1. Laboratorio di Batteriologia e Micologia Medica, Rome, Italy
2. Servizio Biologico, Istituto Superiore di Sanità, Rome, Italy
3. Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy
4. Institute of Experimental Microbiology, F. Schiller University, Jena, Germany
5. National Institute of Public Health, Prague, Czech Republic