'n Taksonomiese studie van gram-negatiewe, pleomorfe bakterieë soos gevind in die skedes en semen van skaapramme in die Höeveldstreek

Abstract

Actinobacillus actinomycetem comitans, A. seminis and Histophilus ovis are all Gram-negative, pleomorphic bacteria, known to cause ram epididymitis . A. seminis and H. ovis are also described as weak, or even nondisseminators of glucose . A study of the morphology of A. seminis and H. ovis revealed that the feature of pleomorphism is mainly encountered in young cultures . This disappears in older cultures . Both organisms metabolize glucose by fermentation should serum be added to the medium . In contrast older cells ferment glucose faster than young cells from the same isolate . From these findings it could be deduced that a long lag phase in the growth curve of these organisms could be a contributor towards the property of pleomorphism. As pleomorphism appears only when these organisms are cultured on an artifisial medium, temporary variation appears to be the main contributing factor towards this property . Applying the API 20 E system of classification it was impossible to distinguish between A. actinomycetem comitans , A. seminis and H. ovis . Their properties differed however radically from those of Pasteurella haemolytica . Using standard techniques on the other hand , it was possible to distinguish between A. seminis, H. ovis as well as a pleomorphic form of P . haemolytica . Based on the 0NPG- test A. actinomycetem comitans and A. seminis could be differentiated, and by means of the decarboxylation of lysine the existance of 2 possible species of H. ovis was indicated . The final differentiation between the relevant organisms was based on 10 different tests from which the sugar reactions were excluded. Sugar metabolism using different sugars was examined, but due to variable reactions, these results were excluded from the eventual identification. The number of useful tests could however not be regarded as a final proof of the suggested classification . Further investigation must be done however to prove this . Except for A. seminis other known pathogens such as A. actinomycetem comitans and H. ovis are also found in the genital system of rams in the Highveld area. No decisi-0n with regards to the pathogenicity of the pleomorphic form of P . haemolytica found, could be given