Epidemiological studies of human and animal Salmonella - Typhimurium DT104and DT104b isolates in Ireland

A total of 122 human and animal Salmonella Typhimurium DT104 isolates and 6 epidemiologically related DT104b isolates from human and animal products w ere analysed by pulsed-held gel electrophoresis (PFGE). Genomic DNA was sub jected to macrorestriction with three enzymes, SpeI, SfiI and XbaI. A total of 14 restriction fragment length polymorphism (RFLP) profiles were identi fied when the PFGE patterns from the three enzymes were combined. The major ity of isolates (81.2 %) exhibited the same RFLP profile. Six animal DT104 isolates, susceptible to enrofloxacin and resistant to naladixic acid, were identified from the antibiotic susceptibility test. Four of these isolates had a different PFGE profile from the common RFLP. In addition, 4 of the 6 isolates were geographically clustered in one region. It was concluded tha t there was one predominant strain of S. Typhimurium DT104 in Ireland and t hat the potential and selection pressures for emergence of fluoroquinolone- resistant isolates were present.