金黄色葡萄球菌性骨髓炎动物模型构建的研究与进展

文题释义： 骨髓炎：由传染性微生物引起的骨和骨髓的急性或慢性炎症性疾病,可由需氧或厌氧菌、分枝杆菌及真菌引起,流行性病学显示金黄色葡萄球菌是导致骨髓炎最常见、最主要致病菌。骨髓炎好发于长骨、糖尿病患者的足部或由于外伤或手术引起的穿透性骨损伤部位。 菌落形成单位(Colony-Forming Units,CFU)：是指在琼脂平板上经过一定温度和时间培养后形成的每一个菌落,是计算细菌或霉菌数量的单位。这个单位比“菌落数”更准确地反映问题的实质。理论上,一个活细菌可以在条件合适的固体表面上形成一个菌落,但是吸附于微小颗粒上的2个以上菌体或粘连在一起的菌团可能共同形成一个菌落,而且不同环境因素作用下,细菌的生活能力各不相同,会影响其在该条件下形成菌落的能力,致使形成的菌落数远低于实际的活菌数。因此目前可用菌落形成单位代替以往常用的“菌落数”作为平板计数的数量单位。 背景：金黄色葡萄球菌已成为目前全世界骨髓炎最主要的致病菌。优秀而标准的同质性动物模型对骨髓炎感染机制的研究、获得新的预防与治疗措施及新技术转化应用于临床实践的科学研究具有重要作用。 目的：综述国内外金黄色葡萄球菌性骨髓炎动物模型构建的相关研究进展及面临的问题。 方法：计算机检索CNKI数据库、PubMed数据库、MEDLINE数据库、Embase数据库、Cochrane 图书馆的相关文献,中文检索词为“金黄色葡萄球菌;骨感染;骨髓炎;置入物相关骨髓炎;骨缺损骨髓炎;骨折骨髓炎;生物膜;实验性骨髓炎模型;动物模型”;英文检索词为“Staphylococcus aureus; bone infection; osteomyelitis; implant-associated osteomyelitis; bone defect osteomyelitis; fracture osteomyelitis; biofilm; experimental osteomyelitis model”。语言分别设为中文和英文。查阅2010年1月至2019年6月期间收录的相关文章,包括综述、基础研究以及临床研究。通过阅读文题和摘要进行初步筛选,排除与文章主题不相关的文献,根据纳入标准和排除标准,最终纳入45篇文献进行结果分析。 结果与结论：①骨髓炎动物模型的构建方法与多种因素有关,尽管近年来各国研究者对此不断进行改进并逐渐量化感染过程,但尚未形成统一标准;②目前并无单一微生物学或影像学检查方式能明确骨感染,在急性骨髓炎动物模型中,nuc RTQ-PCR技术和生物荧光成像技术等微生物学检测能够早期动态监测并量化骨感染过程;对于慢性骨髓炎动物模型,micro-CT、MRI等影像学技术能动态观察骨溶解、骨重建过程,且¹⁸F-FDG PET/CT等尖端成像技术确认或排除慢性骨髓炎有很高的诊断准确性;③基于骨髓炎动物模型,确定早期诊断及量化诊疗过程中感染细菌数量及活性的标准,也是今后进一步研究的方向。 ORCID: 0000-0002-2767-4895(刘金月) 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Identification of a surrogate marker for infection in the African green monkey model of inhalation anthrax

In 2001, a bioterrorism attack involving Bacillus anthracis spore-laced letters resulted in 22 cases of inhalation anthrax, with five fatalities. This incident identified gaps in our health care system and precipitated a renewed interest in identifying both therapeutics and rapid diagnostic assays. To address those gaps, well-characterized animal models that resemble the human disease are needed. In addition, a rapid assay for a reliable diagnostic marker is key to the success of these efforts. In this study, we exposed African green monkeys to B. anthracis spores; examined clinical signs and physiological parameters, including fever, heart rate, complete blood count, and bacteremia; and evaluated the PCR assay and electrochemiluminescence (ECL) immunoassay for the biomarkers protective antigen and capsule. The results demonstrated that although there were neither objective clinical nor physiological signs that consistently identified either infection or the onset of clinical anthrax disease, the African green monkey is a suitable animal model exhibiting a disease course similar to that observed in the rhesus model and humans. We also demonstrated that detection of the biomarkers protective antigen and capsule correlated with bacterial loads in the blood of these nonhuman primates. The ECL immunoassay described here is simple and sensitive enough to provide results in one to two hours, making this assay a viable option for use in the diagnosis of anthrax, leading to timely initiation of treatment, which is a key component of B. anthracis therapeutic development.     

Model answers: Rational application of murine models in arthritis research

Advances in targeted immune therapeutics have profoundly improved clinical outcomes for patients with inflammatory arthropathies particularly rheumatoid arthritis. The landscape of disease that is observed and the treatment outcomes desired for the future have also progressed. As such there is an increasing move away from traditional models of end‐stage, chronic disease with recognition of the need to consider the earliest phases of pathogenesis as a target for treatment leading to resolution and/or cure. In order to continue the discovery process and enhance our understanding of disease and treatment, we therefore need to continuously revisit the animal models we employ and assess their relevance and utility in the light of contemporary therapeutic goals. In this review, we highlight the areas where we consider new developments in animal models and their application are most required. Thus, we have contextualised the relevant mouse models and their use within the current concepts of human inflammatory arthritis pathogenesis and highlight areas of need.     

First report of the predominance of clonal complex 398 Staphylococcus aureus strains in osteomyelitis complicating diabetic foot ulcers: a national French study

Staphylococcus aureus is the most common pathogen cultured from diabetic foot infection including diabetic foot osteomyelitis. This French multicentre study determined the genetic content of S. aureus isolated from 157 consecutive cases admitted to 12 diabetic foot centres between 2008 and 2011. We describe for the first time the emergence of the CC398 methicillin-susceptible S. aureus clone, the main clone in diabetic foot osteomyelitis, and its tropism for bone. This clone spreads to humans from an animal source through its intrinsic virulence. This adaptation of S. aureus isolates looks to be a worrisome problem and should be carefully monitored.     

Short-course antibiotics for common infections: what do we know and where do we go from here?

BackgroundOver the past 25 years, researchers have performed >120 randomized controlled trials (RCTs) illustrating short courses to be non-inferior to long courses of antibiotics for common bacterial infections.ObjectiveWe sought to determine whether clinical data from RCTs affirm the mantra of ‘shorter is better’ for antibiotic durations in 7 common infections: pneumonia, urinary tract infection, intra-abdominal infection, bacteraemia, skin and soft tissue infection, bone and joint infections, pharyngitis and sinusitis.SourcesPublished RCTs comparing short- versus long-course antibiotic durations were identified through searches of PubMed and clinical guideline documents.ContentShort-course antibiotic durations consistently result in similar treatment success rates as longer antibiotic courses among patients with community-acquired pneumonia, complicated urinary tract infections in women, gram-negative bacteraemia, and skin and soft tissue infections when the diagnosis is confirmed, appropriate antimicrobials are used, and patients show clinical signs of improvement. For patients with osteomyelitis, 6 weeks of antibiotics is adequate for the treatment of osteomyelitis in the absence of implanted foreign bodies and surgical debridement. Whether durations can be further shortened with debridement is unclear, although small studies are promising.ImplicationsWith few exceptions, short courses were non-inferior to long courses; future research should focus on appropriately defining the patient population, ensuring the correct choice and dose of antimicrobials and developing meaningful outcomes relevant for frontline clinicians.     

Evaluation of quinolones in experimental animal models of infections

Many discriminative experimental animal models of infection have been utilized in the evaluation of newer fluoroquinolones. In vivo efficacy of many of the newer agents has been shown in experimental models of meningitis, endocarditis, pneumonia, urinary tract infections, pyelonephritis, osteomyelitis, abscesses of various types, septic arthritis, gastroenteritis, salmonellosis, listeriosis, tuberculosis, syphilis, sinusitis, prostatitis and burn wound sepsis, among others. This review focuses on recent developments in a few selected areas. Although the limitations of animal model studies are well described, these results provide a rationale for the appropriate clinical usage of the newer fluoroquinolones in humans.     

Intestinal proteomic analysis of a novel non-human primate model of experimental colitis reveals signatures of mitochondrial and metabolic dysfunction

Animal models recapitulating features of chronic colitis, such as ulcerative colitis, Crohn's disease, or HIV infection, are critical to study disease pathogenesis and test novel therapeutics. In this study, we used a proteomics approach to explore the molecular intestinal response in two rhesus macaque (RM) animal models of experimentally induced colitis using dextran sulfate sodium (DSS) and simian immunodeficiency virus (SIV) infection. Proteomic analysis detected more than 2500 proteins in colonic tissue collected from 30 RMs. Differential protein expression analysis revealed a protein expression pattern in DSS-treated RMs resembling the proteome of human ulcerative colitis. In a group of 12 DSS-treated RMs compared to 6 with no treatment, decrease in expression of proteins related to mitochondrial energy metabolism, including fatty acid metabolism was noted, while innate immune activation pathways, including complement and coagulation proteins were upregulated. SIV infection of RMs resulted in increased innate immune responses related to viral defense. Proteomic signatures of barrier damage were apparent in both DSS treatment or SIV infection. These results demonstrate that DSS treatment in a non-human primate model resembles features of human ulcerative colitis, making this a promising tool to study important immunological mechanisms in inflammatory bowel disease.     

The influence of foreign body surface area on the outcome of chronic osteomyelitis

Reproducible animal models of osteomyelitis close to the clinical scenario are difficult to obtain as the animals either die shortly after inoculation of bacteria or the bone cures itself of infection. Additional materials used as foreign bodies offer increased chances for localized infection due to bacterial attachment and are closer to clinical pathology.Through in vivo experimentation we investigated here the influence of surface area of a series of foreign bodies on the final outcome of the animal model, in terms of reproducibility, survival rate and time necessary for onset of chronic disease. Stainless steel Kirschner wire segments, stainless steel balls and cotton meshes were employed for this purpose.The clinical, microbiological, radiological and histological results obtained were compared with the simple case where no foreign body was used. The follow-up period was 57 days. The cotton meshes, which had the highest surface area, were observed to provide the best outcome, with the lowest disease onset time interval (of 1 week earlier than the others), the highest survival (of 90%) and disease reproduction rate (90%). The only clinical pattern of the mesh group rabbits was short lived inflammation while the other rabbits presented also some other clinical signs such as rhinorrheas, abscesses, rush and/or dyspnea. Moreover, this model is the most suitable for further treatment studies, as the cotton meshes could be easily removed after disease onset, without any intervention on the bone. This is important, as the treatment would address the bacteria present within the bone parts (marrow, cortex, periosteum etc.) not those forming the biofilm.     

In Vivo Expression of Streptococcus pyogenes Immunogenic Proteins during Tibial Foreign Body Infection

Group A streptococcus (GAS) is an important human pathogen that causes a number of diseases with a wide range of severities. While all known strains of GAS are still sensitive to penicillin, there have been reports of antibiotic treatment failure in as many as 20% to 40% of cases. Biofilm formation has been implicated as a possible cause for these failures. A biofilm is a microbially derived, sessile community where cells grow attached to a surface or as a bacterial conglomerate and surrounded by a complex extracellular matrix. While the ability of group A streptococcus to form biofilms in the laboratory has been shown, there is a lack of understanding of the role of GAS biofilms during an infection. We hypothesized that during infections, GAS exhibits a biofilm phenotype, complete with unique protein expression. To test this hypothesis, a rabbit model of GAS osteomyelitis was developed. A rabbit was inoculated with GAS using an infected indwelling device. Following the infection, blood and tissue samples were collected. Histological samples of the infected tibia were prepared, and the formation of a biofilm in vivo was visualized using peptide nucleic acid fluorescent in situ hybridization (PNA-FISH) and confocal microscopy. In addition, Western blotting with convalescent rabbit serum detected cell wall proteins expressed in vitro under biofilm and planktonic growth conditions. Immunogenic proteins were then identified using matrix-assisted laser desorption ionization–time of flight tandem mass spectrometry (MALDI-TOF/TOF MS). These identities, along with the in vivo results, support the hypothesis that GAS forms biofilms during an infection. This unique phenotype should be taken into consideration when designing a vaccine or any other treatment for group A streptococcus infections.     

Safety assessment of immunomodulatory biologics: The promise and challenges of regulatory T-cell modulation

Regulatory T-cell (T_reg) modulation is developing as an important therapeutic opportunity for the treatment of a number of important diseases, including cancer, autoimmunity, infection, and organ transplant rejection. However, as demonstrated with IL-2 and TGN-1412, our understanding of the complex immunological interactions that occur with T_reg modulation in both non-clinical models and in patients remains limited and appears highly contextual. This lack of understanding will challenge our ability to identify the patient population who might derive the highest benefit from T_reg modulation and creates special challenges as we transition these therapeutics from non-clinical models into humans. Thus, in vivo testing in the most representative animal model systems, with careful progress in the clinic, will remain critical in developing therapeutics targeting T_reg and understanding their clinical utility. Moreover, toxicology models can inform some of the potential liabilities associated with T_reg modulation, but not all, suggesting a continued need to explore and validate predictive models.     

In vivo release of vancomycin from biodegradable beads

The current delivery system of antibiotics for the treatment of osteomyelitis uses polymethylmethacrylate (PMMA) beads as a local drug-release agent. The nonbiodegradable nature of the PMMA, however, necessitates a second operation to remove the beads. This article explores the alternative of using biodegradable polymers as antibiotic beads for a long-term drug release in vivo. To manufacture an antibiotic bead, lactide-glycolide copolymers were mixed with vancomycin. The mixture was compressed and sintered at 55 degrees C to form beads 8 mm in diameter. An in vivo animal model was proposed to characterize the elution rate of antibiotic over a 55-day period. Biodegradable beads released high concentrations of antibiotic (well above the breakpoint sensitivity concentration) in vivo for the period of time needed to treat bone infection; that is, 4-6 weeks. A bacterial inhibition test was also carried out to determine the relative activity of the released antibiotics. The diameter of the sample inhibition zone ranged from 8 to 18 mm, which is equivalent to 9.1 to 100% of relative activity. In addition, the antibiotic concentration of systemic blood was found to be very low. Antibiotic-impregnated biodegradable beads may have a potential role in the prevention and management of surgical infections.     

Targeting impaired nutrient sensing with repurposed therapeutics to prevent or treat age-related cognitive decline and dementia: A systematic review

BackgroundDementia is a debilitating syndrome that significantly impacts individuals over the age of 65 years. There are currently no disease-modifying treatments for dementia. Impairment of nutrient sensing pathways has been implicated in the pathogenesis of dementia, and may offer a novel treatment approach for dementia.AimsThis systematic review collates all available evidence for Food and Drug Administration (FDA)-approved therapeutics that modify nutrient sensing in the context of preventing cognitive decline or improving cognition in ageing, mild cognitive impairment (MCI), and dementia populations.MethodsPubMed, Embase and Web of Science databases were searched using key search terms focusing on available therapeutics such as ‘metformin’, ‘GLP1’, ‘insulin’ and the dementias including ‘Alzheimer’s disease’ and ‘Parkinson’s disease’. Articles were screened using Covidence systematic review software (Veritas Health Innovation, Melbourne, Australia). The risk of bias was assessed using the Cochrane Risk of Bias tool v 2.0 for human studies and SYRCLE’s risk of bias tool for animal studies.ResultsOut of 2619 articles, 114 were included describing 31 different ‘modulation of nutrient sensing pathway’ therapeutics, 13 of which specifically were utilized in human interventional trials for normal ageing or dementia. Growth hormone secretagogues improved cognitive outcomes in human mild cognitive impairment, and potentially normal ageing populations. In animals, all investigated therapeutic classes exhibited some cognitive benefits in dementia models. While the risk of bias was relatively low in human studies, this risk in animal studies was largely unclear.ConclusionsModulation of nutrient sensing pathway therapeutics, particularly growth hormone secretagogues, have the potential to improve cognitive outcomes. Overall, there is a clear lack of translation from animal models to human populations.     

Prevention of infection in external fixator pin sites

Infection in external fixator pins is known to be a significant problem, with incidences between 3% and 80% reported in the literature. An infection occurs when planktonic bacteria adhere to external fixator pins and subsequently produce a biofilm which protects the bacteria from host defences. The most commonly implicated organisms are Staphylococcus aureus and Staphylococcus epidermidis. Once an infection occurs, treatment is difficult. Systemic antibiotics have limited benefits and considerable side-effects. The only definitive management is removal of the pin. This review will consider the current and potential future strategies for reducing pin site infection. Techniques to prevent infection must prevent bacterial adhesion, allow good osteointegration and have a low toxicity. Current areas of interest reviewed are titanium–copper alloys, nanosilver coatings, nitric oxide coatings, chitosan coatings, chlorhexidine and iodine, hydroxyapatite and antibiotic coatings. At present there is no consensus on the prevention of pin site infection, and there is a paucity of randomized controlled trials on which to draw a conclusion. Whilst a number of these strategies have potential future use, many of the above strategies need further studies in animal models to ensure no cytotoxicity and prevention of osteointegration. Following this, well-designed randomized controlled clinical trials are required to give future ways to prevent external fixator pin site infections.     

Experimental model of biofilm implant-related osteomyelitis to test combination biomaterials using biofilms as initial inocula

Currently, the majority of animal models that are used to study biofilm-related infections use planktonic bacterial cells as initial inocula to produce positive signals of infection in biomaterials studies. However, the use of planktonic cells has potentially led to inconsistent results in infection outcomes. In this study, well-established biofilms of methicillin-resistant Staphylococcus aureus were grown and used as initial inocula in an animal model of a Type IIIB open fracture. The goal of the work was to establish, for the first time, a repeatable model of biofilm implant-related osteomyelitis, wherein biofilms were used as initial inocula to test combination biomaterials. Results showed that 100% of animals that were treated with biofilms developed osteomyelitis, whereas 0% of animals not treated with biofilm developed infection. The development of this experimental model may lead to an important shift in biofilm and biomaterials research by showing that when biofilms are used as initial inocula, they may provide additional insights into how biofilm-related infections in the clinic develop and how they can be treated with combination biomaterials to eradicate and/or prevent biofilm formation.     

Modelling hypercholesterolaemia in rats using high cholesterol diet

Hypercholesterolaemia is a complex condition with multiple causes, including both lifestyle and genetic aspects. It is also a risk factor for cardiovascular diseases (CVDs), which are responsible for 172 million deaths/year. Although the reasons for hypercholesterolaemia are known, there are many critical questions that remain to be answered so that new therapeutics can be developed. In order to elucidate the pathobiology of this condition, animal models can mimic the pathology of human hypercholesterolaemia. One example of an animal model is induced by the hypercholesterolaemic diet in Wistar rats. The present review first summarizes the current understanding of the metabolic profile involved in hypercholesterolaemia in humans. Next it comments about the lack of consensus as to which hypercholesterolaemia induction protocol should be used. The present work aimed to review experimental studies that induced hypercholesterolaemia in Wistar rats it was not intended to judge the “best” model, since they all achieved the goal of inducing an increase in serum cholesterol.     

Septic Arthritis and Osteomyelitis Due to Bordetella petrii

A case of Bordetella petrii septic arthritis and osteomyelitis in an elbow resulted from a dirt bike accident in Hawaii. Two months of intravenous antibiotics and repeated surgeries were required to cure this infection. Our case, and literature review, suggests that extended-spectrum penicillins, tetracycline, and trimethoprim-sulfamethoxazole are good treatment options.     

REVIEW ARTICLE: Chlamydia trachomatis,a Hidden Epidemic: Effects on Female Reproduction and Options for Treatment

Citation Carey AJ, Beagley KW. Chlamydia trachomatis, a hidden epidemic: effects on the female reproduction and options for treatment. Am J Reprod Immunol 2010 The number of genital tract Chlamydia trachomatis infections is steadily increasing worldwide, with approximately 50–70% of infections asymptomatic. There is currently no uniform screening practice, current antibiotic treatment has failed to prevent the increased incidence, and there is no vaccine available. We examined studies on the epidemiology of C. trachomatis infections, the effects infections have on the female reproductive tract and subsequent reproductive health and what measures are being taken to reduce these problems. Undetected or multiple infections in women can lead to the development of severe reproductive sequelae, including pelvic inflammatory disease and tubal infertility. There are two possible paradigms of chlamydial pathogenesis, the cellular and immunological paradigms. While many vaccine candidates are being extensively tested in animal models, they are still years from clinical trials. With no vaccine available and antibiotic treatment unable to halt the increased incidence, infection rates will continue to increase and cause a significant burden on health care systems.     

Chlamydia trachomatis infection: host immune responses and potential vaccines

Chlamydia trachomatis causes genital tract infections that affect men, women, and children on a global scale. This review focuses on innate and adaptive immune responses in the female reproductive tract (FRT) to genital tract infections with C. trachomatis. It covers C. trachomatis infections and highlights our current knowledge of genital tract infections, serovar distribution, infectious load, and clinical manifestations of these infections in women. The unique features of the immune system of the FRT will be discussed and will include a review of our current knowledge of innate and adaptive immunity to chlamydial infections at this mucosal site. The use of animal models to study the pathogenesis of, and immunity to, Chlamydia infection of the female genital tract will also be discussed and a review of recent immunization and challenge experiments in the murine model of chlamydial FRT infection will be presented.     

Safety assessment of immunomodulatory biologics: the promise and challenges of regulatory T-cell modulation

Regulatory T-cell (T(reg)) modulation is developing as an important therapeutic opportunity for the treatment of a number of important diseases, including cancer, autoimmunity, infection, and organ transplant rejection. However, as demonstrated with IL-2 and TGN-1412, our understanding of the complex immunological interactions that occur with T(reg) modulation in both non-clinical models and in patients remains limited and appears highly contextual. This lack of understanding will challenge our ability to identify the patient population who might derive the highest benefit from T(reg) modulation and creates special challenges as we transition these therapeutics from non-clinical models into humans. Thus, in vivo testing in the most representative animal model systems, with careful progress in the clinic, will remain critical in developing therapeutics targeting T(reg) and understanding their clinical utility. Moreover, toxicology models can inform some of the potential liabilities associated with T(reg) modulation, but not all, suggesting a continued need to explore and validate predictive models.