ISOLATES OF SALMONELLA-ENTERICA ENTERITIDIS PT4 WITH ENHANCED HEAT AND ACID TOLERANCE ARE MORE VIRULENT IN MICE AND MORE INVASIVE IN CHICKENS

Two Enteritidis PT4 isolates which differed in inherent tolerance to h eat, acid, H2O2 and the ability to survive on surfaces were used to in fect mice, day-old chicks or laying hens. The acid-, heat-, H2O2- and surface-tolerant isolate was more virulent in mice and more invasive i n laying hens, particularly in reproductive tissue. However, no signif icant differences were observed in behaviour in chicks. Both PT4 isola tes were able to infect chicks housed in the same room as infected bir ds, although the heat-tolerant isolate survived significantly better t han the heat-sensitive one in aerosols.