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Antimicrobial properties of Modified Graphene and other advanced 2D Material Coated Surfaces
Published in Craig E. Banks, Dale A. C. Brownson, 2D MATERIALS, 2018
Anthony J. Slate, Nathalie Karaky, Kathryn A. Whitehead
The results showed that after one hour bacterial growth had been inhibited by 72.9% and 68.4%, respectively, and after 24 hours the samples did not contain any viable cells, thus suggesting that the antimicrobial activity was effective against both planktonic and biofilm-forming strains of bacteria.70 Due to graphene’s low cytotoxic activity against human cells and excellent bacterial toxicity, it is an ideal candidate for application with biomaterials. When graphene was used as a surface coating of poly(N-vinylcarbazole) (PVK), results showed inhibition of up to 80% of biofilm growth, after 24 hour of incubation with E. coli and Bacillus subtilis, compared against a NIH 3T3 (mouse) cell line where over 80% of the cells were viable after 24 hours.71 In our laboratories, when 3D graphene foams have been combined with metal ions, using zone of inhibition assays, antimicrobial activity was demonstrated to be increased against Gram positive bacteria (Fig. 3). Antibacterial activity was also demonstrated against the more recalcitrant Gram negative Klebsiella pneumoniae and Acinetobacter baumannii. Further, our work demonstrated that on a 3D graphene foam substrate that has been soaked in a gallium compound, the physiological structure of the bacterial cells becomes altered due to cellular damaged (Fig. 4). Therefore, with further research, graphene could have the potential to be used as a surface coating for both equipment (i.e., nosocomial setting) and/or in wound dressings, due to its variety of antimicrobial mechanisms, including physiochemical interactions such as cell wall penetration, and cell wrapping depending on the lateral size of the graphene particle.
Emergence of carbapenem resistant Acinetobacter baumannii clonal complexes CC2 and CC10 among fecal carriages in an educational hospital
Published in International Journal of Environmental Health Research, 2021
Mohsen Nazari, Omid Azizi, Hamid Solgi, Sepideh Fereshteh, Shervin Shokouhi, Farzad Badmasti
Acinetobacter baumannii is an increasingly important Gram-negative hospital-acquired pathogen that can cause major outbreaks of infection mainly in immunocompromised patients and those admitted to intensive care units (ICUs) (Salimizand et al. 2018). The environment is the main reservoir of Acinetobacter spp. from which strains can be introduced into a hospital (Antunes, Visca, and Towner 2014). A. baumannii is ubiquitous within the environment and the potential to cause outbreaks is enhanced by the ability of the organism to survive in the environment on both dry and nutrient-limited surfaces for prolonged periods of time. The survival of A. baumannii has also been attributed to resistance to many antimicrobial agents (Eveillard et al. 2013; Almasaudi 2018). Based on the CDC announcement, carbapenem-resistant Acinetobacter strains are the top urgent antibiotic resistance threat that needs worldwide surveillance and infection control program. Hospitalized patients are at highly level of risk for acquiring multidrug-resistant A. baumannii (MDR) primarily from the hands of transiently colonized healthcare workers or indirectly from contaminated environmental surfaces (Barnes et al. 2014). The mortality rate in patients with A. baumannii infections, of which ventilator-associated pneumonia and bloodstream infections are the most common, can range from 5% to 54% in general hospital wards to ICU, respectively (Ayoub Moubareck and Hammoudi Halat 2020; Rebmann and Rosenbaum 2011).
Potential of silver nanoparticles synthesized using low active mosquitocidal Lysinibacillus sphaericus as novel antimicrobial agents
Published in Preparative Biochemistry & Biotechnology, 2021
Magda A. El-Bendary, Mohamed Abdelraof, Maysa E. Moharam, Elmahdy M. Elmahdy, Mousa A. Allam
There are many reports about the synergistic effect of AgNPs to different antibiotics against antibiotic resistant bacteria. Katva et al.[20] reported that gentamicin and chloramphenicol conjugated with AgNP showed synergistic effect against Enterococcus faecalis. In 2013, Kora and Rastogi[17] demonstrated that AgNPs produced the highest antimicrobial activity in combination with ampicillin. Antibacterial assays showed that AgNPs enhanced antibacterial potential of both cephradine and vildagliptin compared to the antibiotics alone.[21] The study of Tawfeeq et al.[19] showed synergistic effects of biosynthesized AgNPs at different concentrations with different standard antibiotic disks (tobramycin, chloramphenicol, nitrofuration, ampicillin-clavulanic acid, and nalidixic acid) against multidrug resistant bacteria. Hwang et al.[16] reported synergistic interactions of AgNPs and chloramphenicol against Enterococcus faecium and Pseudomonas aeruginosa. In addition, synergistic interactions of AgNPs and kanamycin were seen against Staphylococcus aureus, Streptococcus mutans, E. coli and Pseudomonas aeruginosa. AgNPs treatment also showed synergistic effects with the antibiotics polymixin B and rifampicin, and an additive effect with tigecycline against carbapenem-resistant Acinetobacter baumannii.[50] A synergistic antifungal activity of AgNPs and epoxiconazole against Setosphaeria turcica was also recorded by Huang et al.[51]
Loss of thermotolerance in antibiotic-resistant Acinetobacter baumannii
Published in International Journal of Environmental Health Research, 2021
Svjetlana Dekić Rozman, Ana Butorac, Rea Bertoša, Jasna Hrenović, Marina Markeš
Acinetobacter baumannii is a notorious hospital pathogen that in immunocompromised patients causes pneumonia, meningitis, bloodstream and urinary infections as well as wound infections (Peleg et al. 2008). Classified as an ESKAPE pathogen (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter sp.) carbapenem-resistant A. baumannii strains were listed by the World Health Organization as top priority pathogens (Lee et al. 2017). A. baumannii is hard to eradicate from the hospital setting because of its ability to form biofilm on various surfaces and endure exposure to environmental conditions. A. baumannii has the ability to endure temperatures far above its optimum. (Dekic et al. 2018) have demonstrated the long-term survival of A. baumannii in water environment exposed to 44°C (5 months) as well as short-term exposure to temperatures ranging from 50 to 80°C. Gram-negative bacteria have a very efficient regulation of the heat-shock response. Under heat-shock, the envelope stress response sigma factor σE facilitates the translation of rpoH and the production of σ32, which is further stabilized by cellular chaperones. The increased levels of stable σ32 induce the expression of heat shock genes leading to the production of chaperones and proteases that participate in protein refolding or elimination of proteins that cannot be repaired (Kumar et al. 2015). The major chaperone systems in bacteria are the DnaK machine (DnaK, DnaJ and GrpE) and GroE machine (GroEL and GroES). GroEL provides a microenvironment for protein refolding, while DnaK protects the exposed regions on unfolded or partially folded proteins from proteolysis and aggregation (Cardoso et al., 2010; Ghazaei 2017). Proteins involved in heat shock response also participate in defence against other stressors such as exposure to heavy metals or antibiotics (Ghazaei 2017). Research regarding the influence of high temperature on antibiotic resistance is scarce. The first such correlation was mentioned in Staphylococcus aureus that lost antibiotic resistance to penicillin and tetracycline after the exposure to 43–44°C (Asheshov 1966). Additionally, (De Silva et al. 2017) have demonstrated that incubation temperature (28°C and 37°C) modulates antibiotic susceptibility in A. baumannii ATCC 17,978. A significant difference in minimum inhibitory concentration was only observed when exposed to aztreonam and trimethoprim-sulfamethoxazole. Clinically relevant A. baumannii have been recovered from environmental samples of wastewaters, wastewater treatment plants, rivers and soil contaminated by human waste (Hrenovic et al. 2016, 2017; Seruga Music et al. 2017; Higgins et al. 2018). Since there is no simple protocol for the isolation of A. baumannii from environmental samples, the selective medium and elevated temperature of incubation (42°C) was employed for recovery (Hrenovic et al. 2016). However, the effect of these selective conditions on the viability of A. baumannii have not been tested in the long-term survival assays.