Table 2

Participants with a discrepancy between laboratory results and dog response

VariablesDog responseLaboratory tests*Diarrhoea on day of detection roundComment
Inconclusive dog response:
Case 1InconclusivePositive resultYesDog appeared distracted by plastic cup on floor
Control 2InconclusiveNegative resultYesDuring this round there was a strong chlorine smell in several rooms, from disinfection, which could have influenced the dog’s response. Tests were done on participants with an inconclusive response in this round
Case 3InconclusivePositive resultYesChlorine round, see comment for control 2
Control 4InconclusiveNot doneNoCase 5 had just changed beds; the dog seemed to have difficulty choosing between two neighbouring patients (control 4 and case 5) and the third (empty) bed across the room; he sat in the middle
Case 5InconclusivePositive resultYesSee comment for control 4
Control 6InconclusiveNegative resultYesOn the ward was a patient with Clostridium difficile infection who refused to participate in the study. The dog was not allowed to enter the patient’s room; however, the dog was excited and tried to enter. When forced to move away, he immediately sat down next to control 6, who was the first participant he encountered. Because of symptoms, tests had been done. The enzyme immunoassay gave a negative result; however, stool culture showed non-toxigenic C difficile
Control 7InconclusiveNegative resultYesNo apparent explanation
False positives†:
Control 8PositiveNegative resultNoChlorine round, see comment for control 2. Enzyme immunoassay gave a negative result; however, stool culture showed non-toxigenic C difficile
Control 9PositiveNot doneNoParticipant offered the dog a cookie
Control 10PositiveNot doneNoParticipant beckoned the dog
Control 11PositiveNegative resultNoDog appeared distracted by urine on the floor from a broken catheter bag
Control 12PositiveNegative resultNoThis participant had been treated for C difficile infection, diagnosed 11 days previously. Since symptoms resolved on the day of the detection round, the patient was included as a control. However, a week after the round symptoms returned and retesting showed a relapse
False negatives‡:
Case 13NegativePositive resultYesNo clear explanation
Case 14NegativePositive resultYesThe enzyme immunoassay gave a positive result; culture was mistakenly not done

*Enzyme immunoassay+toxigenic culture.

†Participants with negative laboratory results but positive dog response.

‡Participants with negative laboratory results but positive dog response.