North American Pulsed-field Type Research Articles

Reprint of: Overview and changing epidemiology of Clostridium difficile infection

There has been an increase in Clostridium difficile infection (CDI) incidence, severity, and mortality during the last decade. Although the elderly receiving antibiotic therapy are the most common group at risk for infection, CDI occurs in all age groups, and recent data indicate that CDI is emerging in groups that have been traditionally considered at low risk for infection. Additionally, approximately one-third of all CDI cases are now considered to be community associated in the U.S. New information is emerging on risk factors for an initial episode of CDI as well as recurrent disease. Increases in the burden of disease and severe outcomes related to CDI has been associated with the emergence of a new epidemic strain, restriction enzyme analysis BI, North American Pulsed-Field Type 1, and PCR Ribotype 027 (BI/NAP1/027) as well as other emerging strains. This article explores the changing epidemiology of CDI based on the latest available data as well as the recent developments in diagnosis and infection control.

Overview and changing epidemiology of Clostridium difficile infection

There has been an increase in Clostridium difficile infection (CDI) incidence, severity, and mortality during the last decade. Although the elderly receiving antibiotic therapy are the most common group at risk for infection, CDI occurs in all age groups, and recent data indicate that CDI is emerging in groups that have been traditionally considered at low risk for infection. Additionally, approximately one-third of all CDI cases are now considered to be community associated in the U.S. New information is emerging on risk factors for an initial episode of CDI as well as recurrent disease. Increases in the burden of disease and severe outcomes related to CDI has been associated with the emergence of a new epidemic strain, restriction enzyme analysis BI, North American Pulsed-Field Type 1, and PCR Ribotype 027 (BI/NAP1/027) as well as other emerging strains. This article explores the changing epidemiology of CDI based on the latest available data as well as the recent developments in diagnosis and infection control.

834 Ileal Transcriptome Analysis Reveals Mucosal Immune Maturation With Increasing Age-of-Onset in Pediatric Crohn Disease and Healthy Controls - A Mucosal Gene Expression Based Signature That Supports the Paris Classification for Age-of-Onset

matched controls without IBD. Information including diagnosis, IBD type, IBD activity, IBD medications, proton pump inhibitor (PPI) use, hospitalizations and antibiotic use was recorded. Patients were followed with repeat fecal and serum samples obtained. Cytotoxic culture for CD along with PCR to detect the toxin B gene was conducted on stool. Pulsed field gel electrophoresis (PFGE) was performed to determine strain type. Enzyme-linked Immunosorbent Assay (ELISA) was used to determine immunoglobulin G, A andM responses to CD toxin A and B from serum. Results: The prevalence of CD carriage was significantly greater in patients with IBD (17%) compared with controls (3%) (p=0.012). PCR to detect the toxin B gene compared to the gold standard of cytotoxic culture had a sensitivity of 92% and specificity of 100%. No patients showed clinical evidence of active CD infection. Among patients with IBD, IBD type, disease activity, IBD therapy, antibiotic use and hospitalizations were not found to be associated with CD carriage. PPI use was significantly more frequent in patients with CD carriage (54% vs. 25%, p,0.05). PFGE identified 6 different North American Pulsed Field Type (NAP) strains that then varied over time. There was a significantly greater proportion of patients with a positive antibody response to toxin A with IBD (69%) vs. controls (53%) (p,0.05), with a parallel trend of increased IgG and IgA responses against both toxin A and toxin B in those with IBD. Conclusions: Our findings show that asymptomatic toxigenic CD carriage, likely acquired in the community, is increased in pediatric IBD outpatients compared with controls. A variety of NAP strains were identified and these changed over time in CD colonized patients. PPI use was associated with an increased risk of carriage. Antibody responses of patients with IBD to CD toxins were increased, potentially promoting asymptomatic colonization. Future studies are needed to identify risk factors for symptomatic CD in pediatric IBD.

833 Malignancies in Children Receiving Infliximab and Other Inflammatory Bowel Disease Therapies: An Inflammatory Bowel Disease Multicenter, Prospective, Long-Term Registry of Pediatric Patients (Develop) Registry Data

matched controls without IBD. Information including diagnosis, IBD type, IBD activity, IBD medications, proton pump inhibitor (PPI) use, hospitalizations and antibiotic use was recorded. Patients were followed with repeat fecal and serum samples obtained. Cytotoxic culture for CD along with PCR to detect the toxin B gene was conducted on stool. Pulsed field gel electrophoresis (PFGE) was performed to determine strain type. Enzyme-linked Immunosorbent Assay (ELISA) was used to determine immunoglobulin G, A andM responses to CD toxin A and B from serum. Results: The prevalence of CD carriage was significantly greater in patients with IBD (17%) compared with controls (3%) (p=0.012). PCR to detect the toxin B gene compared to the gold standard of cytotoxic culture had a sensitivity of 92% and specificity of 100%. No patients showed clinical evidence of active CD infection. Among patients with IBD, IBD type, disease activity, IBD therapy, antibiotic use and hospitalizations were not found to be associated with CD carriage. PPI use was significantly more frequent in patients with CD carriage (54% vs. 25%, p,0.05). PFGE identified 6 different North American Pulsed Field Type (NAP) strains that then varied over time. There was a significantly greater proportion of patients with a positive antibody response to toxin A with IBD (69%) vs. controls (53%) (p,0.05), with a parallel trend of increased IgG and IgA responses against both toxin A and toxin B in those with IBD. Conclusions: Our findings show that asymptomatic toxigenic CD carriage, likely acquired in the community, is increased in pediatric IBD outpatients compared with controls. A variety of NAP strains were identified and these changed over time in CD colonized patients. PPI use was associated with an increased risk of carriage. Antibody responses of patients with IBD to CD toxins were increased, potentially promoting asymptomatic colonization. Future studies are needed to identify risk factors for symptomatic CD in pediatric IBD.

The Clostridium difficile problem: A South African tertiary institution's prospective perspective

The aim of this study is to report the incidence of Clostridium difficile-associated disease (CDAD) in a tertiary-care hospital in South Africa and to identify risk factors, assess patient outcomes and determine the impact of the hypervirulent strain of the organism referred to as North American pulsed-field type 1 (NAP1). Adults who presented with diarrhoea over a period of 15 months were prospectively evaluated for CDAD using stool toxin enzyme immunoassay (EIA). Positive specimens were evaluated by PCR. Patient demographics, laboratory parameters and outcomes were analysed. CDAD was diagnosed in 59 (9.2%) of 643 patients (median age 39 years, IQR 30 - 55). Thirty-four (58%) were female. Recent antibiotic exposure was reported in 39 (66%), 27 (46%) had been hospitalised within 3 months, and 14 (24%) had concomitant inflammatory bowel disease (IBD). Nineteen (32%) had community-acquired CDAD (CA-CDAD). The annual incidence of hospital-acquired CDAD (HA-CDAD) was 8.7 cases/10 000 hospitalisations. Two cases of the hypervirulent strain NAP1 were identified. Seven (12%) patients underwent colectomy (OR 6.83; 95% CI 2.41 - 19.3). On logistic regression, only antibiotic exposure independently predicted for CDAD (OR 2.9; 95% CI 1.6 - 5.1). Three (16%) cases of CA-CDAD reported antibiotic exposure (v. 90% of HA-CDAD, p<0.0001). Twelve (86%) patients had concomitant IBD (p<0.0001 v. HA-CDAD). CA-CDAD was significantly associated with antibiotic exposure (OR 0.04, 95% CI 0.01 - 0.24) and IBD (OR 9.6, 95% CI 1.15 - 79.8). The incidence of HA-CDAD in the South African setting is far lower than that reported in the West. While antibiotic use was a major risk factor for HA-CDAD, CA-CDAD was not associated with antibiotic therapy. Concurrent IBD was a predictor of CA-CDAD.

Community-Acquired Clostridium Difficile Infection: Awareness and Clinical Implications

The epidemiology of Clostridium difficile infection (CDI) is changing. CDI, usually depicted as a nosocomial infection in the elderly, is now occurring in community-dwelling persons who are younger and otherwise dissimilar. A more virulent isolate, North American Pulsed Field type 1, associated with increased morbidity and mortality, has been identified. In 2005, similar strains were associated with severe disease in community-dwelling patients at a rate of 7.6/100,000. Screening patients with potential CDI symptoms and implementing preventive measures, including judicious use of antibiotics, can reduce disease burden.

Fidaxomicin: A Macrocyclic Antibiotic for the Treatment of Clostridium difficile Infection

Clostridium difficile is an emerging pathogen in certain health care systems and community-based populations that is associated with high rates of morbidity and mortality, as well as increased costs for the health care system. As recurrence rates increase, new pharmacologic agents to treat C. difficile infection are needed. Fidaxomicin, a novel macrocyclic antibiotic, was recently approved by the United States Food and Drug Administration for the treatment of C. difficile-associated diarrhea. Originally isolated from fermentation broth of Dactylosporangium aurantiacum subspecies hamdenensis, the drug has a selective spectrum, distinctive pharmacokinetic and pharmaco-dynamic properties, and a favorable adverse-effect profile. Fidaxomicin has demonstrated similar clinical cure rates (i.e., resolution of diarrhea) compared with vancomycin, with lower recurrence rates and higher global cure rates (i.e., resolution of diarrhea without recurrence) in non-restriction endonuclease analysis type BI, North American Pulsed Field type 1 (NAP1), polymerase chain reaction ribotype 027 (or non-BI/NAP1/027) strains. Overall, fidaxomicin has been generally well tolerated, with the most common adverse effects reported as mild gastrointestinal complaints. Fidaxomicin appears to be a useful agent in the treatment of severe C. difficile infection, demonstrating decreased rates of recurrence.

Multi-locus variable number tandem repeat analysis for investigation of the genetic association of Clostridium difficile isolates from food, food animals and humans

Clostridium difficile is the primary known cause of antibiotic-associated diarrhea. Diarrheal disease in food animals due to C. difficile infection has been well documented. Recently, reports of C. difficile infections in patients with no known risk factors for disease have raised concern of community acquisition through food animals and food. In this study, multi-locus variable number tandem repeat analysis (MLVA) was performed on a collection of 97 C. difficile isolates of human, animal and food origin belonging to either the North American pulsed-field type (NAP) 1 or NAP7/NAP8. MLVA discriminated between NAP1 and NAP7/NAP8 populations. Three clusters of food, food animal and human NAP1 isolates were highly related by MLVA. These data suggest the possibility of either laboratory contamination or widespread distribution of clonal C. difficile populations. Community-associated NAP1 isolates were unrelated to NAP1 food and food animal isolates. Two MLVA loci were absent and 1 was invariant in all NAP7/NAP8 isolates. Therefore, MLVA discrimination was not sufficient to make assessments regarding the genetic associations among food, food animal and human isolates belonging to the NAP7/NAP8 pulsovar. Rigorous epidemiologic and laboratory investigations that employ highly discriminatory genotyping methods are necessary to compare C. difficile isolates from food and food animals to those from humans.

Fidaxomicin versus Vancomycin forClostridium difficileInfection

Clostridium difficile infection is a serious diarrheal illness associated with substantial morbidity and mortality. Patients generally have a response to oral vancomycin or metronidazole; however, the rate of recurrence is high. This phase 3 clinical trial compared the efficacy and safety of fidaxomicin with those of vancomycin in treating C. difficile infection. Adults with acute symptoms of C. difficile infection and a positive result on a stool toxin test were eligible for study entry. We randomly assigned patients to receive fidaxomicin (200 mg twice daily) or vancomycin (125 mg four times daily) orally for 10 days. The primary end point was clinical cure (resolution of symptoms and no need for further therapy for C. difficile infection as of the second day after the end of the course of therapy). The secondary end points were recurrence of C. difficile infection (diarrhea and a positive result on a stool toxin test within 4 weeks after treatment) and global cure (i.e., cure with no recurrence). A total of 629 patients were enrolled, of whom 548 (87.1%) could be evaluated for the per-protocol analysis. The rates of clinical cure with fidaxomicin were noninferior to those with vancomycin in both the modified intention-to-treat analysis (88.2% with fidaxomicin and 85.8% with vancomycin) and the per-protocol analysis (92.1% and 89.8%, respectively). Significantly fewer patients in the fidaxomicin group than in the vancomycin group had a recurrence of the infection, in both the modified intention-to-treat analysis (15.4% vs. 25.3%, P=0.005) and the per-protocol analysis (13.3% vs. 24.0%, P=0.004). The lower rate of recurrence was seen in patients with non–North American Pulsed Field type 1 strains. The adverse-event profile was similar for the two therapies. The rates of clinical cure after treatment with fidaxomicin were noninferior to those after treatment with vancomycin. Fidaxomicin was associated with a significantly lower rate of recurrence of C. difficile infection associated with non–North American Pulsed Field type 1 strains. (Funded by Optimer Pharmaceuticals; ClinicalTrials.gov number, NCT00314951.)

Diagnosis, Management, and Prevention of Clostridium difficile Infection in Long‐Term Care Facilities: A Review

Clostridium difficile is a significant healthcare-associated pathogen and the major cause of antibiotic-associated diarrhea. The incidence and severity of C. difficile infection have increased in many parts of North America and Europe in the past few years with the widespread dissemination of a hypervirulent strain of C. difficile, referred to as North American pulsed-field type 1, polymerase chain reaction ribotype 027 (NAP1/027). C. difficile infection appears to affect older adults disproportionately. Long-term care facility (LTCF) residents are at greater risk because of advanced age, the frequent need for hospitalization, and recurrent exposures to antimicrobial agents. Early identification of C. difficile infection and prompt initiation of appropriate therapy are required to reduce morbidity and mortality. Diagnosis is based on the detection of C. difficile toxins A or B in diarrheal stool specimens. The treatment of choice for moderate or severe C. difficile infection (defined as the presence of pseudomembranous colitis, treatment in an intensive care unit, or two of (i) aged 60 and older, (ii) fever greater than 38.3°C, (iii) peripheral leukocytosis (>15,000 cells/mm(3) ), or (iv) hypoalbuminemia (<2.5 mg/dL) should be with oral vancomycin (125 mg four times a day for 10-14 days). Treatment with oral metronidazole should be reserved for those with milder disease. Measures to prevent outbreaks and reduce the risk of C. difficile infection in LCTFs should include antimicrobial stewardship to ensure judicious use of antibiotics, C. difficile infection surveillance, appropriate use of contact or barrier precautions, and careful environmental cleaning and disinfection using sporicidal agents.

Decrease of hypervirulent Clostridium difficile PCR ribotype 027 in the Netherlands

After the first outbreaks of Clostridium difficile PCR ribotype 027 (North American pulsed-field type 1, restriction endonuclease analysis group BI) in the Netherlands in 2005, a national surveillance programme for C. difficile infection (CDI) was started. Furthermore, national guidelines were developed to rapidly recognise type 027 infections and prevent further spread. The mean incidence of CDI measured in 14 hospitals remained stable throughout the years: an incidence of 18 per 10,000 admissions was seen in 2007 and 2008. Between April 2005 and June 2009 a total of 2,788 samples were available for PCR ribotyping. A decrease was seen in the number and incidence of type 027 after the second half of 2006. In the first half of 2009, the percentage of type 027 isolates among all CDI decreased to 3.0%, whereas type 001 increased to 27.5%. Type 014 was present in 9.3% of the isolates and C. difficile type 078 slightly increased to 9.1%. We conclude that currently there is a significant decrease in type 027-associated CDI in the Netherlands.

Clostridium difficile Strain NAP-1 Is Not Associated With Severe Disease in a Nonepidemic Setting

Recent outbreaks of Clostridium difficile infection (CDI) in North America and in Europe with very high case-fatality rates have been associated with infection by North American Pulsed Field Type I (NAP-1) isolates. This study examined whether NAP-1 strains are associated with worse outcomes of CDI in a nonepidemic, nosocomial setting. All cases of CDI that occurred over a 13-month period at a tertiary medical center were examined for risk factors associated with increased severity of CDI and other outcomes. Stool samples from each patient were cultured for C difficile and the resulting isolates were strain-typed by pulsed-field gel electrophoresis. Strain types were obtained from 236 of 272 CDI samples; the NAP-1 strain was identified in 59 (25%). In this inpatient cohort of patients with CDI, the incidence of in hospital death was 12.1% and of death caused by CDI was 4.0%. Of the patients with CDI, 22.1% met the combined outcome end point of severe CDI. In both univariate and multivariate analyses, patients infected with the NAP-1 strain did not have worse outcomes compared with those infected with non-NAP-1 strains. Infection with the NAP-1 strain was correlated with admission from outside health care facilities regardless of whether symptoms of CDI began before or after admission to the study hospital. The NAP-1 strain of C difficile was found to cause 25% of cases of CDI in the hospital where the study was performed. However, compared with non-NAP-1 strains, CDI was not associated with increased severity of disease in this nonepidemic setting.

Rapid Molecular Characterization of Clostridium difficile and Assessment of Populations of C. difficile in Stool Specimens

Our laboratory has developed testing methods that use real-time PCR and pyrosequencing analysis to enable the rapid identification of potential hypervirulent Clostridium difficile strains. We describe a real-time PCR assay that detects four C. difficile genes encoding toxins A (tcdA) and B (tcdB) and the binary toxin genes (cdtA and cdtB), as well as a pyrosequencing assay that detects common deletions in the tcdC gene in less than 4 h. A subset of historical and recent C. difficile isolates (n = 31) was also analyzed by pulsed-field gel electrophoresis to determine the circulating North American pulsed-field (NAP) types that have been isolated in New York State. Thirteen different NAP types were found among the 31 isolates tested, 13 of which were NAP type 1 strains. To further assess the best approach to utilizing our conventional and molecular methods, we studied the populations of C. difficile in patient stool specimens (n = 23). Our results indicated that 13% of individual stool specimens had heterogeneous populations of C. difficile when we compared the molecular characterization results for multiple bacterial isolates (n = 10). Direct molecular analysis of stool specimens gave results that correlated well with the results obtained with cultured stool specimens; the direct molecular analysis was rapid, informative, and less costly than the testing of multiple patient stool isolates.

Clindamycin-Resistant Clone ofClostridium difficilePCR Ribotype 027, Europe

Clindamycin-Resistant Clone of<i>Clostridium difficile</i>PCR Ribotype 027, Europe

Surveillance for Community-Associated Clostridium difficile—Connecticut, 2006

Clostridium difficile is a well-known cause of hospital-acquired infectious diarrhea and is associated with increased health-care costs, prolonged hospitalizations, and increased patient morbidity. Previous antimicrobial use, especially use of clindamycin or ciprofloxacin, is the primary risk factor for development of C. difficile-associated diarrhea (CDAD) because it disrupts normal bowel flora and promotes C. difficile overgrowth. Historically, CDAD has been associated with elderly hospital in-patients or long-term--care facility (LTCF) residents. Since 2000, a strain of C. difficile that has been identified as North American pulsed-field type 1 (NAP1) and produces an extra toxin (binary toxin) and increased amounts of toxins A and B has caused increased morbidity and mortality among hospitalized patients. During 2005, related strains caused severe disease in generally healthy persons in the community at a rate of 7.6 cases per 100,000 population, suggesting that traditional risk factors for C. difficile might not always be factors in development of community-associated CDAD (CA-CDAD). Cases of CA-CDAD are not nationally reportable, and population-based data at a statewide level have not been reported previously. In 2006, the Connecticut Department of Public Health (DPH) implemented a statewide surveillance system to assess the burden of CA-CDAD and to determine the descriptive epidemiology, trends, and risk factors for this disease. This report describes that surveillance system and summarizes results from the first year of surveillance. The findings indicated the presence of occasionally severe CDAD among healthy persons living in the community, including persons with no established risk factors for infection. Clinicians should consider a diagnosis of CA-CDAD in outpatients with severe diarrhea, even in the absence of established risk factors. In addition, continued surveillance is needed to determine trends in occurrence and whether more toxigenic strains are having an increasing impact in the community and in the hospital setting.

Clostridium difficile: changing epidemiology and new treatment options

The review summarizes changes in the epidemiology and treatment of Clostridium difficile-associated disease. Recent outbreaks of Clostridrium difficile-associated diarrhoea with increased severity, high relapse rate and significant mortality, have been related to the emergence of a new, hypervirulent C. difficile strain in north America, Japan and Europe. Definitions have been proposed by the European Centre for Disease Prevention and Control to identify severe cases of Clostridrium difficile-associated diarrhoea and to differentiate community-acquired cases from nosocomial-acquired cases. The emerging strain is referred to as North American pulsed-field type 1 and polymerase chain reaction ribotype 027. The emerging strain has also been detected in calf diarrhoea and ground meat samples in Canada. Attempts to prevent outbreaks caused by type 027 should focus on controlling the overall use of antibiotics, and high-risk antibiotics such as cephalosporins, clindamycin and fluoroquinolones. Several new antibiotic and non-antibiotic alternatives have become available; there is currently no place for probiotic treatments. Patients who suffer multiple relapses of C. difficile-associated diarrhoea present a major therapeutic challenge. The early recognition of Clostridrium difficile-associated diarrhoea caused by NAP1/027 is necessary to start rapid treatment, to prevent complications, and to prevent further spread of the bacterium.

Update of Clostridium difficile-associated disease due to PCR ribotype 027 in Europe

Recent outbreaks of Clostridium difficile-associated diarrhoea (CDAD) with increased severity, high relapse rate and significant mortality have been related to the emergence of a new, hypervirulent C. difficile strain in North America, Japan and Europe. Definitions have been proposed by the European Centre of Disease Prevention and Control (ECDC) to identify severe cases of CDAD and to differentiate community-acquired cases from nosocomial CDAD (http://www.ecdc.europa.eu/documents/pdf/Cl_dif_v2.pdf). CDAD is mainly known as a healthcare-associated disease, but it is also increasingly recognised as a community-associated disease. The emerging strain is referred to as North American pulsed-field type 1 (NAP1) and PCR ribotype 027. Since 2005, individual countries have developed surveillance studies to monitor the spread of this strain. C. difficile type 027 has caused outbreaks in England and Wales, Ireland, the Netherlands, Belgium, Luxembourg, and France, and has also been detected in Austria, Scotland, Switzerland, Poland and Denmark. Preliminary data indicated that type 027 was already present in historical isolates collected in Sweden between 1997 and 2001.

A Portrait of the Geographic Dissemination of the Clostridium difficile North American Pulsed-Field Type 1 Strain and the Epidemiology of C. difficile-Associated Disease in Quebec

An increase in the incidence and severity of Clostridium difficile-associated disease in Québec and the United States has been associated with a hypervirulent strain referred to as North American pulsed-field type 1 (NAP1)/027. In 2005, a prospective study was conducted in 88 Québec hospitals, and 478 consecutive nosocomial isolates of C. difficile were obtained. The isolates were subjected to pulsed-field gel electrophoresis (PFGE) typing, antimicrobial susceptibility testing, and detection of binary toxin genes and tcdC gene deletion. Data on patient age and occurrence of complications were collected. PFGE typing of 478 isolates of C. difficile yielded 61 PFGE profiles. Pulsovars A (57%), B (10%), and B1 (8%) were predominant. The PFGE profile of pulsovar A was identical to that of strain NAP1. It showed 67% relatedness with 15 other PFGE patterns, among which 11 had both binary toxin genes and a partial tcdC deletion but different antibiotic susceptibility profiles. Pulsovars B and B1 were identical to strain NAP2/ribotype 001. In hospitals showing a predominant clonal A or B-B1 PFGE pattern, incidence of C. difficile-associated disease was 2 and 1.3 times higher, respectively, than in hospitals without any predominant clonal PFGE pattern. Severe disease was twice as frequent among patients with strains possessing binary toxin genes and tcdC deletion than among patients with strains lacking these virulence factors. This study helped to quantify the impact of strain NAP1 on the incidence and severity of C. difficile-associated disease in Québec in 2005. The identification of the geographic dissemination of this predominant strain may help to focus regional infection-control efforts.