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Sirvi Autor "Praakle, Kristi (advisor)" järgi

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  • Pisipilt
    Kirje
    Antibacterial activity of biosynthesized graphitic carbon nitride nanohybrid
    (Eesti Maaülikool, 2026) Oberg, Mari-Liis; Praakle, Kristi (advisor); Panchal, Priyanka (advisor); Veterinaarse biomeditsiini ja toiduhügieeni õppetool
    Antimicrobial resistance (AMR) is a rapidly escalating global health threat driven by the excessive and improper use of antibiotics in both human and veterinary medicine. The shared use of antimicrobial agents across these sectors has accelerated the emergence of resistant bacteria, leading to treatment failures, increased mortality, and major economic losses. Due to the declining effectiveness of conventional antibiotics and the limited development of new antimicrobial drugs, nanotechnology has emerged as a promising complementary strategy for AMR control. The aim of this thesis was to evaluate the antibacterial activity of a zinc oxidedoped graphitic carbon nitride nanohybrid (ZnO/GCN-NH) using a green synthesis approach. Antibacterial activity was evaluated using disk diffusion and well diffusion methods against two Gram-positive bacteria, Staphylococcus aureus and Streptococcus dysgalactiae, and two Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa. The ZnO/GCN-NH demonstrated antibacterial activity against all tested bacterial strains. In the disk diffusion method, inhibition zones ranged from 14 to 17.2 mm, while in the well diffusion method they ranged from 17.5 to 18.5 mm. In comparison, the pure plant extract, pure graphitic carbon nitride nanoparticles (GCN-NP) and pure zinc oxide nanoparticles (ZnO-NP) showed only limited antibacterial activity. These results suggest that the formation of the ZnO/GCN-NH improved antibacterial performance compared with the individual components.
  • Pisipilt
    Kirje
    Effects of cobalt nanoparticles on Trichophyton spp. in vitro
    (Eesti Maaülikool, 2026) Tulmin, Karl; Praakle, Kristi (advisor); Rauwel, Erwan (advisor); Veterinaarse biomeditsiini ja toiduhügieeni õppetool
    Dermatophytosis is a common zoonotic fungal skin infection affecting both animals and humans, and is caused by species of the genera Trichophyton, Microsporum, and Epidermophyton. Diagnosis relies on clinical evaluation supported by laboratory methods, with isolation and cultivation remaining among the most reliable approaches. Recent advances in nanotechnology have increased interest in metal nanoparticles due to their antimicrobial properties. Cobalt metal nanoparticles (Co MNPs) have been shown to exhibit inhibitory effects against various microorganisms, including fungi. The aim of this thesis was to study the antifungal properties of Co MNPs against dermatophyte fungi in vitro, with a focus on Trichophyton spp. A fungal isolate of bovine origin associated with dermatophytosis was used as the test organism. Different weight percent concentrations (0, 0.5, 1, and 2 wt%) of Co MNPs incorporated into Aloe vera gel were applied on Sabouraud Dextrose Agar plates at inoculation distances of 1 cm and 2 cm, and their effect on fungal growth was assessed. The observed reduction in fungal growth indicates a concentration- and distance-dependent inhibitory effect, with complete inhibition achieved only at the highest concentration (2 wt%) at a distance of 1 cm. At all other tested concentrations, fungal growth was observable, including 0 wt% at 1 cm, and 0 wt%, 0.5 wt% and 1 wt% at 2 cm distance, although in some cases the growth was very limited (0,5 wt% and 1 wt% at 1 cm, and 2 wt% at 2 cm distance). Nanotechnology offers promising possibilities and Co MNPs may represent a potential option for future antifungal therapies. However, their cytotoxic effects require further investigation before clinical application.
  • Pisipilt
    Kirje
    Prevalence of methicillin-resistant Staphylococcus aureus in shelter dogs in Estonia
    (Eesti Maaülikool, 2025) Neva, Nea Maria Nanette; Praakle, Kristi (advisor); Chair of Veterinary Biomedicine and Food Hygiene
    Antibiotic resistance is an increasing global problem in general, and as part of a broader problem, methicillin-resistant Staphylococcus aureus (MRSA) has high global prevalence rates. In contrast, the development of new effective antibiotics has slowed down, putting both human and veterinary professions in a problematic situation. Due to the zoonotic potential of MRSA and the fact that dogs are increasingly integrated into human households as well as the interest in dog adoption has been increased during previous years, a deeper understanding of MRSA in dogs must be raised among humans since it can help limit its spread to humans and improve resistant infection control strategies. In March and April 2023, a study was performed to investigate the prevalence of MRSA in shelter dogs in Estonia. In total, 74 samples from 37 dogs in four different dog shelters in Estonia were collected. From each dog, one swab sample was taken from the nostrils and oral mucous membrane, and another from the perianal area. The modified protocol of the European Union Reference Laboratory for Antimicrobial Resistance was used to isolate and identify MRSA. Sample analysis was performed at the microbiology laboratory of the Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences. The results of this study showed that none of the collected samples were positive for MRSA. To the authors' knowledge, this study represents the first investigation of MRSA in shelter dogs in Estonia, highlighting the need for this initial research.