تأثير التراكيز الواطئة من المضادات الحياتية على بعض الخواص المزرعية والمظهرية لعزلات من البكتريا المرضية

Abstract

Certain types of the most common pathogenic bacteria affecting humanbeing , being diagnosed using specified biochemical and physiological tests , were included in this study , to demonstrate the effect of very low concentrations of identified susceptibility types of antibiotics on these bacteria , aiming at exploring the effect of improper use of antibiotics , using then in low doses or for short time , irrespective of the doctor's instruction . The results showed that all the isolates were affected by all antibiotics used in this study in different manner . Protues vulgaris reveal heavy growth of 0.01 mg/ml oncentration for all types of used antibiotics, while the growth of Echerichia coli was heavy with concentration of 0.01 to 0.3 mg/ml of tetracycline , Pseudomonas aeruginosa show very profound growth at 0.01 mg/ml concentration of tetracycline as well as Klebsiella pneumonia at 0.2 mg/ml concentration of Bacterim. On the other hand bacterial cells showed morphological and physiological changes in regard to its response to Gram stain , attachment of cells and cluster appearance of Staphylococcus aureus, increase in the size of cells of E. coli than it's normal range , shortening in the length of P. aeruginosa and loss of capability to form capsule of K. pneumonia . On conclusion , low concentration of antibiotics lead to generation of new resistant strains from the same type of pathogenic bacteria when these antimicrobial ents were used incorrectly in response to the doctors instruction .