Incidence of Brucella species in marine mammals of the German North Sea

Abstract

In this study, organ samples from 426 common seals Phoca vitulina, 298 harbour porpoises Phocoena phocoena, 34 grey seals Halichoerus grypus and 10 other marine mammals were assessed for the presence of Brucella species. Forty-seven common seals, 2 harbour porpoises and 1 grey seal were found to be positive for these bacteria. A total of 91 Brucella strains were successfully isolated, due to the fact that Brucella spp. were found in more than one organ sample in 15 animals. The primary organ in which the bacteria were present was the lung. In addition, 2 strains were isolated from lungworms (Parafilaroides spp.). Forty-nine of the isolated strains were selected for further analysis using conventional phenotyping methods. Molecular characterisation was carried out by analysing the IS711 and omp2 loci. With respect to the distribution of the IS711 loci in the genome, the 49 field isolates differed strongly from the terrestrial Brucella species and marginally from the marine Brucella reference strain NCTC12890. Based on the results of the PCR restriction fragment length polymorphism (PCR-RFLP) investigation of the omp2 locus, the majority of the Brucella field isolates were classified as B. pinnipediae, recently proposed B. pinnipedialis, possessing 1 omp2a gene and 1 omp2b gene. Two field isolates revealed the presence of 2 omp2a genes, as has been described for Brucella ovis. To our knowledge, these results confirm for the first time the presence of Brucella species in the marine mammal population of the German North Sea. These findings highlight the need for additional research on the relevance of these Brucella species for marine hosts and their environment. KEY WORDS: Brucella species · Marine mammals · Phenotypic and molecular investigation · German North Sea Resale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESS Contribution to DAO Special 3: 'Marine vertebrate zoonoses'Dis Aquat Org 81: [65][66][67][68][69][70][71] 2008 marine Brucella isolates (Clavareau et al. 1998, Bricker et al. 2000, Cloeckaert et al. 2000.A further distinction of the marine Brucella species is possible when analysing the genus-specific omp2-locus. This locus consists of the 2 closely related genes omp2a and omp2b. Both share an approximated 85% DNA homology; they are separated by 900 bp and oriented in opposite directions (Ficht et al. 1989). Current data suggest the gene arrangement is conserved in all Brucella species. Therefore, distinction between the Brucella species and some of their biovars can be performed by PCR-restiction fragment length polymorphism (PCR-RFLP) analysis (Cloeckaert et al. 1995). In a further study, Cloeckaert et al. (2001) obtained data which led to a subdivision of the marine Brucella isolates into 2 groups. The strains isolated from seals and 1 otter possessed 1 omp2a and 1 omp2b gene, representing the formerly proposed species B. pinnipediae. In contrast, Brucella isolates from dolphins and porpoises possessed no omp2a but 2 omp2b genes, thus iden...

Epizootiology of Brucella Infection in Australian Fur Seals

“…However, the factors that limited culture success would not affect the ability of PCR to detect organisms if present in the tissues examined. Tissues chosen for Brucella investigation were based on those found most commonly to produce isolates in phocid seals from the Northern Hemisphere (Garner et al, 1997;Foster et al, 2002;Prenger-Berninghoff et al, 2008), and it is possible that sites of infection are different for otariid seals. Furthermore, if the proportion of animals harboring infection is low compared with those with antibodies, then the numbers of animals, tissues, swabs, and lungworms examined might have been inadequate to detect a single infected animal.…”

“…Furthermore, if the proportion of animals harboring infection is low compared with those with antibodies, then the numbers of animals, tissues, swabs, and lungworms examined might have been inadequate to detect a single infected animal. The prevalence of infected animals in other pinniped species is mostly unknown, although in one study, isolates were made from 3% (1 of 34) of the grey seals (Halichoerus grypus) and 11% (47 of 426) of the harbor seals (Prenger-Berninghoff et al, 2008).…”

“…Brucella has been isolated from the digestive tract of some pinnipeds (Prenger-Berninghoff et al, 2008). Buccal and rectal microbiologic swabs were collected from six juveniles captured at Seal Rocks in July 2010 for an ecologic study.…”

“…infections in pinnipeds are not associated with a clear pattern of pathology and the bacterium is often isolated from apparently healthy animals (Foster et al, 2002;Prenger-Berninghoff et al, 2008). Brucella spp.…”

“…Brucella spp. infections in pinnipeds appear to be most commonly associated with bronchopneumonia, potentially only acting as a secondary agent after parasitic infection (Prenger-Berninghoff et al, 2008). However, Brucella was recently suggested as a possible cause of abortion in California sea lions (Zalophus californianus; Goldstein et al, 2009).…”