OBJECTIVE: To investigate the ability of repairing bone defect with the compound of coralline hydroxyapatite porous (CHAP), fibrin sealant(FS) and staphylococcus aureus injection (SAI), and the feasibility to use the compounds as bone substitute material. METHODS: The animal model of bone defect was made on the bilateral radius of 54 New Zealand white rabbits, which were randomly divided into the experimental group(the defect was repaired with CHAP-FS-SAI), control group(with autograft) and blank control group(the defect was left unrepaired) with 18 rabbits in each group. The ability of bone defect repair was evaluated by gross observation, histopathological study, X-ray and biomechanical analysis 2, 4, 8 and 12 weeks after repair. RESULTS: (1) In the 2nd week, tight fibro-connection could be found between the implant and fracture site and there were many fibroblasts and capillary proliferation with many chondrocytes around CHAP in the experimental group, while only a few callus formed, and chondrocytes, osteoblast and osteoclast existed in the control group. (2) In experimental group and control group, a large quantity of callus was found 4 and 8 weeks; ossification of chondrocytes with weave bone formation were found 4 weeks and many osteocytes and weave bones and laminar bones were found 8 weeks. (3) In the 12th week, the complete ossification of implant with well bone remodeling, a large number of mature osteocytes and laminar were found in experimental group and control group, and CHAP still existed in the experimental group; the defect area filled with fibro-scar tissue and only many fibroblasts could be seen in blank control group. (4) X-ray findings were the following: In experimental and control groups, callus formation could be seen 2 weeks postoperatively, more callus formed 4 weeks, the bone defect area disappeared and CHAP scattered in the callus 8 weeks; the fracture line disappeared and medullary cavity became united (in control group); and in the 12th week, the cortex became continuous, the medullary cavity became united, and remodeling completed, while bone defect was not still united in blank control group. The maximal torque and torsional stiffness in the experimental group is higher than those in the control group 2 weeks (P lt; 0.05), but there was no significant difference (P gt; 0.05) between the two groups 4, 8, 12 weeks after repair. CONCLUSION: The compound of CHAP-FS-SAI has good biological compatibility, and it can be used for one kind of bone substitute material to repair the bone defect.
ObjectiveTo analyze the characteristics of distribution and drug resistance of clinical isolated staphylococci in the Whire Union Bacterial Resistance Surveillance Network across Sichuan from 2015 to 2018, so as to provide reference for clinical rational drug use and management of drug-resistant bacteria in Sichuan.MethodsA total of 18 023 strains of staphylococci were isolated from 9 hospitals of Whire Union Bacterial Resistance Surveillance Network for four years (2015-2018). Drug susceptibility test was carried out by disk diffusion method or automated instrument method. The data were statistically analyzed by WHONET 5.6 according to CLSI 2016 standard.ResultsThe 18 023 strains of staphylococci included 10 865 (60.28%) Staphylococcus aureus and 7 158 (39.72%) coagulase negative staphylococci. No strains resistant to vancomycin and linezolid were found. The detection rates of methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative staphylococci were 25.10% (2 727/ 10 865) and 75.60% (5 411/7 158), respectively. The sensitivity of methicillin-resistant staphylococci to most antibiotics was significantly lower than that of methicillin-sensitive strains (P<0.05). The susceptibility rate of staphylococci to some antibiotics was significantly different from 2015 to 2018(P<0.05). The susceptibility rates of Staphylococcus aureus from different samples to rifampicin, moxifloxacin, ciprofloxacin, levofloxacin, oxacillin and erythromycin were significantly different (P<0.05). The susceptibility rates of Staphylococcus aureus from different departments in different samples of sulfamethoxazole, rifampicin, moxifloxacin, ciprofloxacin, levofloxacin, oxacillin, gentamicin, tetracycline, clindamycin and erythromycin were significantly different (P<0.05).ConclusionsThe susceptibility of strains isolated from different periods, different specimens and departments to the same antimicrobial agents varies greatly. For the infection of staphylococci, we should use drugs under the guidance of drug susceptibility according to the source of samples, which can avoid the abuse of beta-lactam drugs. Strengthening the monitoring and control of drug-resistant bacteria can prevent or reduce the spread of drug-resistant bacteria.
Objective To validate the advantage of repairing bone defect by staphylococcus aureus injection carried in collagen membrane. Methods Twentyfour adult New Zealand rabbits were divided into two groups randomly. After the experimental model of standard bone defect had been made by operation, collagen membrane/staphylococcus aureus injection and staphylococcus aureus injection with the same quantity were transplanted in bone defect areas of the two groups respectively. The reconstructed tissues were observed by general method, X-ray, histology, and immunohistochemistry at 2nd、4th、6th、8th week respectively. Results The experimental group showed that new bone proliferated distinctly in bone defect areaand the proliferation lasted long, and no excessive connective tissue in defectarea. X-ray observation showed that there was continual callus growth in transplantation area in early stage and the distribution of new bones was even in the group. Histological observation showed that there were many new bone growth centers in bone defect area, trabecular bones were sequentially distributed, and mature bone replacement was complete. Immunohistochemical examination showed that bone morphogenetic protein (BMP) could be seen for a long time and BMP took up a large part in the new bone tissues. Conclusion Collagen membrane could prevent parenchyma from penetrating into bone defect area and provide room for new bone growth. As the carrier of staphylococcus, collagen membrane could reduce the overflow of staphylococcus and improve its curative effect as well.
Objective Mesh infection may occur after incisional hernia repair using prosthetic mesh. Preparation of antibiotics-bonded meshes to prevent infection is one of the solutions. To evaluate the anti-infection effect of polypropylene mesh bonded norvancomycin slow-release microsphere by preparing the rat model of incisional hernia repair contaminatedwith Staphylococcus aureus. Methods The norvancomycin slow-release microspheres were prepared by emulsion and solvent evaporation method and they were bonded to polypropylene mesh (50 mg/mesh). The appearance of the microspheres was observed using scanning electronic microscope (SEM). The content of norvancomycin in microspheres and the release rate of the norvancomycin in norvancomycin-bonded polypropylene mesh were detected using high performance l iquid chromatography method. The rat models of incisional hernia were developed in 40 healthy Sprague Dawley rats, aged 10-11 weeks and weighing 200-250 g. The rats were divided randomly into the experimental group (norvancomycin-bonded polypropylene mesh repair, n=20) and the control group (polypropylene mesh repair, n=20). And then the mesh was contaminated with Staphylococcus aureus. The wound heal ing was observed after operation. At 3 weeks after operation, the mesh and the tissue around the mesh were harvested to perform histological observation and to classify the inflammatory reaction degree. Results The norvancomycin microsphere had integrated appearance and smooth surface with uniform particle diameter, 64% of particlediameter at 60 to 100 μm, and the loading-capacity of norvancomycin was 19.79%. The norvancomycin-bonded polypropylene patch had well-distributed surface and the loading-capacity of norvancomycin was (7.90 ± 0.85) mg/cm2. The release time of norvancomycin in vitro could last above 28 days and the accumulative release rate was 72.6%. The rats of 2 groups all survived to experiment completion. Wound infection occurred in 2 rats of the experimental group (10%) and 20 rats of the control group (100%), showing significant difference (χ2=32.727 3, P=0.000 0). The inflammatory reaction in experimental group was not obvious, grade I in 16 rats and grade II in 4 rats, and numerous inflammatory cell infiltration occurred in the control group, grade II in 3 rats and grade III in 17 rats, showing significant difference (Z=32.314, P=0.000). Conclusion The polypropylene mesh bonded norvancomycin slow-release microsphere has definite anti-infection effect in rat model of incisional hernia repair contaminated by Staphylococcus aureus.
ObjectiveTo investigate the appropriate concentration of methicillin-resistant Staphylococcus aureus (MRSA) in establishing chronic femoral osteomyelitis model in rabbits.MethodsForty-eight adult New Zealand white rabbits were randomly divided into 6 groups with 8 rabbits in each group. Animals in groups B, C, D, E, and F were injected 1×109, 1×108, 1×107, 1×106, 1×105 CFU/mL MRSA on the location of 2 cm of the femoral supracondyle, respectively, and group A was injected with aseptic saline as a control. The general observation were performed at 4 weeks after operation, and the wound secretions were taken for bacteriological examination. The serum C-reactive protein content was detected at preoperation and 2 weeks and 4 weeks after operation. The X-ray, CT scan, and Norden imaging scoring were performed at 4 weeks after operation. At 4 weeks after operation, the animals were sacrificed, and the specimens were observed and evaluated by general scores; and the HE staining and histological score were also performed.ResultsFive rabbits died of severe infection in group B, 2 died in group C, and no rabbit died in groups D, E, and F. General observation showed that the incision healed without soft tissue swelling in group A; most animals had visible incision swelling and sinus formation, femoral thickening, bone destruction, and damage decreased with the decreasing of the concentration of liquid bacterial in groups B-D; the infection signs were seen in groups E and F, and the degree of infection were less than that of group D. Bacteriological examination showed that fistula formation animal in groups B, C, D, and E were cultured with positive results, and with the decrease of concentration, the number of animal fistula formation decreased gradually; and bacteriological culture did not be performed in group F because of no sinus formation. There was no significant difference in the content of C-reactive protein between groups before operation (P>0.05). The contents of C-reactive protein in groups B-F were significantly higher than those in group A at 2 and 4 weeks after operation (P<0.05). At 4 weeks after operation, the content of C-reactive protein was in the order of groups B, C, D, E, F, and A in turn from high to low, showing significant differences between groups (P<0.05). Imaging examination showed that there was no soft tissue swelling and bone destruction in group A; bone destruction, massive sequestrum formation, and soft tissue swelling were found in groups B and C; bone destruction was observed in groups D and E, and the degree of sequestrum formation was not as good as that in group C; and there was a small amount of bone infection in group F. The Norden scores in groups B-F were significantly higher than that in group A, and in groups B and C than those in groups D, E, and F, and in groups D and E than that in group F (P<0.05); there was no significant difference between groups B and C, and between groups D and E (P>0.05). The specimens general observation scores in groups B-F were significantly higher than that in group A, while in groups B and C than those in groups D, E, and F (P<0.05); there was no significant difference between groups D, E, and F (P>0.05). HE staining showed that the structure of bone trabecula in group A was clear and the structure was arranged neatly; in groups B-F, trabecular bone destruction and inflammatory cell infiltration were seen and the degree gradually decreased. The histological scores in groups B-F were significantly higher than that in group A, and in group B than those in groups C-F, in groups C and D than that in group F (P<0.05); there was no significant difference between groups C, D, and E, and between groups E and F (P>0.05).ConclusionThe optimal MRSA concentration of rabbit model of chronic osteomyelitis of femur is between 1×106 and 1×107 CFU/mL.
Objective To investigate the effect of aureolysin （Aur） on staphylococcus aureus biofilm formation of dacron biomaterial surfaces under different Aur concentration. Methods Ninety dacron biomaterials were divided into 3 groups （group A, group IA, control group） with random number table （30 piece in each group）. Dacron biomaterials were put into vials contained staphylococcus aureus （105 CFU/ml） respectively; then Aur was added to make the concentration at 400ng/ml in group A, and group B at 80ng/ml. The thickness and number of staphylococcus aureus biofilm on the surfaces of dacron biomaterials of each group were evaluated by confocal laser microscopy and scanning electron microscopy after incubating 6h, 16h, 24h, 30h, and 48h. Results The thickness and number of staphylococcus aureus biofilm on dacron biomaterials surfaces increased significantly with time dependence in control group. The thickness and number of staphylococcus aureus biofilm in group A were less than those in group B and control group at each time points （P〈0. 05）. The thickness and number in group B were significantly decreased than those in control group （P 〈 0. 05）. Conclusion The study shows that Aur can effectively inhibit the formation of staphylococcus aureus biofilm on dacron biomaterials surfaces with dose dependence.
Objective To investigate the genetic polymorphism of methicillin resistant Staphylococcus aureus ( MRSA) isolated from hospital acquired pneumonia. Methods Seventy-four hospitalized patients were diagnosed as noscomial MRSA pneumonia from January 2007 to January 2008 in Xinhua Hospital, Shanghai Jiaotong Univesity. The genes of MRSA were amplified by random amplified polymorphic DNA typing ( RAPD) assay in 82 clinical isolates from these patients. Results Two to 15 amplified DNA fragments were observed in agarose gel and they were classified into 11 genotypes. Genotypes Ⅲ, Ⅵ and Ⅶ ( 32. 56% , 30. 23% and 13. 95% , respectively) were mainly isolated from the ICU. Both independent genotypes and overlapping genotpyes with those from ICU were identified in isolates from the departments of geriatrics, emergency and respiratory medicine. Outbreak or cluster cases ( 48. 65% ) were found in 36 of the 74 patients while all outbreak cases occurred in the ICU. Conclusions Noscomial MRSA pneumonia is easy to disseminate and small-scale outbreak may occur especially in ICU. RAPD is valuable for identification and prevention of the spread of MRSA in hospital.
ObjectiveTo analyze the pathogenic bacteria distribution, structure and characteristics of drug resistance in patients with acute stroke complicated with pulmonary infection, in order to provide reference for the prevention of hospital infection and rational use of antimicrobial agents.
MethodsA total of 864 clinical specimens of acute stroke complicated with pulmonary infection were chosen for study between January 2012 and December 2014. Separation and cultivation were done in accordance with the operation procedures regulated by the Ministry of Health. Drug sensitivity examination was done by Kirby-Bauer (k-b). Super-extensive spectrum β lactamase (ESBL) and methicillin resistant staphylococcus aureus (MRSA) were detected to analyze the bacterial species and resistance transition.
ResultsA total of 864 samples were cultivated, in which G-bacteria accounted for 61.2%. The main pathogenic bacteria was Klebsiella pneumoniae bacteria, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumanmii and Staphylococcus aureus. Imipenem had high antimicrobial activity to G-bacilli, especially to Escherichia coli and Klebsiella pneumoniae bacteria. Linezolid, vancomycin and teicoplanin had high antibacterial activity to staphylococcus aureus. Vancomycin resistant Staphylococcus aureus was not found. Ciprofloxacin had high antibacterial activity to Pseudomonas aeruginosa, while imipenem had low antibacterial activity to Pseudomonas aeruginosa. Amikacin had high antibacterial activity to acinetobacter.
ConclusionG-bacilli are predominant in acute stroke complicated with pulmonary infection. ESBLs and MRSA detection rate is high, and we should pay attention to the rational use of antibiotics to reduce drug resistance.
Methicillin-resistant Staphylococcus aureus is one of the important pathogens of healthcare-associated infections. In order to prevent and control the transmission of the drug-resistant organism in healthcare facilities, the Healthcare Infection Society and the Infection Prevention Society jointly conducted the guidelines for the prevention and control of methicillin-resistant Staphylococcus aureus in 2021. This article introduces the guide from the background, preparation process, main prevention and control measures and further studies, and compares the guidelines with the current prevention and control measures in China, so as to provide a methodological reference for preparation of the guide for domestic infection prevention and control practitioners, and provide evidence-based prevention and control strategies for clinical practice.
Objective To evaluate the toxic effects of staphylococcus aureus exotoxins and neutrophils on retinal pigment epithelium (RPE) cells (RPEC). Methods An in-vitro model of bacteroidal endophthalmitis was established by co-culturing of human RPE cell line D407 and human peripheral blood neutrophils in the present of staphylococcus aureus exotoxins ATCC29213. The level of lactate dehydrogenase hydroxide（LDH）in the cuture supernant was measured, and the viability of RPE was evlauated by flow cytometry and Hoechst 33342/Propidium Iodide（PI）staining. Results When RPE cells were cultured with the exotoxin ATCC29213, the LDH level and necrotic RPE cells were positive proportional to the dosage of exotoxin, but only 250mu;l or 500mu;l of ATCC29213 had a statistical significant effect. When RPE cells were co-cultured with neutrophils in the present of ATCC29213 for 6 hours, 100mu;l of ATCC29213 already had a statistical significant effect on LDH level and necrotic RPEC, and the effect was proportional to the amount of neutrophils in the culture. Conclusion Both staphylococcus aureus exotoxins and neutrophils can damage the RPEC by inducing necrosis, and their function had synergetic effect.
