Pathogen germs response to low-dose radiation — medical approach

¹ University of Medicine and Pharmacy “Gr. T. Popa” Faculty of Pharmacy - Iasi, Romania
² “Al. I. Cuza” Univesity, Faculty of Physics - Iasi, Romania

^* E-mail: ramona_focea@yahoo.com

Abstract

The side effects of radiation therapy in the case of microbial loading of irradiated organs was considered as phenomenological basis of the experiment carried out on Staphylococcus aureus (ATCC germ) exposed to low X-ray doses. The inoculum was prepared in a liquid culture medium with standard composition, the volumes of 3 ml identical samples (in sterile glass tubes) being irradiated in hospital conditions. Five experimental variants were developed corresponding to irradiation time durations between 25 and 100 minutes. The spectro-colorimetric assay was accomplished at 560 nm and 420 nm, the resulting average values (for three repetitions) being analyzed from the viewpoint of cell density in the irradiated variants compared to control ones. The resistance to antibiotics of the irradiated bacteria was tested on agarized cultures against five antibiotic molecules (ampicillin, cloramphenicol, tetracycline, tobramicin and ofloxacin) by assessing the diameter of inhibition growth areas in each case. The increase of the inhibition area diameter with up to 15% (in the case of tetracycline) was noticed for the lowest irradiation time for all five antibiotics, which is suggesting a weakening of the bacteria resistance to the pharmaceutical agents following the X-ray treatment. This was concordant with the results of the spectro-colorimetric assay of the cell density within the directly irradiated bacteria cultures. The main issue of this study is concerning the optimization of the radiotherapy protocol in patients with potential microbial loading.