Clostridium difficile: A European perspective

Journal of Infection (2013) 66, 115e128

www.elsevierhealth.com/journals/jinf

REVIEW

Clostridium difficile: A European perspective A.M. Jones a,*, E.J. Kuijper b, M.H. Wilcox c a

MSC Ltd, Old Malton YO17 7HD, North Yorkshire, UK Leiden University, Leiden, The Netherlands c Microbiology, Leeds Teaching Hospitals and University of Leeds, Old Medical School, Leeds General Infirmary, Leeds LS1 3EX, UK b

Accepted 18 October 2012 Available online 24 October 2012

KEYWORDS Clostridium difficile infection; Guidelines; Diagnosis; Management

Summary Clostridium difficile infection is the leading cause of diarrhoea in the industrialised world. First identified in 1935, our knowledge about the clonal population structure, toxins and PCR ribotypes is still increasing. New PCR ribotypes and sequence types are frequently added. In the last decade hypervirulent strains have emerged and been associated with increased severity of disease, high recurrence and significant mortality. Although previously a primarily hospital- or health-care acquired infection, since the 1990’s C. difficile infections that are community-acquired have been increasingly reported. Risk factors include hospitalisation, advancing age and prior antibiotic use. The ubiquitous presence of C. difficile in the environment and asymptomatic intestinal colonisation may be important reservoirs for infection and the changing epidemiology of C. difficile infection. Although surveillance in Europe is now a requirement of the European Commission, reporting is not standardised or mandatory. Here we review the current literature, guidelines on diagnosis and treatment and conclude by highlighting a number of areas where further research would increase our understanding. ª 2012 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Historical perspective Initially named Bacillus difficilis, Clostridium difficile (a Gram-positive spore forming anaerobe) was first identified and described in 1935 by Hall and O’Toole as part of the intestinal flora of neonates.1 They demonstrated that C. difficile produces a toxin that was lethal when administered subcutaneously to guinea pigs and rabbits. In the mid

70s, a hamster model for clindamycin-induced ileocecitis was developed,2,3 and in 1978, two groups working independently established the association between antibiotic use and C. difficile infection (CDI).4,5 Work on the molecular analysis of C. difficile toxins began in the 1980s and a standardised nomenclature for C. difficile toxins and toxin gene nomenclature was established in 2004.6 Understanding the epidemiology of C. difficile was facilitated

* Corresponding author. Tel.: þ44 1653 690548; fax: þ44 1653 694622. E-mail addresses: [email protected], [email protected] (A.M. Jones). 0163-4453/$36 ª 2012 The British Infection Association. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jinf.2012.10.019

116 via typing and fingerprinting techniques developed in the 1990s, in particular ribotyping.7,8

Pathophysiology C. difficile has a clonal population structure. In the largest molecular epidemiology study conducted to date, 69 Sequence Types (ST) were identified from 1290 clinical isolates from the UK but new STs are continuously added.9,10 The main virulence factors of the enteropathogenic C. difficile are the two large clostridial toxins, toxin A (TcdA) and toxin B (TcdB). These toxins are glycosyltransferases that disrupt the cytoskeleton and tight junctions of the cells, resulting in apoptosis.11 This induces an inflammatory response and degradation of the intestinal epithelial cell layer. The precise activities of TcdA and TcdB are being reassessed as to their complementary and functional roles. Some strains produce a third toxin known as CDT or binary toxin.12 In vitro, CDT depolymerises the actin cytoskeleton, increases adherence and colonisation of Clostridia by induction of microtubule-based cell protrusions and, eventually, causes death of target cells.13 A lipolysis-stimulated lipoprotein receptor has been identified as the membrane receptor for CDT uptake by target cells.14 A recent published observation from Denmark suggests that CDT also has clinical impact; when comparing 30-day case-fatality rates for patients infected with C. difficile, patients with binary toxin had higher case-fatality rates than patients without binary toxin, in univariate analysis (relative risk [RR] 1.8, 95% confidence interval [CI] 1.2e2.7) and multivariate (RR 1.6, 95% CI 1.0e2.4).15 Initially, it was thought that toxin A was the major virulence factor, but recently the importance of toxin B has been re-stated.12 Both toxin A and toxin B cause extensive colonic inflammation and epithelial tissue damage resulting in fluid loss, which manifests itself as diarrhoea, although it is possible that toxin B only becomes effective once the gut wall has been damaged. Three accessory genes encoding the proteins involved in regulating the expression of TcdA and TcdB have recently been identified: tcdR, tcdC and tcdE.12 The role of these toxins and accessory genes in the virulence of C. difficile was recently reviewed by Carter et al., who concluded that there remains uncertainty about the exact role of the different toxins and other putative virulence factors (e.g. fimbriae, para-cresol, cysteine protease and adhesins).12 Indeed, recent animal model studies using mutants for toxin A and/or B have produced conflicting results. Kuehne et al. conducted experiments using isogenic mutants of C. difficile producing toxin A and/or B, and re-established the importance of both toxin A and toxin B.16 An earlier 2009 study, using different parent strains and different knockout methods conducted by Lyras et al. reported that toxin B alone was responsible for virulence.17 The presence of a naturally occurring mutation in the tcdC has also been associated with the ability of toxigenic strains to become more virulent and with increased toxin production,18 although this again is a controversial finding. Using an isogenic ClosTron-based knockout mutant of tcdC in C. difficile strain 630DErm (CT::tcdC), it was found that transcription levels of the PaLoc genes and the expression levels of the toxins in the wild type strain and

A.M. Jones et al. the tcdC mutant strain only revealed minor differences in transcription and total toxin levels, suggesting TcdC is not a major regulator of toxin expression.19 Based on sequence comparisons between C. difficile strains, a specific 027 insert has been found disrupting thymidylate synthetase (thyX) gene and replacing it with an equivalent, catalytically more efficient, thyA gene. This specific insert is also present in other hypervirulent PCR ribotypes and is another candidate virulence marker.20 Other investigators have identified a novel virulence factor, Srl (sensitivity regulation of C. difficile toxins), that they postulate is responsible for modulating toxin sensitivity of intestinal epithelial cells and enhancing the cytopathic effect of C. difficile toxins.21 However, altered toxin producing capabilities do not fully explain the increasing frequency and severity of the disease.22 Interestingly, recent data show that a diverse set of temperate bacteriophages can be found in C. difficile 027, and it is possible that these could affect strain virulence.23 Furthermore, host factors, notably age, play a role in determining severity and outcome, which is likely why some studies, albeit usually with small or potentially biased patient cohorts,24 have not found a consistent association between strain type and outcome. Further work is needed to understand the interaction between host and microbe and their effect on outcome. It has also been postulated that increased sporulation may be associated with hypervirulence,22,25 although this also remains controversial, particularly as in vitro experiments may not reflect in vivo behaviour. In general, translating in vitro or animal derived data into C. difficile behaviour in humans is not straightforward, and multiple different models for CDI have been described, including varied versions using the same animal (typically hamsters).26 It is likely that multiple factors determine whether a strain is virulent and/or epidemic. Amplification and spread of a C. difficile strain will be facilitated by pronounced/prolonged diarrhoeal symptoms in patient settings where infection control is most challenging. In practice, hospitalised, particularly elderly frail patients have a high potential to provide such an ecological niche.

Epidemiological trends Approximately 7e17% of adult hospitalised patients are colonised by C. difficile, with higher rates seen in elderly long stay individuals.27,28 Highly virulent C. difficile strains have emerged since 2002/3,29,30 in particular PCR-ribotype 027. These strains are also characterised as toxinotype III, North American pulsed field gel electrophoresis type1 (NAP1) and restriction endonuclease analysis group BI and, unlike historical control strains, are fluoroquinolone resistant. NAP1/027/BI has now emerged worldwide29 and has been associated with increased severity, high recurrence, and significant mortality.31,32 In addition, Pepin and coworkers reported a poor response rate to metronidazole in a Canadian outbreak associated with NAP1/027/BI in 2004.33 A recently completed study of 398 European C. difficile isolates, revealed that NAP1/027/BI isolates in general had a two-fold higher MIC90 to metronidazole compared with non-027 isolates, suggesting that this could have a significant association with poor response to metronidazole

Clostridium difficile treatment.34 However, a retrospective case-control study did not find a significant difference in outcome between patients (treated with metronidazole) with CDI due to strains with reduced susceptibility to metronidazole vs. cases caused by fully susceptible strains.35 Nevertheless, response to treatment (including mortality) was generally poor in both groups, emphasising that it is difficult in such patients to determine the effects of changes in strain susceptibility. Other emerging PCR-ribotypes have also been reported and include 012, 017, 019, 036, 078 and 153,20,25 with some ribotypes occurring in both humans and farm or companion animals.36 Interestingly, PCR ribotype 027 shares its sequence type (ST-1) with three other PCR ribotypes (PCR RTs 016, 036 and 176), indicating that these diverse PCR RTs are considered as one type according to MLST.20 CDI in the community setting was first described in the late 1980s and early 90s.37e39 Since that time, the incidence of community-acquired CDI has increased, and in a recently published single centre survey in the United States 41% of 385 cases recorded between 1991 and 2005 were community-acquired.40 Compared with hospitalacquired infections, patients in the community are younger (median age, 50 vs. 72), healthier and more likely to be female (76% vs. 60%). Patients with community-acquired infections were also less likely to have been exposed to antibiotics (78% vs. 94%). Since 2005, PCR ribotype 078 (the predominant stain in pigs and calves) has increased in community and also hospital isolates of C. difficile in Europe.41 Subsequently, C. difficile PCR ribotype 078 was found as the third most prevalent PCR ribotype in a panEuropean surveillance study performed in 2008.42 Ribotypes 014/020 and 001 were the two most frequently found types in that study.42 Interestingly, ribotype 001 was the predominant community strain in two urban settings in the UK at the start of the millenium.43 Compared with patients infected with NAP1/027/BI, patients with ribotype 078 tend to be younger with fewer co-morbidities, have community associated CDI and (similar to 027) be more likely to have received fluoroquinolones.41 However, a significant proportion of patients included in the studies by Goorhuis and Wilcox et al. had not received any antibiotic therapy in the 6 weeks prior to developing CDI in the community,41,43 leading to the hypothesis that there is a yet unknown selection mechanism that favours the emergence of these strains. A recent Centers for Disease Control and Prevention (CDC) survey in USA among CDIs identified in Emerging Infections Program data in 2010, revealed that 94% were associated with receiving health care; of these, 75% had onset among persons not currently hospitalised, including recently discharged patients, outpatients, and nursing home residents.44 Unfortunately European data are not available, but these data emphasise the importance of obtaining a complete patient history to correctly diagnose community-onset, healthcare associated CDI. Direct transmission of C. difficile from animals, food or the environment to humans has not been proven, although similar PCR ribotypes are found. As no outbreaks of CDI have been reported among humans in the community, host factors that increase vulnerability to CDI might be of more importance than increased exposure to C. difficile. Conversely, emerging C. difficile ribotype 078 is found in high numbers in piglets,

117 calves, and their immediate environment. Circumstantial evidence points towards a zoonotic potential of this type.36

Surveillance In Europe and North America, surveillance studies to monitor the incidence of CDI and the spread of hypervirulent strains (such as 027 [generally referred to as NAP1/ 027/BI] and 078) have been established at regional and national levels since 2007,45 although reporting is not mandatory in all EU countries.46 Data from a number of countries may also be limited because testing is not part of routine clinical practice,42 particularly in less severe cases, where there is little information on strain identification. Over the last decade, increases in the incidence and severity of CDI (possibly associated with the emergence of “hypervirulent” strains) have been reported in many European countries.30,32,47 In Europe, the incidence of hospital-associated CDI per 10,000 patient days ranges from 0 in Luxembourg and Turkey to 19.1 in Finland.42 In Austria an increase of 255% between 2003 and 2007 was recorded by the Austrian National Reference Centre for C. difficile.48 Data from the Spanish EPINE study reported a significant increase in CDI between 1999 and 2007 from 3.9 to 12.2 cases per 10,000 hospitalised patients.49 Since 2006, national CDI surveillance has been performed by the National Reference Laboratory (Leiden University Medical Center and Center for Infectious Diseases Control (CIb), RIVM, Bilthoven) in The Netherlands. A decrease of CDI due to C. difficile type 027 has been observed in hospitals participating in this programme,50 though other health care facilities (e.g. nursing homes) report an increase of Type 027. In 2011, the largest outbreak due to type 027 took place in an elderly home.51 The results of the sentinel surveillance in 18 hospitals revealed that the mean incidence of CDI is 15 per 10,000 admissions, varying from 3 to 29 per 10,000 admissions. Type 001 was the most frequently found type (17%), type 014 was found in 13% and type 078 in 12%. Type 027 was found in 3% of patients tested, distributed in seven of 18 hospitals. In other European countries the number of cases has either remained relatively static, as in Belgium,52 or else there has been a substantial reduction in the overall number of cases, as in England and Wales, where cases decreased significantly by >50% from 2008/9 and 2009/10.53 The reduction in CDI incidence in England since 2007e08 was associated in a substantial decrease in the proportion of CDI cases caused by NAP1/027/BI45 C. difficile ribotype 027 accounted for 55%, 36% and 21% of samples submitted to CDRN in 2007e08, 2008e09 and 2009e10, respectively. The reductions in infection rate and prevalence of NAP1/027/BI were manifested by a reversal of the trend of increasing reports of C. difficile related deaths up until 200754; the number of death certificates in England mentioning C. difficile decreased between 2007 and 10 by 70% from 7916 to 2335. While multiple interventions likely contributed to these changes, providing timely information on which ribotypes were causing CDI cases, and especially clusters, probably helped infection control teams to focus prevention measures more effectively.45 In a recent pan-European survey the most frequently reported toxigenic strains were

118 014/020 (16%), 001 (10%), 078 (8%), 018 (6%) and 106, 027 and 002 (5%) (Fig. 1).42 Table 1 summarises the available data from Eurosurveillance and other sources on reports of NAP1/027/BI in Europe.

Carriage and colonisation Rea and co-workers recently conducted a retrospective review of colonisation rates in elderly individuals in hospitals and long-term care facilities in Ireland.55 Colonisation rates ranged from 1.6% for subjects in the community to 9.5% in outpatients and to 21% of patients in hospitals or long term care settings. In this study 50% of the culture positive but asymptomatic patients had a history of prior antibiotic use in the previous 4-week period. An additional survey from the UK reported colonisation rates of 4% amongst elderly subjects residing in the community, of which two thirds were non-toxigenic.56 In a recent survey conducted in Germany, colonisation amongst nursing home residents was 4.6% compared with 0.8% in elderly people residing in the community, with 90% of the isolates from long-term care facilities being toxigenic (predominantly 014 [30%] and 001 [20%]).57 Developing an understanding of reservoirs colonised by disease causing C. difficile strains (e.g. the paediatric and

A.M. Jones et al. elderly populations) is important if effective infection control measures are to be developed and implemented.58 Reservoirs of infection may also go some way to providing an explanation for the emergence of community-associated CDI. An ongoing longitudinal study from Oxford is measuring C. difficile colonisation/carriage in infants and associated risk factors.59 Faecal samples from 276 children <2 years old in Oxfordshire, UK, March 2010eApril 2012, were cultured for C. difficile, and a subset (n Z 67) aged <6 months provided samples monthly for up to 10 months. Isolates from children <2 years in Oxfordshire appeared to be (MLST) clade-restricted, with no clade 2 (NAP1/ribotype027), 3 or 5 (NAP7, 8/ribotype 078) isolates identified. Multivariable logistic and time-dependent Cox regression were used to explore potential risk factors for presence and time to first acquisition of C. difficile. Nutritional factors, childcare and pets were found to be associated with carriage and acquisition of C. difficile. Such provocative findings emphasise the importance of studies to better understand hitherto poorly described potential C. difficile reservoirs.

Clinical features European guidelines for clinical management of CDI were published in 2009.60 The Infectious Diseases Society of

Figure 1 European distribution of ribotypes. Geographical distribution of Clostridium difficile PCR ribotypes in European countries with more than five typable isolates, November, 2008Pie charts show proportion of most common PCR-ribotypes per country. The number in the centre of pie charts is the number of typed isolates in the country. Reproduced with permission from Bauer et al.42

Clostridium difficile

Table 1

119

European surveillance of NAP1/027/BI.

Country

Year

Austria

2006 2008e9

Belgium

2005

Casesa/ isolates (n) 1 38

4

Overall mortality (%)

Relapse (%)

4/28 (14)

(25)

2009e10

Denmark

2008e09

Finland

2007

73 3

2007e2008

131

2008

120

France

2006

194

Germany

2006 2006e07 2008e09 2007

266 529 102 37

2009 2007

27 1

2006

20

2006e08 2004e05

96 33

2007e2008

51

Norway

2008e2009 2009e2010 2010e2011 2011e2012 2007e08

33 28 51 71 3

Spain Sweden

2008e09

3

2003e05 2007e08 2007e08

498 71 278

Hungary Ireland

Luxembourg The Netherlands

UK

a

confirmed cases.

13/59

9/59

100

28/120 (23) (6)

15 (6) 164 (31) 6/36 (17)

Notes

Reference

Voluntary surveillance since 2006120 2003e07 CDI increased from 777 to 2761 cases, not attributable to NAP1/027/BI Compulsory reporting from 200752

Kuijper120 Indra48

Proportion of hospitals reporting NAP1/027/BI significantly reduced from 46% to 28% (p < 0.03) Regional active surveillance encouraged since 2006120 First report and 2 further cases identified. Protocol prepared for surveillance.120 5 month period. 027 reported from 4:9 healthcare districts. Predominantly long-term or primary care. 36% of isolates 027, 16% 001.

Viseur52

Mandatory notification of severe cases or outbreaks to local health departments120 027 isolated from 11 healthcare facilities and 1 nursing home

Tachon125

Mandatory surveillance of severe cases since 2007120 Bavaria: 4.6% of isolates tested, 488/587,001 Single isolated case Surveillance and ribotyping since 2003.131 Notifiable disease since 2008120 1st case 2005. Two clusters 2006.

(15e21) (6)

(25.5) 15/67 (22)

(12)

Surveillance started 2006. Reporting encouraged since 2005.120 Both surveillance of outbreaks and national sentinel surveillance in 20 hospitals. A significant decrease has been reported in 027 since 2006 until 2010, but a re-emerge has been found, mainly due to outbreaks in long term care facilities.133 C. difficile not cultured by most laboratories. Little known about ribotype distribution.120,135 No national surveillance programme.120 Voluntary web reporting from 2009.67 Only 3027 isolates reported. Mandatory surveillance England and Wales since 2004. 15.4% increase (25.9%e41.3%) in 027 from 2005.136

Joseph121

Bacci122 Lyytikainen123 Kuijper120 Kotila124

Coignard126 Birgand127 Birgand127 Kleinkauf128

Reil129 Terhes130

Drudy and Long131,132 Kuijper120 Van Steenbergen134

Ingebretsen135

Akerlund67 Barbut32 Aldeyab137

120 America (IDSA) and the Society for Hospital Epidemiology of America (SHEA) also published revised guidelines for CDI in 2010.61 These guidelines provide recommendations regarding:  strategies for diagnosis  appropriate therapy  the minimum epidemiological data that should be collected and how the data should be reported  infection control measures for hospitals to implement routinely and during an outbreak CDI is the most frequent cause of nosocomial diarrhoea in the industrialised world. It can range from mild diarrhoea to fulminant pseudomembranous colitis.61,62 A frequently used case definition for CDI is: diarrhoea defined as >3 unformed stools in less than 24 h, stool test positive for toxigenic C. difficile or its toxins/toxin genes or colonoscopic/histopathologic findings demonstrating pseudomembranous colitis.61 Prior antibiotic use is the predominant risk factor for the acquisition of CDI, and between 15% and 20% of all cases of antibiotic-associated diarrhoea result from CDI.61,62 Antibiotic use not only increases the risk for CDI during therapy but also in the period of 3 months after cessation of antibiotic therapy. The highest risk for CDI is found during and in the first month after antibiotic use.63 The clinical presentation of CDI differs from other antibiotic-associated diarrhoea in that there is often evidence of colitis (i.e. cramps, fever and faecal leukocytes). Other risk factors include hospitalisation, advanced age (with patients 65 years having a 20-fold higher risk for acquisition than the younger population), and immunosuppression.62 Proton pump inhibitors (PPIs) have also been identified as a potential risk factor (particularly in recurrent infections), although this association is controversial.64 There is accumulating evidence to support a modest increased risk of CDI associated with PPIs, including data showing a dose response effect.65 Other groups at risk for CDI include peripartum women and those in contact with individuals colonised with C. difficile.61 Interestingly, a recent European survey identified older age and prior use of clindamycin and immunosuppressive agents as a risk factor for ribotype 017 and older age and fluoroquinolone use with ribotype 027,66 012, 017 and 046 in Sweden.67 A recent study identified factors associated with colonisation as: prior hospitalisation, chemotherapy, use of H2 blockers and antibodies against toxin B.68 It should be emphasised that available risk factor data largely pertain to healthcare associated CDI; as discussed above, community associated cases may have different aetiologies.

Diagnosis and C. difficile transmission Many alternative laboratory testing techniques are in use although there is an increasing recognition of the strengths and weaknesses of the different options.69,70 The performance of different tests varies widely, crucially in terms of positive predictive value which is affected by disease prevalence. Put simply, positive results are more likely to

A.M. Jones et al. represent true positives in outbreak/high CDI rate settings; the converse means that test results, especially from many toxin detection kits, are less reliable when CDI is relatively uncommon e.g. in community patients. In most countries, detection of C. difficile toxins by immunoassay has been the preferred method.71 In the UK, new guidelines have recently been published on diagnosis based on the largest diagnostic study ever conducted and provide an algorithm for the management of patients (Fig. 2).72 These guidelines recommend a combination of two tests, the first of which should be a nucleic acid amplification test (NAAT) or a glutamate dehydrogenase (GDH) enzyme immunoassay (EIA) followed by a sensitive toxin EIA test. The report also reiterates69,70,73 that C. difficile toxin EIAs are not suitable as stand alone tests for the detection of C. difficile or diagnosis of CDI. Using the two-test approach allows the detection of patients, although with symptoms not apparently due to CDI, who could be excreting C. difficile. Such ‘potential C. difficile excretors’ could represent a source of transmission to other patients, especially in healthcare settings. Use of either GDH or NAAT testing alone is poorly predictive of CDI (positive predictive values of 42.7e54%).74 Importantly, detection of toxin in faecal samples correlates with outcome; thus, the presence of toxin is significantly associated with increased mortality, whereas the detection of toxigenic C. difficile (but no toxin) is not associated with outcomes worse than those for patients with diarrhoea but negative for toxigenic C. difficile.75 Typing and enhanced DNA fingerprinting may useful to confirm or refute true CDI case clusters.76 New data on transmission of C. difficile have recently been published.77 Over a 2.5 year period, 1276 isolates were studied, representing all C. difficile-positive stools received by the Oxford-Radcliffe hospitals NHS trust. These clustered into 69 STs. Multi-locus sequencing tests (MLST) showed that no more than 25% of cases could be linked to a wardbased inpatient source. The majority (65%) of putative transmissions occurred shortly (1 week) after the onset of symptoms with only 8% occurring after 8 weeks or more. Incubation periods ranged from 4 weeks (61%) to >12 weeks (13%). The authors conclude that the high number of unlinked cases in the series is suggestive of transmission from asymptomatic carriers. Such possibilities emphasise that patients with diarrhoea, even if subsequently shown not to be due to CDI, should still be considered as having increased infection control risk.

Costs The incidence, mortality, and medical care costs of CDIs have reached historic highs. Recent excess health-care costs of hospital-onset CDI in USA are estimated to be $5042e$7179 per case with a national annual estimate (limited to the subset of hospital-onset CDIs only) of $897 million to $1.3 billion.78 C. difficile infection is indeed costly, not only to third-party payers and the hospital, but to society as well. An economic computer simulation model suggested that the annual US economic burden of CDI would be $496 million (hospital perspective), $547 million (third-party payer perspective) and $796 million (societal perspective).79

Clostridium difficile

121

Figure 2

UK algorithm for the diagnosis of CDI. Reproduced from Ref.72

The economic costs of CDI also represent a significant burden on healthcare systems in Europe. These costs are also likely to increase as the population ages. The European Centre for Disease Protection and Control (ECDC) has estimated the costs as V5.000e15.000 per case in England and $1.1 billion per year in the USA.80 Assuming the population of the European Union to be 500 million, CDI can be estimated to potentially cost the EU V3000 million per annum. This figure is expected to almost double over the next four decades. In a recent systematic review of the clinical and economic burden of CDI in the EU, the incremental costs

of CDI ranged from £4577 in Ireland, £6986 in the UK and £8843 in Germany (standardised to 2010 prices), although the number of studies with economic data in the literature was very limited.81 These costs may also be an underestimate of the burden of CDI as not all studies included the costs of testing or staffing in their calculations. In terms of outcomes, 30-day mortality was the outcome most frequently reported. Data from 31 primary articles from 10 EU countries were reviewed. Weighted average 30-day mortality ranged from 3% in France to 30% in the UK. These differences may reflect differences in risk and comorbidities in the patient groups reported in the literature,

122 rather than a wide variation at country level in terms of outcome. This hypothesis is supported by the heterogeneity of the data in terms of methods and reporting. Fourteen studies included in the review included data on recurrence, which ranged from w3 to 4% in Germany and Switzerland to 36% in Ireland. Length of stay data was included in 16 primary papers from 9 EU countries and ranged from a median of 7.8 days in Belgium to 37 days in the UK. Hospital readmission and healthcare-associated infections are common healthcare problems with important clinical and financial implications for both patients and hospitals. An analysis at an academic, tertiary care referral centre of 8 years of hospital admissions, suggested that there was a significant association between patients with a clinical culture positive for 1 of 3 prevalent nosocomial pathogens (MRSA, VRE and C. difficile) obtained more than 48 h after hospital admission and hospital readmission.82 A hazard of 1.35 (95% CI, 1.26e1.45) was found for patients with positive cultures of C. difficile.

Management Principal recommendations to prevent CDI include improving antibiotic use, early and reliable detection of CDI, isolation of symptomatic patients, and reducing C. difficile contamination of health-care environmental surfaces.47 C. difficile is not susceptible to cephalosporins and the outbreak ribotype 027 strains are quinolone resistant, highlighting the need to restrict the widespread and wholesale use of these classes in an endemic setting of C. difficile disease.83,84 The European guidelines recommend oral metronidazole (500 mg tid) for 10 days for nonsevere CDI and oral vancomycin (125 mg qid) for 10 days for severe CDI.60 Where oral therapy is not possible, the recommendations are for metronidazole 500 mg tid intravenously for 10 days for non-severe CDI and for severe infections metronidazole 500 mg intravenously for 10 days plus intracolonic vancomycin 500 mg in 100 mL of normal saline every 4e12 h and/or vancomycin 500 mg qid by nasogastric tube. For the treatment of the second or further recurrence, the guidelines recommend vancomycin 125 mg qid orally for a minimum of 10 days or tapered dosing or, where oral therapy is not possible, metronidazole 500 mg tid intravenously for 10e14 days plus retention enema of vancomycin 500 mg in 100 mL of normal saline every 4e12 h and/or vancomycin qid by nasogastric tube. In a recently published systematic review of the comparative effectiveness of CDI treatments, the three studies directly comparing vancomycin and metronidazole failed to show a significant difference between the two treatments.85 Cure rates with vancomycin ranged from 84% to 94% and those with metronidazole 73%e94%. However, one of the studies had a pre-defined subgroup analysis of CDI cases according to disease severity.86 Zar et al. stratified 172 patients into mild and severe disease groups according to a severity assessment score that was specifically developed for the study. Among patients with mild CDI, treatment with metronidazole or vancomycin resulted in clinical cure in 90% and 98% of the patients, respectively (p Z 0.36). However, in patients with severe CDI, treatment with metronidazole or vancomycin resulted

A.M. Jones et al. in clinical cure in 76% and 97% of the patients, respectively (p Z 0.02). In addition to metronidazole and vancomycin, the systematic review also included one of the registrations study for fidaxomicin.87 Fidaxomicin was recently approved for the treatment of C. difficile infection. It inhibits transcription by bacterial RNA polymerase and is minimally absorbed from the intestinal tract after oral administration.88 Subsequently, plasma concentrations are low for fidaxomicin but faecal levels are usually >5000 times the minimum inhibitory concentration for C. difficile.89 In the North American registration study the rates of clinical cure with fidaxomicin were non-inferior 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).87 However, fewer patients treated with fidaxomicin experienced a recurrence in both the modified intention-to-treat analysis (15.4% vs. 25.3%, p Z 0.005) and the per-protocol analysis (13.3% vs. 24.0%, p Z 0.004). The results from this study were repeated in a second study, which included centres in Europe, and was published in 2012.90 In this second study cure rates for vancomycin and fidaxomicin were 90.6% and 91.7% in the per-protocol population, respectively. Subjects in this study also had a significantly lower rate of recurrence (12.7% vs. 26.9%; p Z 0.0002) and a higher rate of sustained response (76.6% vs. 63.4%; p Z 0.001) in the fidaxomicin arm. Louie et al. suggested that preservation of the microflora by fidaxomicin is associated with a lower likelihood of CDI recurrence.91 These studies confirm that fidaxomicin could be an alternative to vancomycin for the treatment of CDI. Interestingly, the clinical cure rate of patients infected with the epidemic PCR ribotype 027 C. difficile strain is lower than the cure rate of those infected with non-BI strains whether treated with fidaxomicin or vancomycin.92 Other agents with clinical trial data include rifaximin,93,94 rifaximin and tigecycline in recurrent CDI,95 faecal transplantation,86,96e98 and the use of synbiotics and probiotics,99,100 a daptomycin derivative (CB 183, 315) that has completed phase 2 studies,101 case reports of vaccination with Toxoid B,102 and phase II studies of monoclonal antibodies.103 To date the data for these therapies remains inconclusive though faeces transplantation has gained more interest and is investigated in a prospective controlled trial.104,105 Case reports have suggested that tigecycline may be successful for treatment of severe or severe complicated CDI, when prior therapy has failed.95,106,107 Moreover, antibiotic susceptibility, gut model and clinical trial data suggest that tigecycline is associated with a relatively low risk of CDI.108

More information needed Despite many of the recent advances in the understanding of CDI, there remain a number of areas where further study is needed. Considerable progress has been made on studies of the human microbiome associated with various disease entities, including CDI. However, a better understanding of the protective role of the human microbiome could be translated into therapeutic options to restore the intestinal defence against CDI. The precise role of toxins and other

Clostridium difficile microbe and host factors in hypervirulence18,22 is also largely unknown. It remains unclear whether C. difficile reservoirs in children or animals are a contributory factor in humans.58,109 Other areas where further research are needed are in asymptomatic carriage and whether this is protective against recurrent infection,55,57,110 and the relative contributions of mixed infection, relapse and reinfection to recurrent CDI.111e113 As knowledge about the clonality and genetic makeup of C. difficile increases, it is also becoming clear that emergent ribotypes need to be monitored prospectively.45,114 As stated by other investigators, in addition to national surveillance, there is a need for a central European database with the capability to characterise and report emerging types and distribution patterns.67 Recently, the European Centre for Disease Prevention and Control (ECDC) initiated a “Supporting capacity building for surveillance of Clostridium difficile infections at European level” which should stimulate development of a European wide standardised surveillance to CDI (tenders: Dr. Ed Kuijper and Prof. Mark Wilcox). http://www.ecdisnet.eu/. Attempts are underway to use whole genome sequencing (WGS) to track transmission115 and for the development of new and more standardised typing methods for C. difficile, for example by comparing the number of single nucleotide polymorphisms. Similarly, WGS can contribute to recognition of specific diagnostic markers for certain C. difficile types, as has been found for Types 027 and 078.10 Additionally, comparative proteomic analysis of pathogenic C. difficile strains can lead to a deeper understanding of its virulence, physiology and metabolism under varying stresses.

123 In Europe, the European Centre for Disease Prevention and Control (ECDC) estimated that more than 4 million patients are affected by HCAIs each year, with some patients having multiple and complex infections.116 Healthcare associated infections have an enormous societal and personal impact; prolonging the length of hospital stay, increasing long term disability and mortality, increasing resistance to antimicrobials and placing a massive financial burden on healthcare systems. In Europe, HCAIs cause 16 million extra days of hospital stay, 37,000 attributable deaths and contribute to an additional 110,000 per annum. Globally, five infections (central line associated bloodstream infections, catheter-associated urinary tract infections, surgical site infections, CDI and healthcare associated pneumonia) account for 85% of HCAIs in the industrialised world.117 As part of the “Improving Patient Safety in Europe” initiative, surveillance of these infections is now a requirement by the European Commission (decision 2119/98/), although as discussed earlier, reporting of HCAIs (including CDI) is neither mandatory nor standardised across all European countries. Over the last decade, data from the European Antimicrobial Resistance Surveillance (EARSS) Network has reported a decline in a number of European countries in the total annual number of MRSA bacteraemias118 and a number of European countries have also reported a decline in CDIs.32,42 Data from England and Wales also shows a decline in these infections since the implementation of mandatory reporting and other infection control measures (Fig. 3).119 However, CDI is 12e14 times more common than MRSA bacteraemia, and probably

Figure 3 England and Wales: MRSA bacteraemias and CDI (2007e2010). Source HPA data: http://www.hpa.org.uk/Topics/ InfectiousDiseases/.

124 accounts for the high level of litigation relating to CDI. Developing good quality surveillance will facilitate an increased understanding of HAIs, including trends and potential areas for improvement from within the diverse and complex systems operating in Europe.

Transparency declaration AJ works as an independent scientific consultant to a number of bodies and pharmaceutical companies including the British Society for Antimicrobial Chemotherapy, International Society for Chemotherapy, Becton Dickinson (Diagnostics), Novartis (Anti-Infectives), Astellas (AntiInfectives), Smith & Nephew (Wound Care), Wyeth and Pfizer (Anti-Infectives and Vaccines).

Funding This manuscript was commissioned by Astellas Pharma Europe Ltd, providing editorial and financial support.

Acknowledgements EK, AJ and MW do not have any conflict of interest to declare. The authors confirm that they have complied with the ICMJE guidelines and have contributed equally to the review.

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