Isolation of Mycoplasma from bovine aborted fetuses and weak calves, with reference to histopathological findings and detection of the causative species in fresh frozen tissue sections, using immunofluorescent tests.

摘要

A total of 22 aborted cattle fetuses, 12 placentas, 5 dead calves and 8 samples of cows lochia in Egypt were subjected for Mycoplasma spp. isolation [date not given]. Tissue specimens from placentas and internal organs of aborted fetuses and dead calves (liver, lungs, kidneys, spleen and heart) as well as samples from fetal and calf abomasal content and lochia were cultured for Mycoplasma spp. Representative tissue specimens from each organ were subjected for histopathologic examination. Frozen tissue sections from positive cases were subjected for immunofluorescent test. It was shown that the most prevalent site of Mycoplasma species isolation was from lungs of calves and aborted fetuses (60.0 and 18.18%, respectively), followed by the liver (20.0 and 9.09%, respectively). While no Mycoplasma spp. were isolated from abomasal contents of calves, the recovery rate from abomasal contents of aborted fetuses was 13.64%. There was a simultaneous isolation of Mycoplasma species by conventional cultural method and detection by immunofluorescent technique (IFT) applied on sections of the frozen lung tissues of aborted fetuses and weak calves (100%). While IFT could detect Mycoplasma species in the frozen sections of liver (75.0%) of the positive aborted fetuses, only 50.0% were colonized by M. bovis. M. bovis was detected by IFT in 66.67% of the dead calves' liver, but the conventional cultural method identified only 33.33% positive results. The most prominent histopathologic lesions that were detected on the lung and liver tissues of aborted fetuses and weak calves were interstitial pneumonia, pleuritis and necrotizing hepatitis. Sections of fresh lung and liver tissues with histopathologic lesions of weak calves also had a highly positive fluorescent reaction. M. bovis antigen was detected within the cytoplasm of an alveolar macrophage, in cells located in the interalveolar septa, epithelial lining of the intercellular bronchi and on the surface of the epithelium of the bronchi, or localized at the periphery of the areas of necrosis, in necrotic exudates and between hepatocytes.