The pathogenicity of coagulase negative staphylococcus in the presence of silicone rubber implants

Coagulase negative staphylococci have long been thought to be harmless skin commensals. However they are now recognised as important pathogens in patients who have undergone insertion of prosthetic devices. We present three patients with infection following the insertion of silicone polymer prostheses, in whom a coagulase negative staphylococcus was the pathogen. All responded to antibiotic treatment. It is important to alert the bacteriologist to the presence of an implanted prosthesis when wound swabs are sent from an area showing clinical signs of infection. The coagulase negative staphylococci may otherwise be regarded falsely as merely skin contaminants.     

Methicillin-resistant staphylococcal infections: an important consideration for orthopedic surgeons

Postoperative infections in joint prostheses and fracture-fixation devices commonly involve both MRSA and methicillin resistant coagulase-negative staphylococcus. In addition, community-acquired MRSA has also become an important consideration when infected patients are admitted to the hospital from the community. Preoperative colonization with MRSA and methicillin resistant coagulase-negative staphylococcus increases the risk of postoperative surgical site infections in orthopedic patients. Up to 5.3% of orthopedic patients are colonized with these organisms on hospital admission. Screening and decolonization of methicillin resistant staphylococci decrease the incidence of postoperative surgical site infections in the orthopedic patient. This may be particularly important in orthopedic implants given the difficulty encountered in treating infected prosthesis. Current US guidelines advocate screening for methicillin resistant staphylococci only when risk factors are present. Growing evidence suggests that screening and decolinization of all patients having elective orthopedic procedures, especially those including prosthetic implants, will decrease the incidence of postoperative infections. The infected prosthesis may be potentially salvaged if the clinical manifestations of infection have been present for < or = 10 days, the implant is stable, and the etiologic organisms are susceptible to oral antibiotics.     

Effect of time of onset and depth of infection on the outcome of total knee arthroplasty infections

The treatment results of 24 infected total knee arthroplasties with a minimum follow-up period of two years are presented. The most common pathogens were coagulase-positive staphylococci (50%), coagulase-negative staphylococci (29.2%), and enterococci (12.5%). Eleven patients with early postoperative infections (occurring within one month of prosthesis implantation) were treated with debridement, retention of the prosthesis, and intravenous antibiotics. Treatment was successful in all five patients with superficial infections not extending into the joint. In six patients with deep infections, treatment was successful in only two (33%), despite a longer course of antibiotic therapy (four to six weeks) and the use of tobramycin-impregnated polymethylmethacrylate beads. Three patients continued to have recurrent drainage, and one patient was subsequently successfully treated with a delayed exchange arthroplasty. Thirteen patients were diagnosed with late infections. One patient with a late, superficial infection and another with an acute (hematogenous seeding), deep infection were successfully managed with debridement and intravenous antibiotics. Prosthesis removal was not required. Eleven patients presented with late, deep infections. Of three patients who were treated without removal of the prosthesis, infection was arrested in only one. The remaining eight patients were treated with debridement, intravenous antibiotics, tobramycin-impregnated polymethylmethacrylate beads, and delayed exchange arthroplasty. The median interval to reimplantation was eight weeks (range, seven to 25 weeks). Treatment was successful in six cases (75%). The overall success rate in the treatment of total knee arthroplasty infections was 71%. In 19 patients with deep infections, treatment success was seen in 78% of patients treated with delayed exchange arthroplasty, but this value was only 40% in patients who were not treated with prosthesis removal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cost of infection after surgery for intracapsular fracture of the femoral neck

Introduction

We investigated the financial and human costs of postoperative infection for intracapsular fracture of the femoral neck at a district general hospital in the UK.

Methods

Data on postoperative infections after surgical treatment for intracapsular fracture of the femoral neck were collected prospectively from June 2005 to April 2009. Infected patients were pairwise-matched (1:2 ratio) with a non-infected group of patients from a database on hip fractures. Costs of additional surgery, duration of hospital stay, and opportunity costs were calculated using Primary Care Trust (PCT) tariffs and PCT-specific data.

Results

A total of 525 patients were treated with total hip replacement (n=110) or hip hemiarthroplasty (n=415). Seventeen patients (3.2%) were identified as having a surgical-site infection. Eight (1.5%) deep infections and nine (1.7%) superficial infections were documented. Compared with the non-infected group, duration of hospital stay and the prevalence of mortality doubled. Repeat surgery and the costs associated with hospital admission were increased significantly in the infected group. Mean financial loss associated with an infected patient was £7,726, whereas an uninfected patient brought £153 of profit to the hospital. When opportunity costs were considered, an infected patient represented £24,397 of lost income.

Conclusions

Postoperative infection after surgical treatment for intracapsular fracture of the femoral neck has a significant negative impact on duration of hospital stay and financial costs, and demonstrates a trend towards an increase in the prevalence of mortality.     

Guideline of antimicrobial therapy in the area of cardiovascular surgery

Although cardiovascular surgery is considered to be aseptic, prolonged hospital stay before and after surgery, the use of artificial materials and cardiopulmonary bypass, long-term use of intratracheal tubes or intravenous catheters, and an increase in surgeries on high-risk patients increase the incidence of postoperative infections. Therefore meticulous management to minimize bacterial contamination before and after surgery and identification of patient risk factors are important to reduce their incidence and severity, in addition to optimal antimicrobial therapy. As the targets of prophylactic antibiotics are usually superficial and environmental bacteria, those of choice are first or second-generation cephalosporins or penicillin with sulbactam. If postoperative infection is suspected, identification of the infectious site and pathogens and their susceptibility to anitimicrobials is useful to control infections. The use of broad-spectrum antibiotics is not recommended because these drugs induce bacterial resistance to antibiotics. Infectious endocarditis (IE) and deep wound infections, such as mediastinitis, are major serious infections after cardiovascular surgery. Antibiotics should be selected by considering the susceptibility of pathogens and pharmacokinetic properties of antibiotics, such as concentration in infected tissue. In patients reluctant to medical therapies, surgical intervention such as valve repair or replacement in IE and debridement and omental flap in mediastinitis should be considered.     

Use of superficial femoropopliteal vein for suprainguinal arterial reconstruction in the presence of infection

BACKGROUND: Conventional treatment of mycotic aneurysms or graft infections of the aortoiliac segment by in situ or extra-anatomic prosthetic reconstruction has a high mortality and morbidity rate, with a substantial risk of persistent graft infection. The use of autologous vein may reduce this. METHODS: Eleven patients with suprainguinal arterial infections including two with mycotic aortic aneurysms, four with aortic graft infections, four infected femorofemoral grafts and an infected axillofemoral graft were treated by debridement and in situ reconstruction with autologous superficial femoropopliteal vein. All patients received appropriate antibiotic therapy and were followed by regular postoperative duplex imaging. Preoperative femoral vein duplex imaging was performed in eight of the 11 patients. RESULTS: Ten of the 11 patients survived with a functioning graft and without limb loss or evidence of infection at 4-33 months. One patient died from myocardial infarction after operation. Three patients had minor swelling of one leg. Four patients required subsequent angioplasty of anastomotic stenoses detected by duplex surveillance. CONCLUSION: Superficial femoropopliteal vein is an excellent conduit for suprainguinal reconstruction in the presence of infection. Duplex imaging is useful for confirming the suitability of deep veins for use as a graft and for postoperative surveillance.     

Incidence study of nosocomial infection in pediatric trauma patients

In this article we intend to describe the epidemiological profile of nosocomial infection in pediatric patients with multiple trauma. We conducted a prospective study from July to November 2003 in a pediatric teaching hospital in Barcelona. We used US Centers for Disease Control and Prevention standard criteria to define nosocomial infection. Of the 121 patients included in the study, 33% had at least one episode of nosocomial infection, with an incidence rate of 9.9 infections per 100 admissions and 1.1 infections per 100 patient-days. The most frequent episode of nosocomial infection was bacteremia. Coagulase-negative staphylococci were the most common pathogens. Nosocomial infection rates per 100 device-days were 3.2 for bacteremia, 1.6 for respiratory infection and 1.0 for urinary tract infection. These findings suggest the need to evaluate infection control measures aimed at reducing the morbidity associated with infections.     

Comparison between the Staphylococci aureus and coagulase-negative staphylococci infected total joint arthroplasty treated by two-stage revision: A retrospective study with two year minimum follow-up

Background

Staphylococcus species are major pathogens of peri-prosthetic joint infection (PJI). Coagulase-positive staphylococci and coagulase-negative staphylococci have different intrinsic virulences. However, few studies have specifically compared the clinical manifestations and two-stage revision outcomes of PJI caused by these two species.

Wound infections after cardiac surgery--a wound scoring system may improve early detection

OBJECTIVE: This study was aimed at describing the early development of wound infections after cardiac surgery to identify markers for upcoming infections. DESIGN: We followed a cohort of 200 patients for 3 months after cardiac surgery to establish the incidence of all types of postoperative infections. Wound healing and C-reactive protein (CRP) were followed for the first 2 weeks. RESULTS: A total of 175 patients out of 200 could be followed up. Using a broad definition of wound infection a total of 30% of the patients had some kind of wound infection. The diagnosis of most infections occurred after the patients had left the cardiac surgery unit (median 12 d after surgery). Our wound scoring method shows significant differences at an early stage between infected and non-infected wounds. At the time of diagnoses CRP was elevated in patients with deep sternal infection. CONCLUSION: A long follow-up period is needed to establish the true incidence of infection. Wound scoring can give an early indication of wound infections and CRP can help in the diagnoses of deep infections.     

Skin and osteoarticular infections of the diabetic foot. Role of infection

A MAJOR PROBLEM: Two-thirds of all amputations involve infection. Infection is favored by dysfunction of the antibacterial defense systems due to high blood glucose and vascular disorders. DIAGNOSIS: General signs of infection are usually not found. A careful exploration is required to rule out or confirm osteitis in order to guide surgery and plan the antibiotic regimen. A history of chronic and/or recurrent ulceration or direct signs at inspection may be suggestive of osteitis. Radiographic signs are late and nonspecific. Scintigraphy scans are difficult to interpret. Magnetic resonance imaging can be quite helpful in difficult cases. BACTERIOLOGICAL PROOF: Staphylococcus aureus and to a lesser extent streptococci account for almost all of the superficial infections in the diabetic foot. In case of deep ulceration, it is important to obtain deep specimens at surgical cleansing as more superficial samples are easily contaminated. Nevertheless, if Staphylococcus aureus is isolated from pus coming from a deep zone fistulizing to the skin, it is likely the causal agent since 80% of all bone infections involve S. aureus. Other germs besides staphylococci and streptococci include enterobacteria (40%), enterococci (26%) and pseudomonas (7%). Several germs are involved in about 70% of cases with a probable synergetic effect between the different bacterial colonies within the infected tissues.     

Risk factors associated with methicillin-resistant staphylococcal wound infection after spinal surgery.

We used the data from a retrospective case controlled study to identify risk factors for methicillin-resistant staphylococcal wound infection after spinal surgery. Thirty-five cases and 35 uninfected control patients were matched for indication for initial surgery and approximate operative date. Preoperative, intraoperative, and postoperative risk factors were examined. At our institution between 1989 and 1995, 35 adult patients developed spinal wound infection requiring operative debridement; 16 infections were caused by methicillin-resistant staphylococci (MRS). Significant risk factors for MRS infection were lymphopenia, history of chronic infections, alcohol abuse, recent hospitalization, and prolonged postoperative wound drainage. Patients with MRS infections were also somewhat less likely to have received vancomycin prophylaxis. In contrast, the only factor associated with infection caused by other pathogens was alcohol abuse. A number of preoperative risk factors were significantly associated with subsequent MRS spinal wound infection. Chemoprophylaxis with vancomycin should be targeted to patients at increased risk, because overuse may promote the emergence of vancomycin-resistant pathogens.     

Deep sternal wound infections following open heart surgery in Iceland: a population-based study

OBJECTIVE: The aim of this nationwide case-control study was to study the epidemiology and identify risk factors of deep sternal wound infections (DSWI) in Iceland. PATIENTS AND METHODS: Between 1997-2004, 1 650 adults underwent open cardiac surgery in Iceland. For every infected patient four control subjects were chosen (n =163), matched for time of operation. The groups were compared by multivariable logistic regression analysis. RESULTS: Forty one patients (2.5%) developed DSWI, most often following CABG (76%). The most common pathogens were Staphylococcus aureus (39%) and coagulase-negative staphylococci (24%). All except two patients underwent debridement and rewiring of the sternum. Length of hospital stay was significantly longer in the DSWI group with a trend for increased hospital mortality and significantly greater 1-year mortality (17% vs. 5%, p =0.02). History of stroke (OR 5.12), peripheral arterial disease (OR 5), corticosteroid use (OR 4.25), smoking (OR 3.66) and re-operation for bleeding (OR 4.66) were the strongest independent predictors for DSWI. CONCLUSION: Incidence of DSWI in Iceland (2.5%) is comparable to other recently published studies, with similar risk factors and significantly reduced survival at one year following the infection.     

Postoperative mediastinitis in cardiac surgery - microbiology and pathogenesis.

OBJECTIVE: During 1992-2000, postoperative mediastinitis developed after 126 (1.32%) of 9557 consecutive cardiac surgery procedures. The study was done to describe the variation in clinical characteristics and microbiological etiology in mediastinitis. METHODS: The records of 126 cases of postoperative mediastinitis were reviewed. RESULTS: The median time from operation to the development of mediastinitis was 7 days. Sternal dehiscence was seen in 86 patients (68%). Coagulase negative staphylococci (CNS) were isolated in 46% of the cases with a verified microbiological etiology, Staphylococcus aureus in 26% and gram-negative bacteria in 18%. CNS were more frequently isolated in patients with sternal dehiscence (44/80, 55%) than in patients with stable sternum (10/38, 26%) (P=0.003). However, S. aureus was more frequent in patients with stable sternum (18/38, 47%) than in patients with sternal dehiscence (13/80, 16%) (P<0.001). High body mass index was associated with coagulase negative staphylococci (P<0.001) and with sternal dehiscence (P=0.008). Chronic obstructive pulmonary disease was also associated with sternal dehiscence (P<0.001) and with coagulase negative staphylococci (P=0.04). Patients who had been reoperated before onset of mediastinitis tended to have an increased risk for a gram-negative etiology (32 vs. 15% in patients not reoperated, P=0.06). The overall 90-day all cause mortality in patients with mediastinitis was 19%. High age, need for reoperation before mediastinitis, and a long primary operation time was associated with increased mortality (P=0.02, P=0.007 and P=0.001, respectively). No specific bacterial etiology was associated with increased mortality nor was the presence of bacteriemia. CONCLUSIONS: Three different types of postoperative mediastinitis can be distinguished: (1) mediastinitis associated with obesity, chronic obstructive pulmonary disease, and sternal dehiscence, typically caused by coagulase negative staphylococci; (2) mediastinitis following peroperative contamination of the mediastinal space, often caused by S. aureus, and (3) mediastinitis mainly caused by spread from concomitant infections in other sites during the postoperative period, often caused by gram negative rods. The proposed classification of mediastinitis into three groups with different pathogenic mechanisms may be useful in understanding which prophylactic counter measures have the potentials to be effective in a given situation.     

Wound Infections after Cardiac Surgery - a Wound Scoring System may Improve Early Detection

Objective - This study was aimed at describing the early development of wound infections after cardiac surgery to identify markers for upcoming infections. Design - We followed a cohort of 200 patients for 3 months after cardiac surgery to establish the incidence of all types of postoperative infections. Wound healing and C-reactive protein (CRP) were followed for the first 2 weeks. Results - A total of 175 patients out of 200 could be followed up. Using a broad definition of wound infection a total of 30% of the patients had some kind of wound infection. The diagnosis of most infections occurred after the patients had left the cardiac surgery unit (median 12 d after surgery). Our wound scoring method shows significant differences at an early stage between infected and non-infected wounds. At the time of diagnoses CRP was elevated in patients with deep sternal infection. Conclusion - A long follow-up period is needed to establish the true incidence of infection. Wound scoring can give an early indication of wound infections and CRP can help in the diagnoses of deep infections.     

双氧水在多节段腰椎术中抗感染及降低术后引流量效果的研究

目的探讨双氧水在多节段腰椎术中抗感染及降低术后引流量的效果。方法回顾性分析2017年1月-2018年1月手术治疗的510例多节段腰椎退行性疾病患者临床资料,其中230例切口缝合前采用双氧水冲洗(研究组),280例采用生理盐水冲洗(对照组)。两组患者性别、年龄、病变类型、病程、手术节段等一般资料比较,差异均无统计学意义(P>0.05)。记录并比较两组患者手术时间、术中出血量、术后引流量及术后感染率,采用美国疾病控制和预防中心(CDC)标准评价感染发生情况。结果两组患者手术时间、术中出血量比较差异无统计学意义(P>0.05),研究组术后引流量明显少于对照组(t=-2.990,P=0.005)。术后13例患者发生感染,其中浅部感染10例(研究组2例、对照组8例),感染持续时间(7.3±1.5)d;深部感染3例(均为对照组患者),感染持续时间(16.6±3.1)d。研究组浅部和深部感染发生率均低于对照组,但差异无统计学意义(χ^2=2.595,P=0.123;P=0.256)。浅部感染均为金黄色葡萄球菌感染,经积极换药后康复;深部感染患者中2例为金黄色葡萄球菌感染、1例为大肠埃希菌感染,均经彻底清洗缝合并积极换药后康复。结论多节段腰椎手术中,切口缝合前使用双氧水冲洗可降低术后感染发生率和术后引流量。     

The economic implications of infection in cardiac surgery

To assess the economic impact of infection, the records of 496 patients aged 18 to 82 years (mean, 61 years) undergoing open-heart operations in 1981 and 1982 were reviewed, and the costs (length of stay, hospital charges, pharmacy charges) were compared for matched pairs of patients with and without infection who had coronary artery bypass grafting (CABG) procedures. Patients received a 5-day regimen of prophylactic cephalosporin. Operative site infections occurred within 6 months of operation in 17 patients (3.4%), urinary tract infections in 9 (1.8%), and pulmonary infections in 6 (1.2%). Early and late mortality was each 2%. No deaths were infection related, and no postoperative bacterial endocarditis occurred (minimum one-year follow-up). For the matched CABG patient in whom a postoperative wound infection developed, the average length of hospital stay was 16.7 days longer and the average hospital bill was $8,118 greater, with the average cost to the hospital $6,605 greater.     

The diagnostic value of C-reactive protein in infected total hip arthroplasties

In 50 patients with non-infected total hip arthroplasties (THA), 233 C-reactive protein (CRP) values were obtained over a three-year period. Six of these 50 patients occasionally had CRP values of over 20 mg/l. The erythrocyte sedimentation rate (ESR) and CRP concentration were measured in 23 patients with deep infections of THA before revision. In 11 patients the infections were caused by coagulase-negative staphylococci. CRP exceeded 20 mg/l in 18 patients and the ESR was more than 30 mm/hr in 14. In only one infected patient were both CRP and ESR below these levels. All of 33 patients with non-septic loosening had CRP less than 20 mg/l and ESR less than 30 mm/hr before revision. C-reactive protein seems to be a valuable supplement to the ESR in the monitoring of infection after THA.     

经尿道前列腺电切术后早期拔除留置导尿管的可行性及安全性

目的探讨经尿道前列腺电切术后早期拔除留置导尿管对降低术后并发症及住院费用的影响及临床应用安全性。方法将200例患者随机分为2组,实验组患者术后3 d拔除留置导尿管。对照组术后4~5 d拔除留置导尿管,观察2组患者拔除留置导尿管后尿路感染、尿道热、重新留置导尿、继发性出血、深静脉血栓的发生率。结果术后3 d拔除留置导尿管能降低TURP术后尿路感染的发生率（P〈0.05）,减少住院费用,缩短平均住院日（P〈0.05）。结论前列腺经尿道电切术后早期拔除留置尿管不但可以减少术后并发症,而且可以降低手术费用,值得推广应用。     

Vacuum assisted wound closure in postoperative periprosthetic groin infections: a new gold standard?

AIM: This study was designed to control the results of conservative treatment using vacuum assisted wound closure (VAWC) applied exclusively to cases of deep groin infections with involvement of alloplastic graft material. METHODS: During a 2 year period 10 patients with 11 deep inguinal infections involving alloplastic graft material were treated with supportive VAWC. Intraoperative management included extensive debridement, sartorius myoplastic and VAWC application. A retrospective case-note review was performed. Variables comorbidity, surgical management of the infection, microbiological results, complications and Doppler results were analysed. RESULTS: Six early graft infections (< 30 days after implantation) and 5 late infections were treated. In 3 cases (27.3%) the infected graft material was replaced by a silver-coated Dacron prosthesis. The mean duration of VAWC was 16+/-7.7 days; postoperative mean hospital stay was 25.3+/-8.5 days. Mean postoperative follow-up was 13.1 months with no procedure-related mortality. CONCLUSION: Even in the presence of synthetic vascular graft material, negative pressure therapy can greatly simplify challenging wound healing problems under maintenance of the alloplastic grafts. These preliminary results demonstrate the safety and effectiveness of VAWC for the treatment of deep alloplastic graft infections.     

Infected aortic aneurysms: clinical outcome and risk factor analysis

PURPOSE: Infected aortic aneurysms are difficult to treat, and are associated with significant mortality. Hospital survival is poor in patients with severe aortic infection, Salmonella species infection, Staphylococcus aureus infection, aneurysm rupture, and suprarenal aneurysm location. We reviewed the clinical outcome in 46 patients with primary infected aortic aneurysms and identified clinical variables associated with prognosis. METHODS: Data were collected by means of retrospective chart review. Univariate and multivariate logistic regression models were used for risk factor analysis. RESULTS: Between August 1995 and March 2003, 48 patients with primary infected aortic aneurysms were treated at our hospitals. Two patients with negative culture results were excluded. Of the remaining 46 patients, 35 patients had aortic aneurysms infected with Salmonella species and 11 patients had aortic aneurysms infected with microorganisms other than Salmonella species. There were 20 suprarenal infections and 26 infrarenal infections. Surgical debridement and in situ graft replacement were performed in 35 patients, with an early mortality rate of 11%. The incidence of late prosthetic graft infection was 10%. The 90-day mortality rate in patients operated on was 0% for elective operation and 36% for nonelective operation (P =.006, Fisher exact test). Independent predictors of aneurysm-related death were advanced age, non-Salmonella infection, and no operation. CONCLUSION: With timely surgical intervention and prolonged antibiotic treatment, in situ graft replacement provides an excellent outcome in patients with primary infected aortic aneurysms and elective operation. Mortality is still high in patients undergoing urgent operation. Advanced age, non-Salmonella infection, and no operation are major determinants of mortality.