Adaptive immune response to Clostridium difficile infection: A perspective for prevention and therapy

Clostridium difficile infection (CDI) is one of the most important nosocomial illnesses and a major cause of morbidity and mortality. While initial treatment of CDI is usually successful, unprovoked relapses remain an important and frustrating problem. This review examines the literature describing the natural immune response to CDI, and to what extent it can explain the propensity for relapses. In particular, we discuss studies on antibody and, to a lesser extent, B cell and T cell responses in CDI. Despite years of study, there remains incomplete understanding of the natural antibody response to the major pathogenic toxins, TcdA and TcdB, and other bacterial antigens, in CDI. Recent literature suggests that a specific subset of neutralizing antibodies that target the putative carbohydrate‐binding domains of TcdB and possibly TcdA have the greatest protective ability. This is further supported by recent successful clinical trials of a humanized monoclonal antibody to the major toxin TcdB. A better understanding of how and why the most protective adaptive immune response develops may lead to improved vaccine and therapeutic targets for recurrent CDI.     

Clinical management of severe,fulminant, and refractory Clostridioides difficile infection

ABSTRACT

Introduction: Up to 15% of hospitalized patients with Clostridioides difficile infection (CDI) develop severe CDI (SCDI) or Fulminant CDI (FCDI). Due to high rates of mortality in medically-refractory CDI cases, 30% of patients with severe infection historically require surgical intervention. However, colectomy itself is an imperfect solution because it is difficult to predict who will fail medical therapy, patients with SCDI are more likely to have underlying medical conditions that make them poor surgical candidates, and post-surgical mortality still approaches 30–50%.

Areas covered: This review will serve as a clinically-based review of severe and fulminant CDI management including discussion of models to predict severe infection, emerging treatments, novel targets for therapy, and innovations in surgical management.

Expert opinion: Among the most promising studies to emerge in the last decade have involved fecal microbiota transplantation (FMT), which is already recommended by multiple society guidelines for recurrent CDI (RCDI). In the case of SCDI/FCDI, multiple studies have safely and successfully utilized FMT to produce rates of cure in the 70–90% range. Additionally, patients who have FCDI refractory to medical therapy and are poor candidates for colectomy may benefit from FMT as salvage therapy.     

莫西沙星耐药的艰难梭菌多重聚合酶链反应检测和基因分型

目的：建立一种多重 PCR 方法用于莫西沙星耐药的艰难梭菌鉴定和初步基因分型。方法根据艰难梭菌 slpA 可变区间核苷酸序列的差异设计5种 slpA 基因型（gr、hr、fr、gc08和078）的特异性 PCR 引物,同时加入检测艰难梭菌管家基因磷酸甘油醛异构酶基因 tpi 的种特异性引物,构建多重PCR 方法;利用9种肠道常见的正常或致病菌验证多重 PCR 方法的特异性,利用46株分属于11个slpA 基因型的艰难梭菌参考菌株来验证方法的检测和分型能力;利用建立的多重 PCR 方法检测39株莫西沙星耐药的临床菌株,以 slpA 测序分型法为参照方法,评估该方法的临床实用性。结果多重PCR 检测9种肠道常见的正常或致病菌 tpi 和5种 slpA 基因型均为阴性;46株艰难梭菌参考菌株 tpi均为阳性,36株分属于5种靶 slpA 基因型（gr、hr、fr、gc08和078）的菌株被正确分型,10株分属于其他6种基因型的参考菌株均无法分型。39株莫西沙星耐药的艰难梭菌临床菌株 tpi 均为阳性,32株检出具体基因型,其中22株为 slpA 基因型 gc08,6株为 hr,2株为 fr,2株为078,与 slpA 测序分型结果一致;7株多重 PCR 无法分型,slpA 测序分型结果显示其基因型均不包含在多重 PCR 分型范围内。结论成功建立一种简单、快捷、临床实验室适用的艰难梭菌检测,且能够分辨出5种 slpA 基因型的多重PCR 方法;莫西沙星耐药的艰难梭菌主要为 slpA 基因型 gc08。     

Inhibition of adhesion of Clostridium difficile to human intestinal cells after treatment with serum and intestinal fluid isolated from mice immunized with nontoxigenic C. difficile membrane fraction

Diarrhea and pseudomembrane colitis caused by Clostridium difficile infection is a global health concern because of the high recurrence rate after standard antibiotic therapy. Vaccination presents a powerful countermeasure against disease recurrence. In this study, mice vaccinated with the nontoxigenic C. difficile membrane fraction generated a marked immune response to the antigen, as demonstrated by the serum IgG and intestinal fluid IgA levels. Significantly, pretreatment with harvested IgG- and IgA-containing fluids was sufficient to prevent in vitro adhesion of C. difficile to human Caco-2 intestinal cells. These results highlight the potential of nontoxigenic C. difficile membrane fraction as a vaccine candidate for C. difficile infection.     

How do Clostridium difficile infections affect nurses’ everyday hospital work: A qualitative study

This qualitative study explored the impact of Clostridium difficile infections on nurses’ everyday work in the hospital. Twelve nurses (six in France and six in the United States) were interviewed in depth using a semi‐structured interview guide. Thematic analysis of the interviews was performed. Managing diarrhoea and taking precautionary measures for infection control were the two most inconvenient aspects nurses reported with C. difficile patient management. Precautions included contact isolation, hand hygiene and reorganization/coordination of nursing care and ward. Precautions were time consuming and significantly increased nurses’ workload when combined with caring for patients with uncontrollable, frequent bouts of diarrhoea. Management of C. difficile infection is extremely burdensome for nurses in their everyday work and disruptive to hospital organizations as a whole. Prevention of C. difficile infections, together with coordinated team work and communication, would therefore contribute to decreasing nurses’ workload and the burden to health‐care facilities associated with caring for these patients.     

Clostridium difficile infection, Colorado and the northwestern United States, 2007

To determine the incidence of Clostridium difficile infection during 2007, we examined infection in adult inpatient and outpatient members of a managed-care organization. Incidence was 14.9 C. difficile infections per 10,000 patient-years. Extrapolating this rate to US adults, we estimate that 284,875 C. difficile infections occurred during 2007.     

Clostridium difficile

Clostridium difficile is the leading cause of healthcare‐associated infectious diarrhea. Although C difficile is part of normal flora in some healthy individuals, patients with selective risk factors are often vulnerable to the toxigenic potential of this virulent healthcare pathogen. The spectrum of C difficile infection (CDI) is highly variable, ranging from mild to severe illness, presenting with single to multiple disease recurrences. Current approaches to treatment are based on severity of illness, number of recurrences, and clinical presentation. Oral vancomycin and metronidazole have formed the foundation for treatment of CDI, but therapeutic failures are commonly reported, especially involving hypervirulent clones. Alternative therapies, including newer antimicrobials, probiotics, immunotherapy, and fecal transplantation, have all met with varying degrees of efficacy. Although toxigenic culture (TC) testing from anaerobic culture remains the gold standard, newer technologies, including enzyme immunoassay, common antigen (glutamate dehydrogenase) testing, and real‐time polymerase chain reaction (PCR) are less time‐consuming and rapid. However, TC and PCR have reported high specificity and sensitivity when compared with other laboratory tests. Because of the significant morbidity and mortality associated with CDI, a high index of suspicion is warranted. Prevention and eradication of CDI require a multidisciplinary approach, including early disease recognition through appropriate surveillance, implementation of effective contact isolation strategies, adherence to environmental controls, judicious hand hygiene, evidence‐based treatment, and management that includes antibiotic stewardship, continuous education of healthcare workers, and administrative support.     

Portrait Toxigenic Clostridium difficile assay,an isothermal amplification assay detects toxigenic C. difficile in clinical stool specimens

The Portrait Toxigenic Clostridium difficile assay is a rapid, qualitative assay for the detection of the tcdB gene of C. difficile in stool specimens from patients suspected of C. difficile infections, and received 510(k) clearance by the US FDA in March 2012. The Portrait Toxigenic C. difficile assay combines novel blocked-primer-mediated helicase-dependent multiplex amplification (bpHDA) technology and chip-based detection in an automated sample-to-result format. The assay requires minimal sample preparation and results are available within 90 min. In a multicenter evaluation, the Portrait Toxigenic C. difficile assay had a sensitivity of 98.2% and specificity of 92.8% compared with toxigenic culture. A comparative study between the Portrait Toxigenic C. difficile assay and three FDA-cleared molecular assays for the detection of toxigenic C. difficile exhibited a high degree of agreement (93.8–97.5%). The Portrait Toxigenic C. difficile assay provides a simple, cost-effective method with broad applicability to panel-based approaches, potentially simplifying workflow.     

难辨梭菌相关性疾病临床危险因素的研究

目的 分析难辨梭菌相关性疾病(CDAD)的临床治疗和用药危险因素,为遏止CDAD发病上升趋势,降低医疗成本提供依据.方法 对45例CDAD患者与85例非CDAD患者病例进行回顾性对照研究;比较两组患者在治疗药物、措施:胃肠道手术、灌肠术,实验室化验指标:白细胞、白蛋白的差异;各研究变量先进行单因素分析,有统计学差异的纳入logistic回归模型进行多因素分析.结果 回归模型显示,头孢菌素类:OR=3.321,95％CI:1.54～7.14,β=1.647、喹诺酮类OR=2.438,95％CI:1.15～5.15,β=1.255、糖肽类OR=0.232,95％CI:0.06～0.83,β=-2.130,抗菌药物的使用与CDAD存在显著性相关性(P＜0.05).结论 头孢菌素类、喹诺酮类抗菌药物的不合理使用,是导致CDAD发生的主要危险因素,糖肽类药物使用可以作为预防CDAD发生的保护性因素.