- Email: [email protected]
Which specimens should be tested for Clostridium difficile toxin?
280
Letters to the Editor
available. Provisional data from 200 responses during our trial has already demonstrated that 78% of people prefer the ease of use of our product compared to present disposable alternatives and 84% thought that it was on par with the ‘gold standard’ reusable tourniquet, with an additional 15% preferring Tournistrip. From a patient perspective, 65% thought that it was more comfortable compared to reusable tourniquets, with 30% thinking it was about the same. These features, we hope, will encourage more hygienic practices.
not automatically be suitable for all situations where standard devices were previously utilized. Needle protective devices must also be introduced only after a robust education package, as even intuitive devices will require training in their use. In addition, it should always be remembered that NPDs may not be 100% effective at eliminating NSIs, despite considerable evidence that they reduce the incidence.3 In considering the efficacy of NPDs, it is important to ensure that they are evaluated for an appropriate length of time to allow sufficient numbers to be studied.
References
References 1. Ormerod JOM, Williams J, Lewis J, Dawson SJ. Risk of MRSA transmission from tourniquets. J Hosp Infect 2006;64: 300e301. 2. Fellowes C, Kerstein K, Azadian BS. MRSA on tourniquets and keyboards. J Hosp Infect 2006;64:86e88.
C. Fellowes* R. Kerstein B. Azadian Department of Microbiology, Chelsea and Westminster Hospital, London, UK E-mail address: [email protected] Available online 2 February 2007 * Corresponding author. Address: Department of Microbiology, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK. Tel.: þ44 208 846 7259; fax: þ44 208 846 7260.
1. Cullen BL, Genasi F, Symington I, et al. Potential for reported needlestick injury prevention among healthcare workers through safety device usage and improvement guideline adherence: expert panel assessment. J Hosp Infect 2006; 63:445e451. 2. Adams D, Elliott TSJ. Impact of safety needle devices on occupationally acquired needlestick injuries: a four year prospective study. J Hosp Infect 2006;64:50e55. 3. Tuma S, Sepkowitz KA. Efficacy of safety-engineered device implementation in the prevention of percutaneous injuries: a review of published studies. Clin Infect Dis 2006;42: 1159e1170.
D. Adams* T.S.J. Elliott Microbiology Research and Development Group, University Hospital Birmingham, NHS Foundation Trust, The Queen Elizabeth Hospital, Edgbaston, Birmingham, UK E-mail address: [email protected] Available online 2 February 2007
ª 2007 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2006.12.001
Needle protective devices
Madam, It was with great interest that we read the article by Cullen et al. regarding the prevention of needlestick injuries (NSIs) in healthcare workers.1 Following our recent four year evaluation of a safety needle device (SafetyGlide; BD, UK) we agree with the recommendations regarding the introduction of needle protective devices (NPDs) into the healthcare setting.2 However, we would add that the selection of any NPD for clinical areas must involve the end-users. This is because NPDs may
* Corresponding author. Address: Clinical Microbiology, University Hospital Birmingham, NHS Foundation Trust, Edgbaston, Birmingham B15 2TH, UK. Tel.: þ44 1214721311x3451; fax: þ44 121 414 1682. ª 2006 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2006.11.008
Which specimens should be tested for Clostridium difficile toxin?
Madam, The national C. difficile surveillance scheme requires that all diarrhoeal stools from patients aged 65 years or more are tested for C. difficile
Letters to the Editor toxin (CDT) unless the patient has been captured as a case within the previous 28 days. It also requires that non-diarrhoeal stools are not tested. The resulting laboratory-derived dataset is thought to be reasonably representative of clinical C. difficileassociated disease (CDAD) in the elderly, although it will miss cases diagnosed in other ways (for instance by sigmoidoscopy or histology), and it will include CDT-positive patients whose diarrhoea has an alternative cause. Data from the first two years of the scheme are now in the public domain.1,2 For the purposes of the surveillance scheme, a diarrhoeal specimen is defined as one that is soft enough to take up the shape of its container. During consultation on the draft of the recommendations that eventually informed the scheme, some respondents felt that this was too restrictive (arguing for instance that the consistency of stools can vary during the illness, or that testing shortly after clinical recovery might still be useful), while others felt it was too inclusive (and for instance that testing should be restricted to liquid samples only).3 Anecdotally it remains controversial. We sought to address this question in Sunderland, where we test samples for toxins A and B using a commercially available enzyme-linked immunosorbent assay method. Over a four-month period, tested samples were assessed visually and distinguished as either liquid or soft (meaning diarrhoeal according to the definition above, but not liquid). For some samples assessment was impossible (for instance because they were too small), and for some the assessment was missed; these unclassified specimens are assumed to be randomly distributed. The clinical significance of positive toxin tests was prospectively assessed by a medical microbiologist. Positive tests were classed as significant (making a clear diagnosis of CDAD and incurring some form of active management), not significant (no further symptoms since the specimen was taken, or a clear alternative diagnosis), or of unknown significance (no information available). During the study period, 976 clinical specimens were booked into our laboratory for CDT testing. Some of these were not requested by the clinician but were tested because they were diarrhoeal and from patients aged 65 years or over. Of those that were requested, 58 were not processed: six were leaking, three were unlabelled, one was from a patient with an alternative diagnosis that was felt to obviate CDT testing, three were from patients under the age of two years and 45 were not diarrhoeal. Three of the remaining 918 tested specimens have been excluded from the analysis
281 because they should not have been tested: two were non-diarrhoeal and one was from an infant. The remaining 915 tested specimens and their results were analysed. These were from patients with a mean age of 70.6 years (range: 4e100, 75% aged 65 years or over). In all, 419 specimens (45.8%) were liquid, 458 (50.1%) were soft, and 38 (4.1%) were not classified. Overall, 143 (15.6%) were toxin positive, and 113 of these results were assessed as being of clinical significance. Among the 419 liquid specimens, 55 (13.1%) were toxin positive, of which 43 were deemed significant. Among the 458 soft specimens, 78 (17.0%) were toxin positive, of which 62 were deemed significant. The toxin positivity and significant toxin positivity rates were not significantly different between liquid and soft specimens (P ¼ 0.106 and P ¼ 0.134 respectively). When analysis was restricted to the 689 tested specimens from patients aged 65 years or over (i.e. the population subject to surveillance), 115 (16.7%) were toxin positive and 91 of these results were assessed as clinically significant. Among the 262 liquid samples 40 (13.2%) were toxin positive (29 clinically significant), whereas among the 290 soft specimens 68 (19.0%) were toxin positive (56 clinically significant). Interestingly, in this subgroup the rates of both positive tests and of clinically significant positive tests were significantly higher for soft stools than for liquid stools (P ¼ 0.0437 and P ¼ 0.0187 respectively). This is unexplained e perhaps in the elderly the toxin is less concentrated in liquid samples, leading to a lower test sensitivity, or perhaps liquid samples are more likely to have an alternative cause. Forty-five requested tests (from 45 different patients, 31 of whom were aged 65 years or more) were refused because the sample was not diarrhoeal. None of these patients was diagnosed with CDAD during the following four weeks: one was already being treated for CDAD diagnosed a few days earlier, and three submitted repeat samples that were diarrhoeal but proved to be CDT negative. Four died, but with no suggestion that they were suffering from CDAD. In summary, in this analysis of 915 specimens tested for CDT, restricting testing to liquid samples only would have missed at least 62 (54.9%) of 113 clinically significant results, while refusing to test samples that did not take up the shape of their container did not seem to cause the diagnosis of CDAD to be delayed or missed. These data support the recommendation that CDT testing should be performed on, and only on, stools that take up the shape of their container.
282
Letters to the Editor
References 1. Results of the first year of mandatory Clostridium difficile reporting: January to December 2004. CDR Weekly 2005; 15(34). 2. Mandatory Surveillance of Healthcare Associated Infections Report, 2006. London: Health Protection Agency; July 2006. 3. National Clostridium difficile Standards Group report to the Department of Health. J Hosp Infect 2004;56(Suppl. 1):1e38.
Andrew Berrington* C.D. Settle Sunderland Royal Hospital, Sunderland, UK
E-mail address: andrew.berrington@ chs.northy.nhs.uk Available online 2 February 2007 * Corresponding author. Address: Department of Microbiology, Sunderland Royal Hospital, Kayll Road, Sunderland SR4 7TP, UK. Tel.: þ44 191 5656256; fax: þ44 191 5410531. ª 2006 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2006.12.011
Letters to the Editor
available. Provisional data from 200 responses during our trial has already demonstrated that 78% of people prefer the ease of use of our product compared to present disposable alternatives and 84% thought that it was on par with the ‘gold standard’ reusable tourniquet, with an additional 15% preferring Tournistrip. From a patient perspective, 65% thought that it was more comfortable compared to reusable tourniquets, with 30% thinking it was about the same. These features, we hope, will encourage more hygienic practices.
not automatically be suitable for all situations where standard devices were previously utilized. Needle protective devices must also be introduced only after a robust education package, as even intuitive devices will require training in their use. In addition, it should always be remembered that NPDs may not be 100% effective at eliminating NSIs, despite considerable evidence that they reduce the incidence.3 In considering the efficacy of NPDs, it is important to ensure that they are evaluated for an appropriate length of time to allow sufficient numbers to be studied.
References
References 1. Ormerod JOM, Williams J, Lewis J, Dawson SJ. Risk of MRSA transmission from tourniquets. J Hosp Infect 2006;64: 300e301. 2. Fellowes C, Kerstein K, Azadian BS. MRSA on tourniquets and keyboards. J Hosp Infect 2006;64:86e88.
C. Fellowes* R. Kerstein B. Azadian Department of Microbiology, Chelsea and Westminster Hospital, London, UK E-mail address: [email protected] Available online 2 February 2007 * Corresponding author. Address: Department of Microbiology, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK. Tel.: þ44 208 846 7259; fax: þ44 208 846 7260.
1. Cullen BL, Genasi F, Symington I, et al. Potential for reported needlestick injury prevention among healthcare workers through safety device usage and improvement guideline adherence: expert panel assessment. J Hosp Infect 2006; 63:445e451. 2. Adams D, Elliott TSJ. Impact of safety needle devices on occupationally acquired needlestick injuries: a four year prospective study. J Hosp Infect 2006;64:50e55. 3. Tuma S, Sepkowitz KA. Efficacy of safety-engineered device implementation in the prevention of percutaneous injuries: a review of published studies. Clin Infect Dis 2006;42: 1159e1170.
D. Adams* T.S.J. Elliott Microbiology Research and Development Group, University Hospital Birmingham, NHS Foundation Trust, The Queen Elizabeth Hospital, Edgbaston, Birmingham, UK E-mail address: [email protected] Available online 2 February 2007
ª 2007 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2006.12.001
Needle protective devices
Madam, It was with great interest that we read the article by Cullen et al. regarding the prevention of needlestick injuries (NSIs) in healthcare workers.1 Following our recent four year evaluation of a safety needle device (SafetyGlide; BD, UK) we agree with the recommendations regarding the introduction of needle protective devices (NPDs) into the healthcare setting.2 However, we would add that the selection of any NPD for clinical areas must involve the end-users. This is because NPDs may
* Corresponding author. Address: Clinical Microbiology, University Hospital Birmingham, NHS Foundation Trust, Edgbaston, Birmingham B15 2TH, UK. Tel.: þ44 1214721311x3451; fax: þ44 121 414 1682. ª 2006 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2006.11.008
Which specimens should be tested for Clostridium difficile toxin?
Madam, The national C. difficile surveillance scheme requires that all diarrhoeal stools from patients aged 65 years or more are tested for C. difficile
Letters to the Editor toxin (CDT) unless the patient has been captured as a case within the previous 28 days. It also requires that non-diarrhoeal stools are not tested. The resulting laboratory-derived dataset is thought to be reasonably representative of clinical C. difficileassociated disease (CDAD) in the elderly, although it will miss cases diagnosed in other ways (for instance by sigmoidoscopy or histology), and it will include CDT-positive patients whose diarrhoea has an alternative cause. Data from the first two years of the scheme are now in the public domain.1,2 For the purposes of the surveillance scheme, a diarrhoeal specimen is defined as one that is soft enough to take up the shape of its container. During consultation on the draft of the recommendations that eventually informed the scheme, some respondents felt that this was too restrictive (arguing for instance that the consistency of stools can vary during the illness, or that testing shortly after clinical recovery might still be useful), while others felt it was too inclusive (and for instance that testing should be restricted to liquid samples only).3 Anecdotally it remains controversial. We sought to address this question in Sunderland, where we test samples for toxins A and B using a commercially available enzyme-linked immunosorbent assay method. Over a four-month period, tested samples were assessed visually and distinguished as either liquid or soft (meaning diarrhoeal according to the definition above, but not liquid). For some samples assessment was impossible (for instance because they were too small), and for some the assessment was missed; these unclassified specimens are assumed to be randomly distributed. The clinical significance of positive toxin tests was prospectively assessed by a medical microbiologist. Positive tests were classed as significant (making a clear diagnosis of CDAD and incurring some form of active management), not significant (no further symptoms since the specimen was taken, or a clear alternative diagnosis), or of unknown significance (no information available). During the study period, 976 clinical specimens were booked into our laboratory for CDT testing. Some of these were not requested by the clinician but were tested because they were diarrhoeal and from patients aged 65 years or over. Of those that were requested, 58 were not processed: six were leaking, three were unlabelled, one was from a patient with an alternative diagnosis that was felt to obviate CDT testing, three were from patients under the age of two years and 45 were not diarrhoeal. Three of the remaining 918 tested specimens have been excluded from the analysis
281 because they should not have been tested: two were non-diarrhoeal and one was from an infant. The remaining 915 tested specimens and their results were analysed. These were from patients with a mean age of 70.6 years (range: 4e100, 75% aged 65 years or over). In all, 419 specimens (45.8%) were liquid, 458 (50.1%) were soft, and 38 (4.1%) were not classified. Overall, 143 (15.6%) were toxin positive, and 113 of these results were assessed as being of clinical significance. Among the 419 liquid specimens, 55 (13.1%) were toxin positive, of which 43 were deemed significant. Among the 458 soft specimens, 78 (17.0%) were toxin positive, of which 62 were deemed significant. The toxin positivity and significant toxin positivity rates were not significantly different between liquid and soft specimens (P ¼ 0.106 and P ¼ 0.134 respectively). When analysis was restricted to the 689 tested specimens from patients aged 65 years or over (i.e. the population subject to surveillance), 115 (16.7%) were toxin positive and 91 of these results were assessed as clinically significant. Among the 262 liquid samples 40 (13.2%) were toxin positive (29 clinically significant), whereas among the 290 soft specimens 68 (19.0%) were toxin positive (56 clinically significant). Interestingly, in this subgroup the rates of both positive tests and of clinically significant positive tests were significantly higher for soft stools than for liquid stools (P ¼ 0.0437 and P ¼ 0.0187 respectively). This is unexplained e perhaps in the elderly the toxin is less concentrated in liquid samples, leading to a lower test sensitivity, or perhaps liquid samples are more likely to have an alternative cause. Forty-five requested tests (from 45 different patients, 31 of whom were aged 65 years or more) were refused because the sample was not diarrhoeal. None of these patients was diagnosed with CDAD during the following four weeks: one was already being treated for CDAD diagnosed a few days earlier, and three submitted repeat samples that were diarrhoeal but proved to be CDT negative. Four died, but with no suggestion that they were suffering from CDAD. In summary, in this analysis of 915 specimens tested for CDT, restricting testing to liquid samples only would have missed at least 62 (54.9%) of 113 clinically significant results, while refusing to test samples that did not take up the shape of their container did not seem to cause the diagnosis of CDAD to be delayed or missed. These data support the recommendation that CDT testing should be performed on, and only on, stools that take up the shape of their container.
282
Letters to the Editor
References 1. Results of the first year of mandatory Clostridium difficile reporting: January to December 2004. CDR Weekly 2005; 15(34). 2. Mandatory Surveillance of Healthcare Associated Infections Report, 2006. London: Health Protection Agency; July 2006. 3. National Clostridium difficile Standards Group report to the Department of Health. J Hosp Infect 2004;56(Suppl. 1):1e38.
Andrew Berrington* C.D. Settle Sunderland Royal Hospital, Sunderland, UK
E-mail address: andrew.berrington@ chs.northy.nhs.uk Available online 2 February 2007 * Corresponding author. Address: Department of Microbiology, Sunderland Royal Hospital, Kayll Road, Sunderland SR4 7TP, UK. Tel.: þ44 191 5656256; fax: þ44 191 5410531. ª 2006 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2006.12.011