The effect of Nd:YAG laser (30 mW, 532 nm) photoirradiation on the growth and colony formation of two strains of the Gram-negative bacteria Proteus mirabilis, the wild type S1959 and the mutant R45, differing in polysaccharide content in the bacterial cell wall lipopolysaccharide (LPS), was tested in the presence of the photosensitizer merocyanine 540 (MC540). Simultaneous action of MC540 and Nd:YAG laser light showed a differentiated influence depending on LPS structure: their bactericidal effect increased with depletion of the polysaccharide chain in LPS. Moreover, MC540 and laser illumination induced a dramatic increase in lipopolysaccharide toxicity, as monitored by means of the Limulus amebocyte lysate (LAL) test. This effect should be taken into account when applying combined photosensitizer-mediated laser irradiation for the photodynamic sterilization of blood transfusion products.
|Number of pages||5|
|State||Published - 1 Sep 2003|