Multilocus sequence typing of Cronobacter spp. from powdered infant formula and milk powder production factories

This study applied the Cronobacter spp. multilocus sequence typing (MLST) scheme to three strain collections, then known as Enterobacter sakazakii, which had been isolated between 1988 and 2009 from 14 countries. The results revealed the predominance (85%) of Cronobacter sakazakii (72 strains) in all three collections. The remaining strains were Cronobacter turicensis (10%), Cronobacter malonaticus (4%), and Cronobacter muytjensii (1%). No strains of Cronobacter dublinensis, Cronobacter universalis or Cronobacter condimenti were identified. Twenty-one out of seventy-two C. sakazakii strains were in the clinically significant ST4 clonal complex, and were found in all three strain collections. These results confirm C. sakazakii ST4 is one of the predominant clonal complexes over the past 20 years in several parts of the world. Further understanding of the ecosystem and sources of the organism may be used for the development of improved intervention strategies in the diary industry.