scholarly journals Non-contact induction heating and SAAP-148 eliminate persisters within MRSA biofilms mimicking a metal implant infection

2021 ◽  
Vol 42 ◽  
pp. 34-42
Author(s):  
M Verheul ◽  
JW Drijfhout ◽  
BG Pijls ◽  
PH Nibbering
Keyword(s):  
Induction Heating ◽  
Orthopaedic Surgery ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Maximum Temperature ◽  
Implant Infection ◽  
Metal Implant ◽  
Surface Temperatures ◽  
Promising Treatment ◽  
High Doses ◽  
Titanium Aluminium

Implant-associated infections are the primary cause of complications following orthopaedic surgery. Due to biofilm and persister formation, current treatments, i.e. surgical debridement followed by antibiotics, often fail. There is an urgent need for alternative strategies to combat such infections. Therefore, the present study investigated the effects of non-contact induction heating (NCIH), the antimicrobial peptide SAAP-148 and combinations thereof on bacterial counts in 7 d mature biofilms and in persister-enriched biofilms of methicillin-resistant Staphylococcus aureus (MRSA) on titanium-aluminium-niobium (TAN) discs. Enrichment of persisters was achieved by daily exposure of mature biofilms to high doses of rifampicin and ciprofloxacin for 3 consecutive days. To heat up the TAN discs, a miniaturised induction heater was built and successfully validated. Using this apparatus, NCIH resulting in surface temperatures up to 85 °C eradicated all the bacteria in immature biofilms but not in mature biofilms, whereas persisters were already eliminated at surface temperatures ≥ 70 °C. SAAP-148 at concentrations > 25.6 µmol/L reduced the persister counts in antibiotics-exposed, mature biofilms. As surface temperatures > 60 °C can have detrimental effects on the surrounding tissues, the maximum temperature of NCIH used in combination with SAAP-148 on persisters was set to 60 °C. Results revealed that this combination was slightly more effective than the peptide or NCIH alone in eliminating biofilm-embedded persisters. NCIH and SAAP-148 can be applied both invasively and non-invasively in various treatment scenarios. Together, combinations of NCIH and SAAP-148 might be a promising treatment strategy to combat metal-implant-associated infections.

scholarly journals Trends in orthopaedic antimicrobial prophylaxis in the UK between 2005 and 2011

2013 ◽  
Vol 95 (7) ◽  
pp. 495-502 ◽  
Author(s):  
RS Aujla ◽  
DJ Bryson ◽  
A Gulihar ◽  
GJ Taylor
Keyword(s):  
Orthopaedic Surgery ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Elective Surgery ◽  
Antimicrobial Prophylaxis ◽  
Trauma Surgery ◽  
Surgical Site Infections ◽  
Freedom Of Information ◽  
Infection Rates ◽  
Freedom Of Information Act ◽  
The Uk

Introduction Antimicrobial prophylaxis remains the most powerful tool used to reduce infection rates in orthopaedics but the choice of antibiotic is complex. The aim of this study was to examine trends in antimicrobial prophylaxis in orthopaedic surgery involving the insertion of metalwork between 2005 and 2011. Methods Two questionnaires (one in 2008 and one in 2011) were sent to all National Health Service trusts in the UK using the Freedom of Information Act. Results In total, 87% of trusts that perform orthopaedic surgery responded. The use of cefuroxime more than halved between 2005 and 2011 from 80% to 36% and 78% to 26% in elective surgery and trauma surgery respectively. Combination therapy with flucloxacillin and gentamicin rose from 1% to 32% in elective and 1% to 34% in trauma surgery. Other increasingly popular regimes include teicoplanin and gentamicin (1% to 10% in elective, 1% to 6% in trauma) and co-amoxiclav (3% to 8% in elective, 4% to 14% in trauma). The majority of changes occurred between 2008 and 2010. Over half (56%) of the trusts stated that Clostridium difficile was the main reason for changing regimes. Conclusions In 2008 a systematic review involving 11,343 participants failed to show a difference in surgical site infections when comparing different antimicrobial prophylaxis regimes in orthopaedic surgery. Concerns over C difficile and methicillin resistant Staphylococcus aureus have influenced antimicrobial regimes in both trauma and elective surgery. Teicoplanin would be an appropriate choice for antimicrobial prophylaxis in both trauma and elective units but this is not reflected in its current level of popularity.

scholarly journals MRSA – ‘Bug-Bear’ of a Surgical Practice: Reducing the Incidence of MRSA Surgical Site Infections

2006 ◽  
Vol 88 (2) ◽  
pp. 222-223 ◽  
Author(s):  
Andrea Guyot ◽  
Graham Layer
Keyword(s):  
Staphylococcus Aureus ◽  
Surgical Site Infection ◽  
Orthopaedic Surgery ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Surgical Site Infections ◽  
Site Infection ◽  
Infection Rates ◽  
Methicillin Resistant ◽  
Surgical Practice ◽  
Department Of Health

Adverse publicity (the ‘superbug') has demonstrated that the problem of MRSA (methicillin-resistant Staphylococcus aureus) is prevalent in many of the country's most prestigious hospitals. The results of the mandatory UK Department of Health (DH) surveillance for early surgical site infections in orthopaedic surgery (SSIS) have been published recently for the period April 2004 to March 2005 when 41,242 operations were studied (< http://www.dh.gov.uk/PublicationsAndStatistics/Publications/PublicationsStatistic > 28 October 2005). Infection rates were generally and gratifyingly low but 48% of surgical site infections were caused by Staph. aureus and of those 68% were MRSA. The following article will discuss the aetiology and prevention of MRSA surgical site infection.

The effect of temperature on the field softening of hard seed of Stylosanthes humilis and S. hamata in a dry monsoonal climate

1982 ◽  
Vol 33 (1) ◽  
pp. 75 ◽  
Author(s):  
GM McKeon ◽  
JJ Mott
Keyword(s):  
Management Practices ◽  
Soil Surface ◽  
Field Studies ◽  
Effect Of Temperature ◽  
Maximum Temperature ◽  
Hard Seed ◽  
Surface Temperatures ◽  
Stylosanthes Humilis ◽  
One Year ◽  
Field And Laboratory Conditions

The changes in hard-seed content in pastures of Stylosanthes humilis and S. hamata cv. Verano were studied at Katherine, N.T. Both field studies and laboratory ovens with diurnal temperature changes showed that maximum soil surface temperatures greater than 50-55�C were required to produce substantial softening of hard seed. The rate of softening increased with higher maximum temperature. At Katherine, only the September-November period (late dry season) was likely to produce soil surface temperatures high enough for softening in naturally occurring seed populations. S. hamata did not soften to the same extent as S. humilis under both field and laboratory conditions. In established pastures only 35 % of S. hamata seed softened in one year, compared with 60-80% in S. humilis. Management practices may be required to improve seedling regeneration or establishment of new pastures in S. hamata.

Frictional heating of bearing materials tested in a hip joint wear simulator

1997 ◽  
Vol 211 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Z Lu ◽  
H McKellop
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Frictional Heating ◽  
Element Model ◽  
Maximum Temperature ◽  
Zirconia Ceramic ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
Surface Temperatures ◽  
Ability To Act

In a hip simulator wear test using bovine serum as a lubricant, the heat generated by ball-cup friction may cause precipitation of the proteins from the lubricant. The resultant accumulation of a solid layer of precipitated protein between the ball and cup could artificially protect the bearing surfaces from wear, in a manner that does not occur in vivo. Alternatively, the gradual depletion of the soluble proteins could interfere with their ability to act as boundary lubricants on the bearing surfaces, thereby artificially increasing the wear rate. Because the rate of protein precipitation may depend on the maximum temperature at the bearing surfaces during sliding, rather than the mean temperature of the bulk lubricant, this study determined the transient surface temperatures using an array of thermocouples embedded in acetabular cups of GUR 415 ultra-high molecular weight polyethylene (UHMWPE) and femoral balls of metal or ceramic, in conjunction with a finite element model of the temperature distribution. The prostheses were tested at one cycle/s under a Paul-type, physiological load profile with 2030 N maximum force, with the load cycle synchronized to the motion cycle. The steady state temperatures of the bulk lubricant were 38°C for the zirconia balls, 36°C for the cobalt-chromium and 33°C for the alumina. However, the corresponding surface temperatures of the polyethylene, calculated with the finite element model, were 99°C with zirconia ceramic, 60°C with cobalt-chromium alloy, and 45°C with alumina ceramic. The rank order of the surface temperatures corresponded to the relative amounts of protein that were precipitated in the test chambers during wear tests with these materials.

scholarly journals Strategy to control methicillin-resistant Staphylococcus aureus post-operative infection in orthopaedic surgery

2004 ◽  
Vol 28 (1) ◽  
pp. 16-20 ◽  
Author(s):  
J. C. De Lucas-Villarrubia ◽  
M. Lopez-Franco ◽  
J. J. Granizo ◽  
J. C. De Lucas-Garcia ◽  
E. Gomez-Barrena
Keyword(s):  
Staphylococcus Aureus ◽  
Orthopaedic Surgery ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Methicillin Resistant

scholarly journals The Sensitivity of Urban Meteorology to Soil Moisture Boundary Conditions: A Case Study in Melbourne, Australia

2017 ◽  
Vol 56 (8) ◽  
pp. 2155-2172 ◽  
Author(s):  
Stephanie J. Jacobs ◽  
Ailie J. E. Gallant ◽  
Nigel J. Tapper
Keyword(s):  
Soil Moisture ◽  
Rural Areas ◽  
Urban Areas ◽  
Maximum Temperature ◽  
Weather Research And Forecasting ◽  
Near Surface ◽  
Australian Water ◽  
Surface Temperatures ◽  
Order Of Magnitude

AbstractThe sensitivity of near-surface urban meteorological conditions to three different soil moisture initialization experiments under heat-wave conditions is investigated for the city of Melbourne, Australia. The Weather Research and Forecasting Model is used to simulate a domain over Melbourne and its surrounding rural areas. The experiments employ three suites of simulations. Two suites initialize the model with soil moisture from the top layer of the ERA-Interim soil moisture data with a 3-month and 24-h coupled spinup period, respectively. The third suite initializes the model with the arguably more realistic soil moistures from the Australian Water Availability Project (AWAP), which are an order of magnitude drier than the ERA-Interim data, again using a 24-h spinup period. The simulations employing the AWAP data are found to have smaller errors when compared with observations, with biases in urban maximum temperature reduced by 4.1°C and biases in the skin temperature reduced by 3.0°C relative to the biases of the 3-month-spinup experiment. Despite urban areas only having a small proportion of soil-covered surfaces, the results show that urban soils have a greater influence on urban near-surface temperatures at night, whereas rural soils have a greater influence on urban near-surface temperatures during the daytime.

scholarly journals Two-channel time-optimal control of induction heating process with maximum temperature constraint

2020 ◽  
Vol 28 (2) ◽  
pp. 41-58
Author(s):  
Natalya A. Il`ina
Keyword(s):  
Optimal Control ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Induction Heating ◽  
Time Optimal Control ◽  
Maximum Temperature ◽  
Heating Process ◽  
Problem Of Time ◽  
Control Actions ◽  
Time Optimal

The formulation and method of solution of the problem of time-optimal control of induction heating process of an unlimited plate with two control actions on the value of internal heat sources with technological constraint in relation to a one-dimensional model of the temperature field are proposed. The problem is solved under the conditions of a given accuracy of uniform approximation of the final temperature distribution over the thickness of the plate to the required. The method of finite integral transformations is used to search for the input-output characteristics of an object with distributed parameters with two control actions. The preliminary parameterization of control actions based on analytical optimality conditions in the form of the Pontryagin maximum principle is used. At the next stage reduction is performed to the problem of semi-infinite optimization, the solution of which is found using the alternance method. The alternance properties of the final resulting temperature state at the end of the optimal process lead to a basic system of relations, which, if there is additional information about the shape of the temperature distribution curve, is reduced to a system of equations that can be solved. An example of solving the problem of time-optimal control of temperature field of an unlimited plate with two offices is carried out in two stages. At first stage the case of induction heating without maximum temperature constraints is considered, at the second stage is carried out on the basis of the results of the first stage to obtain the solution subject to the limitation on the maximum temperature of the heated billet.

scholarly journals OPTIMAL INDUCTOR DESIGN FOR SURFACE HARDENING OF CYLINDRICAL BILLETS BASED ON NUMERICAL TWO-DIMENSIONAL MODEL

2019 ◽  
pp. 40-50
Author(s):  
Yuliya Edgarovna Pleshivtseva ◽  
Anton Valerjevich Popov ◽  
Mariya Aleksandrovna Popova ◽  
Maxim Yurjevich Derevyanov
Keyword(s):  
Optimal Design ◽  
Induction Heating ◽  
Operation Mode ◽  
Heating Time ◽  
Temperature Fields ◽  
Maximum Temperature ◽  
Design Parameters ◽  
Distributed Parameters ◽  
Heating Installation ◽  
And Control

Contemporary industrial production widely uses induction heating prior to the plastic deformation and heat treatment operations due to the benefits it provides in comparison with other types of heating technologies. In order to increase the efficiency of induction heating units and develop their operation mode, the research should be directed towards new design solutions in optimizing constructive parameters of inductors and control algorithms of heating processes. The main goal of the research is developing the best inductor design, which provides maximum temperature uniformity in the surface layer of the billet at the end of heating time. There has been formulated the problem of the inductor unit optimal design with respect to steel cylindrical billets, which can be solved by using the alternance method of parametric optimization of the systems with distributed parameters. Design parameters of the induction heating installation that include the geometry features and the current of power supply are considered as optimized parameters. Software package FLUX was used for developing 2D numerical model of interrelated magnetic and temperature fields in the process of induction heating to describe the system ‘induction heater - billet’. The results of numeric solution of the problem of optimal design have been analyzed.

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