In Switzerland, there is evidence for an outbreak in 2006 as the annual incidence almost doubled. A total of 30 strains (28%) were resistant or showed intermediate resistance to one to three antimicrobials and 48 strains (45%) displayed resistance to more than three antibiotics. We found a high prevalence (67%) of nalidixic acid resistance, and 58%were resistant to ciprofloxacin. One strain was a producer of extended-spectrum 尾-lactamase (ESBL). PFGE discriminated four clusters (similarity coefficient cut off at 80%).
The resistance situation among the strains isolated from 2004 to 2009 in Switzerland is discussed and shown to coincide with findings in other European countries. Based on genetic subtyping, a so far undetected outbreak is likely to have occurred in Switzerland in 2006. Finally, our data identified travelling to Northern Africa as a risk factor for S. Kentucky infections.