Genomic fingerprinting of Haemophilus somnus by a combination of PCR methods

Twenty-three isolates of Haemophilus somnus were typed by repetitive extragenic palindromic (REP) element-based PCR, enterobacterial repetitive intergenic consensus (ERIC)-based PCR, and PCR ribotyping. A total of 11 types were distinguished by REP-PCR, 13 types were distinguished by ERIC-PCR, and 5 types were distinguished by PCR ribotyping. PCR ribotyping produced a relatively simple pattern and a small number of distinct types, whereas REP- and ERIC-PCR both produced more complex banding patterns but increased the discrimination between strains. Clearly distinguishable profiles were obtained for respiratory and genital isolates of H. somnus by all three typing methods. The results suggest that a combination of all three primer sets provides a high-resolution fingerprinting method for epidemiological studies of H. somnus and for its differentiation from related species.