Evaluating the Inhibitory Effect of Streptomyces Bacteria against Pathogenic Bacteria and Study its Compatibility with Some Antibiotic Types

Abstract

All Streptomyces sp isolates were screened for their antibacterial activity on Yeast extract-malt extract agar medium (ISP2) using scross-streak technique against two pathogenic bacteria include Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. Among three Streptomyces sp isolates that obtained from Baghdad city (Al-Jadriya), one isolates (B2) didn’t show any antibacterial activity against any type of pathogenic bacteria (Gram-negative and Gram-positive bacteria), while two Streptomyces sp isolates (B1 and B3) showed antibacterial activity against Gram Two-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus). Screening was performed by Agar-Well Diffusion method and growth inhibition zones were measured in millimeters for each of the Streptomyces isolates (B1 and B3). Tested isolates have shown potent in vitro antibacterial activities against all tested pathogens. The highest activities were shown by isolate B1 against S. aureus 19.5 mm, Pseudomonas aeruginosa 14 mm. It is also evident that B3 isolate has shown activities against all pathogenic bacteria with inhibition zone diameters ranging between 17 and 13 mm against S. aureus and P. aeruginosa respectively. The effects of Levofloxacin, Sulfamethoxazole, Ciprofloxacin, Ceftriaxone, Aztreonam, Amikacin and Gentamicin on growth of Streptomyces sp were evaluated over a 48 h period. Morphology and growth of Streptomyces sp. were not affected by all antibiotics, all Streptomyces isolates (B1, B2) were screened for resistance against seven antibiotics, all Streptomyces isolates were resistance against all antibiotics.