1. Department of Microbiology, Medical School, Aristotle University of Thessaloniki, 54 006 Thessaloniki,1 and
2. Department of Microbiology, AHEPA University Hospital, 54 636 Thessaloniki,2 Greece, and
3. Antibiotic Resistance Monitoring and Reference Laboratory, Central Public Health Laboratory, London NW9 5HT, United Kingdom3