Isolation of Mycoplasma bovoculi from genitally diseased bovines and its experimental pathogenicity in pregnant guinea pigs.

Thirteen strains of M. bovoculi, 6 from frozen bull-semen (3.5% of 168), 3 from neat bull-semen (3.0% of 100), one each from heart blood and stomach contents of aborted foetus of 85 (1.18%) bovine-abortions, one each from stomach contents and pooled internal organs of 9 (11.1%) stillborn calves, were isolated. All the isolates were resistant to ampicillin and sensitive to spiramycin, vibramycin, demeclocyclin, oxytetracycline, lincomycin and tylosin. However, variation in resistance to tetracycline, erythromycin, neomycin, kanamycin and streptomycin was observed. The gross lesions like congestion of lungs, liver, kidney and spleen were noted only in stillborn calf. However, significant microscopic lesions were encountered in internal tissues of both the aborted bovine fetuses and stillborn calf. Thickened alveolar wall, congestion of blood vessels, mesenchymal cell proliferation along with infiltration of lymphocytes and macrophages were observed in lungs. The liver showed mild infiltration of lymphocytes, macrophages in hepatic triad and necrosis of hepatic cells. The kidney tissues had focal lymphocytic infiltration in the interstitium. One strain of M. bovoculi (isolate # SBC-7/84,IO) isolated from a stillborn calf was found abortigenic upon experimental inoculation in pregnant guinea pigs.

Experimental pathogenicity evaluation of Mycoplasma canadense from bovine mastitis in vitro and in vivo laboratory models.

Mycoplasma canadense, a clinical isolate from milk of a mastitic buffalo, was experimentally tested for its pathogenic potential in hamster tracheal ring and rabbit fallopian tube explant organ cultures (in vitro) and rat and rabbit mammary gland (in vivo) models. The activity percentage reduction in M. canadense infected hamster tracheal rings was 99.1% in comparison to 16.4% in control rings. Mycoplasma canadense, also induced complete ciliostasis at 11-day post-infection in rabbit fallopian tube explants. Histopathological lesions in these infected organ cultures were loss of cilia, desquamation or denudation of epithelium, infiltration of inflammatory cells and proliferation of macrophages as well as oedema in lamina propria. At the end of the experiments, M. canadense organisms were reisolated in pure colonies from the infected but not the control organ cultures. In the rat and rabbit mammary glands, M. canadense organisms persisted upto 6-day and 7-day postinfection, respectively and caused histopathological changes suggestive of subacute to chronic mastitis during the experimental period. The results indicate that the tested M. canadense clinical isolate was virulent.

Experimental mastitogenicity of Mycoplasma capricolum subsp. capripneumoniae for rabbit mammary glands.

Mycoplasma capricolum subsp. capripneumoniae of cow-udder origin was tested in rabbit mammary-glands for its mastitogenic capability. Establishment of mycoplasma organisms and presence of histopathological lesions in mammary glands were the parameters for describing mastitogenic potential. The reisolation of injected Mycoplasma capricolum subsp. capripneumoniae organisms in the pure form from the infected glands along with the occurrence of histopathological changes were suggestive of mastitis during the entire 8-days period of observation. Rabbit mammary-gland is recommended as a potential in vivo experimental laboratory model to screen the mastitogenic potential of mycoplasmas of animal-udder origin.

Experimental infection of rat (Rattus norvigus, strain Wistar) mammary gland by Mollicutes from the bovine udders.

Seven isolates of Mollicutes, Mycoplasma F-38; M. mycoides var. capri; mixed isolates of M. bovigenitalium and M. bovirhinis; M. bovigenitalium, Mycoplasma F-38 and M. bovirhinis; M. bovis, M. bovigenitalium, Mycoplasma F-38 and A. laidlawii; A. axanthum; A. laidlawii from bovine udders and a M. bovis type strain (NCTC-10131) produced significant histopathological changes characterized by infiltration of neutrophils in lumen of acini, interlobular and intralobular ducts along with the hyperplasia of lining cells of acini, interlobular and intralobular ducts and infiltration of mononuclear cells and fibroblasts in interstitium in the mammary gland of rat suggestive of mastitis. A. laidlawii and A. axanthum produced only mild changes suggestive of their negligible role in the bovine mastitis. Rat mammary gland is recommended as a suitable in vivo experimental laboratory model to screen the mastitogenic potential of Mollicutes.

Experimental pathogenicity of Mollicutes of bovine udder origin in hamster tracheal ring organ culture.

Hamster tracheal-ring organ culture was employed to examine pathogenic effects of 8 isolates of Mollicutes of bovine udder origin. The tested Mollicutes could be categorized into two groups: (i) Mycoplasma F-38, M. mycoides var. capri, M. bovigenitalium mixed with M. bovirhinis, and M. bovigenitalium mixed with M. bovirhinis and Mycoplasma F-38 produced significant ciliostatic effect and infiltration of neutrophils and lymphocytes in lamina propria/subepithelium, hyperplasia and desquamation of epithelial lining cells and loss of cilia; and (ii) A. laidlawii, A. axanthum, an unidentified Acholeplasma and a mixed isolate of M. bovis, M. bovigenitalium, Mycoplasma F-38 and A. laidlawii showed insignificant ciliostatic effects and produced mild histopathological lesions. This correlates with the disease causing potentials of the strains.

Experimental pathogenicity of mollicutes from bovines with reproductive disorders in rabbit fallopian tube organ culture.

Mollicutes (10) belonging to Mycoplasma and Acholeplasma isolated from various reproductive disorders were tested in rabbit fallopian tube (FT) organ culture. Parameter for describing pathogenic status of Mollicutes in rabbit FT organ culture included multiplication of organisms, and its effect on ciliary activity along with histopathological changes in FT explants. M. mycoides (LC, Y-Goat), M. bovoculi, M. bovigenitalium, Mycoplasma sp. and A. oculi were categorized as pathogenic; A. axanthum and A. laidlawii as mildly pathogenic; and M. bovis, M. arginini. and A. granularum, as nonpathogenic to rabbit FT organ culture. Thus, rabbit FT organ culture is recommended for use as a suitable and economical in vitro model to assess the pathogenicity of Mollicutes of reproductive tract origin.