Finally, the 16S rRNA gene sequences proved to be identical for the two type strains of P. l. larvae and P. l. pulvifaciens (Kilwinski et al., 2004) and the resulting problems in the development of a PCR-test suitable for the differentiation between the pathogenic agent of American Foulbrood (P. l. larvae) and the presumably non-pathogenic close relative P. l. pulvifaciens