1. Faculty of pharmacy, University Gr. T. Popa, Iasi, Romania.

2. Faculty of physics, University Al. I. Cuza, Iasi, Romania.

Different types of pathogen microorganism, provided by patients of the University Hospital clinics were tested against several antibiotics with different cellular targets. Main bacterial strains with-drawn from patients biological liquids (urine, feces, amniotic liquid) were related to Gram negative species such as E. collie, Pseudomonas and Enterobacter, which are difficult to combat with usual antibiotic drugs because of their complex cell wall. Their resistance to antibiotics was evaluated by means of NIC (minimum inhibitory concentration) measured using agar dilution method. Serial doubled antibiotic concentrations were tested in the case of every antibiotic drug from 0.25 ml / l to 128 ml / l. Several antibiotics with different cellular targets (cell membrane, cell nucleus, nucleic acid biosynthesis) were chosen for the experiment, mainly antibiotics with broad spectrum (active against both Gram positive and Gram negative microorganisms). Classical antibiotics like tetracycline together with modern antibiotics from the last cephalosporine generations were tested. The same microbial strains were analyzed when developed on culture medium supplied with ferrofluid in relatively low concentrations (from 20 ml / l to 100 ml / l ) and in the presence of permanent magnets. Both magnetic orientations of the permanent magnets were taken into account (parallel anti-parallel to the Earth local magnetic field). In order to assure the experiment validity an adequate number of repetitions for every bacterial strains was analyzed. Three bacteria classes were revealed: non-sensitive strains, strains with enhanced resistance to antibiotics in the ferrofluid presence and strains with diminished resistance to antibiotics after ferrofluid addition. Most bacterial strains that emphasized magnetic sensitivity behaved similarly what ever the orientation of the magnetic field was. All three types of behavior were detected for every bacterial species. Though no correlation between the microbial species genetic features and the percentage of ferrofluid sensitive strains belonging to the corresponding biological sample range was noticed, a remarkable statistic increase of the resistance to antibiotics was observed for E. coil.

Different situations appeared for different antibiotics tested on this microorganism, ubiquitous in the human digestive system, a considerable ferrofluid influence being revealed for the antibiotics able to delay the protein biosynthesis in the bacterial cells. Data analysis was carried out using both numerical and graphical statistic tests. Student tube-test was applied to emphasis putative non-significant average values in ferrofluid treated samples in comparison to the control ones. Box-plot technique was used to give a graphical comparison of experimental data series by means of the representation of whole distribution curves for every microorganism strains. In several cases regression curves revealed correlation between bacteria resistance to antibiotic and the ferrofluid concentration. The statistic signification of every correlation coefficient was assessed. Ferrofluid influence on the microorganisms resistance to antibiotics may be related mainly to the role of iron in their cell metabolism. However the challenging supposition that magnetic contamination of bacterial cells, generated by ubiquitous metal particles from both the inside and outside environments of human living spaces, inducted microorganism sensitivity to ferrofluid need also to be considered.

References:

1. Binhi V. N. Magnetobiology Underlying Physical Problems, Academic Press 2002, San Diego – San Francisco – New – York – Boston – London – Sydney – Tokyo.

2. Binhi V. N. Interference of ion quantum states within a protein explains weak magnetic field’s effect on biosystems. // Electro-magnetobiology, 16 (3) (1997) 203 – 214.