Emerging antibiotic resistance in Salmonella Typhimurium in Norway

The antimicrobial resistance of 809 Salmonella Typhimurium isolates collect ed from humans in Norway between 1975 and 1998 was studied. The material wa s subdivided into domestic and foreign isolates according to whether the pa tient had recently travelled abroad or not. In imported isolates the larges t increase in resistance was in 1996 when 35% of the isolates were multi-re sistant. The first multi-resistant isolate acquired in Norway appeared in 1 994, but already in 1998 23% of the isolates domestically acquired were mul ti-resistant, and a majority were S. Typhimurium DT104. We found no ciprofl oxacin resistance in domestically acquired isolates. Amplified fragment len gth polymorphism analysis was performed on selected multiresistant isolates . The method discriminated well between different multi-resistant isolates, but not between DT104 isolates. Resistant and multi-resistant S. Typhimuri um were until 1998 essentially recovered from patients who had travelled ab road, but multi-resistant isolates, mainly DT104, are now also being transm itted within the country.