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[This corrects the article DOI: 10.1016/j.infpip.2019.100005.].
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Background: Trained canines are capable of detecting Clostridioides (Clostridium) difficile (CD) in the environment; however, the primary odour of interest on which the dogs alert is unclear. Aim: To evaluate the inter-rater reliability of two canine detection teams for their ability to discriminate between scent pads containing CD-toxin-positive and -negative odours and their ability to discriminate between clostridial strains. Methods: During a six-month period, two canine teams were tested weekly for their ability to detect CD-toxin-positive odours and discriminate between these and -negative odours. To further determine the canines' discrimination capability, scent pads impregnated with odours from reference isolates representing common CD toxin types (including toxin-negative CD isolates) or from clinical isolates representing other clostridial species were used. Results: A total of 264 samples were tested with an overall sensitivity of 94.7% (Team A) and 86.8% (Team B) and specificities of 96.9% and 98.7%, respectively. Inter-rater reliability was very good (Cohen's kappa 0.87). When challenged with toxin- and non-toxin-producing strains, the teams alerted on 96.3% of all CD isolate odours (including nontoxigenic strains) and 46.7% of closely related species. Conclusions: The canine teams exhibited strong inter-rater reliability on both clinical faecal specimens and reference CD isolates (both toxin and non-toxin producing) but were challenged to discriminate between CD and closely related clostridial species. These findings strongly support the development of scent detection programmes provided dogs and their handlers are properly trained and used in the right context.
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BACKGROUND AND AIM: Prompted by an article describing a dog trained to detect Clostridium difficile in patients, our institution evaluated a dog's ability to detect C. difficile scent from equipment and surfaces to assist in strategic deployment of adjunctive cleaning measures. METHODS: An expert in drug and explosives scent dog handling trained a canine to identify odours from pure cultures and/or faecal specimens positive for C. difficile. Methods used to assess explosive and drug detection dogs were adapted and included evaluation of (i) odour recognition, using containers positive and negative for the scent of C. difficile, and of (ii) search capability, on a simulation ward with hidden scents. After demonstration that the canine could accurately and reliably detect the scent of C. difficile, formal assessments of all clinical areas began. FINDINGS: Odour recognition (N = 75 containers) had a sensitivity of 100% and specificity of 97%. Search capability was 80% sensitive and 92.9% specific after removal of results from one room where dog and trainer fatigue influenced performance. Both odour recognition and search capability had an overall sensitivity of 92.3% and specificity of 95.4%. The clinical unit sweeps over a period of five months revealed a sensitivity of 100% in alerting on positive quality control hides. These clinical unit sweeps also resulted in 83 alerts during 49 sweep days. CONCLUSION: A dog can be trained to accurately and reliably detect C. difficile odour from environmental sources to guide the best deployment of adjunctive cleaning measures and can be successfully integrated into a quality infection control programme.
