Xpert艰难梭菌检测系统的临床应用评价

目的评估Xpert艰难梭菌检测系统的临床应用价值。方法选取43份腹泻粪便标本,采用厌氧培养法、VIDAS检测A/B毒素法和Xpert艰难梭菌检测系统检测艰难梭菌,以产毒培养法作为金标准对检测方法进行评价,并比较不同检测方法对临床标本检测结果的一致性。通过自配027型标准菌株模拟粪便标本,验证Xpert艰难梭菌检测系统筛选027型流行株的能力。结果以产毒培养法为金标准,Xpert艰难梭菌检测系统的敏感性和特异性分别为90.9%和93.8%,阳性和阴性预测值分别为83.3%和96.8%。与产毒培养法结果一致性检验Kappa值为0.822(P0.05),与VIDAS检测A/B毒素法结果一致性检验Kappa值为0.419(P0.05);027型标准菌株模拟粪便标本检测结果阳性并报告为027型。结论 Xpert艰难梭菌检测系统能够快速准确地检测粪便标本中的艰难梭菌相关基因,且能准确报告027型高产毒力菌株。     

Antimicrobial stewardship in daily practice: Managing an important resource

Antimicrobial stewardship is a recent concept that embodies the practical, judicious use of antimicrobials to decrease adverse outcomes from antimicrobials while optimizing the treatment of bacterial infections to reduce the emergence of resistant pathogens. The objectives of the present statement are to illustrate the principles of antimicrobial stewardship and to offer practical examples of how to make antimicrobial stewardship part of everyday hospital and outpatient practice. Vital components of antimicrobial stewardship include appropriate testing to diagnose whether infections are viral or bacterial, and using clinical follow-up rather than antibiotics in cases in which the child is not very ill and uncertainty exists. Other specific, important actions include questioning whether positive urine cultures are contaminated when there is no evidence of pyuria or inflammatory changes, and obtaining a chest radiograph to support a diagnosis of bacterial pneumonia. Optimizing the choice and dosage of antimicrobials also reduces the probability of clinical failures and subsequent courses of antimicrobials. A list of common clinical scenarios to promote stew-ardship is included.     

Extraintestinal Clostridium difficile Infections: A Single-Center Experience

ObjectivesTo evaluate the clinical burden of extraintestinal Clostridium difficile infection (CDI) seen at a single institution and to characterize the management and outcomes of these rare infections.Patients and MethodsA retrospective medical record review was conducted to identify patients with isolation of C difficile from extraintestinal sites from January 1, 2004, through December 31, 2013. Medical records were reviewed and data, including demographic characteristics, microbiology, clinical associations, management, and infection outcomes, were abstracted.ResultsOverall, 40 patients with extraintestinal CDI were identified: 25 had abdominopelvic infections, 11 had bloodstream infections, 3 had wound infections, and 1 had pulmonary infection. C difficile was isolated with other organisms in 63% of cases. A total of 85% of infections were nosocomial. Factors associated with extraintestinal CDI included surgical manipulation of the gastrointestinal tract (88%), recent antibiotic exposure (88%), malignant tumors (50%), and proton pump inhibitor use (50%). Diarrhea was present in 18 patients (45%), 12 of whom had C difficile polymerase chain reaction (PCR)–positive stool samples. All isolates tested were susceptible to metronidazole and piperacillin-tazobactam. Management included both antimicrobial therapy and guided drainage or surgical intervention in all but one patient. The infection-associated mortality rate was 25%, with death a median of 16 days (range, 1-61 days) after isolation of C difficile.ConclusionExtraintestinal CDI is uncommon and often occurs in patients with surgical manipulation of the gastrointestinal tract and well-recognized risk factors for intestinal CDI. Management of extraintestinal CDI includes both antimicrobial and surgical therapies. Extraintestinal CDI is characterized by poor outcome with high mortality.     

艰难梭菌毒素B受体结合区CDB3融合蛋白诱导表达条件优化及其纯化

目的：优化艰难梭菌毒素B受体结合区CDB3融合蛋白诱导表达条件,在获得高表达融合蛋白后对其进行纯化,为艰难梭菌毒素B受体结合区CDB3单克隆抗体的制备奠定基础。方法以诱导前菌液600 nm处的光密度值（OD600）、诱导温度、诱导剂异丙基-β-D巯基半乳糖苷（IPTG）浓度和诱导时间为单变量,分别诱导融合蛋白的表达,在此基础上采用正交试验对融合蛋白的诱导表达条件进行优化,通过十二烷基磺酸钠-聚丙烯酰胺凝胶电泳半定量分析融合蛋白的表达量及表达形式,以Western blot对融合蛋白进行鉴定,以GST 亲和层析柱对融合蛋白进行纯化。结果融合蛋白诱导表达的最佳条件为诱导前菌液OD6000．8、IPTG浓度0．6 mmol/L、诱导时间12 h、诱导温度30℃,融合蛋白以可溶性蛋白表达形式为主,经纯化后,融合蛋白纯度超过90％。结论本研究成功优化了艰难梭菌毒素B受体结合区CDB3融合蛋白的诱导表达条件,获得大量表达,并成功对其进行了纯化,为后续单克隆抗体的制备奠定了基础。     

难辨梭菌鉴定培养基临床应用评估

目的评估难辨梭菌鉴定培养基(CDIF)的应用价值。方法用方法学评估研究。对临床收集的255份粪便标本同步进行CDIF培养基和环丝氨酸-头孢西丁-果糖琼脂培养基(CCFA)培养,并对CDIF培养基上的所有菌株及CCFA培养基上的典型菌株进行基质辅助激光解吸/电离飞行时间质谱鉴定。结果 255份粪便标本中,经CDIF培养24 h后出现典型菌株64株,经质谱鉴定为难辨梭菌58株;另有3株无色透明菌落的菌株被质谱鉴定为难辨梭菌。以质谱鉴定结果为参考,CDIF培养基对难辨梭菌鉴定的敏感性、特异性、阳性预测值、阴性预测值分别为95.1%(58/61)、96.9%(188/194)、90.6%(58/64)和98.4%(188/191)。CCFA培养48 h后生长的典型菌株经质谱鉴定为难辨梭菌61株。CDIF培养基和CCFA培养基上经质谱鉴定为难辨梭菌的菌落中,分离单一菌种比例分别为80.3%(49/61)和77.0%(47/61);CDIF培养基上菌落生长密度高于CCFA培养基。结论 CDIF培养基具有快速准确、操作简便、成本较低的特点,为难辨梭菌感染的实验室诊断提供了新的选择。     

一种用于艰难梭菌分离培养的新型显色培养基的性能评价

目的评价自主研发的艰难梭菌显色培养基(CDCA)性能。方法选用艰难梭菌及其他细菌的标准株进行CDCA显色的特异性评价;将艰难梭菌标准菌株梯度稀释后测定BD公司CDSA、生物梅里埃公司CDIF和CDCA的灵敏度。收集临床120份粪便样本分别采用3种培养基进行艰难梭菌分离培养,并对生长菌落进行质谱鉴定和tpi基因检测,以3种平板中任1种能培养出艰难梭菌的样本定义为真阳性。结果在CDCA平板上除了梭形梭菌、双酶梭菌、第三梭菌、脆弱拟杆菌等菌种能够少量生长并显色外,对其他实验菌种均有抑制作用。CDSA、CDIF和CDCA检测艰难梭菌的灵敏度分别为2.0×10~5 CFU/mL、8.0×10~1 CFU/mL和4.0×10~2 CFU/mL。120份标本中检出艰难梭菌31份(25.8%),CDSA、CDIF和CDCA培养阳性标本分别为25份(20.8%)、28份(23.3%)和26份(21.7%),3种显色培养基对临床腹泻标本检测阳性率差异无统计学意义(χ~2=0.418,P=0.811)。3种显色培养基的敏感性、特异性、阳性预测值、阴性预测值分别为:CDCA 83.8%、100%、100%、94.7%;CDIF 90.3%、98.9%、96.6%、96.7%;CDSA 80.6%、100%、100%、93.7%。结论本实验室研发的CDCA的特异性和灵敏度较高,可用于临床艰难梭菌的初步分离。     

Actoxumab + bezlotoxumab combination: what promise for Clostridium difficile treatment?

Introduction: Clostridium difficile infection (CDI) is the most common healthcare-associated infection worldwide. As standard CDI antibiotic therapies can result in unacceptably high recurrence rates, novel therapeutic strategies for CDI are necessary. A recently emerged immunological therapy is a monoclonal antibody against C. difficile toxin B.

Areas covered: In this review, the authors summarize the available pharmacological, preclinical, and clinical data for the CDI treatment based on anti-toxin A (actoxumab) and anti-toxin B (bezlotoxumab) human monoclonal antibodies (HuMabs), and discuss about the potentiality of a therapy that includes HuMab combined administration for CDI.

Expert opinion: Although only bezlotoxumab is indicated to reduce recurrence of CDI, experimental studies using a combination of HuMabs actoxumab and bezlotoxumab have shown that bolstering the host immune response against both the C. difficile toxins may be effective in primary and secondary CDI prevention. Besides neutralizing both the key virulence factors, combination of two HuMabs could potentially offer an advantage for a yet to emerge C. difficile strain, which is a steady threat for patients at high risk of CDI. However, as actoxumab development was halted, passive immunotherapy with actoxumab/bezlotoxumab is actually impracticable. Future research will be needed to assess HuMab combination as a therapeutic strategy in clinical and microbiological cure of CDI.     

Clostridioides (Clostridium) difficile infection in Japanese hospitals 2008–2017: A real-world nationwide analysis of treatment pattern,incidence and testing density

ObjectiveTo characterize treatment pattern, incidence and diagnosis of hospital-onset Clostridioides difficile infection (CDI) in Japan, cases were studied over a 9-year period using a large, administrative database.MethodsThis was a retrospective, cross-sectional analysis of inpatients at 320 Japanese Diagnosis-Procedure Combination (DPC) hospitals. Hospitalizations between April 2008 and March 2017 were extracted for patients aged ≥18 years. CDI was defined as CDI treatment plus CDI diagnosis or positive enzyme immunoassay (EIA) result. Endpoints included treatment (type, route, daily dose, duration), time to CDI onset from admission, and time to recurrence (rCDI) from the end of treatment. Chronological changes were reported for treatment pattern, CDI incidence and EIA testing.ResultsThe analysis included 11,823 CDI hospitalizations, 1359 with rCDI. Overall, oral metronidazole (MNZ), oral vancomycin (VCM), and intravenous MNZ were used in 50.2%, 42.1% and 1.2% of CDI hospitalizations, respectively. From 2009 to 2017, CDI hospitalizations treated with MNZ more than doubled and VCM more than halved. Median (Q1–Q3) time to CDI and rCDI onset was 25 (11–52) days and 10 (6–17.5) days, respectively. Median treatment duration ranged from 8 to 10 days and median dose was 1 g/day for both MNZ and VCM. CDI incidence remained steady from 2010 until 2017 (0.99/10,000 patient-days) and EIA testing density doubled from 2008 to 2017 (24.46/10,000 patient-days).ConclusionOral MNZ has become the primary CDI treatment in Japanese DPC hospitals. The treatment duration and dose were aligned to the package insert. CDI diagnostic testing density increased over time, CDI incidence did not.Clinical trial registration numberN/A.     

PSEUDOMEMBRANOUS COLITIS COMPLICATING ULCERATIVE COLITIS

Clostridium difficile toxin (CD toxin) causes antibiotic‐associated colitis, or pseudomembranous colitis (PMC). Although CD toxin is sometimes found in the stools of patients with ulcerative colitis (UC), UC is rarely complicated by PMC. We report herein a case of PMC complicating UC, and present a review of the literature. A 71‐year‐old woman was diagnosed as having UC of the left colon, and treated with prednisolone and mesalazine. Later, however, lumbar spinal stenosis was also detected. After surgery for lumbar spinal stenosis, she suffered postoperative infection of the lumbar region. After 3‐week treatment with antibiotics, she developed diarrhea, bloody stools, and abdominal pain. Colonoscopy revealed PMC of the cecum, ascending colon, sigmoid colon, and rectum. Stools were positive for CD toxin. As cefotiam hydrochloride, levofloxacin hydrate (LVFX), and prednisolone were suspected as the causative agents, she was treated with 1.5 g vancomycin (VCM) daily for 2 weeks without ceasing LVFX. Her symptoms improved, and colonoscopy confirmed resolution of PMC. The possibility of PMC should be considered in UC patients treated with antibiotics, immunosuppressive agents or corticosteroids who complain of gastrointestinal symptoms. These patients should be thoroughly investigated by several modalities, including colonoscopy and CD toxin testing.