[Subcontracting a steam sterilization activity: Impact on surgical instruments]. / Externalisation de l'activité de stérilisation : impact sur l'état des instruments chirurgicaux.

Subcontracting our institution's sterilization activity induced the implementation of an automated cleaning facility. Following this development, some of the resterilizable stainless steel needle holders started to show abnormal corrosion. Our study goal was to investigate the causes of this corrosion in order to optimize the sterilization circuit. A full sterilization process mapping and Ishikawa diagram enabled us to identify potential causes of corrosion. The needle holders' intrinsic characteristics, like steel quality and manufacturing, were analyzed as well as extrinsic factors such as the influence of preprocessing soaking conditions, steel passivation, water quality and the impact of corrosion inhibitors. Each potential factor of corrosion was tested in real conditions on needle holders' kits. The needle holders steel grade complies with medical standards and the tests showed that passivation and pre-processing conditions were not involved in the occurrence of corrosion, contrary to soaking length and use of softened rinsing water, containing more chloride than reverse osmosis water, and, thus conducive to rust formation. Moreover, corrosion inhibitors were deemed ineffective or incompatible. Due to this analysis, the incidence of corrosion was reduced by switching softened water to osmosis water and by introducing dynamic drying in the automated cleaning process. In addition, this work stresses the importance of minimizing waiting times and auditing the sterilization circuit before any subcontracting. Management Guidelines related to sterilization's outsourcing would probably have helped to limit this episode.

Therapeutic evaluation of free and nanocapsule-encapsulated atovaquone in the treatment of murine visceral leishmaniasis.

The activities of free atovaquone (ATV) and of poly(D,L-lactide) nanocapsules loaded with the drug, in the treatment of mice with visceral leishmaniasis caused by Leishmania infantum, were compared. Each mouse was infected intravenously with 2x10(7) promastigotes, on day 0. On days 15, 17 and 19, most of the infected mice were treated either with free ATV, in a dimethylsulphoxide/cremophor/water mixture, or with the ATV-loaded nanocapsules (at, respectively, 0.2-1.6 and 0.125-1.0 mg ATV/kg, on each treatment day). The rest of the mice were left untreated, as controls. All the mice were killed on day 21 and dissected so that their livers and spleens could be weighed. The liver parasite burdens, evaluated using the Stauber method, indicated that the ATV-loaded nanocapsules were significantly more effective than the free drug. In nanocapsules, for example, a total dose of 3.0 mg ATV/kg reduced liver burdens by 71.3%, whereas treatment with a higher total dose of the free drug (4.8 mg/kg) only cut the number of liver parasites by 34.4%. The dose-response data indicated that livers would have been cleared of parasites if the nanocapsule preparation had been given as three doses each equivalent to 3 mg ATV/kg, whereas the maximum suppression possible with the free drug would have been about 61%, whatever the dose.

Characterisation of atovaquone resistance in Leishmania infantum promastigotes.

Atovaquone, an antiparasitic agent, could possibly represent an alternative therapy after relapse following classical treatment for visceral leishmaniasis. Atovaquone-resistant strains were selected in vitro by stepwise drug pressure to study the mechanism of resistance in Leishmania. Characteristics of a promastigote strain resistant to 250 microg/ml of atovaquone were compared with those of the wild type (WT) strain. Resistant strains were shown to have a high level of resistance (45 times). They were stable in drug-free medium for 6 months, and showed no cross-resistance with other antileishmanial drugs. Rhodamine uptake and efflux were studied. They were not modified in the resistant strain, indicating the absence of P-glycoprotein overexpession. The effect of atovaquone on membrane lipidic composition was determined in both WT and atovaquone-resistant promastigotes. Analysis of lipid composition of the atovaquone-resistant strain showed that sterol biosynthesis was decreased in atovaquone-resistant parasites. Cholesterol was found to be the major membrane sterol as opposed to the WT strain. Cholesterol, due to its ordering effect, could decrease membrane fluidity and subsequently block the passage of atovaquone through the membrane. Increased membrane cholesterol content and altered drug membrane fluidity resulted from possible decrease of ergosterol biosynthesis by atovaquone, incorporation of cholesterol by promastigotes in the culture medium, solubilisation of atovaquone by cholesterol and co-passage of the two compounds or influence of dimethylsulfoxide. These results indicate that different cellular alterations may participate in the resistant phenotype, by altering drug membrane permeability.

Therapeutic evaluation of free and liposome-encapsulated atovaquone in the treatment of murine leishmaniasis.

The use of drug delivery systems may reduce the toxicity and improve the activity of anti-leishmanial compounds. The activity of atovaquone (ATV)-loaded liposomes was compared by determination of median effective doses (ED(25) and ED(50)), with that of free ATV in a murine model of visceral leishmaniasis induced by Leishmania infantum. On day 0, mice were infected intravenously with 4.10(7) promastigotes and treated via the tail vein on days 15, 17 and 19 by free drug in a DMSO/cremophor/water solution (0.2 to 1.6 mg/kg body weight) or by liposomal drug (0.04 to 0.32 mg/kg body weight). Mice were killed and livers and spleens were removed and weighed on day 21 p.i. and liver parasite burdens evaluated using the Stauber method. Effective doses were determined using the Hill representation relating the percentage of parasite suppression to the dose. Liposomal ATV was significantly more effective than the free drug in reducing liver parasites (61.6% of parasite suppression at a dose of 0.32 mg/kg vs 34.9% at a dose of 1.6mg/kg). Liposomal ATV was 23 times more active than the free drug (ED(25) value=0. 02+/-0.01 mg/kg vs 0.46+/-0.15 mg/kg for free drug). It was not possible to obtain the ED(50) for free ATV because the dose-response curve reached a plateau around 33% of parasite suppression. Conversely, the ED(50) for liposomal ATV was 0.17+/-0.05 mg/kg. 100% efficacy of bound ATV could be obtained with a concentration of 1. 77+/-0.35 mg/kg. A significant decrease in spleen weights was also observed reflecting a leishmanicidal activity of ATV. These results suggest that liposome loaded ATV is more efficacious than the free drug against Leishmania infantum in this murine model.