Poor predictive value of broad-range PCR for the detection of arthroplasty infection in 92 cases

Background The diagnosis of prosthetic infection remains a challenge, as no test is 100% sensitive and 100% specific Recent advances in molecular biology have enabled the detection of infection in culture negative cases.

Patients and methods We evaluated the effectiveness of polymerase chain reaction (PCR) in detecting infection in failed joint replacements prospectively in 91 consecutive patients (92 prosthetic joints) undergoing revision total hip or knee arthroplasty. Synovial fluid was collected intraoperatively and examined by broad-range PCR assay for detection of bacterial DNA. The clinical diagnosis of infection was based on the results of blood tests, preoperative joint aspiration, culture and histology of multiple intraoperative tissue samples, as well as the surgeon's assessment.

12 joints (13%) were infected, but the PCR was positive in 32 cases. The sensitivity of the technique was 92%, the specificity 74%, the accuracy 76%, the positive predictive value 34%, and the negative predictive value was 98%.

Interpretation The PCR technique cannot be recommended for the routine detection of prosthetic infection. The large number of false positive results may represent sample contamination, or bacterial presence related to low-virulence organisms, low bacterial load, or a strong host immune response.     

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目的　探讨腹部外科手术病人全血细菌DNA检测结果与血细菌培养、术后全身炎症反应综合征(SIRS)及感染的关系。方法　将 2 0 0 3年 5～ 10月收治的 6 3例腹部外科病人分为 :胃肠手术组和非胃肠手术组 ;大手术组和中等手术组 ;术后发生SIRS组和未发生SIRS组。术前和术后 2h、2 4h、4 8h采集外周血 ,利用聚合酶链反应 (PCR)技术进行细菌DNA检测。结果　术前PCR均为阴性 ,术后共有 12例PCR阳性。术后 2h、2 4h和4 8hPCR阳性率差异无显著性 (P >0 .0 5 )。胃肠和非胃肠手术组PCR阳性率分别为 2 0 .6 %和 17.2 %(P >0 0 5 )。大手术组和中手术组PCR阳性率分别为 36 .0 %和 7.9% (P <0 .0 1)。术后出现SIRS的病人PCR阳性率为 4 1.7% ,高于无SIRS组的 5 .1% (P <0 .0 1)。PCR阳性组SIRS发生率为 83.3% ,阴性组为 2 7.5 %(P <0 0 1)。PCR阳性者 6 6 6 7%发生感染并发症 ,阴性者无一发生 (P <0 .0 1)。术后血细菌培养阳性率 4 .8% ,显著低于PCR的 19.0 % (P <0 .0 1) ;培养阳性者 ,PCR均呈阳性。PCR阳性结果中大肠杆菌DNA阳性占6 6 7%。结论　腹部外科术后早期 (2h)即可发生肠道细菌易位 (BT) ,以大肠杆菌为主。BT与手术时间长 (>3h)和 (或 )失血量大 (>5 0 0mL)有关 ,而与是否胃肠手术无关。术后SIRS和感染并     

Poor performance of microbiological sampling in the prediction of recurrent arthroplasty infection

During a two-stage revision for prosthetic joint infections (PJI), joint aspirations, open tissue sampling and serum inflammatory markers are performed before re-implantation to exclude ongoing silent infection. We investigated the performance of these diagnostic procedures on the risk of recurrence of PJI among asymptomatic patients undergoing a two-stage revision. A total of 62 PJI were found in 58 patients. All patients had intra-operative surgical exploration during re-implantation, and 48 of them had intra-operative microbiological swabs. Additionally, 18 joint aspirations and one open biopsy were performed before second-stage reimplantation. Recurrence or persistence of PJI occurred in 12 cases with a mean delay of 218 days after re-implantation, but only four pre- or intraoperative invasive joint samples had grown a pathogen in cultures. In at least seven recurrent PJIs (58%), patients had a normal C-reactive protein (CRP, <10 mg/l) level before re-implantation. The sensitivity, specificity, positive predictive and negative predictive values of pre-operative invasive joint aspiration and CRP for the prediction of PJI recurrence was 0.58, 0.88, 0.5, 0.84 and 0.17, 0.81, 0.13, 0.86, respectively. As a conclusion, pre-operative joint aspiration, intraoperative bacterial sampling, surgical exploration and serum inflammatory markers are poor predictors of PJI recurrence. The onset of reinfection usually occurs far later than reimplantation.     

Bacterial load in tissues and its predictive value for infection in open fractures

The role of quantitative bacteriology is considered controversial for the prediction of infection in open fractures. A study was done in 20 patients with open fractures. Post debridement pieces of skin, muscle and periosteal tissue were obtained for quantitative bacterial counts. Among a total of 50 samples from all of the tissues, 29 showed positive bacterial counts (16 of 20 skin, 11 of 20 muscle and 2 of 10 periosteum samples). By quantitative estimation, the bacterial load was >10(5) per gram in 10 skin and 3 muscle tissue samples. Infection developed in 9 of the 20 cases within one month, and eight of these patients had contamination of >10(5) per gram in 8 of the skin but only 3 muscle samples. It was concluded that with tissue specific bacterial load estimation, prediction of subsequent infection can be made if skin tissue contains >10(5) per gram, or if muscle tissue carries any level of bacterial presence.     

120例人工膝关节置换术后感染诊断回顾性分析

目的探讨膝关节表面置换术后感染的相关影响因素和诊断方法的差异性,为早期预防该类感染提供临床依据。方法对本组自2001年2月至2011年7月收治的120例膝关节表面置换术后感染的患者进行回顾性分析,其中男47例,女73例,平均年龄69岁,采用Logistic多因素回归分析方法对患者发病的相关因素和医生诊断该病的方法进行分析。结果 Logistic回归分析表明,类风湿关节炎（P〈0.05）、糖尿病（P〈0.05）、肿瘤（P〈0.01）、激素服用史（P〈0.01）、高血尿酸症（P〈0.05）和伴发其它系统感染（P〈0.05）是关节表面置换术后感染的高危险因素,WBC（P〈0.01）、ESR（P〈0.01）、CRP（P〈0.01）、关节液常规生化（P〈0.01）、关节液细菌培养（P〈0.05）、组织微生物培养（P〈0.01）指标对膝关节表面置换术后感染的早期诊断较其他方法更加方便。结论早期详细询问病史,积极治疗合并症对预防术后感染有重要的作用,同时,在对感染做诊断时,联合多种指标检测,能够提高膝关节表面置换术后感染的诊断率。     

The diagnostic and predictive value of hip anesthetic arthrograms in selected patients before total hip arthroplasty

Concurrent osteoarthritis of the hip and lumbar spine occurs frequently. Our study tests the hypothesis that hip anesthetic arthrograms can be used as predictive diagnostic tool before total hip arthroplasty when standard evaluation techniques fail to provide convincing evidence of the source of pain. Thirty-four consecutive hip anesthetic arthrograms were reviewed retrospectively. Quantified outcome measures included Visual Analog Pain Score, Harris Hip Score, and patient satisfaction. The pain relief after hip anesthetic arthrogram accurately predicted pain relief after hip arthroplasty (positive predictive value = 95.23%, negative predictive value = 87.5%). Our study supports the selected use of hip anesthetic arthrograms in the preoperative assessment of patients with concurrent hip and lumbar spine osteoarthritis associated with nondiagnostic history and physical examinations.     

Revision total hip arthroplasty: analysis of the predictive value of a radiographic classification system for assessment of bone stock loss

AIM: The aim of this study was to evaluate the predictive value of a radiographic classification system concerning implant and bone graft in revision total hip arthroplasty. This classification is used to assess bone stock loss prior to surgery, thus hypothetically enabling an adequate choice of the implant and bone graft required. METHOD: 33 consecutive patients with the diagnosis of aseptic failure of total hip arthroplasty were included in the study. The investigation was performed using the classification system according to Saleh et al. The predictive value was analyzed by comparing the radiographically based recommendation concerning implant and bone graft and the intraoperative procedure according to a blinded observer technique. The Spearman coefficient of correlation (r (s)) was used to establish levels of agreement among multiple ordinal variables. RESULTS: Analysis of correlation between preoperative radiological estimations and intraoperative conclusions concerning implant and bone graft revealed coefficients of correlation (r (s)) of 0.53 (p < 0.01) for the acetabular and of 0.63 (p < 0.01) for the femoral classification. CONCLUSION: Our results indicate that the Saleh classification does not provide sufficient information for preoperative assessment of the revision implant and bone graft required concerning the acetabular side, whereas planning of the operative procedure regarding the femoral implant seems to be possible. These ambivalent findings should be taken into account prior to revision total hip arthroplasty.     

Primary total joint arthroplasty performed in operating rooms following cases of known infection

No study has examined infection rates in "clean" cases following "dirty" cases. This study evaluated patients undergoing elective primary total joint arthroplasties performed in operating rooms following cases of known infection for development of postoperative infection. A retrospective review of all elective primary total joint arthroplasties performed over a 5-year period at our institution was conducted. Patients who underwent primary total joint arthroplasties that followed cases of known infection in the same operating room were examined (minimum follow-up of 1 year) to determine the occurrence of infection based on culture data and subsequent procedures. Thirty-nine total joint arthroplasties (27 total knee arthroplasties and 12 total hip arthroplasties) in 35 patients were performed following cases of known infection in the same operating room. Of these patients, 1 (2.6%) developed a periprosthetic joint infection. The infecting organism (Propionibacterium acnes) was the same as that isolated from the preceding "dirty" case. Further investigation is necessary to determine whether performing primary total joint arthroplasties immediately following "dirty" cases increases risk of infection.     

Laparoscopic surgery of the liver, in 92 cases

We analyze the experience in laparoscopic hepatic surgery of the Research Center of Laparoscopic and Open Surgery from Ia?i between 1993-2006. This study includes 92 patients (0.9% from 10,367 laparoscopic operations) with liver pathology considered for laparoscopic treatment. We performed 42 Lin procedures (wide fenestration technique) for serous hepatic cysts, 32 cystectomies for hepatic hydatid disease, 10 non-anatomical hepatic resections (for 2 adenomas, 4 haemangiomas, 4 metastasis) and 8 steam water thermo-necrosis (for multiple hepatic metastasis). Conversion to open surgery rate was 8.7% (hepatic hydatid cysts--6 cases, serous hepatic cyst--1 case with associated acute cholecystitis, thermo-necrosis--1 case). We had no postoperative mortality and morbidity rate was 6.5%. The follow-up was available in all patients for a mean time of 12 months, by abdominal ultrasound exam and/or computed tomography. No evidence of disease recurrence was registered. We are at the beginning of the laparoscopic hepatic surgery and these results need to be confirmed. For the hepatic serous cysts the laparoscopic fenestration is the best treatment, but for the hepatic hydatid cyst, the laparoscopic approach is indicated only in selected cases: uni-vesicular hydatid cyst, noncomplicated, localised into the "laparoscopic" segments of the liver. Albendazole treatment is also necessary in these cases. For all types of benign liver tumours, the best indication remains small, superficial lesions, located in the anterior or the lateral segments of the liver. When performed by expert liver and laparoscopic surgeons using an adequate surgical technique, the laparoscopic approach is safe for performing minor liver resection for malignant tumours and is accompanied by the usual postoperative benefits of laparoscopic surgery.     

肾移植术后巨细胞病毒感染的危险因素分析和血清甘露聚糖结合凝集素的预测价值

探讨肾移植受者巨细胞病毒(CMV)感染的危险因素,观察天然免疫分子甘露聚糖结合凝集素(mannose-binding lectin,MBL)对于肾移植术后CMV感染的预测价值.方法 选择2010年1月到2011年6月在山东大学附属山东省千佛山医院接受肾移植的83例受者作为研究对象.入选受者均经伦理委员会批准及其本人的同意.所有受者随访时间≥6个月.随访期间定期采用实时荧光定量聚合酶链反应检测血液、尿液CMV脱氧核糖核酸(DNA)拷贝数,血液或浓缩尿中检测CMV DNA≥103 copies/ml诊断为CMV感染.将83例受者分为CMV感染组和非CMV感染组,应用酶联免疫吸附试验(ELISA)检测两组肾移植受者术前血清MBL水平并进行比较.将可能影响CMV感染的6项指标先进行单因素分析,将有统计学意义的因素再进行多因素分析(Logistic回归),筛选出CMV感染的独立危险因素.结果 随访6个月内共有18例(22%)受者发生CMV感染(CMV感染组),另65例受者未发生CMV感染(非感染组).CMV感染组受者的术前血清MBL水平明显低于非感染组受者,两者比较差异有统计学意义(P<0.01).18例CMV感染受者经更昔洛韦治疗后,病毒拷贝数下降转阴,无一例发生CMV肺炎或移植物失功.单因素分析发现术前供体CMV血清学阳性/受体阴性(D +/R-)、MBL< 500 ng/ml、应用抗胸腺细胞球蛋白和发生术后排斥反应是CMV感染的危险因素(分别为P =0.018、0.001、0.011、0.005).Logistic回归分析发现术前MBL水平<500 ng/ml是CMV感染的独立危险因素,优势比为5.691,95%可信区间1.746~ 18.548,P=0.004.CMV血清学阳性/受体阴性(D +/R-)亦是CMV感染的独立危险因素,优势比为7.673,95%可信区间1.107 ~53.178,P=0.039.结论 术前MBL水平(<500 ng/ml)和术前供体CMV血清学阳性/受体阴性是肾移植术后CMV感染的独立危险因素.术前检测受者的血浆MBL水平对术后CMV感染有预测价值,一旦术前检测血浆MBL< 500 ng/ml可以术前提前应用抗病毒预防治疗.在供受体配对方面,应尽量避免将血清CMV阳性供肾移植给CMV阴性的受体.     

Revision total knee arthroplasty: infection should be ruled out in all cases

We hypothesized that some aseptic revision total knee arthroplasty failures are indeed caused by occult infection. This prospective study recruited 65 patients undergoing revision total knee arthroplasty. The mean follow-up period was 19 months. Collected synovial fluid was analyzed by Ibis T5000 biosensor (Abbott Molecular Inc, Ill; a multiplex polymerase chain reaction technology). Cases were considered as infected or aseptic based on the surgeon's judgment and Ibis findings. Based on Ibis biosensor, 17 aseptic cases were indeed infected that had been missed. Of these 17 cases, 2 developed infection after the index revision. A considerable number of so-called aseptic failures seem to be occult infections that were not adequately investigated and/or miscategorized as aseptic failure. We recommend that all patients undergoing revision arthroplasty be investigated for periprosthetic joint infection.     

Hip and knee arthroplasty infection: In-111 -IgG scintigraphy in 102 cases

We studied indium-111-labeled immunoglobulin G (ln-111-IgG) scintigraphy for evaluation of total hip and knee arthroplasty infection in 100 patients (102 arthroplasties) where infection was suspected (85 total hip and 17 total knee replacements, 23 of which proved to be infected, all but 2 late infections). The sensitivity of ln-111-IgG scintigraphy for infection was 1.0, for hip and knee arthroplasties the specificities were 0.8 and 0.5, respectively. False-positive results for infection occurred in cementless total hip arthroplasties up to 14 months after implantation. Aseptic inflammation due to formation of ectopic ossification and foreign-body response, following wear of the polyethylene socket, was responsible for false-positive results. The images should be read in conjunction with radiographs, which reduces the rate of false-positive results, ln-111 -IgG is a highly sensitive and fairly specific tool for detecting of late infection of total hip and total knee arthroplasties.     

Recalcitrant infection following total knee arthroplasty: a report of two cases

Infection following total knee arthroplasty can be devastating. Even with established treatment protocols, eradication of the infection may not be feasible. We report 2 patients who required above-knee amputation to eradicate recalcitrant infection.     

Iontophoresed segmental allografts in revision arthroplasty for infection

Revision arthroplasty after infection can often be complicated by both extensive bone loss and a relatively high rate of re-infection. Using allograft to address the bone loss in such patients is controversial because of the perceived risk of bacterial infection from the use of avascular graft material. We describe 12 two-stage revisions for infection in which segmental allografts were loaded with antibiotics using iontophoresis, a technique using an electrical potential to drive ionised antibiotics into cortical bone. Iontophoresis produced high levels of antibiotic in the allograft, which eluted into the surrounding tissues. We postulate that this offers protection from infection in the high-risk peri-operative period. None of the 12 patients who had two-stage revision with iontophoresed allografts had further infection after a mean period of 47 months (14 to 78).