35 research outputs found
Sensitivity of antibiotic resistant coagulase-negative staphylococci to antiseptic piсloxydin
Background. Coagulase-negative staphylococci (CNS), primarily Staphylococcus epidermidis, predominate in the normal microflora of the eye. However, due to irrational antibiotic therapy, resistant strains are widely distributed among CNS.
Aim. To study the sensitivity of the antibiotic resistant CNS isolates to picloxydine, an antiseptic.
Methods. The species, sensitivity to antibiotics and picloxydine were determined for 39 isolates of bacteria obtained from the conjunctival swabs. The cells morphology under the antiseptics influence was studied by electron microscopy.
Results. 33 isolates of S. epidermidis (17 sensitive or resistant to drugs of no more than 2 classes of antibiotics and 16 MDR), 2 S. haemolyticus (1 resistant to 2 classes of antibiotics and 1 MDR), 3 S. hominis (1 sensitive and 2 MDR), 1 S. caprae (MDR) were characterized. In in vitro tests, picloxydine showed high efficiency in suppressing the growth of staphylococci regardless of their sensitivity to antibiotics, as well as bactericidal activity at concentrations of 15.631.2 g/ml, close to those of chlorhexidine. At these concentrations, the antiseptic had a destructive effect on the surface structures of bacterial cells.
Conclusion. The picloxydine antiseptic is equally effective against antibiotic- sensitive and antibiotic-resistant coagulase-negative staphylococci
Photoinactivation of coronaviruses: Going along the optical spectrum
The COVID-19 pandemic has updated research on inactivation of coronaviruses with physical, chemical, and physical-chemical treatments. The review focuses on the inactivation of coronaviruses including the recent SARS-CoV-2 and viruses of other groups with analogous structure using optical radiation. The antiviral effects of different optical ranges from vacuum ultraviolet to infrared radiation are described in terms of the mechanisms of virus photoinactivation, sensitive molecular targets and efficacy. Direct and photosensitized damaging effects of light on the viral molecular structures are considered. Information on the applied pathogen photoinactivation technologies and the advantages of light sources for future applications is provided
Molecular Mechanism of Uptake of Cationic Photoantimicrobial Phthalocyanine across Bacterial Membranes Revealed by Molecular Dynamics Simulations
Phthalocyanines
are aromatic macrocyclic compounds, which are structurally
related to porphyrins. In clinical practice, phthalocyanines are used
in fluorescence imaging and photodynamic therapy of cancer and noncancer
lesions. Certain forms of the substituted polycationic metallophthalocyanines
have been previously shown to be active in photodynamic inactivation
of both Gram-negative and Gram-positive bacteria; one of them is zinc
octakis(cholinyl)phthalocyanine (ZnPcChol<sup>8+</sup>). However,
the molecular details of how these compounds translocate across bacterial
membranes still remain unclear. In the present work, we have developed
a coarse-grained (CG) molecular model of ZnPcChol<sup>8+</sup> within
the framework of the popular MARTINI CG force field. The obtained
model was used to probe the solvation behavior of phthalocyanine molecules,
which agreed with experimental results. Subsequently, it was used
to investigate the molecular details of interactions between phthalocyanines
and membranes of various compositions. The results demonstrate that
ZnPcChol<sup>8+</sup> has high affinity to both the inner and the
outer model membranes of Gram-negative bacteria, although this species
does not show noticeable affinity to the 1-palmitoyl-2-oleoyl-<i>sn</i>-glycero-3-phosphatidylcholine membrane. Furthermore,
we found out that the process of ZnPcChol<sup>8+</sup> penetration
toward the center of the outer bacterial membrane is energetically
favorable and leads to its overall disturbance and formation of the
aqueous pore. Such intramembrane localization of ZnPcChol<sup>8+</sup> suggests their twofold cytotoxic effect on bacterial cells: (1)
via induction of lipid peroxidation by enhanced production of reactive
oxygen species (i.e., photodynamic toxicity); (2) via rendering the
bacterial membrane more permeable for additional Pc molecules as well
as other compounds. We also found that the kinetics of penetration
depends on the presence of phospholipid defects in the lipopolysaccharide
leaflet of the outer membrane and the type of counterions, which stabilize
it. Thus, the results of our simulations provide a detailed molecular
view of ZnPcChol<sup>8+</sup> “self-promoted uptake”,
the pathway previously proposed for some small molecules crossing
the outer bacterial membrane