To isolate, evaluate and characterize potential antibiotic producing actinomycetes from water and sediments of Lake Tana, Ethiopia. Methods: A total of 31 strains of actinomycetes were isolated and tested against Gram positive and Gram negative bacterial strains by primary screening. In the primary screening, 11 promising isolates were identified and subjected to solid state and submerged state fermentation methods to produce crude extracts. The fermented biomass was extracted by organic solvent extraction method and tested against bacterial strains by disc and agar well diffusion methods. The isolates were characterized by using morphological, physiological and biochemical methods. Results: The result obtained from agar well diffusion method was better than disc diffusion method. The crude extract showed higher inhibition zone against Gram positive bacteria than Gram negative bacteria. One-way analysis of variance confirmed most of the crude extracts were statistically significant at 95% confidence interval. The minimum inhibitory concentration and minimum bactericidal concentration of crude extracts were 1.65 mg/mL and 3.30 mg/mL against Staphylococcus aureus, and 1.84 mg/mL and 3.80 mg/mL against Escherichia coli respectively. The growth of aerial and substrate mycelium varied in different culture media used. Most of the isolates were able to hydrolysis starch and urea; able to survive at 5% concentration of sodium chloride; optimum temperature for their growth was 30 °C. Conclusions: The results of the present study revealed that freshwater actinomycetes of Lake Tana appear to have immense potential as a source of antibacterial compounds.

Objective: To evaluate the antibacterial activities of the crude leaves extracts of Zehneria scabra (Z. scabra) and Ricinus communis (R. communis) against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and methicillin resistance S. aureus. Methods: The crude powdered leaves of Z. scabra and R. communis were extracted successively by organic solvents in increasing polarity [benzene, chloroform:acetone (1:1), 70% alcohol and distilled water]. The antibacterial susceptibility of the crude leaves extracts of were tested against standard strains of E. coli (ATCC 25922) and S. aureus (ATCC 2923) and clinical isolates of E. coli, S. aureus and methicillin resistance S. aureus using agar well diffusion method. Results: In Z. scabra and R. communis leaf extracts, the most sensitive standard strain was S. aureus with an inhibition zone of (14.00±1.20) mm and (15.90±2.13) mm, respectively. The minimum inhibitory concentration (MIC) values of Z. scabra extracts against test organisms ranged from 1.95 mg/mL for extract 3 in clinical and standard strains of S. aureus to 250 mg/mL for extract 1 and 4 in clinical and standard strains of E. coli. The MIC values of R. communis extracts against test organisms ranged from 1.95 mg/mL for extract 2 and 3 standard strains of S. aureus to 250 mg/mL for extract 1 in clinical isolate of E. coli. Most of the minimum bactericidal concentration and MIC values of plant extracts were almost similar particularly in R. communis, or minimum bactericidal concentration equal to one dilution factor less than MIC value of the extracts mainly in Z. scabra. Conclusions: The potency of plant extracts against test organisms were depend on different organic solvents used. Clinical isolate of bacterial pathogens showed less zones of diameter compared to the standard strains. Gram-positive had wide inhibition zones than Gram-negative bacteria. Further studies should be carried out to isolate the pure compounds and standardization of the methods of plant extracts for an in vitro testing.

Sepsis is one of the major causes and predictors of death in patients with visceral leishmaniasis (VL). Globally, incidence rate of sepsis ranged from 56-91 cases per 100 000 people, with a mortality rate of 30%. Incidence of sepsis has been raised due to aging of the population and the higher incidence of immunosuppressive conditions such as HIV, VL and others. The prevalence of sepsis was reported from 4.2% to 32.3% and 14.1% in VL and VL-HIV coinfected patients, respectively. The mortality rate of VL patients with sepsis is greater than 50%. Factors associated with sepsis in VL patients are immune suppression, pancytopenia, HIV co-infection, age <1 year old and >40 years old, indwelling of central venous lines and hospitalization. Although antimicrobial susceptibility patterns were not well reported, both Gram-positive and Gram-negative bacteria were isolated from patients with VL. So far, limited information is available on sepsis in VL, especially in VL-HIV coinfected patients. Therefore, further studies about sepsis prevalence, causative agents and their antibiotic patterns, and associated factors among VL and VL-HIV coinfected patients are necessary. This review provides information about bacterial sepsis in patients with VL.