Antibacterial and antibiofilm potential of silver nanoparticles against antibiotic-sensitive and multidrug-resistant Pseudomonas aeruginosa strains

Abstract

Due to the severity of infections caused by P. aeruginosa and the limitations in treatment, it is necessary to find new therapeutic alternatives. Thus, the use of silver nanoparticles (AgNPs) is a viable alternative because of their potential actions in the combat of microorganisms, showing efficacy against Gram-positive and Gram-negative bacteria, including multidrug-resistant microorganisms (MDR). In this sense, the aim of this work was to conduct a literature review related to the antibacterial and antibiofilm activity of AgNPs against antibiotic-sensitive and multidrug-resistant Pseudomonas aeruginosa strains. The AgNPs are promising for future applications, which may match the clinical need for effective antibiotic therapy. The size of AgNPs is a crucial element to determine the therapeutic activity of nanoparticles, since smaller particles present a larger surface area of contact with the microorganism, affecting their vital functioning. AgNPs adhere to the cytoplasmic membrane and cell wall of microorganisms, causing disruption, penetrating the cell, interacting with cellular structures and biomolecules, and inducing the generation of reactive oxygen species and free radicals. Studies describe the antimicrobial activity of AgNPs at minimum inhibitory concentration (MIC) between 1 and 200 μg/mL against susceptible and MDR P. aeruginosa strains. These studies have also shown antibiofilm activity through disruption of biofilm structure, and oxidative stress, inhibiting biofilm growth at concentrations between 1 and 600 μg/mL of AgNPs. This study evidences the advance of AgNPs as an antibacterial and antibiofilm agent against Pseudomonas aeruginosa strains, demonstrating to be an extremely promising approach to the development of new antimicrobial systems.

Inorganic Nanoparticles and Composite Films for Antimicrobial Therapies

“…While their efficiency has been proven against more than 650 microorganisms, including Gram-positive and Gram-negative bacteria, fungi, and viruses, the precise mechanism of action of AgNPs is still not completely elucidated [ 82 , 83 ]. The primary mechanism is based on the interaction between the positively charged AgNPs and the negatively charged plasma cell membranes, which further results in the accumulation within the membrane and the consequent structural modifications and permeabilization due to cis-trans isomerization of the unsaturated membrane fatty acids [ 73 , 80 , 82 , 84 ]. In this manner, Ag + is released from the outer surface of the NP, thus interacting with nucleic acids and proteins and further generating high amounts of ROS, namely, singlet oxygen, hypochlorous acid, hydroxyl radical, superoxide anion, and hydrogen peroxide [ 73 , 80 , 82 , 83 ].…”

“…In this manner, the enzyme is unable to perform its functions, thus causing cell or organism death [ 82 ]. Similar to AuNPs, AgNPs have proven higher efficiency towards Gram-negative bacteria due to a reduced cell wall thickness and an increased number of negative charges [ 73 , 84 ]. In the case of fungi, AgNPs interfere with the cell metabolism through the generation of ROS and modification of ergosterol levels and lead to cell lysis.…”

“…In the case of fungi, AgNPs interfere with the cell metabolism through the generation of ROS and modification of ergosterol levels and lead to cell lysis. Additionally, AgNPs are capable of inactivating viruses through the interaction with surface receptors and the consequent blocking of the viral entry phase, e.g., the sulfur groups of gp120 protein spikes onto the membrane of the human immunodeficiency virus or the viral envelope glycoproteins onto the herpes simplex virus type 1 through sulfonate groups [ 83 , 84 ].…”

Silver Nanoparticle-Anchored Human Hair Kerateine/PEO/PVA Nanofibers for Antibacterial Application and Cell Proliferation

“…Silver nanoparticles (AgNPs) can better attach to microorganisms due to their large surface areas and nano effects, showing a high antibacterial performance [ 28 ]. AgNPs adhere to the cytoplasmic membrane and cell wall of microorganisms, causing disruption, penetrating the cell, interacting with sulfur-containing proteins and phosphorous compounds such as DNA in bacterial cells and inducing the generation of reactive oxygen species and free radicals to attack the respiratory chain, leading to cell death [ 29 ]. In turn, AgNPs are released from bacterial cells, so their concentrations and properties do not change, thus enhancing their bactericidal persistence.…”

Development of Anti-Virulence Therapeutics against Mono-ADP-Ribosyltransferase Toxins

“…The elevated incidence of flesh-eating diseases [ 12 ], fatalities due to contaminated drinking water [ 13 ], Listeria monocytogenes contamination of foods [ 14 ], Escherichia coli O157 contamination of meats (500 deaths annually in the U.S.) [ 15 ], Salmonella -related food poisoning such as vegetable contamination (4 million U.S. cases/y) [ 16 ], and the appearance of multi-drug-resistant bacteria [ 17 ] clearly necessitate immediate action to search for novel antimicrobials. In hospitals, Pseudomonas aeruginosa is a notorious, opportunistic, multi-drug-resistant human pathogen frequently encountered in nosocomial infections; the third most common bacterial isolate from blood-borne infections; and the most frequent cause of nosocomial pneumonia [ 18 , 19 , 20 ]. It is known to form drug-immune biofilms and to cause urinary tract infections; ear, nose, and throat infections; and cardiovascular and bloodstream infections.…”