Tetanus in patients with chronic wounds – are we aware?

Abstract

The incidence of tetanus in patients with wounds is unknown; however, recently concern has been raised over the proportion of tetanus cases in which a chronic wound is the portal of entry for Clostridium tetani. Varicose ulcers, dermatosis and necrosed tumours are estimated to be the point of entry for C. tetani spores in 11–14% of three cases. Of diabetic patients in the USA who contracted tetanus, a diabetic foot ulcer was responsible in 25% of cases despite this chronic wounds have yet to be considered as a risk factor for tetanus. An audit was undertaken and a survey devised to form the basis of the data collection to assess if patients with chronic wounds are up‐to‐date in accordance with the tetanus immunisation programme. Over a 5‐day period, the data were prospectively collected and the tetanus status of a 100 patients retrospectively analysed. The status was then compared with general practitioner (GP) records via telephone follow‐up. One hundred patients (n = 100) were available in the audit period, with the majority being male (n = 51). The age range was 22–91 years old (median 70 years). Nearly half of the samples (n = 48) were diabetic, with the majority of patients (n = 35) having venous leg ulcers. Only 15% had a biopsy of their wound. The duration of wounds varied from 1 to 480 months. Patients were asked to confirm their tetanus status. Almost half of the patients were unsure of their tetanus status 48% (n = 48), almost a third 30% (n = 30) thought they were not covered and 22% (n = 22) thought they were up‐to‐date. After confirming with the GP records, the results were as follows: almost half of the patients, 43% (n = 43) were not covered, 33% (n = 33) were up‐to‐date, 13% had no immunisation records available at the GPs, 10% had no GP contact details and 1% no contact was possible. Currently, tetanus prophylaxis is given based on the vaccination history of the patient but as identified that this can prove to be unreliable. With the burden of chronic wound and ageing population set to increase, levels of protection amplify the risk of tetanus faced by those suffering from chronic wounds. Strict caution should be taken in those patients who were born before the national childhood vaccination programme, implemented in 1961. Moreover, every effort should be made to ensure that such individuals complete their primary course. By ensuring each patient is actively immunised, protection against tetanus, a potential killer, is provided.

INTRODUCTION

Tetanus is a preventable and potentially fatal, muscle‐spasm disease caused by a motile, spore forming, Gram‐positive bacillus, Clostridium tetani. It is a ubiquitous organism although mostly found in the soil, it has been isolated from animal and human faeces. Acute injuries are the most frequent source of infection. Injuries that have a high risk for tetanus include needle injuries, lacerations, abrasions, avulsions, frostbite, burns and contaminated secretions (1). Among the non acute aetiologies of tetanus are chronic wounds, drug abuse and diabetic complications (2).

Epidemiology and immunisation

Global levels of this potentially fatal disease have remained high, with WHO 2004 figures estimating that the disease has caused 251, 000 deaths (3) (Figure 1). Infection does not confer immunity and vaccination is the only definite means of prevention. Since the introduction of the vaccination programme in 1961, there has been a dramatic decline in the number of reported cases of tetanus in western countries (4). Vaccinations start at the age of 2 months, with three injections performed at monthly intervals. A booster is given before the age of 5 years to prolong immunity, despite which immunity is not lifelong (5). Revaccination is recommended every 10 years in the USA. In the UK, only two boosters are recommended at adulthood; hence, the vaccinations do not extend beyond the third decade. The UK and USA serological surveys have shown an increasing number of people losing immunity over time; 49% to 66% over the age of 60 years had antibody levels below the protective levels (5).

Figure 1.

Depicting the overall burden of annual reported tetanus cases and immunisation (DTP3) coverage, as per WHO 2010 database (3).

It is now estimated that the UK along with most western countries, have an annual incidence of 0·2 cases per million. However, this triples to 0·66 cases per million in some groups of the population, namely older (>60 years) individuals. Although the incidence is now relatively low, the mortality rate in the over 1960s remains above 50% (5).

A necrotic and infected wound forms an ideal environment for this obligate anaerobe, which secretes two toxins – tetanolysin and tetanospasmin. The former causes local tissue damage and the latter leads to the classical neuromuscular features of generalised tetanus. The route of entry for the spores has long been recognised as the acute and contaminated wound and thus immunisation has become an integral part of accident & emergency (A&E) tetanus prevention. However, despite growing evidence of chronic wounds being an entry point for the spores 6, 7, 8, they are yet to be recognised as a risk factor. Varicose ulcers, dermatosis and necrosed tumours are estimated to be the point of entry in 11–14% of cases (9).

Of diabetic patients in the USA who contracted tetanus, a diabetic foot ulcer was responsible in 25% of cases (7).

Some 200 000 patients in the UK have chronic wounds, with more than 65% prevalence among elderly (aged >65 years) and diabetics (10). With the US census bureau predicting an increase in the elderly and diabetic populations, the overall wound burden is bound to exponentially increase.

As alluded to, any wound is a potential entry site for tetanus infection and chronic wounds pose a higher risk. Diagnostic dilemmas among many chronic wounds necessitate one or more biopsies during the course of their management. A recent case report of 67‐year‐old man developing severe life‐threatening tetanus following biopsy of a chronic wound (11), in conjunction with the increasing rate of incidences in tetanus of the elderly raises a concern of tetanus epidemic among this group.

METHODS

An audit was undertaken and a survey devised to form the basis of the data collection. Over a 5‐day period in May 2010, the data were prospectively collected from patients attending the wound healing clinics, at University Hospital Wales in Cardiff, Cardiff Royal Infirmary and the Royal Gwent Hospital, Newport. The tetanus status of 100 patients was then retrospectively analysed. The locally collected data were compared with current guidelines to identify what action is required to improve practice (Figure 2).

Figure 2.

Description of the audit cycle.

Outcome measures

Patients were asked to define themselves as: ‘up‐to‐date’, ‘not covered’ or ‘unsure’. ‘Up‐to‐date’ is based on the health protection agency guidelines that a full five‐dose course offers lifelong protection (Table 1).

Table 1.

Health protection agency guidelines (9)

Schedule	Children	Adults
Primary course	Three doses of vaccine (usually as DTaP) at 2–4 months of age	Three doses of vaccine (as Td) each 1 month apart
Fourth dose	At least 3 years after the primary course, usually preschool entry (as DTaP)	10 years after primary course (as Td)
Fifth dose	Aged 13–18 years before leaving school (as Td/IPV)	10 years after fourth dose

DTaP, Diphtheria/tetanus/acellular pertussiss; Td/IPV, tetanus diphtheria/inactivated polio vaccine.

For the purpose of this audit, we have defined ‘up‐to‐date’ as having received a booster within the last 10 years (thus covering individuals that had not completed the primary course) in adherence with the national immunisation programme.

Data were then input into Microsoft Excel 2004 and an auditor chosen random proportion of 20% was checked against patients' outpatients nurse notes to check for any input error.

A telephone follow‐up contacting all the patients' GPs was conducted to validate each patient's tetanus status against their GP immunisation records (Table 2).

Table 2.

Criteria for tetanus protection for GP follow‐up

Tetanus status	Outcome measure
Up‐to‐date	Completion of full five doses in childhood or received a booster in the last 10 years
Not covered	Not completed the primary course of five doses of tetanus vaccine or has not had a booster in the last 10 years
No record	GPs had no documentation of the patient's status
No GP contact records	There were no GP contact details for the patient in question on our hospital records
Unable to contact	Could not get hold of the GP in question to obtain the records needed

The mainstay of the analysis was to compare and assess the rate of fully immunised patients attending the clinic. Where the patient was ‘unsure’ or ‘not covered’ we made telephone contact with their GP practices, where possible, to confirm their status.

Following completion of this study, in accordance with the clinical audit cycle, the data will be recollected and analysed to assess if the improvements have been made. For the purpose of this clinical audit, no ethical approval was required as the care of the patients have not altered as a result of this study. Along with the above mentioned, other variables of such as incidence of diabetes were collected.

RESULTS

One hundred patients were available in the audit period: 51 of whom were male (median 70 years) and 49 female (median 75 years). The age range was 22–91 years old (median 70 years). Among all of them, only 15 previously had a biopsy of their wound. The duration of wounds varied from 1 to 480 months.

Tetanus status

Almost half of the patients were unsure of their tetanus status 48% (n = 48), a third 30% (n = 30) thought they were not covered and 22% (n = 22) thought they were up‐to‐date (Figure 3).

Figure 3.

Depicting awareness among patient of their tetanus status. Nearly half of the patients were unaware of their tetanus status with a third of them not up‐to‐date.

Tetanus status as confirmed by the GP

After confirming with GP records, the results were as follows: almost half of the patients, 43% (n = 43) were not covered, 33% (n = 33) were up‐to‐date, 13% had no immunisation records available at the GPs and no GP contact details could be found for one patient. The number of ‘up‐to‐date’ patients have increased by 11% when compared with the above patient tetanus status awareness group.

For the patients who were ‘unsure’ or ‘not covered’, we made telephone contact with their GP practices. This was not possible with 10 of the patients because of lack of contact details through incomplete hospital records, and with another 13 no immunisation records were found (Figure 4).

Figure 4.

Depicting patient tetanus status as in the GP records. More than a third of patents were not covered with up‐to‐date immunisation, with 12% having no GP records of their status.

Diabetes in the group

Diabetes was a factor in a high proportion of the patients as shown in Figure 5.

Figure 5.

Of the diabetic status, nearly half (48%) of the patients were diabetic with 14% having type 1 and 52% having type 2 diabetes.

Nearly half (48%) of this study group were diabetic patients. Of those who suffered with diabetes, majority (52%) had type 2 diabetes and 14% had type 1 diabetes.

Wound aetiologies

The majority of wounds (N=36), were venous leg ulcers, with mixed or arterial aetiology accounted for (N=6) and (N=8), respectively. Among the 48 diabetic patients, 22 had neuropathic diabetic foot ulcers, 10 had venous leg ulcers, 5 had arterial ulcers and the remaining 11 had causes ranging from surgery to trauma. As noted from the locations almost 55 of these wounds were present in the leg with 29 of the ulcers involving the foot (Figure 6).

Figure 6.

Depicting the different aetiologies of wounds. Large majority was venous leg and diabetic foot ulcers. Arterial and mixed leg ulcers together accounted for 14%.

DISCUSSION

The average age of the patients in this study was 70, and although data on the tetanus coverage of this age group are sparse (12), it is this subgroup of the population that accounts for 75% of deaths from tetanus as showed by an American study 13, 14. This pattern is reflected in other western countries that have long‐established immunisation programmes and is explained not only by the year of programme implementation but also zero‐epidemiologic data showing decreased immunity in the elderly (15).

The research has shown that through measuring the concentration of immunoglobulin G antibodies against C. tetani that 47% of patients may not have levels of immunoglobulin sufficient to provide protection despite the completion of a full course of vaccinations. This increases dramatically to 70% in those patients over the age of 80 (16). Bearing the above in mind, with already decreased protection, elderly patients are also at a higher risk of developing chronic wounds with the prevalence doubling to 2% in patients over the age of 80 17, 18. Alongside this, a considerable number of elderly have tetanus antibody levels below the protective threshold; 53% of those aged 60 years and older are protected against tetanus, compared with 80% in 35–39 years old (19). The mean age of the patients in the audit was 70 years old. This age group is facing the utmost risk from tetanus and should be treated as a high‐risk population.

Currently, tetanus prophylaxis is given based on the vaccination history of the patient but it has been identified that this can prove to be unreliable 20, 21. Our study discovered that around half (48%) of patients are unsure and only as many as a third (33%) of patients with chronic wounds are up‐to‐date with their vaccination. This is in keeping with other studies that have estimated that when questioned 57% of patients will not correctly know their tetanus status (22). The recent findings have showed that although covered on paper their immunity may be lacking through a decline in postvaccination antibody concentration (23), which has been found to be particularly true in the elderly (>65) and female patients 20, 23. As a result, vaccination history may not always be the best method of assessing immunity.

However, ignorance of tetanus status was not isolated to the lay population; 13% of the GPs contacted had no record of their patients' tetanus status. The reliance on accurate GP records is therefore a limitation of this study. However, incomplete medical records are not a new problem and certainly not confined to vaccination records. Health care staff should aim to rectify this but this may not be realistic to achieve (24).

The average age of the sample population is made all the more important when active childhood immunisation of the full five doses is taken into account. The administration of the full five doses is considered to be the gold standard; however, the latter was not introduced until 1961. The cohort of people born before this date, in the case of this audit (n = 89), are more likely not to have completed their primary series of immunisation.

Perhaps, future guidelines should therefore incorporate measuring the tetanus antitoxin levels of patients. This is ultimately both too time‐consuming and expensive, however, a single‐step immunoassay is currently being developed, which is set to determine the status with one drop of blood in 10 minutes; something which could perhaps being advantageous in wound healing clinics in the future (19).

As in the recent case report, it has been shown that the biopsy of a chronic ulcerated skin lesion is in fact prospective portals of entry for C. tetani (11). Wound biopsies were undertaken in 15% of the sample population of the audit. It is therefore essential that before taking any biopsies in this high‐risk population every effort should be made to ensure completion of their five‐dose tetanus. A simple vaccine could be an effective life saver.

The mean tetanus antitoxin levels have been shown to be significantly lower in patients with diabetes mellitus compared with healthy subjects implicating a greater susceptibility to tetanus infection in diabetes mellitus 25, 26. In the tetanus surveillance data between 1998 and 2000, there were 130 deaths from tetanus and 16 (12%) of them were diabetic patients 14, 26. The annual rate of developing tetanus was 0·26 cases per million (4 cases) in patients with known diabetes who were aged between 20 and 59 years and was 0·70 cases per million (12 cases) in the elderly over 60 years of age (14).

The findings of this audit would ultimately fit into the larger framework of clinical governance (27). New protocols must be created to guarantee that all patients with chronic ulcers are up‐to‐date with the immunisation programme for tetanus. Therefore, it would be of great value to include an assessment of their tetanus status into any ‘wound assessment documentation’.

Education is certainly the key. A poster has been designed for health care workers in outpatients to emphasise the importance of being up‐to‐date with vaccinations. We would suggest that the guidelines for treatment of chronic ulcers by NICE be reviewed to include an assessment of the patient's tetanus status (28).

CONCLUSION

Our audit has brought to light a distinct lack of awareness concerning tetanus among the elderly, high‐risk patient group which extends to the health care professionals. With the decline of cases of tetanus, the risk of an open wound being inoculated with spores of C. tetani has potentially been overlooked. Tetanus prophylaxis is not just an important consideration when evaluating acute traumatic wounds, but should be considered a routine protocol when managing chronic wounds.

The combination of an ageing population and the decreasing levels of protection amplify the risk of tetanus faced by those suffering from chronic wounds and thus a booster should be offered as part of routine management. The extension of tetanus prophylaxis from acute to chronic wounds should be implemented to overcome the potential deficit in protection.

It is recommended through our findings, that tetanus be taken into consideration during initial assessment of the patient. We aim to repeat this baseline audit to assess the effectiveness of the changes according to the audit cycle in 12 months time. Thus we will be able to assess the importance of vaccination. Tetanus can occur in all wounds not only the major. With no ways of detecting which wounds will give rise to infection, protection is so much better than cure (29).