A complement fixation test with rabbit antisera was used to differentiate 82 cultures of Mycoplasma from man, mammalian cell cultures, laboratory rats and mice, cattle, goats, poultry, embryonated eggs and sewage.
Seventeen serotypes were distinguished, 5 from man, 1 from mammalian cell cultures, 4 from rats and mice, 4 from cattle and goats, 2 from poultry and one saprophytic. Most of these corresponded to recognized species of Mycoplasma, but 1 of human origin (represented by 1 strain, Navel), and 1 from tissue cultures (5 strains), may represent new species. R38, one of the serotypes from rats, could be distinguished from the species M. arthritidis, but is probably an antigenic variant rather than a distinct species. Two species hitherto recognized as distinct, M. arthritidis and M. hominis type 2, could not be distinguished and appear to constitute a single species. These findings illustrate the necessity, from the viewpoint of taxonomy, of comparing mycoplasma strains by serological methods.
The serotypes of human and animal origin were largely host-specific. Exceptions were the inclusion of M. arthritidis from rats and M. hominis type 2 from man in a single serotype, the finding of a bovine organism among the strains isolated from goats and of a saprophytic strain in a rat.
In relation to the aetiology of disease in man and animals, the isolation of an endogenous Mycoplasma from embryonated eggs used to passage infective material illustrates the importance of identifying these organisms serologically. The demonstration of mixed mycoplasma infections in lesions in two rats shows the necessity of adequately purifying all cultures of Mycoplasma before examination.
I would like to thank those workers mentioned in Table 1 who kindly provided the cultures which they isolated. In addition I wish to thank the following who sent cultures: Prof. A. C. Ruys and Dr D. Herderscheê (Amsterdam) for G2, Prof. H. E. Morton (Philadelphia) for Campo and 07, Dr D. G. ff. Edward (Beckenham) for Campo (PG27), M. bovigenitalium (PG11), M. iners, and M. gallinarum, Dr R. G. Wittler for H606 and Miss A. G. Newnham for A36, TU, PSU4 and TC727.
My thanks are also due to Dr L. H. Collier of this Institute, Dr G. W. Csonka (London), Prof. A. E. Macdonald (Aberdeen), Dr J. Payne (Edmonton, Alberta), Mr A. A. Tuffrey (Carshalton) and Dr D. Weisinger (Basle) who provided material from which PPLO were isolated. I gratefully acknowledge all the information so generously supplied by these workers about the strains or material provided.
I am indebted to Miss A. G. Newnham for carrying out an agglutination test on the avian strains.
Part of this work was carried out by the author under the author aegis of the Medical Research Council Working Party on Non-Specific Urethritis with the aid of a grant from the U.S. Public Health Service.