scholarly journals Characterization and Rate of Killing of Conjugated Silver Nanoparticles Against Selected Clinical Bacterial Isolates

2022 ◽  
Author(s):  
Stephen Oloninefa ◽  
Abalaka Moses Enemaduku ◽  
Daniyan Safiya Yahaya ◽  
Mann Abdullahi

The menace of drug resistance, bioavailability and drug delivery to the target sites has motivated researchers to search for new antimicrobial agents from medicinal plants and subsequently use them for the biosynthesis of silver nanoparticles for effective killing of bacteria challenging to kill using crude extracts. The biosynthesis of silver nanoparticles was done using aqueous extract (AQE) of E<i>uphorbia heterophylla</i>, while characterization and the killing rate of conjugated silver nanoparticles (CA<sub>g</sub>NP<sub>s</sub>) were carried out using standard methods. The maximum wavelength obtained for CA<sub>g</sub>NP<sub>s</sub> was 410.33 nm, while the size distribution was 237.8 d.nm. The Fourier Transform Infra-Red result showed O-H (3308.94 cm<sup>-1</sup>), which is responsible for stabilising and reducing silver ions, while the Transmission Electron Microscopy revealed the presence of monodispersed spherical shapes CA<sub>g</sub>NP<sub>s</sub>. The Energy Dispersive Spectroscopy confirmed the presence of silver. There were reductions in the clinical bacterial isolates exposed to CA<sub>g</sub>NP<sub>s</sub> as the exposure time increased. <i>Escherichia coli</i> was killed between 6-7 h while<i> Salmonella typhimurium</i> was killed at the seven has the value of 0.00 log<sub>10</sub> CFU/ml was recorded respectively. However, there were increments in the populations of clinical bacterial isolates in control as the time of exposure increased. Therefore, the study suggests that the CA<sub>g</sub>NP<sub>s</sub> exhibit intense antimicrobial activity and the potential to be developed as an alternative agent to treat bacterial infections, curb multidrug-resistant bacterial infection, and promote speedy drug delivery to the target sites.

Author(s):  
Viola Zaki ◽  
Ahmed EL-gamal ◽  
Yasmin Reyad

he present research carried out to study the common bacterial infections in Oreochromis niloticus (Nile tilapia) in Manzala area at Dakahlia governorate and possible antimicrobial agents used for treatment. A total number of 400 fish were randomly collected from Manzala private farms at Dakahlia governorate and subjected to the clinical, bacteriological and histopathological examination. The highest prevalence of bacterial isolates during the whole period of examination of naturally infected O.niloticus was recorded for A.hydrophila (22.66%), followed by V.alginolyticus (19.01%), V.parahemolyticus (13.80%), Streptococcus spp. (12.24%), A.caviae (11.72%), V.cholera (10.16%), A.salmonicida (7.55%), while the lowest prevalence was recorded for Klebsiella oxytoca (2.86%). The seasonal highest total prevalence of bacterial isolates from examined naturally infected O. niloticus was recorded in spring (30.21%), followed by autumn (28.39%), then summer (22.40%) and the lowest prevalence was recorded in winter (19.01%). Histopathological findings of the tissue samples which collected from different organs of naturally infected O.niloticus revealed that spleen show marked hemosiderosis and sever hemorrhage, gills showsever congestion of lamellar capillaries with marked aneurysm, necrosis and hemorrhage of lamellar epithelium and liver show sever hydropic degeneration and necrosis of hepatocytes, Ciprofloxacin was the most effective antibiotic against all isolated bacterial strains


Author(s):  
Shyla Marjorie Haqq ◽  
Amit Chattree

  This review is based on the synthesis of silver nanoparticles (AgNPs) using a green approach which is biofabricated from various medicinal plants. AgNPs were prepared from the various parts of the plants such as the flowers, stems, leaves, and fruits. Various physiochemical characterizations were performed using the ultraviolet (UV)-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, transmission electron microscopy, and energy dispersive spectroscopy. AgNPs were also used to inhibit the growth of bacterial pathogens and were found to be effective against both the Gram-positive and Gram-negative bacteria. For the silver to have antimicrobial properties, it must be present in the ionized form. All the forms of silver-containing compounds with the observed antimicrobial properties are in one way or another source of silver ions. Although the antimicrobial properties of silver have been known, it is thought that the silver atoms bind to the thiol groups in enzymes and subsequently leads to the deactivation of enzymes. For the silver to have antimicrobial properties, it must be present in the ionized form. The study suggested that the action of the AgNPs on the microbial cells resulted into cell lysis and DNA damage. AgNPs have proved their candidature as a potential antibacterial against the multidrug-resistant microbes. The biological agents for synthesizing AgNPs cover compounds produced naturally in microbes and plants. Reaction parameters under which the AgNPs were being synthesized hold prominent impact on their size, shape, and application. Silver nanoparticle synthesis and their application are summarized and critically discussed in this review.


Author(s):  
Na Li ◽  
Yigang Zeng ◽  
Rong Bao ◽  
Tongyu Zhu ◽  
Demeng Tan ◽  
...  

Klebsiella pneumoniae is a dominant cause of community-acquired and nosocomial infections, specifically among immunocompromised individuals. The increasing occurrence of multidrug-resistant (MDR) isolates has significantly impacted the effectiveness of antimicrobial agents. As antibiotic resistance is becoming increasingly prevalent worldwide, the use of bacteriophages to treat pathogenic bacterial infections has recently gained attention. Elucidating the details of phage-bacteria interactions will provide insights into phage biology and the better development of phage therapy. In this study, a total of 22 K. pneumoniae isolates were assessed for their genetic and phenotypic relatedness by multi-locus sequence typing (MLST), endonuclease S1 nuclease pulsed-field gel electrophoresis (S1-PFGE), and in vitro antibiotic susceptibility testing. In addition, the beta-lactamase gene (blaKPC) was characterized to determine the spread and outbreak of K. pneumoniae carbapenemase (KPC)-producing enterobacterial pathogens. Using these ST11 carbapenem-resistant K. pneumoniae isolates, three phages (NL_ZS_1, NL_ZS_2, and NL_ZS_3) from the family of Podoviridae were isolated and characterized to evaluate the application of lytic phages against the MDR K. pneumoniae isolates. In vitro inhibition assays with three phages and K. pneumoniae strain ZS15 demonstrated the strong lytic potential of the phages, however, followed by the rapid growth of phage-resistant and phage-sensitive mutants, suggesting several anti-phage mechanisms had developed in the host populations. Together, this data adds more comprehensive knowledge to known phage biology and further emphasizes their complexity and future challenges to overcome prior to using phages for controlling this important MDR bacterium.


2020 ◽  
Vol 50 (11) ◽  
pp. 1150-1156
Author(s):  
Jogender Tanwar ◽  
Madhu Sharma ◽  
Aparna Parmar ◽  
Nimisha Tehri ◽  
Neelam Verma ◽  
...  

2020 ◽  
Vol 8 (2) ◽  
pp. 191 ◽  
Author(s):  
Despoina Koulenti ◽  
Elena Xu ◽  
Andrew Song ◽  
Isaac Yin Sum Mok ◽  
Drosos E. Karageorgopoulos ◽  
...  

Antimicrobial agents are currently the mainstay of treatment for bacterial infections worldwide. However, due to the increased use of antimicrobials in both human and animal medicine, pathogens have now evolved to possess high levels of multi-drug resistance, leading to the persistence and spread of difficult-to-treat infections. Several current antibacterial agents active against Gram-positive bacteria will be rendered useless in the face of increasing resistance rates. There are several emerging antibiotics under development, some of which have been shown to be more effective with an improved safety profile than current treatment regimens against Gram-positive bacteria. We will extensively discuss these antibiotics under clinical development (phase I-III clinical trials) to combat Gram-positive bacteria, such as Staphylococcus aureus, Enterococcus faecium and Streptococcus pneumoniae. We will delve into the mechanism of actions, microbiological spectrum, and, where available, the pharmacokinetics, safety profile, and efficacy of these drugs, aiming to provide a comprehensive review to the involved stakeholders.


2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Marc B. Habash ◽  
Mara C. Goodyear ◽  
Amber J. Park ◽  
Matthew D. Surette ◽  
Emily C. Vis ◽  
...  

ABSTRACT Increasing antibiotic resistance among pathogenic bacterial species is a serious public health problem and has prompted research examining the antibacterial effects of alternative compounds and novel treatment strategies. Compounding this problem is the ability of many pathogenic bacteria to form biofilms during chronic infections. Importantly, these communities are often recalcitrant to antibiotic treatments that show effectiveness against acute infection. The antimicrobial properties of silver have been known for decades, but recently silver and silver-containing compounds have seen renewed interest as antimicrobial agents for treating bacterial infections. The goal of this study was to assess the ability of citrate-capped silver nanoparticles (AgNPs) of various sizes, alone and in combination with the aminoglycoside antibiotic tobramycin, to inhibit established Pseudomonas aeruginosa biofilms. Our results demonstrate that smaller 10-nm and 20-nm AgNPs were more effective at synergistically potentiating the activity of tobramycin. Visualization of biofilms treated with combinations of 10-nm AgNPs and tobramycin reveals that the synergistic bactericidal effect may be caused by disrupting cellular membranes. Minimum biofilm eradication concentration (MBEC) assays using clinical P. aeruginosa isolates shows that small AgNPs are more effective than larger AgNPs at inhibiting biofilms, but that the synergy effect is likely a strain-dependent phenomenon. These data suggest that small AgNPs synergistically potentiate the activity of tobramycin against P. aeruginosa in vitro and may reveal a potential role for AgNP/antibiotic combinations in treating patients with chronic infections in a strain-specific manner.


2021 ◽  
Vol 3 ◽  
Author(s):  
Kenneth Ssekatawa ◽  
Denis K. Byarugaba ◽  
Charles D. Kato ◽  
Eddie M. Wampande ◽  
Francis Ejobi ◽  
...  

Antibiotics have been the nucleus of chemotherapy since their discovery and introduction into the healthcare system in the 1940s. They are routinely used to treat bacterial infections and to prevent infections in patients with compromised immune systems and enhancing growth in livestock. However, resistance to last-resort antibiotics used in the treatment of multidrug-resistant infections has been reported worldwide. Therefore, this study aimed to evaluate green synthesized nanomaterials such as silver nanoparticles (AgNPs) as alternatives to antibiotics. UV-vis spectroscopy surface plasmon resonance peaks for AgNPs were obtained between 417 and 475 nm. An X-ray diffraction analysis generated four peaks for both Prunus africana extract (PAE) and Camellia sinensis extract (CSE) biosynthesized AgNPs positioned at 2θ angles of 38.2°, 44.4°, 64.5°, and 77.4° corresponding to crystal planes (111), (200), (220), and (311), respectively. A dynamic light-scattering analysis registered the mean zeta potential of +6.3 mV and +0.9 mV for PAE and CSE biosynthesized nanoparticles, respectively. Fourier transform infrared spectroscopy spectra exhibited bands corresponding to different organic functional groups confirming the capping of AgNPs by PAE and CSE phytochemicals. Field emission scanning electron microscopy imaging showed that AgNPs were spherical with average size distribution ranging from 10 to 19 nm. Biosynthesized AgNPs exhibited maximum growth inhibitory zones of 21 mm with minimum inhibitory concentration and minimum bactericidal concentration of 125 and 250 μg/ml, respectively, against carbapenem-resistant bacteria.


2020 ◽  
Vol 10 (03) ◽  
pp. 337-343
Author(s):  
Anwer J. Faisal ◽  
Munim Radwan Ali ◽  
Layla Abdulhamid Said

Pseudomonas aeruginosa can regulate different group actives and physiological processes through the quorum sensing mechanism. The aims of this research were to detect the presence of quorum sensing genes in 50 clinical P. aeruginosa isolates, which represent by (lasI, lasR, rhlI, and rhlR) and Pseudomonas quinolone signal (PQS) (PgsA, PgsB, PgsC, PgsD, PgsE, and MvfR) genes by Polymerase chain reaction (PCR) technique and interaction between the two systems. Isolates were subjected to test their susceptibility to 12 antimicrobial drugs, 64% of isolates showed resistance to ceftazidime, followed by carbencillin (56%), while only 8% were resistant to imipenem. In addition, all of the bacterial isolates were distributed within three multidrug-resistant (MDR) patterns, viz., A, B, and C. The highest rate of MDR was showed with MDR pattern C, in which bacterial isolates showed resistance to resist (9→11) antimicrobial drugs. Results revealed that P. aeruginosa isolates have different gene patterns, viz., A to E. According to quorum sensing genes production, pattern A found to express all the genes in LasI, RhI, and PQS system, while pattern B has a defective for the production of lasR, rhlR genes, while the same isolates have the PQS system all present. Significantly, there is a positive relationship between las and rhl system and regulation of antibiotics resistance, in which the bacterial isolates that have las and rhl genes showed high resistance to common antimicrobial agents under study. These findings suggest that PQS can function as an intercellular signal in P. aeruginosa that is not restricted only to alkyl homoserine lactones (AHL).


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