Programme: Applied Biology

Permanent URI for this collectionhttp://itsupport.cu.edu.ng:4000/handle/123456789/28776

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Author: search.filters.author.Covenant University, DissertationHas files: Yes

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    EVALUATION OF LYTIC BACTERIOPHAGES FOR MULTI-DRUG RESISTANT Pseudomonas aeruginosa ISOLATED FROM SELECTED CLINICAL SAMPLES
    (Covenant University, Ota, 2026-08) ADELEYE, Olufunmilayo Damilola; Covenant University, Dissertation
    Pseudomonas aeruginosa is one of the Gram-negative pathogens most difficult to isolate clinically because of its propensity to acquire resistance determinants against almost all antibiotics currently in use. The goal of this study was to define the spectrum of resistance in clinical isolates from a local region and to examine the hypothesis that indigenous phages obtained from the environment might serve as a biological control for these isolates. Specimens (wound, urine, high vaginal, urethral, anus and ear swabs) were plated onto selective and general growth media and the isolates presumptive to be Pseudomonas were confirmed by microscopical and biochemical tests (gram stain, oxidase, catalase, TSI). The confirmed isolates were tested for sensitivity to twelve antibiotic agents by the Kirby-Bauer disc diffusion method, and in some cases further confirmed using 16S rRNA gene sequencing. Raw sewage was screened as a potential phage source by enrichment using a clinical strain, filtration, double-layer agar plating, and Transmission electron microscopy to visualise the phages present in the environment. We collected 12 Pseudomonas strains from 36 clinical samples; it was evident that all the isolates were multi-resistant to almost every tested β-lactam, fluoroquinolone, macrolide and aminoglycoside drugs; isolates are sensitive to levofloxacin and gentamicin, respectively. The 16S rRNA sequences showed not only Pseudomonas aeruginosa but also three related species: Pseudomonas putida, Pseudomonas mendocina, Pseudomonas stutzeri. The later information suggests that after culturing and biochemical testing a wider range of species can be identified from a bacterial population. The enrichment allowed us to obtain lytic phages able to lyse all of the multi-resistant Pseudomonas strains: the zones of lysis were round, distinct and 1-3 mm in diameter; the particles identified via electron microscopy were tailed icosahedral phages of approx. 20 nm and with short, non-contractile tails. In conclusion, multi-resistant Pseudomonas isolates do remain present in the investigated population of Nigeria, and the sewage is an easily and accessible natural source of Pseudomonas-active lytic phages. This study gives useful data specific for Nigeria to be further investigated on the lytic activity of phages against Pseudomonas aeruginosa.
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    IN VIVO IN VITRO ANTI-PLASMODIAL ACTIVITY OF CHEMICALLY SYNTHESISED IMIDAZOLE COMPOUNDS
    (Covenant University, Ota, 2026-09) OJO, Oluwaferanmi Esther; Covenant University, Dissertation
    Malaria remains a leading cause of morbidity and mortality globally, with the continued emergence of Plasmodium falciparum resistance to artemisinin-based therapies rendering the identification of novel chemotherapeutic scaffolds an urgent priority. The imidazole family of compounds, with their adaptable framework and ability to engage parasite-specific targets such as falcipain-2 and hemozoin biosynthesis machinery, represent compelling synthetic leads. This study evaluates the in vitro anti-plasmodial activity and in vivo efficacy and safety profiles of two newly synthesised compounds: 4,5-diphenyl-2-(m-tolyl)-1H-imidazole (IM1) and 4,5-diphenyl-2- (m-tolyl)-1-tosyl-1H-imidazole (IM2). In vitro susceptibility was assessed using a schizont maturation inhibition assay against the chloroquine-sensitive P. falciparum 3D7 strain. In vivo evaluation employed Peter's 4-d suppressive test in P. berghei ANKA-infected Swiss albino mice administered oral doses of 20–400 mg/kg. Acute toxicity was assessed according to the OECD 423 guidelines through haematological, biochemical, oxidative stress, and histopathological analyses. In vitro, IM1 demonstrated higher intrinsic potency, exhibiting a half-maximal inhibitory concentration (IC50) of 3.6 ± 0.2 μg/mL compared to 7.8 ± 0.5 μg/mL for IM2. However, in vivo evaluation revealed a distinct efficacy paradox: IM2 demonstrated superior systemic efficacy, achieving up to 68% parasitaemia suppression at 400 mg/kg, surpassing the 52% suppression observed with IM1. IM2 also significantly extended the mean survival time of infected mice to 12.3 d, compared with 8.1 d for untreated controls. Systemically, IM2 maintained physiological homeostasis, preserved hepatic and renal architecture, and induced significant modulation and stabilization of circulating lymphocytes (p=0.049), compared with the abnormal increase observed in untreated infections. A strong positive correlation between malondialdehyde and glutathione (r=0.839, p=0.005) indicated a well-tolerated, reactive oxygen species-mediated parasiticidal mechanism for IM2. On the other hand, high-dose IM1 (400 mg/kg) induced dose-dependent hepatotoxicity, as evidenced by elevated alanine aminotransferase (44.47 U/L) and histopathological evidence of hepatocyte vacuolation. Ultimately, whilst IM1's highly lipophilic core necessitates structural optimization to mitigate hepatic stress, IM2 represents a promising lead compound that requires further pre-clinical investigations.