it can be concluded that ICG loaded nanofibers as an innovative wound dressing represent a promising strategy against chronic wounds associated with skin infections.
- MeSH
- biokompatibilní materiály chemie farmakologie MeSH
- buněčné linie MeSH
- chorioalantoická membrána krevní zásobení účinky léků MeSH
- Escherichia coli účinky léků růst a vývoj MeSH
- fibroblasty cytologie účinky léků MeSH
- fotochemoterapie MeSH
- indokyanová zeleň chemie farmakologie MeSH
- mikrobiální viabilita účinky léků MeSH
- myši MeSH
- nanovlákna MeSH
- obvazy MeSH
- polyestery chemie MeSH
- proliferace buněk účinky léků MeSH
- Staphylococcus aureus účinky léků růst a vývoj MeSH
- Staphylococcus saprophyticus účinky léků růst a vývoj MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
It is generally believed that antibacterial essential oils have the potential to become one of the alternatives in preventing diarrheal diseases of monogastric animals. The disadvantage is their low efficiency per oral due to easy degradation during digestion in the stomach. This study compares the efficacy of chitosan, alginate-chitosan, guar gum-chitosan, xanthan gum-chitosan and pectin-chitosan nanocapsules to the synthesis of pH-responsive biopolymeric nanocapsule for Thymus vulgaris, Rosmarinus officinalis and Syzygium aromaticum essential oils. Using spectrophotometric approach and gas chromatography, release kinetics were determined in pH 3, 5.6 and 7.4. The growth rates of S. aureus and E. coli, as well as minimal inhibition concentration of essential oils were studied. The average encapsulation efficiency was 60%, and the loading efficiency was 70%. The size of the nanocapsules ranged from 100 nm to 500 nm. Results showed that chitosan-guar gum and chitosan-pectin nanocapsules released 30% of essential oils (EOs) at pH 3 and 80% at pH 7.4 during 3 h. Similar release kinetics were confirmed for thymol, eugenol and α-pinene. Minimal inhibition concentrations of Thymus vulgaris and Syzygium aromaticum essential oils ranged from 0.025 to 0.5%. Findings of this study suggest that the suitable pH-responsive nanocapsule for release, low toxicity and antibacterial activity is based on chitosan-guar gum structure.
- MeSH
- antibakteriální látky chemie farmakologie MeSH
- erytrocyty cytologie účinky léků MeSH
- Escherichia coli účinky léků růst a vývoj MeSH
- hemolýza účinky léků MeSH
- koncentrace vodíkových iontů MeSH
- lidé MeSH
- mikrobiální testy citlivosti MeSH
- nanokapsle aplikace a dávkování chemie MeSH
- oleje prchavé chemie farmakologie MeSH
- polymery chemie MeSH
- Staphylococcus aureus účinky léků růst a vývoj MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
External fixators of serious fractures could be an attractive substrate on which microorganisms can accumulate. Therefore, this study aimed to develop a suitable method for enabling the simulation of a real situation when osteosynthetic fixation material is open for the potential threat of bacterial attack. Agar-based media represented human tissue, and the metallic pin characterized the screw in the fixation. Various types of agar, supplements, and contamination strategy by Staphylococcus aureus were tested. The influence of the initial bacterial concentration was also examined. Surfaces were observed by scanning electron microscopy (SEM), and all results were compared. Brain Heart Infusion Agar with the Egg Yolk Tellurite Emulsion was established in a transparent test tube as a suitable system for enabling the good interpretability of bacterial contamination in the pin's surroundings. Pin contamination has been found to be an appropriate approach for testing microbial growth, rather than agar surface contamination, which distorted obtained results. A lower initial colony forming units (CFU) provided better clarity of the test. SEM observation of the pin surface was comparable with the visual evaluations in the test tubes. Results were assembled for positive and negative control samples as well. Screening method for the most common bacteria S. aureus has been standardized and developed. This experimental setup could also be a useful tool for surface modification with antibacterial properties testing.
- MeSH
- antibakteriální látky farmakologie MeSH
- biofilmy účinky léků růst a vývoj MeSH
- externí fixátory mikrobiologie MeSH
- kontaminace zdravotnického vybavení * MeSH
- kultivační média MeSH
- lidé MeSH
- mikroskopie elektronová rastrovací MeSH
- počet mikrobiálních kolonií MeSH
- Staphylococcus aureus účinky léků růst a vývoj ultrastruktura MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Staphylococcus aureus may be a highly virulent human pathogen, especially when it is able to form a biofilm, and it is resistant to antibiotic. Infections caused by these bacteria significantly affect morbidity and mortality, primarily in hospitalized patients. Treatment becomes more expensive, more toxic, and prolonged. This is the reason why research on alternative therapies should be one of the main priorities of medicine and biotechnology. A promising alternative treatment approach is bacteriophage therapy. The effect of the anti-staphylococcal bacteriophage preparation Stafal® on biofilm reduction was assessed on nine S. aureus strains using both sonication with subsequent quantification of surviving cells on the catheter surface and evaluation of biofilm reduction in microtiter plates. It was demonstrated that the bacteriophages destroy planktonic cells very effectively. However, to destroy cells embedded in the biofilm effectively requires a concentration at least ten times higher than that provided by the commercial preparation. The catheter disc method (CDM) allowed easier comparison of the effect on planktonic cells and cells in a biofilm than the microtiter plate (MTP) method.
- MeSH
- antiinfekční látky * MeSH
- bakteriologické techniky MeSH
- biofilmy * MeSH
- lidé MeSH
- methicilin rezistentní Staphylococcus aureus růst a vývoj izolace a purifikace virologie MeSH
- mikrobiální viabilita MeSH
- počet mikrobiálních kolonií MeSH
- stafylokokové bakteriofágy fyziologie MeSH
- stafylokokové infekce mikrobiologie MeSH
- Staphylococcus aureus růst a vývoj izolace a purifikace virologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Lactobionic acid (LBA) is a newly identified natural polyhydroxy acid that is widely used in the food industry. In this study, the antibacterial effects and underlying mechanism of action of LBA against Staphylococcus aureus were investigated. LBA exhibited significant antibacterial activity against S. aureus with a determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 15 mg/mL and 50 mg/mL, respectively. The Growth curves indicated that LBA directly inhibited the growth of S. aureus. Moreover, LBA induced the leakage of alkaline phosphatase and nucleotides in the culture medium, indicating damage to the integrity of the S. aureus cell wall membrane, which was confirmed by transmission electron microscopy observations. The relative electric conductivity measurements indicated that LBA changed the cell membrane permeability. The preservation effect of LBA was evaluated by quantifying the total number of colonies, total volatile base nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS). Overall, these results revealed that LBA exerts its antibacterial activity by breaking down the structure of the bacterial cell wall and membrane, thereby releasing the cellular contents as well as inhibiting protein synthesis, which ultimately lead to cell death. The total number of colonies, the TVB-N value, and the TBARS of cold fresh meat treated with preservatives were significantly lower than those of the control group (P < 0.05). With these antibacterial characteristics, LBA has potential to be used as a safe food additive in the food industry.
- MeSH
- antibakteriální látky farmakologie MeSH
- buněčná membrána účinky léků metabolismus MeSH
- buněčná stěna účinky léků metabolismus MeSH
- disacharidy farmakologie MeSH
- dusík analýza MeSH
- konzervace potravin MeSH
- látky reagující s kyselinou thiobarbiturovou analýza MeSH
- mikrobiální testy citlivosti MeSH
- mikrobiální viabilita účinky léků MeSH
- permeabilita buněčné membrány účinky léků MeSH
- počet mikrobiálních kolonií MeSH
- Staphylococcus aureus účinky léků růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
Lytic bacteriophages are valuable therapeutic agents against bacterial infections. There is continual effort to obtain new phages to increase the effectivity of phage preparations against emerging phage-resistant strains. Here we described the genomic diversity of spontaneous host-range mutants of kayvirus 812. Five mutant phages were isolated as rare plaques on phage-resistant Staphylococcus aureus strains. The host range of phage 812-derived mutants was 42% higher than the wild type, determined on a set of 186 methicillin-resistant S. aureus strains representing the globally circulating human and livestock-associated clones. Comparative genomics revealed that single-nucleotide polymorphisms from the parental phage 812 population were fixed in next-step mutants, mostly in genes for tail and baseplate components, and the acquired point mutations led to diverse receptor binding proteins in the phage mutants. Numerous genome changes associated with rearrangements between direct repeat motifs or intron loss were found. Alterations occurred in host-takeover and terminal genomic regions or the endolysin gene of mutants that exhibited the highest lytic activity, which implied various mechanisms of overcoming bacterial resistance. The genomic data revealed that Kayvirus spontaneous mutants are free from undesirable genes and their lytic properties proved their suitability for rapidly updating phage therapeutics.
- MeSH
- bakteriální léková rezistence MeSH
- bakteriofágy genetika MeSH
- délka genomu MeSH
- genom virový MeSH
- genomika MeSH
- jednonukleotidový polymorfismus MeSH
- methicilin farmakologie MeSH
- mutace * MeSH
- Staphylococcus aureus růst a vývoj virologie MeSH
- zastoupení bazí MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Bio-artificial polymeric systems are a new class of polymeric constituents based on blends of synthetic and natural polymers, designed with the purpose of producing new materials that exhibit enhanced properties with respect to the individual components. In this frame, a combination of polyvinyl alcohol (PVA) and chitosan, blended with a widely used antibiotic, sodium ampicillin, has been developed showing a moderate behavior in terms of antibacterial properties. Thus, aqueous solutions of PVA at 1 wt.% were mixed with acid solutions of chitosan at 1 wt.%, followed by adding ampicillin ranging from 0.3 to 1.0 wt.% related to the total amount of the polymers. The prepared bio-artificial polymeric system was characterized by FTIR, SEM, DSC, contact angle measurements, antibacterial activity against Staphylococcus aureus and Escherichia coli and antibiotic release studies. The statistical significance of the antibacterial activity was determined using a multifactorial analysis of variance with ρ < 0.05 (ANOVA). The characterization techniques did not show alterations in the ampicillin structure and the interactions with polymers were limited to intermolecular forces. Therefore, the antibiotic was efficiently released from the matrix and its antibacterial activity was preserved. The system disclosed moderate antibacterial activity against bacterial strains without adding a high antibiotic concentration. The findings of this study suggest that the system may be effective against healthcare-associated infections, a promising view in the design of novel antimicrobial biomaterials potentially suitable for tissue engineering applications.
- MeSH
- ampicilin * chemie farmakologie MeSH
- antibakteriální látky * chemická syntéza chemie farmakologie MeSH
- chitosan * chemie farmakologie MeSH
- Escherichia coli růst a vývoj MeSH
- polyvinylalkohol * chemie farmakologie MeSH
- Staphylococcus aureus růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
