Gangrenous mastitis in dromedary camels in UAE caused by Streptococcus agalactiae

Abstract

Background: Mastitis is a disease of economic concern that affects dairy industry worldwide. This study aimed to investigate and identify possible etiologies encountered in an episode of acute gangrenous mastitis in lactating she-camels in Al Dhafra region, Abu Dhabi Emirate, United Arab Emirates (UAE). Beside the routine clinical examination, conventional bacteriological methods were used to isolate and identify possible aerobic/anaerobic bacterial or fungal pathogens from cultured milk samples collected from the mastitic she-camels. Moreover, quantitative real-time polymerase chain reaction (qPCR) was used for the detection of Mycoplasma agalactiae and Mycoplasma bovis strains, and the 16S rRNA gene was sequenced to confirm the isolation. The isolates were also tested for their susceptibility to antimicrobials. Results: Acute gangrenous mastitis is reported in the dromedary camel herd with about 80% morbidity rate among lactating she-camels exhibited acute, painful hard swelling of affected teat, quarter or entire udder. About 41.7% of the infected animals were stamped out for culling due to complete or partial amputation of udder quarters. Streptococcus agalactiae was the sole isolated organism (6 isolates). The antimicrobial susceptibility testing revealed that, the Streptococcus agalactiae isolates were sensitive to both penicillin and ampicillin. Comparison of the 16S rRNA gene sequencing results by BLASTN confirmed the presence of Streptococcus agalactiae with high confidence (100% identity). Phylogenetic analysis indicated clustering of one isolate (CMAUAE accession number; MN267805.1) with Streptococcus agalactiae that infects multi-hosts including humans, while strains (CMBUAE to CMFUAE with accession numbers; MN267806.1 to MN267810.1 respectively) clustered with Streptococcus agalactiae that infects humans. No Mycoplasma spp was detected by qPCR analysis. Conclusions: In the present study, the Streptococcus agalactiae was found to be the main cause of acute gangrenous mastitis in dromedary camels in UAE. More research should be done to investigate other possible causes of clinical or subclinical mastitis in dromedary camels in UAE.