Document Type : Original Article
Radiation Microbiology Department, National Centre for Radiation Research and Technology (NCRRT), Egyptian Atomic Energy Authority, Cairo, Egypt
Because there are few effective treatments for some bacterial pathogens, primarily those that cause infections acquired in hospitals and community, antibiotic resistance had reached a critical point, necessitating the creation of novel bioactive substances with a wide range of effects. Streptomyces species have been important as a source of secondary metabolites with a variety of biological functions, including antibiotics. The current investigation aimed to study the antibacterial potency of the two Streptomyces sp. (Streptomyces umbrosus M1 and Streptomyces catenulae M6) against infectious diseases causing bacterial pathogens in comparison with commercial antibiotics. Thirty five isolates from urinary tract infections (UTIs) samples were isolated, out of them, 13 isolates (37.1 %) exhibited 100% of antibiotic resistance. The inhibitory effects of extracts from two Streptomyces strains (M1 and M6) showed highly antibacterial activity with varying degrees. Isolates with the codes (12) and (29) demonstrated a high susceptibility towards two extracts, particularly M6. The Minimum Inhibitory Concentrations (MICs) of the extract M6 against Gram positive bacteria displayed MICs ranged from (12.5- 37.5 µg/ml), isolate no 12 had the lowest MIC (12.5 µg/ml). Whereas Gram negative bacteria exhibited the highest MIC values, they recorded MICs in the range of (25-100 µg/ml), isolate no. 29 had the lowest MIC (25 µg/ml). Using 16srRNA, the highly sensitive isolates to the tested extract which had the lowest MIC were identified as Ochrobactrum grignonense and Enterococcus faecalis.
The inhibitory effects of extract M6 was further confirmed by scanning electron microscopic examination, which showed considerable morphological alterations and cell membrane rupture in the tested strains. As a result, the current research proved that Streptomyces sp. was a promising candidate for the treatment of the UTIs pathogens.