EU legislation
Some microbiological contaminants in certain foodstuffs are regulated by the European Commission: Commission regulation (EC) N° 2073/2005 of 15 November 2005 on microbiological criteria for foodstuffs.
More information on the EU legislation and topics including Listeria monocytogenes, Salmonella and Campylobacter can be found at the specific page of DG SANTE
Belgian legislation
The Royal Decree of 26 April 2009 on microbiological criteria for foodstuffs regulates some process hygiene criteria for certain foodstuffs.