Antimicrobial drug resistance in isolates of Salmonella enterica from cases of salmonellosis in humans in Europe in 2000: results of international multi-centre surveillance.

The Enter-net surveillance system received results of antimicrobial sensitivity tests for isolates from over 27 000 cases of human salmonellosis in 2000 in 10 European countries. Almost 40% of isolates were resistant to at least one antimicrobial, with 18% multiresistant. Resistance to ampicillin, streptomycin, sulphonamides and tetracyclines was common, with over 20% of isolates resistant to at least one of these antimicrobials. Clinical resistance to ciprofloxacin was rare, with only 0.5% of isolates exhibiting such resistance (MIC >1.0 mg/l). Resistance to nalidixic acid coupled with a decreased susceptibility to ciprofloxacin (MIC 0.25-1.0 mg/l) was more common, with 14% of isolates showing these properties. Resistance to third-generation cephalosporins was rare with only 0.6% of isolates resistant to cefotaxime. In all countries multiple resistance was most common in Salmonella enterica serotype Typhimurium, with 51% of isolates multiresistant in total. In England and Wales multiple resistance was also prevalent in S. Virchow and S. Hadar, whereas in other countries multiple resistance was common in serotypes such as S. Blockley.