The effects of a dipolar static magnetic field of strength 400, 800, 1200 and 1600 Gauss were prepared locally, on the ultra-structure of E. coli type 1 bacterium cells have been studied. Equal volumes of liquid culture media were exposed to the magnetic field for different periods, the three most effective periods, namely: 24 hrs, 48 hrs and 72 hrs were chosen for all our experimental studies. After API kit test of treated E. coli culture media as control group. Results indicated that exposure of the microorganisms to the demonstrated magnetic field caused pronounced changes in the Arginine dihydrolase (ADH), Citrate utilization (CIT) and Gelatinase (GEL) were observed on the cell growth. Besides, changes in the morphology of the E. coli colonies were observed after exposure period and subculture on MacConkey agar. Furthermore, the bacterial growth subculture tested for morphological and biological activity, the results suggested that a mutation occurred in bacterial cells.

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A new method developed for in-vitro susceptibility test in medical laboratories consist of micro tubes or gloves containing dehydrated tryptic soya broth, 5% glucose, 0.1% bromothymol blue and one type of antibiotics (ampicillin, tetracycline and chloramphenicol) with critical concentration MIC (minimum inhibitory concentration) for susceptibility. Standard quality control strains of bacterial (Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa) suspension were adjusted to 0.5 McFarland turbidity standard (1 × 10 6 cell/mL) were used in inoculation the media and incubated two hours at 37 °C. The MIC of ampicillin against E. coli, S. aureus, and P. aeruginosa were 4, 32, and 256 µg/mL of the media for the bacteria respectively, while the MIC of tetracycline against bacteria were 512, 512 and 32 µg/mL respectively, the MIC of chloramphenicol were 512, 32 and 512 µg/mL, respectively. Where, the resistant bacteria to the antibiotics could grow and ferment glucose sugar producing a color change of the media from blue to yellow, while the sensitive bacteria do not grow or show no change in color. Our study result compared with common used antibiotic disk method obtaining similar results. This developed method characterized by fast (only two hours) and less cost in comparison to conventional technique. The new micro tube strip is highly stable (more than one year) with more sensitive in detection of variable pathogenic bacteria including standard bacteria strains compared with conventional technique.

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