In order to overcome that and improve the sensitivity of the culture, reducing false-negative results, enrichment in tryptose broth supplemented with antimicrobials (Farrell’s supplement) was used before plating. Thisapproach is reported to enhance the rate of isolation of B. abortusfrom infected animals by 50% (Minharro, 2009) and has an analyt-ical sensitivity of 200 B. abortus CFUs/mL of milk (data not shown).