Phenotypic and molecular epidemiologic evaluation of a Nocardia farcinica mastitis epizootic

• Published in: Veterinary microbiology Vol. 125; no. 1; pp. 66 - 72
• Main Authors: Brown, June M., Cowley, Karyn D., Manninen, Kenneth I., McNeil, Michael M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.11.2007; Elsevier Science
• Subjects: amikacin; Amikacin-resistant; Animals; Anti-Bacterial Agents - pharmacology; antibiotic resistance; Bacteriology; Base Sequence; Biological and medical sciences; bovine mastitis; Canada - epidemiology; Cattle; clones; cows; dairy herds; disease outbreaks; Disease Outbreaks - veterinary; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; dry period; epizootics; Female; Fundamental and applied biological sciences. Psychology; genotype; intramammary products; Mastitis, Bovine - epidemiology; Mastitis, Bovine - microbiology; microbial genetics; Microbial Sensitivity Tests; Microbiology; Miscellaneous; Molecular Epidemiology; Molecular Sequence Data; N. farcinica epizootic; Nocardia - genetics; Nocardia - isolation & purification; Nocardia - metabolism; Nocardia farcinica; Nocardia Infections - epidemiology; Nocardia Infections - microbiology; Nocardia Infections - veterinary; phenotypic correlation; Polymerase Chain Reaction - veterinary; Polymorphism, Restriction Fragment Length; Ribotyping - veterinary; RNA, Ribosomal, 16S - chemistry; RNA, Ribosomal, 16S - genetics; strain differences; strains; Canada; N. farcinica epizootic; Nocardia farcinica; Amikacin-resistant; Mastitis; Amikacin; Nocardiaceae; Actinomycetales; Resistance; Mammary gland diseases; Antibiotic; Aminoglycoside; Bacteria; Actinomycetes; Protein synthesis inhibitor; Antibacterial agent
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/j.vetmic.2007.04.044

Nineteen putative Nocardia farcinica isolates epidemiologically associated with intramammary products containing neomycin were obtained from clinical cases in a Canada-wide mastitis epizootic. Epidemiologic investigations were unable to identify the mechanism for transmission. To evaluate the hypotheses generated (intrinsic versus extrinsic contamination) and to confirm the identity of N. farcinica, we compared these isolates phenotypically (biochemicals and antimicrobial susceptibility studies) and genotypically (16S rRNA gene sequencing analysis, chromosomal DNA and ribotyping profiles) with the type and reference strains of N. farcinica. Results of biochemical studies and 16S rRNA gene sequencing identified the isolates as N. farcinica. Results of chromosomal DNA and ribotyping profiles and antimicrobial resistance to amikacin indicated all were a unique clone of N. farcinica that differed from the control isolates. Our study suggests the epizootic was caused by transmission of a unique clone of N. farcinica through intrinsically contaminated dry cow intramammary products rather than an extrinsic source.