Although the study predates extensive use of echinocandins and voriconazole, these findings demonstrate that posaconazole is an alternative to salvage therapy for patients with invasive aspergillosis who are refractory to or intolerant of previous antifungal therapy.

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In the setting of catheter-related bloodstream infections, intraluminal antibiotic lock therapy could be useful for the salvage of vascular catheters. In this in vitro study, we investigated the efficacies of the newer antibiotics daptomycin, linezolid, and tigecycline, in comparison with those of vancomycin, minocycline, and rifampin, against methicillin-resistant Staphylococcus aureus (MRSA) embedded in biofilm. We also assessed the emergence of MRSA strains resistant to these antibiotics, alone or in combination with rifampin, after 4-hour daily use for catheter lock therapy. Minocycline, daptomycin, and tigecycline were more efficacious in inhibiting MRSA in biofilm than linezolid, vancomycin, and the negative control (P < 0.001) after the first day of exposure to these antibiotics, with minocycline being the most active, followed by daptomycin and then tigecycline, and with vancomycin and linezolid lacking activity, similar to the negative control. After 3 days of 4-hour daily exposures, daptomycin was the fastest in eradicating MRSA from biofilm, followed by minocycline and tigecycline, which were faster than linezolid, rifampin, and vancomycin (P < 0.001). When rifampin was used alone, it was the least effective in eradicating MRSA from biofilm after 5 days of 4-hour daily exposures, as it was associated with the emergence of rifampin-resistant MRSA. However, when rifampin was used in combination with other antibiotics, the combination was significantly effective in eliminating MRSA colonization in biofilm more rapidly than each of the antibiotics alone. In summary, daptomycin, minocycline, and tigecycline should be considered further for antibiotic lock therapy, and rifampin should be considered for enhanced antistaphylococcal activity but not as a single agent.Intraluminal colonization of the central venous catheter (CVC) is universal and is often caused by methicillin-resistant staphylococci that embed themselves in the biofilm layer in the lumen of the catheter, resulting in catheter-related bloodstream infections (CRBSI) (21). Given the cost, difficulty, and complications associated with the removal of a long-term CVC and the insertion of a new CVC at a different site, recent guidelines have suggested the use of antibiotic catheter lock therapy (ALT) for the prevention and salvage treatment of CRBSI in high-risk patients (16).Few antibiotics with activity against methicillin-resistant Staphylococcus aureus (MRSA) may be used for intraluminal ALT (6,8,10,14,27). However, MRSA organisms that are susceptible to glycopeptides, such as vancomycin in suspension, become resistant to this antibiotic when embedded in biofilm on catheter surfaces (6,8,9,23,27). In the present study, we used an in vitro silicone disk biofilm colonization model to determine the activities of novel antistaphylococcal antibiotics (daptomycin, linezolid, and tigecycline) against catheter-related bacteremic MRSA embedded in biofilm, in comparison with one another and with older agents, such as vancomycin, minocycline, and rifampin. ...

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Published models apply particle size to predict bioleaching reactor performance. In this study mathematical models predicting the overall reaction rate of a bioleach reactor system are developed to establish which particle parameters are necessary to describe reactor performance. Since the intrinsic leaching rate is surface area dependent, the inlet particle size and residence time are model inputs. Three models, distinguished by the incorporation of age and/or size distributions, were developed from first principles through a segregation approach. Explicit dependence on the age distribution, allows the model extension to unsteady state behavior and imperfect mixing. The models are validated against pilot plant data for pyrite‐arsenopyrite concentrates obtained from the Fairview Mine in South Africa. Simulation results indicate that only a model that considers both the particle age and size distribution is in good agreement with the data. © 2008 American Institute of Chemical Engineers AIChE J, 2008