title: Real-time PCR assays for detection of Brucella spp. and the identification of genotype ST27 in bottlenose dolphins (Tursiops truncatus).
abstract: Rapid detection of Brucella spp. in marine mammals is challenging. Microbiologic culture is used for definitive diagnosis of brucellosis, but is time consuming, has low sensitivity and can be hazardous to laboratory personnel. Serological methods can aid in diagnosis, but may not differentiate prior exposure versus current active infection and may cross-react with unrelated Gram-negative bacteria. This study reports a real-time PCR assay for the detection of Brucella spp. and application to screen clinical samples from bottlenose dolphins stranded along the coast of South Carolina, USA. The assay was found to be 100% sensitive for the Brucella strains tested, and the limit of detection was 0.27fg of genomic DNA from Brucella ceti B1/94 per PCR volume. No amplification was detected for the non-Brucella pathogens tested. Brucella DNA was detected in 31% (55/178) of clinical samples tested. These studies indicate that the real-time PCR assay is highly sensitive and specific for the detection of Brucella spp. in bottlenose dolphins. We also developed a second real-time PCR assay for rapid identification of Brucella ST27, a genotype that is associated with human zoonotic infection. Positive results were obtained for Brucella strains which had been identified as ST27 by multilocus sequence typing. No amplification was found for other Brucella strains included in this study. ST27 was identified in 33% (18/54) of Brucella spp. DNA-positive clinical samples. To our knowledge, this is the first report on the use of a real-time PCR assay for identification of Brucella genotype ST27 in marine mammals.
authors.affiliation: Hollings Marine Laboratory, National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic Atmospheric Administration, Charleston, SC 29412, USA. Electronic address: qingzhongwu@yahoo.com.
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Center for Coastal Environmental Health and Biomolecular Research, National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic and Atmospheric Administration, Charleston, SC 29412, USA.
authors.forename: Wayne E
authors.initials: WE
authors.lastname: McFee
authors.affiliation: One Health Institute, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Tracey
authors.initials: T
authors.lastname: Goldstein
authors.affiliation: Zoonoses and Select Agent Laboratory, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: Rebekah V
authors.initials: RV
authors.lastname: Tiller
authors.affiliation: Hollings Marine Laboratory, National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic Atmospheric Administration, Charleston, SC 29412, USA.
authors.forename: Lori
authors.initials: L
authors.lastname: Schwacke
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000382:microbiology; D001431:Bacteriological Techniques / Q000379:methods*; D050681:Bottle-Nosed Dolphin / Q000382:microbiology*; D002002:Brucella / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D002006:Brucellosis / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D005838:Genotype; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013022:South Carolina
keywords: Bottlenose dolphins; Brain; Brucella spp.; IS711; Lung; Real-time PCR