Scottish Surveillance of Healthcare Associated Infection Programme (SSHAIP)

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Clostridium difficile Infection

Mandatory Surveillance of Clostridium difficile Infection (CDI) in Scotland

CDI (formerly known as Clostridium difficile associated disease (CDAD)) is increasingly recognised as one of the most important healthcare associated infections. The term CDI has recently been introduced to reflect changes in recent international literature.1

What is the background for introducing a mandatory surveillance programme in Scotland?

CDI is increasingly recognised as one of the most important healthcare associated infections. A number of aspects classify CDI as a severe potential threat associated with receiving healthcare. The number of cases reported on a weekly basis has steadily increased in Scotland over the last 10 years. Increasing numbers of outbreaks in hospitals and other healthcare institutions have been observed in Scotland as well as the rest of the UK. Some of these outbreaks have included cases of severe disease and deaths. Mortality rates for all deaths mentioning CDI as underlying or direct cause of disease have more than doubled from 1999-2004 in England and Wales. Reports indicate that patients complicated with CDI spend 1-3 weeks longer in hospitals than control group patients. Frequent relapses of the disease are contributing to difficulties with the treatment and may cause adverse health effects. The increasing numbers of elderly is furthermore expected to increase the risk of epidemics in the future.

A mandatory surveillance system is currently being introduced in Scotland in order to detect and monitor rates of CDI in the healthcare system. The establishment of a national surveillance system is essential to control and prevent CDI in the healthcare system.

What is monitored in the mandatory Scottish CDI surveillance programme?

A case is defined as 'someone in whose stool C. difficile toxin has been identified at the same time as they have experienced diarrhoea not attributable to any other cause, or from cases whose stool has been cultured at the same time as they have been diagnosed with pseudomembranous colitis (PMC)'. In diagnostic laboratories all diarrhoeal specimens received from patients aged 65 and over are tested for toxin A and B using either an immunoassay or a cell cytotoxicity assay.

In the new mandatory surveillance programme all cases of CDI, in those aged 65 and over, who have been in contact with the healthcare system are included. In reality this means that all cases (aged 65 and over) are included in the statistics since no efficient system for distinguishing between community and healthcare acquired infections currently exists in Scotland.

A secondary purpose of the surveillance programme is to identify new emerging strains of C. difficile. CDI caused by certain strain types, in particular 027, have been associated with a more severe course of disease, higher mortality and increased transmissibility between persons. Early detection of new emerging hypervirulent strains is essential to control and prevent the spread of such clones. In the new mandatory surveillance programme, laboratories should culture for C. difficile from cases of severe CDI (including cases of PMC) and from cases in suspected outbreaks. The cultured isolates will then be compared by ribotyping in a central reference laboratory.

The full protocol for the mandatory CDI surveillance can be accessed on this website under SSHAIP Guidlines.

1Suetens C. Clostridium difficile: summary of actions in the European Union. Euro Surveill. 2008;13(31):pii=18944. Available online:

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Background Information on CDI

The microorganism

Clostridium difficile is an anaerobic, Gram-positive bacterium, which forms heat resistant spores that can survive for long periods in the environment. It is a part of the normal gut flora in a small proportion of healthy adults. However C. difficile colonisation of the large intestinal mucosa can also lead to disease. Pathogenic strains of C. difficile excrete two toxins, toxin A and toxin B, which cause diarrhoea, inflammation and injury of the mucosa of the large intestine.

Clinical description

The term ' Clostridium difficile Infection' (CDI) covers a broad spectrum of disease ranging from mild diarrhoea to severe disease, including colitis, pseudomembranous colitis (PMC) and toxic megacolon that can result in gut perforation. Furthermore, severe cases of CDI can be fatal.

Infection with C. difficile is considered a leading cause of diarrhoea in hospitals and other healthcare institutions. Treatment with broad-spectrum antibiotics or invasive surgical procedures, which disturb the normal intestinal flora, can lead to overgrowth of C. difficile, resulting in either asymptomatic colonisation or infection. Typical clinical signs of CDI include abdominal cramps, profuse diarrhoea, the passage of mucoid greenish foul-smelling watery stools, low-grade fever and leukocytosis.


C. difficile is a very robust microorganism that survives in the environment either as viable bacteria or as spores. It is transmitted via faeces (the faecal-oral route), by direct contact between patients, on the hands of healthcare workers or via contact with contaminated surfaces. Most people acquire the infection in hospitals or other healthcare institutions although infections acquired in the community are currently increasing. C. difficile spores are resistant to heat, alcohol and other disinfectants and may therefore persist for months in the hospital ward environment. It is estimated that up to 3% of healthy adults and about 20 % of hospitalised patients carry C. difficile. Both infected patients and healthy carriers are known to be sources of infection.

Trends in Scotland

Data on C. difficile infections have been collected in Scotland on a voluntary basis since 1994. From 1994-2005 the number of reports of C. difficile has increased steadily and increasing numbers of outbreaks in hospitals and other healthcare institutions have been observed. The majority of the reported cases were from patients aged 65 and over. Since the data on C. difficile infections was collected on a voluntary basis and no guidelines on testing and reporting were available until September 2006, the magnitude of the problem is unknown.

From September 2006 mandatory surveillance of CDI in the healthcare setting in Scotland will be implemented in patients aged 65 years and over.

Risk factors for CDI

In particular, elderly, immunocompromised and patients with other underlying diseases are at high risk for developing disease. There is an elevated risk of acquiring CDI after treatment with broad-spectrum antibiotics and invasive gastrointestinal surgery. Furthermore, some studies suggest that the use of gastric acid-suppressive drugs, including proton pump inhibitors and H2-antagonists, increase the risk of acquiring CDI.

Treatment of CDI

Stopping the offending antibiotic lead to spontaneous resolution of symptoms in up to 25% of patients. This approach is complicated since one cannot predict which patients will clear the infection spontaneously, and to discontinue systemic antibiotics is often not feasible.

Two antimicrobial drugs, metronidazole and vancomycin are currently used to treat CDI. Comparative studies of these two drugs have shown similar responses to treatment, however, an increasing concern over selection for vancomycin resistant bacteria in the intestinal microflora has lead authorities to recommend metronidazole over vancomycin as first line of treatment

Prevention and control

Hospitals and healthcare institutions should carefully monitor C. difficile among their patients to detect individual cases and outbreaks. Early detection of the disease followed by appropriate antibiotic treatment and infection control measures are essential to prevent outbreaks of CDI. If the disease is related to antibiotic therapy, discontinuation of the treatment or shift to another drug class may be required. Infection control measures include isolation of infected patients, thorough cleaning of the environment and equipment, improved hand hygiene and other preventive measures such as healthcare staff wearing gloves and aprons while caring for infected patients.

Recommended reading

  1. Scottish C. difficile data from the voluntary reporting system obtained in the period 1994-2005:
  2. A thorough review on epidemiology, clinical aspects and financial impact of CDAD in Europe and North America:
    Kuijper, E.J., B. Coignard, and P. Tull, Emergence of Clostridium difficile-associated disease in North America and Europe. Clin Microbiol Infect, 2006. 12 Suppl 6: p. 2-18.
  3. A review on treatment of CDAD:
    Aslam, S., R.J. Hamill, and D.M. Musher, Treatment of Clostridium difficile-associated disease: old therapies and new strategies. Lancet Infect Dis, 2005. 5(9): p. 549-57.

Scottish Antimicrobial Prescribing Group (SAPG) Recommendations

Infection Prevention and Control


A toolkit containing documents to assist with the prevention and control of CDI has been produced for use by Infection Control Teams.


HPS have created a Clostridium difficile Infection (CDI) care bundle, including associated supporting documents, that is aimed at minimising cross-transmission in wards with high prevalence of CDI.


A-Lan Banks
Project Manager
Tel: 0141 282 2923

Camilla Wiuff
Senior Epidemiologist
Tel: 0141 282 2927