[Analysis of pathogen distribution and drug resistance of acute,delayed and chronic periprosthetic joint infection].

Objective: To analyze the pathogen distribution and drug resistance in acute,delayed and chronic periprosthetic joint infection (PJI). Methods: The clinical data of 316 patients with periprosthetic infection after primary hip and knee arthroplasty admitted to the Department of Arthroplasty,the First Affiliated Hospital,Xinjiang Medical University from August 2010 to August 2020 were retrospectively analyzed.There were 146 males and 170 females,aged (62.3±14.2) years (range:22 to 89 years).One hundred and sixty one patients underwent total hip arthroplasty and 155 patients underwent total knee arthroplasty.According to the time of postoperative infection,the patients were divided into acute PJI group (65 cases),delayed PJI group (83 cases) and chronic PJI group (168 cases).The results of pathogen species,composition ratio and drug susceptibility tests were collected,and the independent sample t test,Chi-square test or Fisher's exact probability test were used for comparison. Results: Gram-positive bacteria were the main pathogens of PJI (49.7%,157/316),and the positive rates of culture in patients with acute PJI,delayed PJI and chronic PJI were 33.8% (22/65),55.4% (46/83) and 53.0% (89/168),and the difference was statistically significant(χ²=8.343,P=0.015).The common bacteria were coagulase-negative Staphylococcus (54.8%,86/157) and Staphylococcus aureus (30.6%,48/157),The drug-sensitivity to linezolid,vancomycin and tigacycline was 100%.The gram-negative bacteria were mainly Escherichia coli and Enterobacter cloacae,and the drug resistance rate to carbapenems was low,ranging from 0 to 9.09%.The drug resistance rates of acute PJI patients to rifampicin,ciprofloxacin and erythromycin were significantly higher than those of late onset and chronic PJI patients,the difference was statistically significant(rifampicin:χ²=14.332,P=0.001;ciprofloxacin:χ²=12.086,P=0.002;erythromycin:χ²=9.096,P=0.010);The drug resistance rate of acute PJI patients to levofloxacin,clindamycin and tetracycline was higher than that of chronic PJI patients,and the difference was statistically significant(levofloxacin:χ²=10.500,P=0.002; clindamycin: χ²=7.103,P=0.007; tetracycline: χ²=6.909,P =0.012).The resistance rate of ampicillin/sulbactam in acute PJI (60.0%) was significantly higher than that in chronic PJI (16.7%),and the difference was statistically significant(χ²= 5.853,P=0.040). Conclusion: Gram-positive bacteria are the main pathogens of PJI,and the resistance rate of pathogens of acute PJI is higher than that of late onset and chronic PJI.

[Bilateral internal jugular vein thrombosis in a patient with severe burn].

A 33 years old male patient who suffered from a flame burn of 88% total body surface area was admitted to our hospital on November 28th, 2016. During his hospitalization, we repeatedly performed central vein catheterization in internal jugular veins, subclavian veins, or femoral veins for fluid transfusion. We incidentally found bilateral internal jugular vein thrombosis by performing a point-of-care ultrasound examination before catheterizing sometime. We treated the patient by avoiding catheterization in the affected internal jugular veins, anticoagulating with low molecular weight heparin, closing the wounds with skin autografting, and guiding the patient to practice functional exercise. The thrombus disappeared in the end. The patient was cured and discharged 3 months post burn.

Features of the volume change and a new constitutive equation of hydrogels under uniaxial compression.

For high-water content hydrogels in compression, the water inside of hydrogels contributes to the response of hydrogels to external loads directly, but part of the water is expelled from hydrogels in the meantime to change the volume of the hydrogel and reduce the contribution. In order to consider the contribution of the water in the constitution equation, PVA (polyvinyl alcohol) hydrogels with high-water content were used as examples, and compressive experiments were carried out to measure both the stress-strain relation and the change of the volume in the meantime. By considering the effect of the difference of the contribution of water in different directions of the hydrogel, we deduced a new constitutive equation, which can pretty well depict the stress-strain of hydrogels with different water contents. The results showed that the contribution of water to the total stress increases with the compression strain and even exceed that of the polymer, although the expelled water reduces the contribution at the early loading stage, which well explains the difference of elastic moduli of hydrogels in compression and tension.

Predicting the aquatic toxicity mode of action using logistic regression and linear discriminant analysis.

The paper highlights the use of the logistic regression (LR) method in the construction of acceptable statistically significant, robust and predictive models for the classification of chemicals according to their aquatic toxic modes of action. Essentials accounting for a reliable model were all considered carefully. The model predictors were selected by stepwise forward discriminant analysis (LDA) from a combined pool of experimental data and chemical structure-based descriptors calculated by the CODESSA and DRAGON software packages. Model predictive ability was validated both internally and externally. The applicability domain was checked by the leverage approach to verify prediction reliability. The obtained models are simple and easy to interpret. In general, LR performs much better than LDA and seems to be more attractive for the prediction of the more toxic compounds, i.e. compounds that exhibit excess toxicity versus non-polar narcotic compounds and more reactive compounds versus less reactive compounds. In addition, model fit and regression diagnostics was done through the influence plot which reflects the hat-values, studentized residuals, and Cook's distance statistics of each sample. Overdispersion was also checked for the LR model. The relationships between the descriptors and the aquatic toxic behaviour of compounds are also discussed.

[Pathological changes of diffuse Pneumocystis carinii infection in the liver of an AIDS patient].

OBJECTIVE: To examine the pathological changes in the liver of an AIDS patient with complicated infection of Pneumocystis carinii(PC). METHODS: A liver biopsy was made. The tissue was stained with HE, PAS, Giemsa, GMS, and acid-fast staining, and examined under light microscope and transmission electron microscope. RESULTS: Granulomas (acid-fast negative) in the tissue and numerous pathogens (PAS positive) in hepatic sinusoids were detected. Giemsa and GMS staining and electron microscopy all confirmed that the pathogen was Pneumocystis carinii. CONCLUSION: The pathological findings revealed a diffuse extrapulmonary infection of Pneumocystis carinii in the patient of AIDS.