title: Prevalence and genotype of Mycoplasma bovis in beef cattle after arrival at a feedlot.
abstract: OBJECTIVE
  To determine the prevalence of Mycoplasma bovis infection in the lungs of cattle at various times after arrival at a feedlot, to measure the relationship between clinical disease status and the concentration and genotype of M bovis within the lungs, and to investigate changes in the genotype of M bovis over time.
  
  
  METHODS
  Bronchoalveolar lavage fluid (BALF) from 328 healthy or pneumonic beef cattle and 20 M bovis isolates obtained from postmortem samples.
  
  
  METHODS
  The concentration of M bovis in BALF was determined via real-time PCR assays, and M bovis isolates from BALF were genotyped via amplified fragment length polymorphism (AFLP) analysis.
  
  
  RESULTS
  Prevalence of M bovis in BALF was 1 of 60 (1.7%) at arrival to a feedlot and 26 of 36 (72.2%) and 36 of 42 (85.7%) at ≤ 15 days and 55 days after arrival, respectively. Neither the concentration nor the AFLP type of M bovis in BALF was correlated with clinical disease status. The M bovis AFLP type differed between early and later sampling periods in 14 of 17 cattle.
  
  
  CONCLUSIONS
  The findings implied spread of M bovis among calves and suggested that host factors and copathogens may determine disease outcomes in infected calves. Chronic pulmonary infection with M bovis may represent a dynamic situation of bacterial clearance and reinfection with strains of different AFLP type, rather than continuous infection with a single clone. These findings impact our understanding of why cattle with chronic pneumonia and polyarthritis syndrome inadequately respond to antimicrobial treatment.
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, N1G 2W1 ON, Canada.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Castillo-Alcala
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Bateman
authors.forename: Hugh Y
authors.initials: HY
authors.lastname: Cai
authors.forename: Courtney R
authors.initials: CR
authors.lastname: Schott
authors.forename: Lois
authors.initials: L
authors.lastname: Parker
authors.forename: Mary Ellen
authors.initials: ME
authors.lastname: Clark
authors.forename: Patricia
authors.initials: P
authors.lastname: McRaild
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: McDowall
authors.forename: Robert A
authors.initials: RA
authors.lastname: Foster
authors.forename: Marie
authors.initials: M
authors.lastname: Archambault
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Caswell
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis / Q000662:veterinary; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood / Q000453:epidemiology / Q000382:microbiology*; D015169:Colony Count, Microbial / Q000662:veterinary; D005260:Female; D005838:Genotype; D008168:Lung / Q000382:microbiology; D009175:Mycoplasma Infections / Q000097:blood / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D045682:Mycoplasma bovis / Q000145:classification* / Q000254:growth & development / Q000302:isolation & purification*; D009864:Ontario / Q000453:epidemiology; D015995:Prevalence; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D012141:Respiratory Tract Infections / Q000097:blood / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D016036:Seroepidemiologic Studies; D013997:Time Factors