2020. 2. 20. 05:51ㆍ카테고리 없음
Intelligent interactive multimedia systems and services will be ever more important in computer systems. Nowadays, computers are widespread and computer users range from highly qualified scientists to non-computer expert professionals. Therefore, designing dynamic personalization and adaptivity methods to store, process, transmit and retrieve information is critical for matching the technological progress with the consumer needs.
This book contains the contributions presented at the eighth international KES conference on Intelligent Interactive Multimedia: Systems and Services, which took place in Sorrento, Italy, June 17-19, 2015. It contains 33 peer-reviewed scientific contributions that focus on issues ranging from intelligent image or video storage, retrieval, transmission and analysis to knowledge-based technologies, from advanced information technology architectures for video processing and transmission to advanced functionalities of information and knowledge-based services. We believe that this book will serve as a useful source of knowledge for both academia and industry, for all those faculty members, research scientists, scholars, Ph.D. Students and practitioners, who are interested in fundamental and applied facets of intelligent interactive multimedia. Ernesto Damiani.
1. Robert J. Howlett. 2. Lakhmi C. Jain. 3.
Luigi Gallo. 4.
Giuseppe De Pietro. 5. 1. Department of Information Technology University of Milan Crema Italy. 2. KES International Shoreham-by-sea United Kingdom. 3.
Faculty of Education, Science, Technology and Mathematics University of Canberra Canberra Australia. 4. Institute for High-Performance Computing and Networking (CNR-ICAR) National Research Council of Italy Naples Italy.
5. Institute for High-Performance Computing and Networking (CNR-ICAR) National Research Council of Italy Naples Italy.
AbstractA host of technical and operative improvements have seen the rates of infection associated with joint replacement reach historic lows. However, the increasing number of operations being performed means that the absolute number of such infections remains significant. Diagnosis may be challenging and delaying appropriate treatment can lead to reduced joint function and the need for more complex, perhaps multiple, procedures. Individual centres tend to see small numbers of such cases, and in the absence of large clinical trials management varies. Early diagnosis, selection of an appropriate surgical strategy, accurate identification of the responsible microorganisms and construction of an appropriate antibiotic regimen are essential elements of any management strategy. Such packages of care are best delivered by a multidisciplinary team composed of orthopaedic and plastic surgeons, microbiologists, infectious disease physicians, specialist nurses, physiotherapists and occupational therapists.
Each treatment plan must be developed in consultation with the patient, taking into account their aims and realistic goals. This review provides an overview of current understanding regarding diagnosis and treatment of prosthetic joint infections and suggests a treatment algorithm. IntroductionThe last five decades have seen a host of technical and operative improvements for the use of prosthetic joints that have reduced the risk of infection. Rates today stand at around 1% for hip and 0.7% for knee replacement. However, the increasing number of joint replacements being performed means the absolute number of such infections will remain significant and pose substantial costs to healthcare systems worldwide. Diagnosis may be challenging as symptoms are variable and diagnostic tests non-specific. Delayed diagnosis may lead to reduced function, increased morbidity and the need for more complex surgery, often involving multiple procedures.
Individual centres tend to see small numbers of such cases and in the absence of large clinical trials management varies.This review provides an overview of current understanding regarding diagnosis and treatment of prosthetic joint infections and suggests a treatment algorithm. The following case study demonstrates the complexity of such infections, raising the issues this review goes on to examine.
Case studyA man in his late thirties was referred to a specialist bone infection service. He had congenital hip dysplasia which had necessitated bilateral hip replacements by the age of 21 years. In his early thirties, the left prosthetic hip was revised because of mechanical problems, with the right side revised the following year. A year later he developed bilateral discharging sinuses over the hips and underwent several incision and drainage procedures. On one occasion he developed severe sepsis as a result of hip infection and required high dependency unit care.
Various bone, tissue and fluid samples grew either methicillin-susceptible Staphylococcus aureus (MSSA) or coagulase-negative staphylococci (CoNS), with one sample from the left hip growing methicillin-resistant S. Aureus (MRSA). He was allergic to penicillin and linezolid. Over the next 2 years he received multiple courses of antibiotics, including a prolonged course of vancomycin. The hips remained painful, more so on the left than the right, and both were discharging thick pus through scarred wounds despite many months of appropriate antibiotic therapy.He was referred to a multidisciplinary bone infection service.
X-rays demonstrated evidence of loosening of both hips—worse on the left than the right (Figure a and b). A decision was made to proceed with bilateral two-stage revisions. All antibiotics were stopped and the patient was carefully monitored for signs of developing sepsis. Twelve days later the left hip prosthesis and all cement and a large amount of necrotic tissue were removed (an excision arthroplasty/Girdlestone procedure) but closure was obtained without the need for a muscle flap (Figure d). Post-operatively he was started on vancomycin and meropenem. Of six samples taken, five grew MSSA and two grew Proteus mirabilis, and his antibiotic regimen was changed to ceftriaxone only. Flowchart summarizing the selection of an appropriate management strategy for an infected prosthetic joint.
Drawn on the evidence summarized in the text and clinical experience at the Bone Infection Unit, Nuffield Orthopaedic Centre, Oxford, UK. This scheme refers to systemic therapy only—the use of local antibiotics is discussed in the text. It should be remembered that certain frail patients with poor mobility for other reasons may gain little from a new prosthesis and conservative (non-surgical) management or an excision arthroplasty may be all that is appropriate. 1A negative aspiration does not rule out infection. 2Consider endocarditis and metastatic osteomyelitis particularly if S. Aureus is isolated. 3DAIR, debridement, antibiotics, implant retention.
If a prosthesis is found to be unexpectedly loose it may be necessary to change to a one- or two-stage revision intra-operatively and patients should be consented appropriately. 4Empirical antibiotics should be selected on the basis of local susceptibility data.
5Excision arthroplasty alone may be appropriate in certain patients for either social or technical reasons. Flowchart summarizing the selection of an appropriate management strategy for an infected prosthetic joint. Drawn on the evidence summarized in the text and clinical experience at the Bone Infection Unit, Nuffield Orthopaedic Centre, Oxford, UK. This scheme refers to systemic therapy only—the use of local antibiotics is discussed in the text.
It should be remembered that certain frail patients with poor mobility for other reasons may gain little from a new prosthesis and conservative (non-surgical) management or an excision arthroplasty may be all that is appropriate. 1A negative aspiration does not rule out infection. 2Consider endocarditis and metastatic osteomyelitis particularly if S. Aureus is isolated. 3DAIR, debridement, antibiotics, implant retention. If a prosthesis is found to be unexpectedly loose it may be necessary to change to a one- or two-stage revision intra-operatively and patients should be consented appropriately. 4Empirical antibiotics should be selected on the basis of local susceptibility data.
5Excision arthroplasty alone may be appropriate in certain patients for either social or technical reasons.Two-stage revisions are the most widely favoured. However, they are demanding for healthcare facilities and the patient in terms of the repeated procedures and the limited mobility between stages.
They allow effective debridement and the option of local antibiotic delivery by drug-eluting cement spacers. Antibiotics may be delivered locally, systemically (either intravenously or oral) or both. What few data exist suggest that outcomes are broadly similar regardless of the means of antibiotic delivery—this is discussed in more detail below.One-stage revision may be appropriate for selected cases and is common practice in some centres. In particular it may be appropriate for those too frail to withstand two procedures and the demanding rehabilitation that follows a long period of relative immobility. It may not be advisable in those with resistant or difficult-to-treat organisms.
What evidence exists suggests outcomes are broadly similar to those with two-stage revision, but trials are needed. Antibiotic therapyThere is little evidence to guide the choice of the route or duration of antibiotic therapy and there is great variation in practice. The antibiotic can be delivered systemically or locally to the joint, usually through the use of loaded cement. If local delivery is to be relied upon, it is useful for the causative organisms and their susceptibilities to be defined pre-operatively. If systemic delivery is selected, a suitable empirical regimen must be designed whilst the results of intraoperative cultures are awaited. This should be guided by local organism susceptibilities and must be active against staphylococci and a wide range of nosocomial multiresistant Gram-negative organisms (for example, a glycopeptide and a carbapenem).
Two-stage revisionsLocal antibiotics can be delivered via a cement spacer. Caution must be exercised in deciding which antibiotic to use and how much as they may alter cement characteristics such as strength and viscosity, although this is of less concern with a temporary spacer in a two-stage procedure than it might be in a single stage operation. It is possible for antibiotic levels to remain at clinically effective levels locally for a prolonged period and rarely reach significant levels within the bloodstream. Some practitioners rely on local antibiotics alone, suggesting there is no additional benefit from the co-administration of systemic therapy.
Their published cure rates are similar to those obtained by adopting a systemic approach., An attempt at isolating the infecting organism by joint aspiration prior to the first-stage procedure is of particular importance with this strategy.The more widely accepted practice is to give empirical systemic antibiotics after the first-stage operation whilst awaiting culture results., Specific antibiotic therapy is then given for up to 6 weeks, usually intravenously but orally if an agent of suitable oral bioavailability is available. Failure of inflammatory markers or clinical signs of infection to settle during this time raises the possibility of persistent infection and re-debridement is essential. An antibiotic-free period of around 2 weeks may be considered following completion of therapy prior to the re-implantation second stage to allow microbiological sampling at operation. Empirical antibiotics are given peri-operatively and stopped if cultures are negative.The significance of positive cultures from samples taken at re-implantation is not clear. A retrospective series of 152 patients gave an overall new joint retention rate of 83% at 5.75 years—better for those undergoing their first revision (89%) and worse for the second (73%).
Positive microbiological sampling of the joint space at the second stage did not predict outcome, although the majority of such patients did receive further antibiotics. If there are significant microbiology cultures at re-implantation it may be reasonable to give oral antibiotics of suitable bioavailability for 3–6 months post-operatively with the rationale of preventing biofilm formation in the new joint. One-stage revisionsThe optimum duration of antibiotic treatment following a one-stage revision is not known and reports range from 1 week to several months.
Most series report outcomes broadly similar to those with two-stage revisions, most likely reflecting that a thorough and extensive debridement is the most critical predictor of success. Debridement, antibiotics and implant retention (DAIR)In the studies quoted above long courses of antibiotics were administered, up to 6 weeks intravenously and then an oral equivalent for a mean of 1.5 years. Zimmerli et al. Suggest much shorter courses of between 3 months for a hip and 6 months for a knee. Stopping antibiotics runs the risk of relapse but continuing beyond 6 months does not appear to significantly increase the chance of a cure. However, in selected patients at high risk of relapse it would seem reasonable to continue antibiotics long term with a strategy of suppression rather than cure.
Many units use up to 2 years of oral antibiotics and in selected high-risk patients there may be individualized decisions to go longer, or even indefinitely. More trials are needed to define optimum antibiotic durations. Intravenous or oralWhere systemic antibiotics are used there is no clear evidence to support one route over another at present.
Recommendations vary, with some centres giving intravenous antibiotics only as the empirical regimen whilst awaiting culture results and others routinely giving them for up to 6 weeks. Oral therapy may be an option in those cases where both organism and patient permit the use of an agent with equivalent oral and intravenous bioavailability. Where prolonged intravenous courses are required it is preferable that patients are treated in the community. This should be under the supervision of a specialist outpatient parenteral antimicrobial therapy (OPAT) team trained in both the management of intravenous long lines, the agents administered and safe monitoring and follow-up.
Within this context OPAT has been widely demonstrated to be safe and effective., The British Infection Society and the BSAC are currently in the process of producing standard national guidelines for the safe implementation of OPAT services. Specific agentsThe evidence for the use of specific antibiotics in the setting of prosthetic joint infection is limited., Most studies have examined the treatment of staphylococcal infection. Experimental data support the use of regimens based on rifampicin, as this is an agent with excellent oral bioavailability that achieves high concentrations in biofilms. Used alone, resistance emerges rapidly through a single point mutation in the DNA-dependent RNA polymerase. Animal and clinical data have demonstrated its effectiveness in combination therapy with ciprofloxacin, (another agent of high oral bioavailability) or fucidin. It has also been used in combination with trimethoprim and doxycycline. MRSA isolates demonstrating quinolone resistance have been successfully treated with rifampicin and linezolid or rifampicin and daptomycin.
The duration of linezolid therapy is limited by a high risk of haematological and neurological side effects. Linezolid alone is probably as effective as teicoplanin—indeed it appears to be more effective at the initial clearance of MRSA —but is less well tolerated.
Experimental evidence suggests that when used alone, teicoplanin is not as effective as vancomycin in producing a reduction in viable MRSA counts. It could be combined with another agent such as rifampicin —particularly in those instances in which a prosthetic device has been retained—or used at high dose: trough levels of 20 mg/L are recommended, requiring at least 600 mg a day in most individuals. Co-trimoxazole has been shown to be effective in the treatment of MRSA in vitro and anecdotal data and a prospective study suggest it is effective clinically., No randomized trials have specifically assessed its role in joint infection and treatment failure has been associated with settings in which the bacterial burden is high, emphasizing the importance of thorough operative debridement.Daptomycin is a novel cyclic lipopeptide with activity against MRSA, glycopeptide-intermediate S. Aureus and glycopeptide-resistant enterococci. In vitro studies demonstrate an efficacy equivalent to that of vancomycin and it demonstrates synergy with rifampicin against vancomycin-resistant enterococci and MRSA.The evidence supporting any specific antibiotic regimen for the treatment of Gram-negative joint infection is lacking.
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The combination of ceftazidime and ciprofloxacin has been successful in the treatment of Pseudomonas aeruginosa infection, and the use of ciprofloxacin may be associated with a better outcome when treating any susceptible Gram-negative organism. It is our practice to treat many Gram-negative prosthetic joint infections with a suitable intravenous agent for 4–6 weeks (for example ceftriaxone, ertapenem or meropenem) according to identification and susceptibility and, where indicated, continue with an oral agent. Culture-negative infectionsEven with meticulous sampling, around 7%–11% of prosthetic joint infections confirmed by histology are culture-negative and this may reflect prior antibiotic exposure. Agents should be selected on the basis of the clinical history, the presence of resistant organisms (for example MRSA colonization) and any previously positive samples. Empirical treatment with a glycopeptide and/or cephalosporin may be as effective as specific therapy in those cases in which the organism is known.
PreventionThe high infection rates associated with prosthetic joint implantation in the 1970s have fallen dramatically as a result of improvements in patient selection and preparation, surgical technique, theatre design, prophylactic antibiotics and anaesthesia. The introduction in 2005 of the UK Department of Health's ‘Saving Lives’ delivery programme for acute hospitals was designed to help organizations to reduce healthcare-associated infections. This programme now includes a care bundle aimed at the prevention of surgical site infection. MRSA screening and decolonization is now mandatory for all elective orthopaedic admissions in the UK.There has been controversy over the role of dental prophylaxis for patients with joint replacements. There is no evidence that dental procedures are a risk factor for prosthesis infection, nor that prophylaxis impacts infection rates.
Therefore prophylactic antibiotics prior to dental procedures in patients with prosthetic joints should not be recommended. Future developmentsThe future will no doubt see technical advances in areas such as microbiological diagnostics and biofilm-resistant prosthetics. Today, much of current best practice is supported largely by consensus opinion and data from observational studies or small trials.
Ideally, multicentre randomized trials are needed to tackle the big unanswered questions regarding the diagnosis and treatment of these difficult infections. In which cases is it safe to do a one-stage revision for infection? Are local antibiotics delivered via loaded cement as effective as systemic therapy? Are oral antibiotics as effective as intravenous treatment? How long should antibiotics be continued after a DAIR procedure?Bone and joint infection is increasingly seen as a specialty in its own right. Individual orthopaedic surgeons see relatively few complex cases and it is to be hoped that the future will see the development of further specialist centres capable of providing the multidisciplinary expertise required.
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Transparency declarationsThis article is part of a Supplement sponsored by the BSAC.I. Has received honoraria for serving on advisory boards for Pfizer and has received lecture fees from Pfizer and Nordic Pharma. Will receive an honorarium from the BSAC for this article. Has none to declare.