plasma as antimicrobial agent
Post on 28-Jan-2018
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Naveen Chaudhary
Dept of medical microbiology
PGIMER,CHANDIAGRH
Multidrug resistance bacteria:-challenging to
modern medicine
Bacteria can be inactivated through various physical
and chemical means
Heat
Radiations
Phenol ,alcohol etc
Introduction Plasma :- one of the four fundamental states of
matter, the others being solid, liquid, and gas.
Atmospheric pressure non-thermal plasma (APP):- Efficiently and effectively control multidrug resistant microorganisms
APP :-Efficient source of a combination of electronically excited atoms, charged particles (electrons, ions),ozone (O3), UV photons and radicals
Two types of plasma systems were investigated:
Nano-second pulsed plasma (NPP) as liquid discharge plasma
Argon gas-feeding dielectric barrier discharge (Ar-DBD) as a form of surface plasma
Reactive oxygen species (ROS) :-are chemically reactive molecules containing oxygen
Peroxides
Superoxide
hydroxyl radical
singlet oxygen
Strains used S. aureus (wild type)
Penicillin-resistant S. aureus (PRSA)
Methicillin-resistant S. aureus (MRSA)
Gentamicin-resistant S. aureus (GRSA)
Nano-second pulsed plasma
Shockwave measurement
Argon gas-feeding dielectric barrier discharge
Measurement of the ROS: Bacterial samples in saline were exposed to the 4th discharge of NPP and to 5 min of DBD plasma
All exposed bacterial samples were washed with PBS, and 500 ml of 10 Mm H2DCFDA were added
The mean fluorescence intensity was determined at the corresponding excitation and emission wavelengths
Molecular dynamics (MD) simulations used to study the interaction of the reactive ( O, OH, O3 and H2O2) as well as non-reactive ( O2, H2O) plasma species with PG of S. aureus.
X-ray photoelectron spectroscopy
XPS used to investigate the variation in the functional groups (C-H/C-C, C-OH and C=O) of peptidoglycan (PG)
Morphology analysis by SEM
Quantitative real time PCR:-A quantitative real time polymerase chain reaction (Q-PCR) used for analysis of the level of mecA, mecI,
mecRI and femA gene in the MRSA as well as wild strains was performed after exposure to NPP and DBD plasma
Analysis of change in Temperature and PH
Inactivation of bacterial strains
Colonies and SEM analysis
Gene expression analyses after NPP and Ar-DBD treatment
Composition of bacteria with plasma treatment obtained using XPS
Average fraction of important bonds of the PG after
impact of various plasma species.
Examined the protein oxidation to understand the structural modification for both proteins after NPP treatment
Observed the oxidation in calf thymus DNA after the NPP treatment
Discussion β-lactamase activity and SEM analysis:-If compare
the β –lactamase activity, we can observe that both NPP and DBD resulted in a decrease in activity, which may be due to the inactivation of the β -lactamase enzyme as well as its related gene.
SEM images show that the NPP treatment crushed many bacterial spores due to shock waves while only the DBD treatment changed the morphology
pH role in bacterial inactivationThey observed that the pH in saline solution became
~4.2 after 5 min of DBD treatment and ~5.3 after 4th discharge of NPP treatment.
Found no significant antimicrobial effects for both bacteria lines in an acidic environment, which is also supported by previous research.
Role of combined effect of the RS, pH and shock
waves on the inactivation of bacteria:-The role of the
pH is only to increase the reactivity of the radicals, and
the pH has no direct effect on the bacterial inactivation in
this study.
The inactivation of S. aureus with both plasma Sources
occurs with almost the same radicals, although the
amount can vary from plasma source to plasma source.
The shock waves play an important role in the
inactivation, which creates a difference in the efficiency of
NPP and Ar-DBD treatments
CONCLUSION XPS and MD simulation results show that PG is
oxidized due to plasma action that may help in inactivation of S. aureus. Therefore, research on plasma-liquid interactions is a recommended field for further new advances in plasma medicine like wound healing, dermatology and dentistry
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