Tadesse Eguale

In vitro anthelmintic activity of crude extracts of five medicinal plants against egg-hatching and larval development of Haemonchus contortus.

ETHNOPHARMACOLOGICAL RELEVANCE Senna occidentalis, Leonotis ocymifolia, Leucas martinicensis, Rumex abyssinicus, and Albizia schimperiana are traditionally used for treatment of various ailments including helminth infection in Ethiopia. MATERIALS AND METHODS In vitro egg hatch assay and larval development tests were conducted to determine the possible anthelmintic effects of crude aqueous and hydro-alcoholic extracts of the leaves of Senna occidentalis, aerial parts of Leonotis ocymifolia, Leucas martinicensis, Rumex abyssinicus, and stem bark of Albizia schimperiana on eggs and larvae of Haemonchus contortus. RESULTS Both aqueous and hydro-alcoholic extracts of Leucas martinicensis, Leonotis ocymifolia and aqueous extract of Senna occidentalis and Albizia schimperiana induced complete inhibition of egg hatching at concentration less than or equal to 1mg/ml. Aqueous and hydro-alcoholic extracts of all tested medicinal plants have shown statistically significant and dose dependent egg hatching inhibition. Based on ED(50), the most potent extracts were aqueous and hydro-alcoholic extracts of Leucas martinicensis (0.09 mg/ml), aqueous extracts of Rumex abyssinicus (0.11 mg/ml) and Albizia schimperiana (0.11 mg/ml). Most of the tested plant extracts have shown remarkable larval development inhibition. Aqueous extracts of Leonotis ocymifolia, Leucas martinicensis, Albizia schimperiana and Senna occidentalis induced 100, 99.85, 99.31, and 96.36% inhibition of larval development, respectively; while hydro-alcoholic extracts of Albizia schimperiana induced 99.09 inhibition at the highest concentration tested (50mg/ml). Poor inhibition was recorded for hydro-alcoholic extracts of Senna occidentalis (9%) and Leonotis ocymifolia (37%) at 50mg/ml. CONCLUSIONS The overall findings of the current study indicated that the evaluated medicinal plants have potential anthelmintic effect and further in vitro and in vivo evaluation is indispensable to make use of these plants.

Evaluation of in vivo wound healing activity of methanol extract of Achyranthes aspera L.

ETHNOPHARMACOLOGICAL RELEVANCE The leaves of Achyranthes aspera L. (Amarenthacea) has been used traditionally for the treatment of wound in various parts of Ethiopia. However, the plant has not been explored scientifically for its wound healing activity. Therefore, this study was designed to investigate the wound healing activity of methanol extract of Achyranthes aspera L. leaves in rats. MATERIALS AND METHODS Incision and excision wounds were inflicted on albino rats of either sex, under diethyl ether anesthesia. Group I served as positive control and was treated with 1% silver sulphadiazine, group II, III, IV treated with simple ointment containing 2.5%, 5% and 10% (w/w) methanol extract of the leaves of Achyranthes aspera L., respectively, whereas group V served as negative control and was treated with simple ointment. All the animals were treated topically once a day. Wound healing potential was assessed with excision and incision wound model. Excision wound model was used to assess the change in percentage contraction of wound, epithelization time, DNA content and histological features whereas rats inflicted with the incision wounds were used to determine breaking strength. RESULTS Based on the results of percentage wound contraction, the DNA content and epithelization time, all groups of rats treated with methanol extract of the leaves of Achyranthes aspera L. showed significant (p<0.05) wound healing activity compared to group of rats treated with simple ointment (negative control) group. The difference in breaking strength was, however, significant (p<0.05) only for the 5% and 10% methanol extract of Achyranthes aspera (w/w) ointment treated groups. Histological evaluation showed well organized epidermal layer, increased number of fibrocytes, remarkable degree of neovascularization and epithelization which was comparable to the standard on the 21st day after treatment; especially in the 5% and 10% (w/w) extract treated group. CONCLUSION The present study provides a scientific rationale for the traditional use of the leaf extracts of Achyranthes aspera L. in the treatment of wound.

Inhibition of Salmonella enterica Biofilm Formation Using Small-Molecule Adenosine Mimetics

ABSTRACT Biofilms have been widely implicated in chronic infections and environmental persistence of Salmonella enterica, facilitating enhanced colonization of surfaces and increasing the ability of the bacteria to be transmitted to new hosts. Salmonella enterica serovar Typhi biofilm formation on gallstones from humans and mice enhances gallbladder colonization and bacterial shedding, while Salmonella enterica serovar Typhimurium biofilms facilitate long-term persistence in a number of environments important to food, medical, and farming industries. Salmonella regulates expression of many virulence- and biofilm-related processes using kinase-driven pathways. Kinases play pivotal roles in phosphorylation and energy transfer in cellular processes and possess an ATP-binding pocket required for their functions. Many other cellular proteins also require ATP for their activity. Here we test the hypothesis that pharmacological interference with ATP-requiring enzymes utilizing adenosine mimetic compounds would decrease or inhibit bacterial biofilm formation. Through the screening of a 3,000-member ATP mimetic library, we identified a single compound (compound 7955004) capable of significantly reducing biofilm formation by S. Typhimurium and S. Typhi. The compound was not bactericidal or bacteriostatic toward S. Typhimurium or cytotoxic to mammalian cells. An ATP-Sepharose affinity matrix technique was used to discover potential protein-binding targets of the compound and identified GroEL and DeoD. Compound 7955004 was screened against other known biofilm-forming bacterial species and was found to potently inhibit biofilms of Acinetobacter baumannii as well. The identification of a lead compound with biofilm-inhibiting capabilities toward Salmonella provides a potential new avenue of therapeutic intervention against Salmonella biofilm formation, with applicability to biofilms of other bacterial pathogens.

Association of multicellular behaviour and drug resistance in Salmonella enterica serovars isolated from animals and humans in Ethiopia.

To determine the association between multicellular behaviour, integron status and antibiotic resistance among 87 Ethiopian Salmonella enterica isolates of animal and human origin.

Phenotypic and genotypic characterization of temporally related nontyphoidal Salmonella strains isolated from humans and food animals in central Ethiopia

Salmonella is one of the common causes of food‐borne bacterial illnesses. The primary sources of human nontyphoidal Salmonella (NTS) infection are food animals. This study characterized temporally and spatially related Salmonella isolated during April 2013 to March 2014 from faeces of diarrhoeic human patients in Addis Ababa (n = 68) and food animals (n = 84) in Addis Ababa and surrounding districts (dairy cattle, n = 30; slaughtered cattle, n = 20; poultry, n = 26; swine n = 8). Isolates were serotyped, page typed and tested for antimicrobial susceptibility using Kirby–Bauer disc diffusion method, and genotyped by pulsed‐field gel electrophoresis (PFGE). The dominant Salmonella serovars isolated from food animals were S. Saintpaul (38.1%), S. Typhimurium (17.9%) and S. Kentucky (9.5%), whereas in humans, S. Typhimurium (39.7%), S. Virchow (30.9%) and S. Kottbus (10.3%) were frequently isolated. Resistance to streptomycin, sulfisoxazole, tetracycline, ampicillin and cephalothin was higher in animal isolates than human isolates, and mean number of antimicrobials to which isolates were resistant was significantly higher in isolates from cattle and poultry compared to those from humans (p < 0.05). All S. Kentucky isolated from animals and humans were multidrug resistant (MDR) with shared resistance phenotype (AmpCfCipTeSuSNa). Although this study involved small sample size and was not able to show clear epidemiological linkage among isolates from various sources, genotyping by PFGE analysis demonstrated circulation of closely related genotypes of S. Virchow, S. Typhimurium and S. Kentucky among humans and food animals. Detection of related Salmonella isolates from humans and animals, the high MDR status of isolates from animals and close proximity of farms and human residential areas in the absence of appropriate biosecurity present major public health problem. Integrated surveillance of Salmonella serovars in humans and animals and implementation of appropriate hazard analysis and pathogen control strategies along critical points of the food chain from farm to table is recommended.