Characterisation of Mannheimia spp. strains isolated from bovine nasal exudate and factors associated to isolates, in dairy farms in the Central Valley of Mexico.

Mannheimia spp. strains obtained from bovine nasal exudates of either clinically healthy or clinically affected by respiratory tract disease animals were isolated and characterised to estimate the prevalence of isolated serotypes in dairy farms in Mexico, by means of a trans-sectional descriptive study. Strains were isolated and typified through biochemical and immunological tests. chi(2) or Fisher statistical tests were applied, as well as odds ratio calculation and logistic regression analysis to evaluate the association and effect of some variables on Mannheimia spp. isolation. The apparent prevalence rates of Mannheimia haemolytica was significantly higher in diseased bovines (OR = 1.94; p < 0.05), as well as in bovines younger than 1 year of age (OR = 23.98; p < 0.05), and in bovines not vaccinated against bovine pasteurellosis (OR = 1.52; p < 0.05). Age was the variable that remained in the logistic regression model. Serotype A1 showed the highest prevalence, even when most isolates were not-typable. Bovines younger than one year of age and those with disease were the groups with the highest frequency of M. haemolytica and Mannheimia glucosida isolates.

Serotypes of Pasteurella multocida and Pasteurella haemolytica isolated from pneumonic lesions in cattle and sheep from México.

A total of 13,000 pairs of lungs were examined at Mexico's City abbatoir, where 8,000 corresponded to sheep and 5,000 to cattle. From those, 224 pneumonic lesions were observed, obtaining 97 positive isolates, which yielded 112 strains of Pasteurella sp. Forty isolates were identified as P. haemolytica and 72 as P. multocida. One-hundred percent of P. haemolytica belonged to biotype A. Serotypes were determined by indirect haemagglutination. P. multocida isolates were classified according to the acriflavine and hyaluronidase techniques, 61% belonged to type A, 25% to type D and 14% were untypified. Somatic serotypes were determined by gel immunodiffusion; serotype 3 was more frequent, in sheep 72% and in cattle 77%.