The genus Salmonella can be subdivided into more than 2,400 serotypes. Salmonella enterica subsp. enterica
serotype Typhimurium (S. Typhimurium) and Salmonella enterica subsp. enterica serotype Enteritidis (S.
Enteritidis) are the most frequently isolated serotypes in humans in Ireland. Serotypes are further subdivided
by their resistance to bacteriophages (phage types or lystotypes), antibiotics or heavy metals; their
biochemical characteristics (biovars or biotypes) or their sensitivity to or production of bacteriocins