83 research outputs found
Control of Propionibacterium acnes by natural antimicrobial substances: Role of the bacteriocin AS-48 and lysozyme
We report the high susceptibility of several clinical isolates of Propionibacterium acnes from different
sources (skin, bone, wound exudates, abscess or blood contamination) to the head-to-tail cyclized
bacteriocin AS-48. This peptide is a feasible candidate for further pharmacological development against
this bacterium, due to its physicochemical and biological characteristics, even when it is growing in a
biofilm. Thus, the treatment of pre-formed biofilms with AS-48 resulted in a dose- and time-dependent
disruption of the biofilm architecture beside the decrease of bacterial viability. Furthermore, we
demonstrated the potential of lysozyme to bolster the inhibitory activity of AS-48 against P. acnes,
rendering high reductions in the MIC values, even in matrix-growing cultures, according to the results
obtained using a range of microscopy and bioassay techniques. The improvement of the activity of
AS-48 through its co-formulation with lysozyme may be considered an alternative in the control of P.
acnes, especially after proving the absence of cytotoxicity demonstrated by these natural compounds
on relevant human skin cell lines. In summary, this study supports that compositions comprising the
bacteriocin AS-48 plus lysozyme must be considered as promising candidates for topical applications
with medical and pharmaceutical purposes against dermatological diseases such as acne vulgaris.This research was funded by a grant
from the Spanish Ministry of Economy and Competitiveness (SAF2013-48971-C2-1-R that included funds from
European Regional Development, ERDF), and the Research Group General (BIO160, UGR)
Beyond outputs: pathways to symmetrical evaluations of university sustainable development partnerships
As the United Nations Decade of Education for Sustainable Development (2005–2014) draws to a close, it is timely to review ways in which the sustainable development initiatives of higher education institutions have been, and can be, evaluated. In their efforts to document and assess collaborative sustainable development program outcomes and impacts, universities in the North and South are challenged by similar conundrums that confront development agencies. This article explores pathways to symmetrical evaluations of transnationally partnered research, curricula, and public-outreach initiatives specifically devoted to sustainable development. Drawing on extensive literature and informed by international development experience, the authors present a novel framework for evaluating transnational higher education partnerships devoted to sustainable development that addresses design, management, capacity building, and institutional outreach. The framework is applied by assessing several full-term African higher education evaluation case studies with a view toward identifying key limitations and suggesting useful future symmetrical evaluation pathways. University participants in transnational sustainable development initiatives, and their supporting donors, would be well-served by utilizing an inclusive evaluation framework that is infused with principles of symmetry
Selectively targeting bacteria by tuning the molecular design of membrane-active peptidomimetic amphiphiles
Here we report the design of membrane-active peptidomimetic molecules with a tunable arrangement of hydrophobic and polar groups. In spite of having the same chemical composition, the effective hydrophobicities of the compounds were different as a consequence of their chemical structure and conformational properties. The compound with lower effective hydrophobicity demonstrated antibacterial activity that was highly selective towards bacteria over mammalian cells. This study, highlighting the role in membrane selectivity of the specific arrangement of the different moieties in the molecular structure, provides useful indications for developing non-toxic antibacterial agents
Lysine-Based Small Molecules That Disrupt Biofilms and Kill both Actively Growing Planktonic and Nondividing Stationary Phase Bacteria
The
emergence of bacterial resistance is a major threat to global health.
Alongside this issue, formation of bacterial biofilms is another cause
of concern because most antibiotics are ineffective against these
recalcitrant microbial communities. Ideal future antibacterial therapeutics
should possess both antibacterial and anti-biofilm activities. In
this study we engineered lysine-based small molecules, which showed
not only commendable broad-spectrum antibacterial activity but also
potent biofilm-disrupting properties. Synthesis of these lipophilic
lysine–norspermidine conjugates was achieved in three simple
reaction steps, and the resultant molecules displayed potent antibacterial
activity against various Gram-positive (Staphylococcus
aureus, Enterococcus faecium) and Gram-negative bacteria (Escherichia coli) including drug-resistant superbugs MRSA (methicillin-resistant <i>S. aureus</i>), VRE (vancomycin-resistant <i>E. faecium</i>), and β-lactam-resistant Klebsiella pneumoniae. An optimized compound in the series showed activity against planktonic
bacteria in the concentration range of 3–10 μg/mL, and
bactericidal activity against stationary phase <i>S. aureus</i> was observed within an hour. The compound also displayed about 120-fold
selectivity toward both classes of bacteria (<i>S. aureus</i> and <i>E. coli</i>) over human erythrocytes. This rapidly
bactericidal compound primarily acts on bacteria by causing significant
membrane depolarization and K<sup>+</sup> leakage. Most importantly,
the compound disrupted preformed biofilms of <i>S. aureus</i> and did not trigger bacterial resistance. Therefore, this class
of compounds has high potential to be developed as future antibacterial
drugs for treating infections caused by planktonic bacteria as well
as bacterial biofilms
Fatty Acid Comprising Lysine Conjugates: Anti-MRSA Agents That Display In Vivo Efficacy by Disrupting Biofilms with No Resistance Development
Methicillin-resistant Staphylococcus aureus (MRSA) has developed resistance
to antibiotics of last resort such
as vancomycin, linezolid, and daptomycin. Additionally, their biofilm
forming capability has set an alarming situation in the treatment
of bacterial infections. Herein we report the potency of fatty acid
comprising lysine conjugates as novel anti-MRSA agents, which were
not only capable of killing growing planktonic MRSA at low concentration
(MIC = 3.1–6.3 μg/mL), but also displayed potent activity
against nondividing stationary phase cells. Furthermore, the conjugates
eradicated established biofilms of MRSA. The bactericidal activity
of d-lysine conjugated tetradecanoyl analogue (D-LANA-14)
is attributed to its membrane disruption against these metabolically
distinct cells. In a mouse model of superficial skin infection, D-LANA-14
displayed potent in vivo anti-MRSA activity (2.7 and 3.9 Log reduction
at 20 mg/kg and 40 mg/kg, respectively) without showing any skin toxicity
even at 200 mg/kg of the compound exposure. Additionally, MRSA could
not develop resistance against D-LANA-14 even after 18 subsequent
passages, whereas the topical anti-MRSA antibiotic fusidic acid succumbed
to rapid resistance development. Collectively, the results suggested
that this new class of membrane targeting conjugates bear immense
potential to treat MRSA infections over conventional antibiotic therapy
Mechanical properties of Aningeria superba (Aningre) and Austranella congolensis tannin adhesives
International audienc
Spiroplasma litorale sp. nov., from tabanid flies (Tabanidae : Diptera) in the Southeastern United States
International audienc
Serologic and genomic relatedness of group VIII and group XVII spiroplasmas and subdivision of spiroplasma group VIII into subgroups
International audienc
The Spiroplasma Motility Inhibition Test, a New Method for Determining Intraspecific Variation among Colorado Potato Beetle Spiroplasmas
The Colorado potato beetle, Leptinotarsa decemlineata, is a major holarctic pest of solanaceous crops. Presumably, this insect spread from Solanum species in central America to the Mexican plateau, and this was followed by multiple invasions of North America and Europe. Attempts are being made to control this beetle by using a genetically modified spiroplasma that occurs naturally in its gut. In the current study, spiroplasmas isolated from beetles collected in North America and Poland exhibited serologic (spiroplasma motility inhibition test) and genomic (restriction fragment length polymorphism) profiles that suggest that there were multiple spiroplasma introductions. Two serovars were identified; one is found in northern North America and at high elevations in Poland, and the other is found in southern North America and at low elevations in Poland. The patterns of genovar distribution coincide with the serovar patterns. The existence of such biovars—intraspecific taxal units reflected by serologic and genomic differences—should be taken into consideration when taxonomies are developed and strains are chosen for biocontrol
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