Pathology, bacteriology and molecular studies on caseous lymphadenitis in Camelus dromedarius in the Emirate of Abu Dhabi, UAE, 2015-2020

Abstract

Caseous lymphadenitis (CLA) or pseudotuberculosis is a chronic zoonotic bacterial disease caused by Corynebacterium pseudotuberculosis, which affects livestock and humans. This study aimed to describe the pathology, bacteriology and confirm the identity of the pathogen by 16S rRNA gene sequencing in Camelus dromedarius. A total of 12 camels with suspected CLA in three regions of Abu Dhabi Emirate (Abu Dhabi, Al Ain and Al Dhafra), United Arab Emirate (UAE) were subjected to clinical and postmortem examinations from January 2015 to December 2020. Clinically, camels were emaciated and showed the presence of external caseous abscesses suggestive of CLA. Postmortem examination showed multiple abscesses of variable sizes with caseous material encapsulated by fibrous tissue in the liver, lungs, muscle, and lymph nodes. Following clinical and postmortem examination, blood, pus and different tissue samples were collected for subsequent analysis. Histopathological examination of all organs stained with Hematoxylin and Eosin (H&E) indicated a central caseo-necrotic core that was admixed with bacterial colonies and infiltration of chronic inflammatory cells, surrounded by a pyogenic membrane, and an outer fibrous connective tissue capsule. Bacterial culture identified the isolates of Corynebacterium pseudotuberculosis biotype ovis strain, and these isolates were shown to be sensitive to all antibiotics tested (penicillin, ampicillin, Co-trimoxazole, enrofloxacin and tetracycline). Moreover, the identity of the isolates was confirmed by partial sequencing of the 16S rRNA gene which showed a 100% identity to Corynebacterium pseudotuberculosis. Phylogenetic analysis based on 16S rRNA gene sequence clearly differentiates Corynebacterium pseudotuberculosis from other species of Corynebacterium. Briefly, this study provided the basic information for infection of Corynebacterium pseudotuberculosis in Camels and will help in controlling of this pathogen in the region.

First Report of Caseous Lymphadenitis by Corynebacterium pseudotubercolosis and Pulmonary Verminosis in a Roe Deer (Capreolus capreolus Linnaeus, 1758) in Italy

“…The macroscopic lesions in the roe deer were similar to descriptions of a CL sheep, goats and camelids [1,16]. Two main forms have been described in sheep, a s ficial or cutaneous form, characterized by the involvement of externally explorable ly nodes, and a visceral form, associated with abscesses in the internal organs and ly…”

“…C. pseudotuberculosis infections have been reported in several other species, both domestic and wildlife [14][15][16][17][18]. Nevertheless, C. pseudotuberculosis in suids has rarely been described, (e.g., an infection of pigs from two different farms in Spain) [19], as most infections in wild boars and pigs are caused by C. ulcerans [4,20,21], sometimes recently classified as novel C. sylvaticum [22][23][24].…”

First study on molecular epidemiology of caseous lymphadenitis in slaughtered sheep and goats in Duhok Province, Iraq

“…CLA in small ruminants is diagnosed using a variety of techniques and methods, including clinical signs and characteristics of the lesions, isolation, and identification of the causative agent from pus discharge ( Nassar et al , 2016 ), serological methods ( Yitagesu et al , 2020 ), and PCR ( Issa et al , 2021 ; Terab et al , 2021 ) which is the most reliable, accurate, and rapid method, and it shows high resolution and repeatability in the genetic discrimination of bacterial strains ( Taha, 2022 ). Accordingly, this study aimed to estimate the prevalence rate of CLA among slaughtered sheep and goats and to determine the role of different associated risk factors such as the animals’ species, age, and sex, as well as the geographical distribution of the disease in different locations in Duhok Province, Iraq.…”