[A type strain or a neotype strain of Leptospira]

A deep review of the scientific literature concerning the history of the two oldest icterohaemorrhagiae strains is given in order to promote a decision about the legitimate neotype strain on the genus Leptospira. The strain RGA was found to meet completely the requirements for a Neotype culture given by the International Code of Nomenclature of Bacteria. Its origin from a patient with Weil's disease through guinea pig passages in 1915 is well documented and its culture is unequivocally described by Ungermann in 1916. The strain was maintained in pure culture. Since more than 60 years the strain is used for comparative investigations in classification studies in all laboratories performing such tests. At contrary the history of strain Ictero I is very incomplete. The strain was claimed by Yamamoto to be one of the strain isolated by Inada and Ido in 1915 originally designated as Yamasaki. However, the statement the maintenance of these strains because of loss of virulence was discontinued, is repeatedly mentioned in some old publications of the authors. Moreover it is reported that the strain Ictero I because of contamination with a fungus was recultivated after a passage through a splenectomized mouse, i.e. the strain was not maintained in a pure culture. Beside this it is hardly understandable why has the strain not been submitted to other laboratories before 1965. The strain Ictero I was found to contain an additional thermolabile antigen not present in RGA. At present it is impossible to decide whether this property was already present in the original culture or developed only later, eventually after its mouse passage. Summarizing all these facts, it must be stated that the strain Ictero I cannot be considered to meet all the necessary requirements of its recognition as neotype culture of the Genus Leptospira.