Lessons learned from typing Pseudomonas aeruginosa isolates from hemorrhagic pneumonia in mink using pulsed field gel electrophoresis

Hemorrhagic pneumonia is an acute and fatal disease in farm mink with outbreaks occurring almost exclusively in the autumn months in Denmark. The disease is caused by the bacterium Pseudomonas aeruginosa which is a well known pathogen in immune compromised humans. Serotyping has been the traditional method of typing P. aeruginosa isolates from mink, but in this experiment pulsed-field gel electrophoresis (PFGE) was utilized to acquire a more detailed typing of P. aeruginosa isolates from outbreaks of hemorrhagic pneumonia in Denmark from 2002 to 2011. The results indicate that outbreaks of hemorrhagic pneumonia are often caused by a local P. aeruginosa clone but that some clones or related clones now and then give rise to more than two outbreaks which can be geographically widespread. Our results show that P. aeruginosa can survive on the farm or in a contaminating source and remain virulent for mink for up to five years.