艰难梭菌A毒素的纯化

目的建立一种纯化艰难梭菌A毒素的方法。方法将艰难梭菌VPI 10 4 6 3菌株经透析培养 ,5 0 %饱和硫酸胺盐析 ,酸沉淀 ,再经DEAE Toyopearl 6 5 0M离子交换色谱。结果精制的艰难梭菌A毒素Native PAGE及对流免疫电泳均为单一带 ,相对分子质量为 5 5 0 0 0 0 ,小鼠毒力为 1× 10 6MLD/ml,Vero细胞毒性为 1× 10 7CU/ml。凝血活性为 1∶5 12 ,肠袢试验为阳性。结论该法简便、实用、可行。     

Clostridium difficile antibodies: a patent evaluation (WO2013028810)

Introduction: Incidence and severity of Clostridium difficile infection (CDI) are increasing worldwide. Toxins A (TcdA) and B (TcdB) and host immune response are the major determinates of CD pathogenesis and represent a new, stimulating therapeutic target to control CDI.

Areas covered: The present patent and literature on the pathogenesis and treatment of CD were critically reviewed. The patent was described and put into clinical context, highlighting possible advantages and barriers to use. It consists of a blend of monoclonal antibodies (mAbs) and antigen-binding portions that neutralize TcdA, targeting the enterocyte-binding domain. It demonstrated good efficacy in in vivo models and seems promising in clinical practice. However, recent evidence reshaped the central role of TcdA.

Expert opinion: Current treatments are inadequate to control CDI and recurrence. Toxin-targeted mAbs are one of the most promising approaches for CDI, including infection by hypervirulent strains. At-risk subjects and those experiencing recurrence are the ideal targets for this second-line treatment; however CDI epidemiology is fast-changing and mAbs may represent a powerful option also for other patients. The re-evaluation of the pathogenic role of TcdA may potentially limit the use of this product; however, the possible administration in combination with other therapeutic agents may optimize its efficacy.     

Future novel therapeutic agents for Clostridium difficile infection

Importance of the field: Clostridium difficile is the most important definable cause of healthcare acquired diarrhea. The increasing incidence and mortality associated with this enteric pathogen and the significant rate of treatment failures and recurrences with current antibiotics emphasize the need for the discovery of new and improved therapeutic and preventative agents.

What the reader will gain: We review upcoming novel therapeutic agents and the clinical evidence to support their efficacy in treating C. difficile infection. We also provide an extensive comparison of antimicrobial susceptibilities of C. difficile based on in vitro susceptibilities published in the literature.

Areas covered in this review: This review was conducted by a thorough examination of the public sources, including journals and scientific meeting abstracts, up to February 2009.

Take home message: A number of new therapeutic agents are in development and being tested in clinical trials. However, high costs and concerns for resistance may limit the use of these antimicrobials for the treatment of C. difficile infection. Passive and active immunotherapy may have important future roles as therapeutic and preventative strategies for C. difficile infection.     

Fidaxomicin (OPT-80) for the treatment of Clostridium difficile infection

Importance of the field: Clostridium difficile infection (CDI) has become an increasingly important healthcare-associated complication in many countries. CDI outbreaks, a new ‘hypervirulent’ form and increased worldwide rates have underscored four urgent unmet needs for this disease: i) effective prevention of CDI; ii) therapies to produce faster resolution of CDI symptoms; iii) therapies to treat severe CDI more effectively and reduce its mortality; and iv) therapies to reduce the CDI recurrence rate following treatment.

Areas covered in this review: Fidaxomicin, a new macrocyclic antibiotic, has demonstrated potent in vitro activity against C. difficile with limited or no activity against normal fecal flora. It is minimally absorbed from the intestinal tract, even in the presence of intestinal inflammation. When tested against oral vancomycin in clinical studies of CDI therapy, it has equivalent efficacy for curing CDI at end of treatment and a comparable safety profile to that agent. However, fidaxomicin therapy of CDI is associated with significantly fewer CDI recurrences in the 28 days following treatment. Symptom resolution is also slightly quicker in some CDI patients. Additional fecal flora analysis in the CDI trials showed that fewer individuals developed intestinal colonization with vancomycin-resistant enterococci (VRE) among the fidaxomicin-treated group. This new molecule, which has just completed two large Phase III multicenter studies, successfully addresses two of the four urgent and unmet needs for dealing with CDI.

What the reader will gain: Fidaxomicin is as effective and as safe as vancomycin therapy for treating CDI but is associated with far fewer recurrences post-treatment and a decreased risk of VRE acquisition.

Take home message: Fidaxomicin is a potential new therapy for CDI which has the capacity to substantially decrease post-treatment recurrences and is as safe and well-tolerated as standard vancomycin treatment.     

Clostridium difficile infection in children: a comprehensive review

Abstract

Objective:

To provide a comprehensive review of the literature relating to Clostridium difficile (C. difficile) infection (CDI) in the pediatric population.     

Resistance determinants in strains of Clostridium difficile from two geographically distinct populations

Ninety-three clinical isolates of Clostridium difficile, comprising 65 from Royal Gwent Hospital, Newport and 28 from Southmead Hospital, Bristol were examined to determine the prevalence of genes coding for macrolide resistance and to explore differences in susceptibility patterns. Antibiogram testing produced similar results for both sets of strains with respect to amoxicillin, tetracycline, erythromycin and cefotaxime. Results differed for rifampicin, where 53% of the Bristol isolates were resistant, compared with 3% of the Newport isolates. Clindamycin disc susceptibility testing produced similar resistance rates. However, clindamycin MIC determinations revealed that 53% of the Bristol strains exhibited high-level resistance (MIC > 256 mg/L), whereas strains from Newport had clindamycin MICs ranging from 0.25 to 3 mg/L. erm (B) was present in 15 of the strains from Bristol and in none of the Newport strains. erm (F) and erm (Q) were not detected in either population. The two geographically distinct populations of C. difficile differed considerably in their susceptibility to antibiotics. The possibility that C. difficile may serve as a conservator for resistant determinants subsequent to exposure to antimicrobial agents, has important implications for infection control.     

Non-antibiotic strategies for the prevention/treatment of Clostridium difficile infection

Background: Clostridium difficile infection has become a serious concern in both hospital and secondary healthcare environments. In the presence of repeated or prolonged antibiotic treatment, the C. difficile spores can germinate in the colon and produce toxins that cause colonic inflammation and diarrhea. The standard treatment for C. difficile-associated disease (CDAD) usually involves the withdrawal of the antibiotic treatment that led to the CDAD followed by a course of oral metronidazole or vancomycin, but there has been an increasing number of treatment failures and recurrences of disease. Over the past 10 – 15 years, researchers have begun exploring the possibility of using alternative means to combat C. difficile infection. Objective/methods: Over the course of the past 5 years, there has been a considerable amount of patent literature focused on non-antibiotic alternatives, including passive and active immunizations, monoclonal antibodies, antitoxins, inert binders and probiotic therapies. Results/conclusion: Current antibiotic therapies for the treatment of CDAD are not as effective as they once were. There is some promising work on non-antibiotic alternatives for CDAD prevention and treatment.     

Novel therapeutic strategies for Clostridium difficile infections

Introduction: In recent years, Clostridium difficile has become the primary cause of antibiotic-associated diarrhea and pseudomembranous colitis, resulting in long and complicated hospital stays that represent a serious burden for patients as well as health care systems. Currently, conservative treatment of C. difficile infection (CDI) relies on the antibiotics vancomycin, metronidazole or fidaxomicin, or in case of multiple recurrences, fecal microbiota transplantation (FMT).

Areas covered: The fast-spreading, epidemic nature of this pathogen urgently necessitates the search for alternative treatment strategies as well as antibiotic targets. Accordingly, in this review, we highlight the recent findings regarding virulence associated traits of C. difficile, evaluate their potential as alternative drug targets, and present current efforts in designing inhibitory compounds, with the aim of pointing out possibilities for future treatment strategies.

Expert opinion: Increased attention on systematic analysis of the virulence mechanisms of C. difficile has already led to the identification of several alternative drug targets. In the future, applying state of the art ‘omics’ and the development of novel infection models that mimic the human gut, a highly complex ecological niche, will unveil the genomic and metabolic plasticity of this pathogen and will certainly help dealing with future challenges.     

Clostridium difficile, nosocomial enteropathogen: phylogeny and virulence

Clostridium difficile is recognized as a potentially nosocomial enteric pathogen. It induces diarrhea or pseudomembranous colitis in patients whose digestive flora has been altered by antibiotic treatment and thus allows the colonization with a strain producing toxin A (enterotoxin) and toxin B (cytotoxin) (A+B+, sometimes A-B+ strains). We studied the phylogeny of C. difficile by developing MultiLocus Sequence Typing (MLST) analysis, which reports allelic polymorphism of housekeeping genes through DNA sequencing. C. difficile exhibits genomic stability, with mutational clonal evolution and individualization of phylogenetic lineages. These lineages are not correlated with human or animal hosts. Strains involved in pseudomembranous colitis or in diarrhea do not define distinct lineages, and bi-toxinogenic strains do not segregate from non toxinogenic strains. Conversely, A-B+ strains define a unique clone, highly divergent from the population studied. Allelic sequence data may be available from an centralized internet site, allowing phylogenetic and macro-epidemiologic analyses.     

Prevention of Clostridium difficile Infection in Critically Ill Adults

The incidence and severity of Clostridium difficile infection (CDI) remain high across intensive care units in the United States despite national efforts to decrease this escalating health care burden. Most published literature and guidelines address treatment rather than prevention, yet this approach may be too downstream to limit morbidity and mortality from the disease and its complications. Mechanisms to prevent CDI successfully include reducing modifiable risk factors and minimizing horizontal transmission of C. difficile spores between patients and the health care environment. Because CDI prevention is characterized by a bundled approach, it is difficult to quantify the individual impact of any one element; however, a number of patient- and facility-level strategies can be considered for CDI prevention. Robust hygiene strategies, diagnostic and antimicrobial stewardship, and particular prophylaxis maneuvers such as continuation of oral vancomycin or fidaxomicin in the setting of systemic antibiotics have all demonstrated benefit. The preventive roles of deprescribing acid suppressants, routine use of probiotics, or early fecal microbiota transplantation remain unclear. The focus of this review is to summarize the evidence related to primary and secondary CDI prevention in critically ill adults and provide a concise implementation pathway for clinicians and policymakers.     

ST37型艰难梭菌分子流行病学研究

目的 应用全基因组分析方法对艰难梭菌感染可能的暴发流行进行识别和调查,为艰难梭菌感染防控提供可靠的分子流行病学基础。方法 对8株ST37型艰难梭菌进行第二代高通量测序,并完成序列的拼接和注释。通过对其核心基因组进行SNP分析,根据SNP数量以及相关临床资料分析有无院内暴发流行。同时将Genbank中公布了全基因组序列的艰难梭菌,进行MLST分析,对其分析结果为ST37的菌株与本研究中的8株菌株进行SNP分析比较,了解这8株菌的可能来源。结果 以最早收集的菌株WCHCD770作为参照,其他7株菌株的SNP值,最大为59,最小为38,提示它们并不是近期发生的传播事件。而这8株菌两两相互进行SNP计算,其中WCHCD1577、WCHCD1641仅为10,提示它们可能来源于一个克隆,可能存在院内传播。通过分析比较这8株菌与Genbank中的其他ST37型艰难梭菌发现,它们的致病决定区(PaLoc)序列完全相同,证实了ST37型艰难梭菌的PaLoc在世界范围克隆传播,同时对它们的SNP比较分析,发现WCHCD1577、WCHCD1641、WCHCD1216、WCHCD109、WCHCD159与2...     

Bezlotoxumab: A Novel Agent for the Prevention of Recurrent Clostridium difficile Infection

During the past decade, the incidence and severity of Clostridium difficile infection (CDI) have significantly increased, leading to a rise in CDI‐associated hospitalizations, health care costs, and mortality. Although treatment options exist for CDI, recurrence is frequent following treatment. Furthermore, patients with at least one CDI recurrence are at an increased risk of developing additional recurrences. A novel approach to the prevention of recurrent CDI is the use of monoclonal antibodies directed against the toxins responsible for CDI as an adjunct to antibiotic treatment. Bezlotoxumab, a human monoclonal antibody that binds and neutralizes C. difficile toxin B, is the first therapeutic agent to receive United States Food and Drug Administration approval for the prevention of CDI recurrence. Clinical studies have demonstrated superior efficacy of bezlotoxumab in adults receiving antibiotic therapy for CDI compared with antibiotic therapy alone for the prevention of CDI recurrence. Bezlotoxumab was well tolerated in clinical trials, with the most common adverse effects being nausea, vomiting, fatigue, pyrexia, headache, and diarrhea. The demonstrated efficacy, safety, and characteristics of bezlotoxumab present an advance in prevention of CDI recurrence.     

Cadazolid for the treatment of Clostridium difficile

Introduction: Antibiotic development goals for CDI include potent antimicrobial effect against C. difficile, limited killing of host microbiota, potential effect on spores, and ability to interfere with toxin production. Cadazolid, a novel, non-absorbable hybrid antibiotic has many of these criteria. In phase I and II clinical trials, cadazolid was shown to be safe, well tolerated, and efficacious positioning itself as a potential future viable therapeutic option for CDI.

Areas covered: This review provides an in-depth evaluation of the chemistry, microbiology, pharmacodynamics, pharmacokinetics, and clinical trial results for cadazolid. Clinical therapeutic outcomes are compared between cadazolid, fidaxomicin, and surotomycin.

Expert opinion: Preclinical and early clinical studies demonstrated that cadazolid has unique properties that will likely be valuable to treat CDI and reduce recurrent infection. With compelling phase II clinical results, results from the ongoing phase III trial will better define the role of cadazolid for treating CDI in the future.     

Rethinking Strategies to Select Antibiotic Therapy in Clostridium difficile infection

In recent years, Clostridium difficile infection (CDI) has become a global public health threat associated with increased morbidity, mortality, and economic burden, all of which are exacerbated with disease recurrence. Current guidelines informing treatment decisions are largely based on definitions of disease severity at diagnosis, with subjective components not well delineated across treatment algorithms and clinical trials. Furthermore, there is little evidence linking severity at onset to outcome. However, reducing the risk of recurrence may offer both a better outcome for the individual and decreased downstream economic impact. The authors present data supporting the opinion that patients deemed at low risk for recurrence should receive vancomycin (or metronidazole when cost is an issue), while those at higher risk of recurrence would benefit from fidaxomicin treatment. Although further prospective studies are needed, choosing treatment with the goal of preventing recurrent CDI may offer a better guide than disease severity.     

临床药师参与1例妊娠合并肠道艰难梭菌感染治疗的药学实践

目的 探讨临床药师参与妊娠合并肠道艰难梭菌感染患者的药学实践重点和模式,保障母儿安全.方法 临床药师从药物角度切入,严格按照循证医学证据将药学理论与临床实践相结合,为药物选择、剂量调整、保肝治疗等方面提供全程药学监护,协助医生制定用药方案,积极参与个体化治疗.结果 临床药师融入治疗团队,保障了妊娠期患者用药的有效性和安...     

Current updates in management of Clostridium difficile infection in cancer patients

Background: Clostridium difficile infection (CDI) is a significant health burden, now recognized as the leading cause of acquired diarrhea in patients receiving antibiotic therapy. Complications of infection with this pathogen include severe diarrhea, causing electrolyte imbalances, dehydration, hemodynamic instability, toxic megacolon, shock, and death. Hence it is extremely paramount to stay updated on management options for this infection, especially in cancer patients.

Review: This article presents an in-depth review of literature on the treatment modalities available for CDI in cancer patients. Relevant articles highlighting therapeutic and symptomatic management of CDI patients with underlying malignancy have been summarized.

Conclusions: Despite the current options available, more studies are needed to assess the newer therapeutic options that are being employed for populations other than cancer patients.     

Risk factors for the development of Clostridium difficile toxin‐associated diarrhoea: a pilot study

This study was a pilot investigation of risk factors for the development of Clostridium difficile toxin‐associated diarrhoea and in particular the differential influence of antimicrobial agents. The study was a retrospective case—control design conducted at Freeman Hospital, Newcastle upon Tyne. Cases were inpatients with stool positive C. difficile toxin diarrhoea and two controls were drawn for each case matched for age (+/?5 years) and type of admission (emergency or elective). Using conditional logistic regression analysis, cephalosporins and erythromycin were found to be statistically significantly associated with Clostridium difficile toxin associated‐diarrhoea. The results form the basis for designing a larger, prospective study. Copyright © 2001 John Wiley & Sons, Ltd.     

Risk factors and mortality associated with Clostridium difficile-associated diarrhoea at a VA hospital

The objective of this study was to evaluate the risk of certain patient co-morbidities and antibiotics in the development of Clostridium difficile-associated diarrhoea (CDAD). Hospitalized patients developing CDAD during a specified period were compared with a cohort of patients, matched by age, without a diagnosis of CDAD, who were hospitalized during the same time period. Data collection included demographics, hospital ward, co-morbid conditions, antibiotics received, and mortality. Gender and age were similar in both groups. Co-morbid conditions significantly associated with the case group included cancer and COPD. The most commonly prescribed antibiotics in the case versus control group included levofloxacin, intravenous vancomycin, clindamycin, and piperacillin/tazobactam. The case group was associated with a higher mortality rate.