Isolation of Histophilus somni from the nasal exudates of a clinically healthy adult goat.

METHODS: The nasal exudate from 42 goats of the Mixteca Region in the state of Puebla, Mexico, was evaluated. A strain was isolated after 4 days of incubation. This strain was identified according to its phenotypic characteristics and by means of a species-specific polymerase chain reaction (PCR), as well as by sequencing of the amplified product. RESULTS: The species-specific PCR amplified a 407-bp fragment of 16S RNAr subunit, and the product sequencing revealed 100% homology with Histophilus somni 129PT. The nucleotide sequence was deposited in the GenBank under accession number HM032735. CONCLUSION: This is the first worldwide isolation of H. somni from nasal exudates of a clinically healthy goat.

Haemophilus somnus (Histophilus somni) in bighorn sheep.

Respiratory disease and poor lamb recruitment have been identified as limiting factors for bighorn-sheep populations. Haemophilus somnus (recently reclassified as Histophilus somni) is associated with respiratory disease in American bison, domestic sheep, and cattle. It is also harbored in their reproductive tracts and has been associated with reproductive failure in domestic sheep and cattle. Therefore, reproductive tract and lung samples from bighorn sheep were evaluated for the presence of this organism. Organisms identified as H. somnus were isolated from 6 of 62 vaginal but none of 12 preputial swab samples. Antigen specific to H. somnus was detected by immunohistochemical study in 4 of 12 formalin-fixed lung tissue samples of bighorn sheep that died with evidence of pneumonia. Notably, H. somnus was found in alveolar debris in areas of inflammation. The 6 vaginal isolates and 2 H. somnus isolates previously cultured from pneumonic lungs of bighorn sheep were compared with 3 representative isolates from domestic sheep and 2 from cattle. The profiles of major outer membrane proteins and antigens for all of the isolates were predominantly similar, although differences that may be associated with the host-parasite relationship and virulence were detected. The DNA restriction fragment length profiles of the bighorn-sheep isolates had similarities not shared with the other isolates, suggesting distinct phylogenetic lines. All of the isolates had similar antimicrobial profiles, but the isolates from the bighorn sheep produced less pigment than those from the domestic livestock, and growth of the former was not enhanced by CO2. Wildlife biologists and diagnosticians should be aware of the potential of these organisms to cause disease in bighorn sheep and of growth characteristics that may hinder laboratory detection.