Would it be safe to have a dog in the MRI scanner before your own examination? A multicenter study to establish hygiene facts related to dogs and men.

OBJECTIVES: To determine whether it would be hygienic to evaluate dogs and humans in the same MRI scanner. METHODS: We compared the bacterial load in colony-forming units (CFU) of human-pathogenic microorganisms in specimens taken from 18 men and 30 dogs. In addition, we compared the extent of bacterial contamination of an MRI scanner shared by dogs and humans with two other MRI scanners used exclusively by humans. RESULTS: Our study shows a significantly higher bacterial load in specimens taken from men's beards compared with dogs' fur (p = 0.036). All of the men (18/18) showed high microbial counts, whereas only 23/30 dogs had high microbial counts and 7 dogs moderate microbial counts. Furthermore, human-pathogenic microorganisms were more frequently found in human beards (7/18) than in dog fur (4/30), although this difference did not reach statistical significance (p = 0.074). More microbes were found in human oral cavities than in dog oral cavities (p < 0.001). After MRI of dogs, routine scanner disinfection was undertaken and the CFU found in specimens isolated from the MRI scanning table and receiver coils showed significantly lower bacteria count compared with "human" MRI scanners (p < 0.05). CONCLUSION: Our study shows that bearded men harbour significantly higher burden of microbes and more human-pathogenic strains than dogs. As the MRI scanner used for both dogs and humans was routinely cleaned after animal scanning, there was substantially lower bacterial load compared with scanners used exclusively for humans. KEY POINTS: • Bearded men harbour significantly more microbes than dogs. • Dogs are no risk to humans if they use the same MRI. • Deficits in hospital hygiene are a relevant risk for patients.