Browsing by Author "Eguale, Tadesse"
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Item In Vitro and In Vivo Evaluation of Anthelmintic Activities of Crude Extracts of Selected Medicinal Plants Against Haemonchus Contortus(Addis Ababa University, 2005-12) Eguale, Tadesse; Mekonnen, Eyasu (Professor); Tilahun, Getachew(Associate Professor ); Debella, Asfaw (PhD)In the current study, in vitro experiments were conducted to determine the possible anthelmintic effects of crude aqueous and hydro-alcoholic extracts of the seeds of Croton macrostachyus, Ekebergia capensis, Coriandrum sativum, Acacia nilotica, Terminalia schimperiana, Jatropha curcas, leaves of Lawsonia inermis, Chenopodium ambrosioides, ripe berries of Hedera helix, and bark of Albizia gummifera on eggs and adult Haemonchus contortus. Aqueous extracts of C. sativum and H. helix were also investigated for toxicity (LD50 determination) in Albino mice and for in vivo anthelmintic activity in sheep infected with H. contortus. Both extract types of C. macrostachyus, E. capensis, C. sativum, J. curcas, A. gummifera and aqueous extract of A. nilotica inhibited hatching of eggs at concentration less than or equal to 2 mg/ml. Based on their ED50, the six most potent extracts were aqueous extract of E. capensis (0.06mg/ml), Hydro-alcoholic extract of C. ambrosioides (0.09mg/ml), aqueous extract of C. macrostachyus and J. curcas (0.1mg/ml) aqueous extract of C. sativum and H. helix (0.12mg/ml), in decreasing order of potency. Hydro-alcoholic extract of A. nilotica, both extracts of T. schimperiana and L. inermis did not inhibit hatching of eggs of H. contortus significantly and in dose dependent manner at all concentrations tested. Hydro-alcoholic extracts of most of the plants have shown better in vitro activity against adult parasites compared to the aqueous extract. Hydro-alcoholic extracts of C. macrostachyus, A. gummifera, C. sativum and H. helix produced mortality of adult H. contortus significantly to the level of 90, 86.67,85 and 66.67% at concentration of 8 mg/ml while aqueous extracts produced only 36.67, 33.33, 45,and 29.17% respectively at the same concentration. Like their activity on eggs, extracts of A. nilotica, T. schimperiana, J. curcas and L. inermis have shown no statistically significant effect on survival of the adult parasites at the concentrations tested, and a few mortality cases recorded were not dose dependent (p<0.05). Oral administration of aqueous extract of C. sativum didn’t produce mortality and no clinical sign of toxicity was detected in mice despite the high dose (15000 mg/kg) given, while intraperitonial (IP) administration caused mortality at lower doses. IP LD50 for C. sativum was 2177.5 mg/kg. Oral LD50 for H. helix was 3846.09 mg/kg. In vitro anthelmintic evaluation was conducted in total of 36 male sheep artificially infected with H. contortus. The sheep were randomly divided into six groups of six animals each. The first four groups were treated with crude aqueous extract of C. sativum (0.45g/kg), C. sativum (0.90g/kg), x H. helix (1.13g/kg), H. helix (2.25g/kg) respectively. The fifth group was treated with albendazole at 3.8mg/kg and the last group was left untreated. Efficacy was tested by faecal egg count reduction (FECR) and total worm count reduction (TWC). On day 2 post treatment, significant FECR was detected in group treated with higher dose of C. sativum, both doses of H. helix (p<0.05) and albendazole (p<0.001) compared to untreated control group. The maximum efficacy of the extracts observed on day 2 post treatment was 46.71% for higher dose of H. helix (2.25g/kg) and 24.79% for higher dose of C. sativum (0.9g/kg). On day 7 post treatment, significant reduction was detected only for higher dose of H. helix (p<0.05) and albendazole (p<0.001). The percentage reduction of FEC of sheep treated with both plant extracts decreased gradually on day 7 and day 14 post treatment, while that of albendazole increased from 97.8 on day 2 to 100% on day 14 post treatment. The percentage of larvae recovered from culturing faeces obtained from group of sheep treated with plant extracts was reduced in dose dependant manner compared to faeces obtained from untreated control group. Significant reduction (p<0.05) in TWC was detected for higher dose of C. sativum and both dose levels of H. helix compared to the untreated group. Reduction in male worm count was significant (p<0.05) in all treatment groups except for lower doses of C. sativum, while significant reduction of female worm count was detected only in the case of higher doses of H. helix. No worm was detected in the group treated with albendazole, indicating significant susceptibility of the strain of parasites employed in the current study. Treatment with both doses of H. helix helped the animals maintain their PCV while PCV of animals treated with C. sativum decreased significantly. Treatment with albendazole showed significant increase in PCV (p<0.05). The overall findings of the current study indicated that most of the plants have potential anthelmintic effect and further in vitro and in vivo evaluation is warranted to make use of these plants in the future.Item Phenotypic and Molecular Characterization of Non-typhoidal Salmonella Species in Humans and Animals in Central Ethiopia and Inhibition of Biofilm Formation Using Small Molecule Adenosine Mimetics(Addis Ababa University, 2016-06) Eguale, Tadesse; Asrat, Daniel(PhD); Eingidawork, Ephrem (PhD)This dissertation reports prevalence, serotype distribution and phenotypic and genotypic characteristics of non-typhoidal Salmonella (NTS) in humans and animals in central Ethiopia and effect of small molecule adenosine mimetic compounds on Salmonella biofilm formation. Farm level and animal level Salmonella prevalence was (7.6%, 2.3%) in dairy; (14.6%, 4.7%) in poultry; and (42.6%, 4.4%) in swine farms. The prevalence was 7.2% in diarrheic patients from primary health centers and 2.1% from hospitals. S.Typhimurium (27.6%) was the most frequently isolated serotype, followed by S. Saintpaul (21.7%), S. Virchow (18.4%) and S. Kentucky (6.6%). Salmonella isolation was significantly associated with detection of diarrhea in dairy cattle (p=0.012), and consumption of raw vegetables in humans (OR=1.91, 95% CI=1.29-2.83, χ2=4.74, p=0.025). Drug resistance was more common in dairy farms in Addis Ababa than outside (p=0.009) and overall antimicrobial resistance was more common in animals than in humans. Clonally related genotypes of S.Virchow, S.Typhimurium, S.Kentucky, S.Braendurp and S. Miami were circulating among humans and animals as determined by pulsed-field gel electrophoresis (PFGE). MLST analysis showed 3 novel allele types and 5 novel sequence types among 21 strains examined. The dominant beta-lactamase enzyme was blaTEM type. BlaOXA10 and blaCTX-15 were detected only in a single MDR S. Concord strain. Double mutation in gyrA (Ser83-Phe and Asp87-Gly) as well as parC (Thr57-Ser + Ser80-Ile) subunits of quinolone resistance determining region (QRDR) was the primary mechanism for resistance to quinolones and was detected in all S. Kentucky isolates resistant to both nalidixic acid and ciprofloxacin from animals (n=8) and humans (n=2). Although decreased susceptibility to ciprofloxacin and/or nalidixic acid was observed in some isolates, no mutation in QRDR nor plasmid mediated quinolone resistance (PMQR) genes were detected. Majority of Salmonella ii isolates exhibited robust biofilm formation (89%) and displayed red dry and rough (RDAR) morphotype. Detection of class 1 integron was correlated with expression of multicellular behavior and the extent of MDR. Screening of an ATP-mimetic library, gave a single compound (7955004) capable of significant inhibition of Salmonella enterica and Acinetobacter baumannii biofilm formation. The compound was not bactericidal or bacteriostatic toward S. Typhimurium nor cytotoxic to mammalian cells. GroEL and DeoD were found to be the potential protein-binding targets of the compound as identified by ATP-sepharose affinity matrix. Circulation of clonally related NTS serotypes in food animals and humans, abundance of MDR in isolates from food animals, co-dominance of MDR and multicellular behavior in Salmonella isolates in the study area, increased the risk of spreading resistant Salmonella strains and resistance genes to human population. Integrated surveillance of NTS in humans and animals and implementation of appropriate pathogen control strategy along critical points in food animal production from farm to bench is recommended. The identification of a lead compound with biofilm inhibitory capabilities toward Salmonella provides a potential new avenue of therapeutic intervention against Salmonella and other bacterial pathogens. Further activity guided evaluation of compound 7955004 and its derivatives with the goal of increasing its potency and broadening its spectrum of activity against additional biofilm forming pathogens should be conducted. Key words: Antimicrobial resistance, Biofilm, Non-typhoidal Salmonella, Prevalence, Serotype