Clinical, histopathological, and molecular characterization of Mycoplasma species in sheep and goats in Egypt

Abstract

Background and aim: Mycoplasma infection in small ruminants is a serious problem in sheep and goat herds around the world. It is responsible for high economic losses and decreased animal productivity. This study aimed to highlight the clinical, histopathological, minimum inhibitory concentration (MIC), and molecular characterization of Mycoplasma species in sheep and goats in Menoufiya Governorate, Egypt.

Materials and methods: A total of 234 samples were collected; 104 samples were collected from pneumonic lung tissues from the abattoir, in addition, 10 and 20 samples collected from apparently and diseased sheep, respectively, and 40 and 60 samples were collected from apparently and diseased goats, respectively, which were subjected to isolation onto pleuropneumonia-like organism medium. Polymerase chain reaction (PCR), histopathological examination, and determination of the MIC were also performed.

Results: Of 104 samples of lung tissues showing pneumonic lesions, 56 (53.84%) were positive for Mycoplasma isolation. The positive isolation of Mycoplasma from 10 and 20 samples from apparently and diseased sheep was 30% and 40%, respectively as well as the positive isolation of Mycoplasma was 17% and 56.66% out of 40 and 60 apparently healthy and diseased field goat's cases, respectively. All the diseased sheep and goats showed respiratory manifestations, including cough, bilateral nasal discharge, conjunctivitis, and systemic reaction. Evaluation of the MIC for Mycoplasma ovipneumoniae revealed that lincospectin and tylosin were the most effective antibiotics at 2.5 mg/mL. Histopathological examination of affected lung tissue showed extensive hemorrhagic pneumonia with extensive alveolar hemorrhage. The PCR technique proved to be a rapid, specific, and sensitive method for the detection of M. ovipneumoniae and Mycoplasma arginini at 390 and 326 bp, respectively.

Conclusion: M. ovipneumoniae and M. arginini were the most prevalent species associated with respiratory infections in sheep and goats in the study area. Further studies are needed to investigate the role of these species in dissemination of the disease within herds of small ruminants.

Keywords: Mycoplasma; goats; minimum inhibitory concentration; polymerase chain reaction; prevalence; sheep.

Figure-1

(a) Lamb (3 months old) showed unilateral nasal discharges and ocular discharge with depression. (b) Kid (3 months old) showed bilateral mucopurulent nasal discharges. (c) Lung tissue of a 3-year-old ram showed reddening, consolidation, and localized necrosis in different areas of the lung. (d) Fried egg colonies of mycoplasma using Stereo microscopes.

Figure-2

Lung, sheep. Mycoplasma-positive samples in acute stage of pneumonia: (a) A widespread homogenous eosinophilic inflammatory exudate inside the alveoli (thin arrow) and alveolar hemorrhage (thick arrow). Alveoli (asterisk). (b) Active alveolar macrophages (thin arrow) and alveolar hemorrhages (thick arrow) in homogenous eosinophilic inflammatory exudate inside the alveoli (asterisk). (c) Extensive hemorrhagic pneumonia (thick arrow). (d) Swelling and hydropic degeneration (arrow) and necrosis of epithelium lining of the bronchioles. H and E stain, a and c ×10; b and d ×40.

Figure-3

Lung. (a and b) Mycoplasma-positive sample in subacute of pneumonia from goat lung tissues: (a) Subacute interstitial pneumonia (asterisk). (b) High magnification from figure. (a) Active alveolar macrophages (thin arrows) and thick interalveolar septa by mononuclear cell infiltration (thick arrow) and alveolar capillary dilatation (arrowhead). (c and d) Mycoplasma-positive sample in chronic stage of pneumonia from sheep lung tissues: (C) Multifocal nodules of mononuclear cell infiltration in lung tissues (thick arrow), mononuclear cells aggregate in bold stream (thin arrow) and peribronchiolar lymphoid cell infiltration (arrowhead). (d) Desquamation of necrotic epithelial cells of the bronchioles inside its lumen (arrowhead). H and E stain, a ×10; c ×4; b and d ×40.

Figure-4

1.5% agarose gel showing PCR product of Mycoplasma species using 16S rRNA primer gene for mycoplasma at 1000 bp. M: DNA marker, lane 1: Control +ve, lane 2: Control –ve, lane 3-10: +ve samples.

Figure-5

1.5% agarose gel showing PCR product of Mycoplasma ovipneumoniae at 390 bp using (16S-23S intergenic spacer). M showing the 100 bp-1 kb DNA ladder. Lanes 2, 6, 7, and 10: Positive samples, lanes 1, 3, 4, 5, and 8: Negative samples.

Figure-6

1.5% agarose gel showing PCR product of Mycoplasma arginini using specific primer (16S-23S intergenic spacer) at 326 bp. M showing the 100 bp-1 Kb DNA ladder. Lanes 1, 4, 5, and 8: −ve M. arginine while lanes 2, 3, 6, 7, and 9: +ve M. arginine.