Photodynamic inactivation of methicillin-resistant Staphylococcus aureus by using Giemsa dye as a photosensitizer.

The rise of antibiotic-resistant bacteria calls for innovative approaches to combat multidrug-resistant strains. Here, the potential of the standard histological stain, Giemsa, to act as a photosensitizer (PS) for antimicrobial photodynamic inactivation (aPDI) against methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) strains is reported. Bioassays were performed using various Giemsa concentrations (ranging from 0.0 to 20.0 µM) under 625 nm illumination at a light dose of 30 J cm-2. Remarkably, Giemsa completely inhibited the growth of MSSA and MRSA bacterial colonies for concentrations at 10 µM and higher but exhibited no inhibitory effect without light exposure. Partition coefficient analysis revealed Giemsa's affinity for membranes. Furthermore, we quantified the production of reactive oxygen species (ROS) and singlet oxygen (1O2) to elucidate the aPDI mechanisms underlying bacterial inactivation mediated by Giemsa. These findings highlight Giemsa stain's potential as a PS in aPDI for targeting multidrug-resistant bacteria.

Cutaneous Leishmaniasis with Mucosal Involvement

Leishmaniasis is a protozoan parasitic disease transmitted to humans by infected female sand flies. Turkey has received more than three million immigrants from Syria because of the civil war and political instability. This study reported cases of two patients, who were from Syria and lived in Hatay, with cutaneous leishmaniasis and mucosal involvement. Two patients presented to the infectious diseases clinic with a complaint of facial lesions and were subsequently referred to the parasitology department laboratory. Smears were prepared from the lesions, stained with Giemsa and examined under a microscope. Moreover, aspirates taken from the patients' lesions were inoculated into the modified Novy-MacNeal-Nicolle medium. The diagnosis was made when amastigotes were detected in both smears. Proliferation of promastigotes was observed in one of the clinical specimens inoculated on the medium. By PZR-RFLP, Leishmania tropica were detected in the isolate. Both patients were treated with amphotericin B. One patient was treated again with a pentavalent antimony compound because of the recurrence of the lesion.

Anti-tumoral and anti-inflammatory effects of biological stains.

The biological stains, methylene blue and its metabolite azure B, were evaluated as anti-tumor and anti-inflammatory agents. Azur B, administered in drinking water to tumor-bearing mice, inhibited the growth of transplanted tumors and the growth of primary tumors induced by methylcholanthrene. Inhibition of growth of primary tumors was observed only in female mice. Azure B also reduced the wet weight of carrageenin-induced granulomas in rats. Azure B, given intravenously to BCG-sensitized mice 15 minutes prior to challenge with lipopolysaccharide, decreased TNF production (to 10% of control values) and prevented death from endotoxic shock. Methylene blue decreased TNF production (to 50% of control values) but did not protect the animals from endotoxic shock. Our results suggest that some of the effects previously ascribed to methylene blue are probably mediated via its metabolite, i.e. azure B. Low toxicity and easy administration of the dyes explain their use in clinical settings.

Methylene blue and other agents as inhibitors of calcium oxalithiasis in vivo.

Growth of calcium oxalate on an established calculus upon a zinc nucleus in the bladder of rats was studied. Animals were fed either a regular solid chow or chow containing a potential crystal inhibitor ad libitum, along with drinking water containing 0.75 per cent ethylene glycol. Chow containing 0.2 per cent methylene blue and 0.5 per cent vitamin C not only decreased the growth rate, but calculi were much softer than those in controls. Safranin O was the only other significant growth inhibitor identified. Ethylenediamonotetraacetic acid and ethylenebis (oxyethylenenitrilo)-tetraacetic acid transformed the additional growth from the mono- to the dihydrate form of calcium oxalate.