ObjectiveTo provide the evidence for diagnosis and treatment of the complication by describing the distribution and drug sensitivity of pathogens in patients with prosthetic joint infection (PJI) after primary total knee arthroplasty (TKA). MethodsBetween January 2003 and June 2013,65 cases (65 knees) with PJI after primary TKA were treated.There were 28 males and 37 females with an average age of 63.2 years (range,37-80 years).The median interval between PJI and primary TKA was 2.8 years (range,2 weeks to 11 years),including 29 left knees and 36 right knees.Prosthesis loosening could be found in 27 cases by X-ray examination.The average value of C-reactive protein and erythrocyte sedimentation rate was 37.4 mg/L (range,12.5-197.0 mg/L) and 63.2 mm/1 h (range,29.3-73.8 mm/1 h) respectively.Preoperative and intraoperative synovial fluid as well as intraoperative tissue samples should be submitted for aerobic and anaerobic culture.The four types of infections were made according to the Tsukayama et al.classification standards. ResultsThe patients were all diagnosed as having PJI.There were 5(7.69%) type I infections,4(6.15%) type ⅡA,8(12.31%) type ⅡB,3(4.62%) type Ⅲ,and 45(69.23%) type IV according to the Tsukayama et al.classification standard.Bacterial culture results were negative in 12 cases and positive in 53 cases,the main pathogen was Gram-positive cocci (39/53).The most common organism identified was Coagulase-negative Staphylococcus (24/53) followed by Staphylococcus Aureus (12/53).Resistant bacterium accounted for 61.11%(22/36) of Staphylococcus.These bacterium were all sensitive to vancomycin,linezolid,meropenem,and fluconazole;and highly resistant to erythrocin,penicillin,and cefoxitin.The main pathogenic bacteria of Coagulase-negative Staphylococcus and Staphylococcus aureus had highest resistant rate to penicillin. ConclusionGram-positive cocci is the main pathogen in patients with PJI after primary TKA,which is highly resistant to penicillin and macrolides.Antibiotic treatment of this complication should be based on the result of drug sensitivity test,vancomycin and linezolid may be used before the result of drug sensitivity test.It is important to pay attention to rare and multiple resistant bacteria.
ObjectiveTo explore the clinical characters and histopathologic differences between patients with culture-positive and culture-negative prosthetic joint infection (PJI). MethodsBetween January 2012 and July 2013, 66 PJI patients in accord with diagnostic criteria were enrolled. According to the results of preoperative aspiration and intraoperative cultures, the patients were divided into culture-negative group (CN group, n=21) and culture-positive group (CP group, n=45). There was no significant difference in gender, age, height, weight, and body mass index between 2 groups (P>0.05). Preoperative C reactive protein (CRP), erythrocyte sedimentation rate (ESR), and prosthesis survival time were compared between 2 groups. Intraoperative frozen sections and paraffin sections were both performed to identify infections, and histological typing was performed according to Morawietz's methods. ResultsThe preoperative CRP was (1.29±1.84) mg/ dL in CN group and (5.08±9.57) mg/dL in CP group, showing significant difference (t=2.094, P=0.038). The preoperative ESR was (22.86±28.42) mm/1 h in CN group and (36.74±31.26) mm/1 h in CP group, showing significant difference (t=7.761, P=0.000). The median survival time of prosthesis was 72 months (range, 8-504 months) in CN group and 25 months (range, 15 days-300 months) in CP group, showing significant difference (U=2.231, P=0.026). Morawietz's histological typing results showed that 2 cases were rated as type I, 7 cases as type II, and 12 cases as type III in CN group; 6 cases were rated as type I, 25 cases as type II, 13 cases as type III, and 1 case as type IV in CP group. The positive culture rate was 68.18% (45/66), and pathogenic bacteria was dominated by Staphylococcus, accounting for 68.89%. ConclusionThe patients with culture-negative PJI have slow onset and mild inflammatory response, so comprehensive diagnosis should be made based on pathological detection, laboratory examination, and intraoperative cultures.