Objective: To evaluate the significance of bacteria detection with filter paper method on diagnosis of diabetic foot wound infection. Methods: Eighteen patients with diabetic foot ulcer conforming to the study criteria were hospitalized in Liyuan Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology from July 2014 to July 2015. Diabetic foot ulcer wounds were classified according to the University of Texas diabetic foot classification (hereinafter referred to as Texas grade) system, and general condition of patients with wounds in different Texas grade was compared. Exudate and tissue of wounds were obtained, and filter paper method and biopsy method were adopted to detect the bacteria of wounds of patients respectively. Filter paper method was regarded as the evaluation method, and biopsy method was regarded as the control method. The relevance, difference, and consistency of the detection results of two methods were tested. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of filter paper method in bacteria detection were calculated. Receiver operating characteristic (ROC) curve was drawn based on the specificity and sensitivity of filter paper method in bacteria detection of 18 patients to predict the detection effect of the method. Data were processed with one-way analysis of variance and Fisher's exact test. In patients tested positive for bacteria by biopsy method, the correlation between bacteria number detected by biopsy method and that by filter paper method was analyzed with Pearson correlation analysis. Results: (1) There were no statistically significant differences among patients with wounds in Texas grade 1, 2, and 3 in age, duration of diabetes, duration of wound, wound area, ankle brachial index, glycosylated hemoglobin, fasting blood sugar, blood platelet count, erythrocyte sedimentation rate, C-reactive protein, aspartate aminotransferase, serum creatinine, and urea nitrogen (with F values from 0.029 to 2.916, P values above 0.05), while there were statistically significant differences among patients with wounds in Texas grade 1, 2, and 3 in white blood cell count and alanine aminotransferase (with F values 4.688 and 6.833 respectively, P<0.05 or P<0.01). (2) According to the results of biopsy method, 6 patients were tested negative for bacteria, and 12 patients were tested positive for bacteria, among which 10 patients were with bacterial number above 1×10(5)/g, and 2 patients with bacterial number below 1×10(5)/g. According to the results of filter paper method, 8 patients were tested negative for bacteria, and 10 patients were tested positive for bacteria, among which 7 patients were with bacterial number above 1×10(5)/g, and 3 patients with bacterial number below 1×10(5)/g. There were 7 patients tested positive for bacteria both by biopsy method and filter paper method, 8 patients tested negative for bacteria both by biopsy method and filter paper method, and 3 patients tested positive for bacteria by biopsy method but negative by filter paper method. Patients tested negative for bacteria by biopsy method did not tested positive for bacteria by filter paper method. There was directional association between the detection results of two methods (P=0.004), i. e. if result of biopsy method was positive, result of filter paper method could also be positive. There was no obvious difference in the detection results of two methods (P=0.250). The consistency between the detection results of two methods was ordinary (Kappa=0.68, P=0.002). (3) The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of filter paper method in bacteria detection were 70%, 100%, 1.00, 0.73, and 83.3%, respectively. Total area under ROC curve of bacteria detection by filter paper method in 18 patients was 0.919 (with 95% confidence interval 0-1.000, P=0.030). (4) There were 13 strains of bacteria detected by biopsy method, with 5 strains of Acinetobacter baumannii, 5 strains of Staphylococcus aureus, 1 strain of Pseudomonas aeruginosa, 1 strain of Streptococcus bovis, and 1 strain of bird Enterococcus. There were 11 strains of bacteria detected by filter paper method, with 5 strains of Acinetobacter baumannii, 3 strains of Staphylococcus aureus, 1 strain of Pseudomonas aeruginosa, 1 strain of Streptococcus bovis, and 1 strain of bird Enterococcus. Except for Staphylococcus aureus, the sensitivity and specificity of filter paper method in the detection of the other 4 bacteria were all 100%. The consistency between filter paper method and biopsy method in detecting Acinetobacter baumannii was good (Kappa=1.00, P<0.01), while that in detecting Staphylococcus aureus was ordinary (Kappa=0.68, P<0.05). (5) There was no obvious correlation between the bacteria number of wounds detected by filter paper method and that by biopsy method (r=0.257, P=0.419). There was obvious correlation between the bacteria numbers detected by two methods in wounds with Texas grade 1 and 2 (with r values as 0.999, P values as 0.001). There was no obvious correlation between the bacteria numbers detected by two methods in wounds with Texas grade 3 (r=-0.053, P=0.947). Conclusions: The detection result of filter paper method is in accordance with that of biopsy method in the determination of bacterial infection, and it is of great importance in the diagnosis of local infection of diabetic foot wound.
目的：评价采用滤纸片法检测细菌对诊断糖尿病足创面感染的意义。 方法：选取2014年7月—2015年7月在华中科技大学同济医学院附属梨园医院住院治疗且符合入选标准的糖尿病足溃疡患者18例，按德州大学糖尿病溃疡分级系统对糖尿病足溃疡创面进行分级，比较不同分级创面对应患者一般情况。分别取创面渗出液、创面组织，采用滤纸片法和组织活检法进行创面细菌检测。以组织活检法检测结果为对照，滤纸片法为待评价方法，检验2种方法检测结果的关联性、差异性、一致性。计算滤纸片法检测细菌的敏感度、特异度、阳性预测值、阴性预测值和准确度。根据18例患者滤纸片法检测细菌的特异度和敏感度，绘制受试者工作特征(ROC)曲线，评价滤纸片法的检测效果。对数据行单因素方差分析、Fisher确切概率法检验。针对经组织活检法检出细菌的患者，对组织活检法与滤纸片法检出细菌数进行Pearson相关分析。 结果： (1)德州大学糖尿病溃疡分级1、2、3级创面对应患者间年龄、糖尿病病程、创面病程、创面面积、踝肱指数、糖化Hb、空腹血糖、血小板计数、红细胞沉降率、C反应蛋白、AST、血肌酐、尿素氮差异均无统计学意义(F值为0.029～2.916，P值均大于0.05)，白细胞计数、ALT差异有统计学意义(F值分别为4.688、6.833，P<0.05或P<0.01)。(2)组织活检法检测结果显示患者中有6例未检测出细菌；12例检测出细菌，其中10例细菌数大于1×10(5)个/g，2例细菌数未达到1×10(5)个/g。滤纸片法检测结果显示患者中有8例未检测出细菌；10例检测出细菌，其中7例细菌数大于1×10(5)个/g，3例细菌数未达到1×10(5)个/g。滤纸片法与组织活检法检测细菌同时阳性患者有7例，同时阴性患者有8例，滤纸片法阴性而组织活检法阳性患者有3例，组织活检法阴性的患者中未出现滤纸片法阳性。2种方法检测结果存在方向性关联(P＝0.004)，即组织活检法结果阳性，滤纸片法结果也可能是阳性；2种方法检测结果不存在明显差异(P＝0.250)；2种方法检测结果一致性一般(Kappa＝0.68，P＝0.002)。(3)滤纸片法检测细菌的敏感度为70%、特异度为100%、阳性预测值为1.00、阴性预测值为0.73、准确度为83.3%。18例患者滤纸片法检测细菌ROC曲线下总面积为0.919(95%置信区间为0～1.000，P＝0.030)。(4)组织活检法共检出13株细菌，其中鲍氏不动杆菌5株，金黄色葡萄球菌5株，铜绿假单胞菌、牛链球菌及鸟肠球菌各1株。滤纸片法共检出11株细菌，其中鲍氏不动杆菌5株，金黄色葡萄球菌3株，铜绿假单胞菌、牛链球菌及鸟肠球菌各1株。除金黄色葡萄球菌外，滤纸片法检测其余4种细菌的敏感度、特异度均为100%。滤纸片法与组织活检法检测鲍氏不动杆菌的一致性较好(Kappa＝1.00，P<0.01)，检测金黄色葡萄球菌的一致性一般(Kappa＝0.68，P<0.05)。(5)滤纸片法与组织活检法检出创面细菌数总体无明显相关(r＝0.257，P＝0.419)，其中2种方法检出德州大学糖尿病溃疡分级1、2级创面细菌数均显著相关(r值均为0.999，P值均为0.001)，检出德州大学糖尿病溃疡分级3级创面细菌数无明显相关(r＝-0.053，P＝0.947)。 结论：滤纸片法检测结果在确定是否存在细菌感染方面与组织活检法检测结果具有一致性，对诊断糖尿病足创面局部感染具有重要意义。.
Keywords: Bacterial detection; Biopsy method; Diabetic foot; Diagnosis; Filter paper method; Infection; Wound.