Abstract
Brucellosis is a highly contagious zoonosis that occurs worldwide. Whole-genome sequencing (WGS) has become a widely accepted molecular typing method for outbreak tracing and genomic epidemiology of brucellosis. Twenty-nine Brucella spp. (eight B. abortus biovar 1 and 21 B. melitensis biovar 3) were isolated from lymph nodes, milk, and fetal abomasal contents of infected cattle, buffaloes, sheep, and goats originating from nine districts in Egypt. The isolates were identified by microbiological methods and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Differentiation and genotyping were confirmed using multiplex PCR. Illumina MiSeq® was used to sequence the 29 Brucella isolates. Using MLST typing, ST11 and ST1 were identified among B. melitensis and B. abortus, respectively. Brucella abortus and B. melitensis isolates were divided into two main clusters (clusters 1 and 2) containing two and nine distinct genotypes by core-genome SNP analysis, respectively. The genotypes were irregularly distributed over time and space in the study area. Both Egyptian B. abortus and B. melitensis isolates proved to be genomically unique upon comparison with publicly available sequencing from strains of neighboring Mediterranean, African, and Asian countries. The antimicrobial resistance mechanism caused by mutations in rpoB, gyrA, and gyrB genes associated with rifampicin and ciprofloxacin resistance were identified. To the best of our knowledge, this is the first study investigating the epidemiology of Brucella isolates from livestock belonging to different localities in Egypt based on whole genome analysis.
Highlights
Brucellosis is one of the most widespread zoonoses of public health significance and cause of substantial economic losses in animal production systems globally [1,2]
Twenty-nine isolates were confirmed as Brucella with microbiological/biochemical methods and MALDI-TOF MS (Table S1)
Molecular characterization and genotyping of Brucella isolates from cattle, buffaloes, sheep, and goats obtained from different geographical locations in Egypt were performed
Summary
Brucellosis is one of the most widespread zoonoses of public health significance and cause of substantial economic losses in animal production systems globally [1,2]. The disease is caused by bacteria of the genus Brucella. These bacteria are intracellular, Gram-negative, non-motile, and non-spore forming coccobacilli. Twelve Brucella species are recognized with apparent host preference. Cross infections of brucellae in unusual animal hosts are reported [4,5]. Brucella melitensis is the most pathogenic species as it is most often isolated from human brucellosis cases and provokes severe disease outcomes [1]. Infection with brucellae results in reproductive disorders in domestic animals and chronic debilitating disease in humans [6]
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