Serological, molecular, and antimicrobial susceptibility surveillance of Brucella species in Egypt

Abstract Background Brucellosis, an endemic zoonotic infection in Egypt, presents a significant public health concern. This study aimed to identify Brucella isolates from animal and human samples collected from six governorates using serological, bacteriological, and molecular methods. The susceptibility of the isolates to selected antibiotics was also evaluated. Results Serological testing revealed positive brucellosis in 86.8% of human and 4.7% animal sera. 54 suspected Brucella isolates were recovered from human and animal samples. Brucella melitensis was the predominant species followed by Brucella abortus , which were molecularly confirmed using ( bcsp31 ). The isolates harbored key virulence genes of Brucella ( bvfA , virB , and ure ) and the RNA polymerase- rpoB gene. The isolates expressed overall susceptibility to standard antibiotics used to treat brucellosis, while exhibiting resistance to ceftriaxone, cefotaxime, rifampicin, tetracycline, and linezolid. Conclusions Serological testing proved to be the most practical and rapid detection method for large-scale screening in developing countries, while molecular analysis identified Brucella melitensis to be the predominant species, with the presence of key virulence genes in some isolates. Traditionally prescribed antibiotics remain effective against brucellosis; however, special care should be taken due to the emergence of resistant isolates. Tigecycline and linezolid showed that they can serve as potential alternatives in combination treatments. This study provides a broader, more comprehensive multi-governorate perspective on brucellosis in Egypt offering insights for future surveillance.