Correlation of conversion of Salmonella enterica serovar enteritidis phage type 1, 4, or 6 to phage type 7 with loss of lipopolysaccharide.

Studies of pairs of Salmonella enterica serovar Enteritidis isolates from different poultry flocks showed that phage type (PT) 7 may be derived from PT 1, 4, and 6. The conversion appeared to be associated with loss of lipopolysaccharide. It is concluded that PT 7 may be of little value as an epidemiological marker of S. enterica serovar Enteritidis.