The key role of iroBCDN-lacking pLVPK-like plasmid in the evolution of the most prevalent hypervirulent carbapenem-resistant ST11-KL64 Klebsiella pneumoniae in China.

AIMS: Hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP), coharboring hypervirulence and carbapenem-resistance genes mediated by plasmids, causes infections with extremely high mortality and seriously impacts public health. Exploring the transfer mechanisms of virulence/carbapenem-resistance plasmids, as well as the formation and evolution pathway of hv-CRKP is of great significance to the control of hv-CRKP infections. METHODS: In this study, we identified the predominant clone of hv-CRKP in China and elucidated its genomic characteristics and formation route based on 239 multicenter clinical K. pneumoniae isolates and 1014 GenBank genomes by using comparative genomic analysis. Further, we revealed the factors affecting the transfer of virulence plasmids, and explained the genetic foundation for the prevalence of Chinese predominant hv-CRKP clone. RESULTS: ST11-KL64 is the predominant clone of hv-CRKP in China and primarily evolved from ST11-KL64 CRKP by acquiring the pLVPK-like virulence plasmid from hvKP. Significantly, the virulence gene cluster iroBCDN was lost in the virulence plasmid of ST11-KL64 hv-CRKP but existed in that of hvKP. Moreover, the absence of iroBCDN didn't decrease the virulence of hv-CRKP, which was proved by bacterial test, cell-interaction test and mice infection model. On the contrary, loss of iroBCDN was observed to regulate virulence/carbapenem-resistance plasmid transfer and oxidative stress-related genes in strains and thus promoted the mobilization of nonconjugative virulence plasmid from hvKP into ST11-KL64 CRKP, forming hv-CRKP which finally had elevated antioxidant capacity and enhanced survival capacity in macrophages. The loss of iroBCDN increased the survival ability of hv-CRKP without decreasing its virulence, endowing it with an evolutionary advantage. CONCLUSIONS: Our work provides new insights into the key role of iroBCDN loss in convergence of CRKP and hvKP, and the genetic and biological foundation for the widespread prevalence of ST11-KL64 hv-CRKP in China.

Good short-term outcome of arthroplasty with Wagner SL implants for unstable intertrochanteric osteoporotic fractures.

The purpose of this study was to evaluate the clinical and radiologic results of a consecutive series of Wagner SL arthroplasties in patients with unstable intertrochanteric osteoporotic fractures. Forty-seven consecutive arthroplasties for unstable intertrochanteric fractures using Wagner SL hip stems were studied. All patients had bone mineral density less than -2.5 SD. At average follow-up of 2.7 years, mean Harris Hip Scores were 89.4 (range, 65-100) and 87.7 (range, 57-100) for total hip arthroplasties and hemiarthroplasties, respectively. Twenty-one patients (53.8%) had excellent Harris Hip Scores (>90, 14 [35.9%]). Evidence of clinical and radiologic healing was first noted at a mean follow-up of 3.7 months (3-5 months). Wagner SL hip arthroplasties for unstable intertrochanteric osteoporotic fractures have favourable short-term clinical and radiological outcomes.

Administration of enoxaparin 24 h after total knee arthroplasty: safer for bleeding and equally effective for deep venous thrombosis prevention.

BACKGROUND: The purpose of this study was to determine the safety and effectiveness, as assessed by risk of bleeding and incidence of deep venous thrombosis (DVT), of administering delayed low-molecular-weight heparin (LMWH) after total knee arthroplasty. METHODS: A prospective study of 210 consecutive patients undergoing primary unilateral total knee arthroplasty was undertaken. The patients were randomized into two groups: one of which was managed according to a standard LMWH program (LMWH-s group) and the other with delayed LMWH (LMWH-p). LMWH was initiated 12 h after wound closure in the LMWH-s group, and 24 h after wound closure in the LMWH-p group. RESULTS: The total blood loss in the first three postoperative days was calculated and all complications were recorded. The mean total blood loss was 435 and 387 mL in the LMWH-s group and LMWH-p group, respectively (p < 0.01). No significant difference in the incidence of symptomatic DVT was observed. The mean length of hospital stay was 7.29 days in the LMWH-s group and 6.56 days in the LMWH-p group (p < 0.05). CONCLUSIONS: After total knee arthroplasty, LMWH-p is safer for bleeding than LMWH-s and equally effective concerning prevention of DVT.

Geneticand phenotypic characterization of a novel ST45-K43 carbapenem-resistant Klebsiella pneumoniae strain causing bloodstream infection: a potential clinical threat.

Klebsiella pneumoniae is a common pathogen of nosocomial infection, which can cause pneumonia, urinary tract infection, cystitis, and bloodstream infections (BSIs). Here, we genetically characterize a novel carbapenem-resistant K. pneumoniae (CRKP) strain recovered from the blood of a 44-year-old male patient with severe acute necrotizing pancreatitis and septic shock in China. The strain is a ST45 K. pneumoniae with a novel serotype of K43, named 18SHX166. The susceptibility testing results showed that 18SHX166 was resistant to cephalosporin and carbapenems but still susceptible to ceftazidime-avibactam, quinolones, colistin, and amikacin. Genomic sequencing revealed that 18SHX166 contains three plasmids, namely pSHX166-Hv, pSHX166-KPC, and pSHX166-3. pSHX166-Hv harbored the iucABCD operon, encoding the siderophore of aerobactin. pSHX166-KPC harbored blaKPC-2 gene and possessed complete conjugative regions. The conjugation experiment verified pSHX166-KPC as a self-transmissible plasmid mediating the dissemination of antibiotic resistance, with a conjugation rate of 2.21 × 10-5. Additionally, the growth curve showed that 18SHX166 demonstrates a higher growth rate than the control strains. The characteristics of 18SHX166 indicate a potential high risk of clinical transmission.IMPORTANCEST45-K43 carbapenem-resistant Klebsiella pneumoniae isolate, 18SHX166, carries a carbapenem resistance plasmid and virulence plasmid. It has the characteristics of multidrug resistance, high transmissibility, and a fast growth rate, which could pose a threat to the control of antimicrobial resistance and clinical transmission, causing a severe challenge to public health.

Effect of ceftazidime-avibactam combined with different antimicrobials against carbapenem-resistant Klebsiella pneumoniae.

This study aimed to assess the in vitro efficacy of ceftazidime-avibactam (CZA) in combination with various antimicrobial agents against carbapenem-resistant Klebsiella pneumoniae (CRKP). We selected 59 clinical CRKP isolates containing distinct drug resistance mechanisms. The minimum inhibitory concentrations (MICs) of meropenem (MEM), colistin (COL), eravacycline (ERA), amikacin (AK), fosfomycin (FOS), and aztreonam (ATM), both individually and in combination with CZA, were tested using the checkerboard method. The interactions of antimicrobial agent combinations were assessed by fractional inhibitory concentration index (FICI) and susceptible breakpoint index (SBPI). The time-kill curve assay was employed to dynamically evaluate the effects of these drugs alone and in combination format. In the checkerboard assay, the combination of CZA+MEM showed the highest level of synergistic effect against both KPC-producing and carbapenemase-non-producing isolates, with synergy rates of 91.3% and 100%, respectively. Following closely was the combination of FOS+CZA . For metallo-beta-lactamases (MBLs) producing strains, ATM+CZA displayed complete synergy, while the combination of MEM+CZA showed a synergy rate of only 57.14% for NDM-producing strains and 91.67% for IMP-producing strains. In the time-kill assay, MEM+CZA also demonstrated significant synergistic effects against the two KPC-2-producing isolates (Y070 and L70), the two carbapenemase-non-producing isolates (Y083 and L093), and the NDM-1-producing strain L13, with reductions in log10 CFU/mL exceeding 10 compared to the control. Against the IMP-producing strain Y047, ATM+CZA exhibited the highest synergistic effect, resulting in a log10 CFU/mL reduction of 10.43 compared to the control. The combination of CZA and MEM exhibited good synergistic effects against KPC-producing and non-enzyme-producing strains, followed by the FOS+CZA combination. Among MBL-producing strains, ATM+CZA demonstrated the most pronounced synergistic effect. However, the combinations of CZA with ERA, AK, and COL show irrelevant effects against the tested clinical isolates. IMPORTANCE: Our study confirmed the efficacy of the combination CZA+MEM against KPC-producing and non-carbapenemase-producing strains. For metalloenzyme-producing strains, CZA+ATM demonstrated the most significant synergy. Additionally, CZA exhibited a notable synergy effect when combined with FOS. These combination therapies present promising new options for the treatment of CRKP infection.

[Total hip arthroplasty for the post-traumatic osteoarthritis after open reduction and internal fixation of acetabular fracture].

OBJECTIVE: To explore the surgical strategy of traumatic osteoarthritis of the hip joint secondary to the failure of open reduction and internal fixation (ORIF) treatment on acetabular fractures. METHODS: Eighteen cases of traumatic osteoarthritis of the hip joint received total hip arthroplasties from May 2002 to December 2009, who had undergone the surgery of ORIF after acetabular fractures. There were 12 male and 6 female with an average age of 53 years (45 to 66 years). It was average 11.2 months (6.0 to 24.0 months) from the present of pain and limp to the operation. It was average 35 months (8 to 72 months) from ORIF procedure on acetabular fracture to total hip arthroplasty. Harris score was 50 points in average (26 to 70 points). RESULTS: All 18 cases were followed up 40 months in average (12 to 86 months). They were allowed to get out of bed on 1 week after the operation. The time of full weight bearing lagged to 2 or 3 months after the operation. All patients had the function of their hips improved with Harris score of 86 points in average (80 to 92 points). CONCLUSIONS: The procedures of ORIF on acetabular fracture make lots of trouble to total hip arthroplasty. It is important to rebuild the normal biological mechanisms of acetabulum and uses uncement fixed prosthesis as possible as it can.

Effects of patellar resurfacing on contact area and contact stress in total knee arthroplasty.

The objective of this study was to examine the effects of patellar resurfacing on patellofemoral joint contact pressure and contact area in total knee arthroplasty. We tested seven fresh-frozen cadaveric knees using a custom knee jig which permits the simulation of physiologic quadriceps loading. Before patellar resurfacing, the mean peak contact pressure of medial and lateral patellofemoral joints was less than 10 MPa at knee flexion angles of 30 degrees, 60 degrees and 90 degrees, that of medial and lateral patellofemoral joints were 11.63 MPa and 11.42 MPa at a knee flexion angle of 120 degrees respectively, and the mean contact area of patellofemoral joint ranged from 70 to 150 mm2. After patellar resurfacing, the mean peak contact pressure of medial and lateral patellofemoral joints ranged from 50 to 100 Mpa (P<0.05), which exceeds the yield strength of ultrahigh molecular weight polyethylene, and the mean contact area of patellofemoral joint reduced to 10-15 mm2 (P<0.05). The contact pressure of patellofemoral joint was lower than the yield strength of articular cartilage before patellar resurfacing. Our results indicate that the yield stress of UHMWPE is exceeded after patellar resurfacing.

[Radiographic analysis of rotational malalignment between tibial component and femoral component in total knee arthroplasty].

OBJECTIVE: To identify possible reasons of rotational mismatch between tibial component and femoral component in total knee arthroplasty and choose a right reference axis for placing the components in the operation and to decrease the complications. METHODS: Forty normal Chinese knees were studied. There were 20 men and 20 women, and average age was 34 years (range, 18 - 42 years). The images of cross sections of the distal femur were obtained by spiral CT scanning (0.5 mm thickness). Scan direction was aligned to be in the plane perpendicular to the mechanical axis of the tibia. On the images of the distal femur and the proximal tibia, three baselines for the anteroposterior axis of the femoral component were drawn based on the clinical epicondylar axis and the surgical epicondylar axis and 3 degrees lateral rotated to the posterior condylar surfaces of the femur separately, and a baseline for the anteroposterior axis of the tibial component was drawn based on the medial 1/3 of the tibial tuberosity. The rotational mismatch angles were measured between each component by using the Autocad software. RESULTS: The mean rotational mismatch angle between tibial component and femoral component is 2.94 degrees for the clinical epicondylar axis, 6.50 degrees for the surgical epicondylar axis and 6.83 degrees for 3 degrees lateral rotation of the femoral component referenced to the posterior condylar axis separately. CONCLUSIONS: Landmarks of each bone were the intrinsic cause of the rotational mismatch in total knee arthroplasty. The clinical epicondylar axis can be chosen for the ideal reference to rotational alignment of the femoral component because of its minimal rotational mismatch between each component.

[The use of a closed-suction drain in total knee arthroplasty: a prospective, randomized study].

OBJECTIVE: To determine the value of using a closed-suction drain in cemented knee arthroplasty. METHODS: One hundred patients were prospectively randomized into two groups, one group underwent cemented total knee replacement with a single deep closed-suction drain, and the other group (n = 50) no drain. RESULTS: The total blood loss was significantly greater in those with a drain although those without lost more blood into the dressings. There was no statistical difference in the postoperative swelling or pain score, ecchymosis, deep vein thromboses (DVT), time at which flexion was regained or the incidence of infection at a minimum of two years after surgery in the two groups. CONCLUSION: There is no evidence to support the use of a closed-suction drain in cemented knee arthroplasty.

[The effect of rotational alignment of the femoral components on the patellofemoral biomechanics in total knee arthroplasty].

OBJECTIVE: To study the effect of rotational alignment of the femoral components on the patellofemoral biomechanics in total knee arthroplasty (TKA) demonstrated on autopsy specimens, as the guide for surgeons to choose the correct reference axis for rotational alignment of the femoral components and to reduce the patellofemoral joint complications. METHODS: Select 9 frozen fresh human cadaver knees without gross deformities or instabilities and mount specimens on a patellofemoral joint testing jig connected to a Model 8501 Instron machine (Instron Corporation, Canton, MA). The study simulated the action of squatting from the standing position with the foot firmly planted. Standard TKA was performed in each specimen by the same senior surgeon using Nexgen LPS total knee system (Zimmer Corporation, Warsaw Indiana). Alter rotational alignment of the femoral components referenced to the transepicondylar axis and the Whiteside's line respectively. Measure biomechanics of the patellofemoral joints using Fuji prescale film at 30 degrees , 60 degrees , 90 degrees , 120 degrees of knee flexion respectively. The digital values were obtained by the handheld pressure measurement systems (FPD-305E, FPD-306E) and Autocad software. RESULTS: The rotational alignment of the femoral components paralleled to the transepicondylar axis had the best results of the peak value of the patellofemoral contact pressure (P < 0.05). There were no statistically significant differences in patellofemoral contact area (P > 0.05). But the patellofemoral contact area had the close correlations to the angles of the knee flexion and the specimens. CONCLUSIONS: Rotational alignment of the femoral components has a great influence on the patellofemoral contact pressure in total knee arthroplasty. It is reliable for surgeons to choose the transepicondylar axis as the reference axis to rotate femoral components.

[Clinical experience on postoperative balance of hemostasis and antithrombus for patients with hemophilic arthritis after arthroplasty].

OBJECTIVE: To observe the clinical significance of postoperative personalized antithrombotic therapy for patients with hemophilic arthritis (HA) patients after arthroplasty. METHODS: From September 2005 to October 2013, 11 cases of arthroplasty for hemophilic arthritis in hip and knee total operation 14 times,including 1 case of double knees (calculated as one operation), operation in left knees 6 times, operation in right knees 5 times, 2 in hip. All the patients were male and the age ranged from 23 to 57 years old,with an average of (36.1 ± 11.0) years old; the average weight was (64.1 ± 8.9) kg. All the patients were preoperatively diagnosed and classified as hemophilic arthritis with the radiological images and laboratory tests. According to the function of joints, the risk of postoperative venous thromboembolism (VTE), and dynamic observation of Factor VIII:C (FVIII:C) activity, patients were treated with personalized antithrombus by adjusting the dosage of recombinant human coagulation factor VIII (Kogenate FS). All the patients were orderly divided into postoperatively distal joints moving group and none-moving group to observe the coagulation function. RESULTS: The enrolled patients had no postoperative complication of VTE and pulmonary embolism (PE). The APTT and D-2 were different between two groups in the postoperative early stage. Length of hospital day was shorter in the moving group than none-moving group. CONCLUSION: Because of the self-coagulation disorder, patients with HA tended to bleed. However it doesn't mean that there is no risk of postoperative thrombosis. Therefore,it's important to determine how to control the balance between postoperative antithrombus, hemostasis,and coagulation factor replacement therapy after arthroplasty for HA. Postoperative moving has proved helpful for HA, especially in reducing the risk of hemostasis and shortening the time in hospital.

Preparation and characterization of antimicrobial nano-hydroxyapatite composites.

Deep infection of prosthesis is one of the most frequent complications after joint replacement. One of the most effective ways is to introduce directly some antibiotics in the local site of the surgery. In the present study, an antimicrobial composite has been fabricated using nano-hydroxyapatite particles as carriers for the antimicrobial drug of vancomycin hydrochloride (VAN) and the mixture of oxidation sodium alginate (OSA) and gelatin (GT) as a sticky matrix. Samples have been characterized using X-ray diffraction instrument (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM) and Fourier transform infrared (FTIR) spectra, Brunauer-Emmett-Teller (BET) methods, the rotational rheometer and the texture analyzer. The release of VAN from nano-hydroxyapatite (nHAP) particles was detected by the ultraviolet-visible (UV-vis) spectrophotometer and then bactericidal property of the composite was evaluated using the Staphylococcus aureus (S. aureus) as a bacterial model. Experimental results showed that the composite possessed an adhesive property derived from the gel of OSA and GT, which implied that the composite could bond directly to the fracture surface of bones in surgery. Furthermore, VAN was loaded efficiently on the surface of nHAP particles and could be released slowly from these particles, which endowed the composite with an obvious and continuous antimicrobial performance. The sticky and antimicrobial composite may has a potential application in arthroplasty to overcome deep infection in a simple and direct manner.

[Short-term curative effects of Tantalum rod treatment in early avascular necrosis].

OBJECTIVE: To explore the recent clinical curative effect of Tantalum rod in treating the early avascular necrosis. METHODS: From January 2008 to November 2008, the 25 patients (39 hips) with early avascular necrosis accepted tantalum rod placement and included 9 males (11 hips) and 16 females (28 hips) with an average age of 37 years old ranging from 18 to 74 years old. Four patients (6 hips) caused by Alcoholic, 6 patients (8 hips) by hormone, 2 cases (2 hips) by traumatic, 13 cases (23 hips) by idiopathic. Steinberg preoperative stage involved 7 hips in period I, 24 hips in period II, 8 hips in period III. Curative effect analysis included preoperative and postoperative Harris score, radiographic changes and hip replacement for follow-up to accept the end of the femoral head survival rate. RESULTS: All patients were followed up for 6 to 47 months (averaged 37.4 months). All 12 hips imaging appeard progress,including tantalum rod exit in 1 hip, hip hemiarthroplasty collapse in 3 hips, the area increased to avascular necrosis in 8 hips. Six hips accepted total hip replacement, including imaging progress in 5 hips (41.7%, 5/12), no imaging progress in 1 hip (3.7%,1/27). All hips' Kaplan-Meier survival curves showed 6-month survival rate was (97.4 +/- 2.5)% after tantalum stick insertion, 1-year survival rate was (94.7 +/- 3.6), and 2-year survival rate was (88.6 +/- 5.4)%, 3-year survival rate was (72.5 +/- 11.2). CONCLUSION: It is effective for treatment of avascular necrosis of femoral head in Steinberg I and II by Tantalum rod, and it can effectively relieve femoral head replacement time.