Carbon Nanomaterials and LED Irradiation as Antibacterial Strategies against Gram-Positive Multidrug-Resistant Pathogens.

BACKGROUND: Due to current antibiotic resistance worldwide, there is an urgent need to find new alternative antibacterial approaches capable of dealing with multidrug-resistant pathogens. Most recent studies have demonstrated the antibacterial activity and non-cytotoxicity of carbon nanomaterials such as graphene oxide (GO) and carbon nanofibers (CNFs). On the other hand, light-emitting diodes (LEDs) have shown great potential in a wide range of biomedical applications. METHODS: We investigated a nanotechnological strategy consisting of GO or CNFs combined with light-emitting diod (LED) irradiation as novel nanoweapons against two clinically relevant Gram-positive multidrug-resistant pathogens: methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE). The cytotoxicity of GO and CNFs was studied in the presence of human keratinocyte HaCaT cells. RESULTS: GO or CNFs exhibited no cytotoxicity and high antibacterial activity in direct contact with MRSE and MRSA cells. Furthermore, when GO or CNFs were illuminated with LED light, the MRSE and MRSA cells lost viability. The rate of decrease in colony forming units from 0 to 3 h, measured per mL, increased to 98.5 ± 1.6% and 95.8 ± 1.4% for GO and 99.5 ± 0.6% and 99.7 ± 0.2% for CNFs. CONCLUSIONS: This combined antimicrobial approach opens up many biomedical research opportunities and provides an enhanced strategy for the prevention and treatment of Gram-positive multidrug-resistant infections.

Genetic Variation and Evolutionary Analysis of Eggplant Mottled Dwarf Virus Isolates from Spain.

The genetic variation and population structure of gene N (nucleocapsid) and part of gene L (replicase) from 13 eggplant mottle dwarf virus (EMDV) isolates from Spain were evaluated and compared with sequences of EMDV isolates from other countries retrieved from GenBank. Phylogenetic inference of part of gene L showed three main clades, one containing an EMDV isolate from Australia and the other two containing isolates from Iran and Europe, as well as four subclades. EMDV isolates from Spain were genetically very similar and grouped in a subclade together with one isolate from Germany and one from the UK. No new recombination events were detected in addition to one recombination previously reported, suggesting that recombination is rare for EMDV. The comparison of synonymous and non-synonymous rates showed that negative selection played an important role, and only two codons were under positive selection. Genetic differentiation (Fst test), phylogenetic and nucleotide diversity analyses suggest a unique introduction of EMDV to Spain and low gene flow with other countries. In contrast, Greece and Italy showed diverse populations with high gene flow between both.