Abstract

JARAMILLO-ARANGO, Carlos J. et al. Ribotyping of isolates of Mannheimia haemolytica serotype 1 obtained from nasal exudate of dairy cattle in Mexico. Rev. mex. de cienc. pecuarias [online]. 2017, vol.8, n.2, pp.219-224. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v8i2.4447.

One hundred and six (106) isolates of Mannheimia haemolytica serotype 1 (S1) obtained from nasal exudates of clinically healthy cows (n= 80) and cows diagnosed with pneumonia (n= 26) from two dairy farms located in central and northern Mexico were genetic characterized using a ribotyping technique. DNA was digested by HindIII and a probe containing the rrnB rRNA operon was used for ribotyping. Two ribotyping patterns were identified: Rt1 and Rt2, both with bands of approximate size between 0.78 and 19.70 kb. Rt1 had 11 hybridization bands and Rt2, 13. Ninety-six (96) percent of the isolates (102/106) were grouped into a cluster within Rt1; the similarity value between Rt1, Rt2 and the reference strain was 70 %. There were no differences between Rt isolates from healthy cows or cows with pneumonia. These results show that the majority of the strains were grouped within the Rt1 forming a single cluster, regardless of their geographic origin or the cows’ health status.

Keywords : Mannheimia; Ribotypes; Dairy cows; Nasal exudate.