Enhancement of the antimicrobial properties of orthorhombic molybdenum trioxide by thermal induced fracturing of the hydrates.

The oxides of the transition metal molybdenum exhibit excellent antimicrobial properties. We present the preparation of molybdenum trioxide dihydrate (MoO3 × 2H2O) by an acidification method and demonstrate the thermal phase development and morphological evolution during and after calcination from 25 °C to 600 °C. The thermal dehydration of the material was found to proceed in two steps. Microbiological roll-on tests using Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were performed and exceptional antimicrobial activities were determined for anhydrous samples with orthorhombic lattice symmetry and a large specific surface area. The increase in the specific surface area is due to crack formation and to the loss of the hydrate water after calcination at 300 °C. The results support the proposed antimicrobial mechanism for transition metal oxides, which based on a local acidity increase as a consequence of the augmented specific surface area.

Antimicrobial activity of transition metal acid MoO(3) prevents microbial growth on material surfaces.

Serious infectious complications of patients in healthcare settings are often transmitted by materials and devices colonised by microorganisms (nosocomial infections). Current strategies to generate material surfaces with an antimicrobial activity suffer from the consumption of the antimicrobial agent and emerging multidrug-resistant pathogens amongst others. Consequently, materials surfaces exhibiting a permanent antimicrobial activity without the risk of generating resistant microorganisms are desirable. This publication reports on the extraordinary efficient antimicrobial properties of transition metal acids such as molybdic acid (H(2)MoO(4)), which is based on molybdenum trioxide (MoO(3)). The modification of various materials (e.g. polymers, metals) with MoO(3) particles or sol-gel derived coatings showed that the modified materials surfaces were practically free of microorganisms six hours after contamination with infectious agents. The antimicrobial activity is based on the formation of an acidic surface deteriorating cell growth and proliferation. The application of transition metal acids as antimicrobial surface agents is an innovative approach to prevent the dissemination of microorganisms in healthcare units and public environments.

Incidence and clinical implication of nosocomial infections associated with implantable biomaterials - catheters, ventilator-associated pneumonia, urinary tract infections.

Health care associated infections, the fourth leading cause of disease in industrialised countries, are a major health issue. One part of this condition is based on the increasing insertion and implantation of prosthetic medical devices, since presence of a foreign body significantly reduces the number of bacteria required to produce infection. The most significant hospital-acquired infections, based on frequency and potential severity, are those related to procedures e.g. surgical site infections and medical devices, including urinary tract infection in catheterized patients, pneumonia in patients intubated on a ventilator and bacteraemia related to intravascular catheter use. At least half of all cases of nosocomial infections are associated with medical devices.Modern medical and surgical practices have increasingly utilized implantable medical devices of various kinds. Such devices may be utilized only short-time or intermittently, for months, years or permanently. They improve the therapeutic outcome, save human lives and greatly enhance the quality of life of these patients. However, plastic devices are easily colonized with bacteria and fungi, able to be colonized by microorganisms at a rate of 0.5 cm per hour. A thick biofilm is formed within 24 hours on the entire surface of these plastic devices once inoculated even with a small initial number of bacteria.The aim of the present work is to review the current literature on causes, frequency and preventive measures against infections associated with intravascular devices, catheter-related urinary tract infection, ventilator-associated infection, and infections of other implantable medical devices. Raising awareness for infection associated with implanted medical devices, teaching and training skills of staff, and establishment of surveillance systems monitoring device-related infection seem to be the principal strategies used to achieve reduction and prevention of such infections. The intelligent use of suitable antiseptics in combination with medical devices may further support reduction and prevention of such infections. In addition to reducing the adverse clinical outcomes related with these infections, such reduction may substantially decrease the economic burden caused by device-related infection for health care systems.

Anodic TiO2 nanotube layers electrochemically filled with MoO3 and their antimicrobial properties.

In the present work, the authors produce a Ti surface with a TiO2 nanotube coating and investigate the electrochemical filling of these layers with MoO3. The authors demonstrate that using a potential cycling technique, a homogenous MoO3 coating can be generated. Controllable and variable coating thicknesses are achieved by a variation of the number of cycles. Thicknesses from a few nanometers to complete filling of the nanotube layers can be obtained. A thermal treatment is used to convert the as-deposited amorphous MoO(x) phases into MoO3. These MoO3 loaded nanotube layers were then investigated regarding their antimicrobial properties using strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The authors found that the combination of crystalline MoO3 on TiO2 nanotubes shows excellent antimicrobial properties.

Experience with the use of piperacillin-tazobactam in pediatric non-renal solid organ transplantation.

Bacterial infection remains a major problem after solid organ transplantation (SOT), especially in children. Piperacillin-tazobactam (Pip-Tazo) is a beta-lactam-antibiotic combination with a broad spectrum of activity including gram-positive cocci as well as gram-negative rods, non-fermentative and anaerobic bacteria. The aim of this retrospective study was to critically review our experience with Pip-Tazo as perioperative prophylactic agent in pediatric non-renal SOT. Between 1993 and 2003 Pip-Tazo was used as initial perioperative prophylaxis in 45 pediatric patients who underwent a total of 49 transplants (36 liver-, seven cardiac-, two lung-, and four small bowel-) at our department. Median age of the children was 7.9 (range 0.5-18.1) years. A total of 34 rejection episodes following 27 transplants were diagnosed. During first hospitalization 44 infectious episodes were observed. Bacteria were responsible for 22 episodes including sepsis (n = 10), pneumonia (n = 5), wound infection (n = 4), urinary tract infection (n = 1), and clostridial colitis (n = 2). The isolated organisms were gram-positive cocci (n = 12), gram-negative rods (n = 3), non-fermentative bacilli (n = 4), and anaerobes (n = 3). Ten episodes were caused by Pip-Tazo resistant bacteria. Twenty-one of these infections were observed following antirejection therapy with pulse steroids. At later time points nine infectious episodes were successfully treated with a second course of Pip-Tazo. During follow up, eight patients died. Six deceased perioperatively: five from infection including aspergillosis (n = 4) and Pneumocystis jiroveci pneumonia (n = 1) and cerebrovascular bleeding (n = 1) and two children later on. At present 37 children (82%) are alive with well functioning graft after a median follow up of 39.2 (range 0.6-123.5) months. No severe side effects caused by Pip-Tazo were observed in any of the children. Pip-Tazo may be a suitable single agent for perioperative prophylaxis in pediatric non-renal solid organs recipients, however, a prospective comparative study is needed to make final conclusions.