Evaluation of Antibacterial Activity and Acute Toxicity of Methanol Extracts of Artemisia absinthium, Datura stramonium, and Solanum anguivi.

Background: Bacterial pathogens have evolved numerous defense mechanisms against commercial antimicrobial agents, and their resistance to most of the available antimicrobials is increasing. Medicinal plants are a potential source of antimicrobial agents during the spread and emergence of infectious disease caused by resistant microorganisms. The aim of this study was thus to investigate the antimicrobial activity and acute toxicity of 80% methanol extracts of leaves of Artemisia absinthium, seeds of Datura stramonium, and fruit of Solanum anguivi. Materials and Methods: The 80% methanol extracts were prepared by cold maceration. Antimicrobial activity was evaluated against five bacterial species using agar-well diffusion at concentrations of 125, 250, and 500 mg/mL in the presence of positive and negative controls. Minimum inhibitory concentration was determined by broth dilution. The acute toxicity study was done following OECD guidelines. Results: The 80% methanol extract of the fruit of S. anguivi exhibited better activity against most of the bacterial strains, of which Salmonella enterica serovar Typhimurium was found to be the most susceptible, with minimum inhibitory concentration and minimum bactericidal concentration of 1.3 mg/mL and 1.95 mg/mL, respectively, while the seed extract of D. stramonium showed the least activity against most test organisms. The acute toxicity study showed that all three plants had an LD50 >2,000 mg/kg body weight, and were thus safe. Conclusion: The results of this study revealed that the methanol extracts of the three plants (A. absinthium, D. stramonium, and S. anguivi) had different degrees of antibacterial activity against the selected pathogenic bacteria and were safe at higher doses, thus being of great potential to be developed as antibacterial agents. The study also provided scientific evidence to support the continued traditional use of these medicinal plants by communities in different parts of Ethiopia to treat infectious diseases.

Nontyphoidal Salmonella and Their Antimicrobial Susceptibility among Diarrheic Patients Attending Private Hospitals in Addis Ababa, Ethiopia.

Nontyphoidal Salmonella (NTS) is one of the major causes of bacterial foodborne infection. It is mainly manifested by self-limiting gastroenteritis in healthy individuals but can also cause severe complications including blood stream infection and mortality. The emergence of multidrug-resistant strains of Salmonella is becoming a global public health concern. This study is aimed at estimating the prevalence of Salmonella, identifying serotypes involved, and investigating antimicrobial susceptibility of the isolates among diarrheic patients attending private hospitals in Addis Ababa. We collected a total of 298 stool samples from diarrheic patients attending five private hospitals in Addis Ababa and isolated Salmonella according to standard microbiological techniques; the isolates were serotyped using slide agglutination and microplate agglutination techniques. Antimicrobial susceptibility test of the isolates was carried out using Kirby-Bauer disc diffusion assay according to Clinical Laboratory Standards Institute guidelines. Fourteen stool samples (4.7%) were positive for Salmonella, and Salmonella Kiambu was the most dominant serovar (n = 7, 50%) followed by S. Saintpaul (n = 4, 28.6%) and S. Haifa (n = 2, 14.3%). Three (21.4%) of the isolates were resistant to sulfisoxazole and tetracycline each and 2 (14.3%) to ampicillin. Resistance to two antimicrobials was detected only in 2 (14.3%) of the isolates, and none of the isolates were resistant to more than two antimicrobials. In conclusion, the current study showed low prevalence of NTS in diarrheic patients attending private hospitals in Addis Ababa. Although multidrug resistance to several antimicrobials was not detected in the isolates, prudent use of antimicrobials is recommended to guaranty the long-term use of the available antimicrobials.

Non-typhoidal Salmonella serovars in poultry farms in central Ethiopia: prevalence and antimicrobial resistance.

BACKGROUND: Poultry is one of the common sources of non-typhoidal Salmonella and poultry products are the major sources of human infection with non-typhoidal Salmonella. In spite of flourishing poultry industry in the country, data on prevalence and antimicrobial susceptibility of non-typhoidal Salmonella serovars at farm level is not available in Ethiopia. This study investigated prevalence, serotype distribution and antimicrobial resistance of non-typhoidal Salmonella in poultry farms in Addis Ababa and its surrounding districts. RESULTS: A total of 549 fresh pool of fecal droppings (n = 3 each) were collected from 48 poultry farms and cultured for Salmonella using standard laboratory technique and serotyped using slide agglutination technique. Susceptibility of Salmonella isolates to18 antimicrobials was tested according to CLSI guideline using Kirby-Bauer disk diffusion assay. Salmonella was recovered in 7 (14.6%) of the farms and 26 (4.7%) of the samples. Salmonella was more common in poultry farms with larger flock size than in the smaller ones and in Ada'a district as compared to other districts. All isolates were obtained from farms containing layers. Two out of 6 (33.3%) farms that kept birds in cage were positive for Salmonella while only 5 (11.9%) of the 42 farms who used floor system were positive. Oxytetracycline was used widely in 40 (83.3%) of the farms, followed by amoxicillin 14 (29.2%) and sulfonamides 11 (22.9%). Salmonella Saintpaul was the dominant serotype detected accounting for 20 (76.9%) of all isolates. Other serovars, such as S. Typhimurium3 (11.5%), S. Kentucky 2 (7.7%) and S. Haifa 1 (3.8%) were also detected. Of all the Salmonella isolates tested, 24 (92.3%) were intermediately or fully resistant to sulfisoxazole and streptomycin, 12 (46.2%) to cephalothin, while 11 (42.3%) were resistant to ampicillin, amoxicillin+clavulanic acid, kanamycin and chloramphenicol. Multidrug resistance (MDR) to several drugs was common in S. Kentucky and S. Saintpaul. CONCLUSION: Despite low prevalence of Salmonella in poultry farms in the study area, circulation of MDR strains in some farms warrant special biosecurity measures to hinder dissemination of these pathogens to other farms and the public. Moreover, awareness creation on prudent use of antimicrobials is recommended.

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.

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.

Ovicidal and larvicidal activity of crude extracts of Maesa lanceolata and Plectranthus punctatus against Haemonchus contortus.

The widespread development of anthelmintic resistance and high cost of the conventional anthelmintic drugs, has limited the control of gastrointestinal nematode parasites of sheep and goats and hence led to evaluation of medicinal plants as an alternative source of anthelmintics. In the current study, in vitro ovicidal and larvicidal activity of the leaves and fruits of the aqueous and hydro-alcoholic extracts of Maesa lanceolata and aerial parts of Plectranthus punctatus were evaluated on the egg and larvae of Haemonchus contortus using egg hatch assay and larval development test. All extracts of plants tested have shown complete inhibition of egg hatching at or below 1 mg/ml. ED50 for egg hatch inhibition ranged from 0.11 to 0.29 mg/ml, for both the aqueous and hydro-alcoholic extracts of Plectranthus punctatus and Maesa lanceolata. All extracts have shown dose dependent inhibition of larval development with variable results. The complete inhibition (100%) at the maximum concentration tested (50 mg/ml) was obtained only for hydro-alcoholic extract of the fruits of Maesa lanceolata and the lowest inhibition (50.33%) was recorded for the hydro-alcoholic extract of the leaves of the same plant. The overall findings of the present study has shown that Plectranthus punctatus and Maesa lanceolata contain possible anthelmintic compounds and further evaluation of different extracts and fractions of these plants should be carried out.