Serotypes A1 and A2 ofMannheimia haemolyticaare susceptible to genotypic, capsular and phenotypic variations in contrast to T3 and T4 serotypes ofBibersteinia (Pasteurella) trehalosi

Abstract

Mannheimia haemolytica and Bibersteinia (Pasteurella) trehalosi are the most common bacterial isolates that cause pulmonary diseases in ruminants worldwide. The disease is determined by specific serotypes found in cattle and small ruminants. The molecular epidemiology of strains involved in disease is important in the control of outbreaks as well as in the preparation of vaccines. This study aimed to detect the instability and variations of bacterial strains that may affect the analysis of epidemic strains, or the stability of vaccinal strains. Eight strains of M. haemolytica belonging to serotypes A1 and A2 and three B. trehalosi strains of the T3 and T4 serotypes were used. Strains were subjected to pulsed field gel electrophoresis (PFGE) and capsular and phenotypic typing at each round of a total of 50 successive subcultures. Remarkable stability was found in all selected strains of B. trehalosi in contrast to M. haemoltyica, in which strains of both serotypes showed pattern variations produced by PFGE and capsular and phenotypic analysis. Objective criteria for M. haemolytica and B. trehalosi typing are consequently addressed.

Prevention of Respiratory Disease in Cow/Calf Operations

“…The pathogen previously characterized as Pasteurella trehalosi and recently renamed Bibersteinia trehalosi has long been recognized as a cause of ovine respiratory disease in small ruminants. 37,38 Its role in acute cases of respiratory disease in young dairy and stocker calves seems to be increasing and may be influenced by the use of prophylactic antibiotics given to control other pathogens. 39 Vaccination to control bacterial pathogens gives mixed results in the field.…”

A three-way comparative genomic analysis of Mannheimia haemolytica isolates

“…Furthermore, these serotypes do not conform to the classical Koch's postulates on microbial pathogenesis due to a great deal of genome plasticity and frequent serotype switching [15]. Of these, A1 and A2 are the most prevalent serotypes and are normal residents of the upper respiratory tracts of healthy cattle and sheep worldwide [16,17].…”

Aspectos fármaco-epidemiológicos de la enfermedad respiratoria bovina bacteriana en feedlots. Una problemática a resolver

“…Diversos estudios se han realizado analizando la diversidad genética de los aislamientos de M. haemolytica, explicando que la presión de selección que ocurriría en el periodo de engorde, podría posiblemente resultar en una sustancial alteración en el genoma de dicha bacteria, si dicho nivel de plasticidad in vivo ocurriera al igual que lo reportado in vitro 29,53 . Estos estudios son coincidentes con los resultados de autores que reportaron que los serotipos de M. haemolytica involucrados en la ERB fueron mayormente A1 y A6, habiéndose mencionado que A6 constituyó el 30% del total de serotipos aislados 44 .…”