1. Short communication: Genotypic and phenotypic identification of environmental streptococci and association of Lactococcus lactis ssp. lactis with intramammary infections among different dairy farms.
- Author
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Werner B, Moroni P, Gioia G, Lavín-Alconero L, Yousaf A, Charter ME, Carter BM, Bennett J, Nydam DV, Welcome F, and Schukken YH
- Subjects
- Animals, Anti-Bacterial Agents pharmacology, Cattle, Cell Count veterinary, Colony Count, Microbial veterinary, Drug Resistance, Bacterial, Female, Gram-Positive Bacterial Infections complications, Gram-Positive Bacterial Infections epidemiology, Gram-Positive Bacterial Infections microbiology, Lactococcus lactis classification, Lactococcus lactis drug effects, Lactococcus lactis genetics, Lactococcus lactis isolation & purification, Minnesota, New York, Polymerase Chain Reaction veterinary, Streptococcal Infections complications, Streptococcal Infections epidemiology, Streptococcal Infections microbiology, Streptococcus classification, Streptococcus drug effects, Streptococcus genetics, Streptococcus isolation & purification, Gram-Positive Bacterial Infections veterinary, Lactococcus lactis physiology, Mastitis, Bovine epidemiology, Mastitis, Bovine microbiology, Streptococcal Infections veterinary, Streptococcus physiology
- Abstract
Lactococcus species are counted among a large and closely related group of environmental streptococci and streptococci-like bacteria that include bovine mastitis pathogenic Streptococcus, Enterococcus, and Aerococcus species. Phenotypic and biochemical identification methods can be inaccurate and unreliable for species within this group, particularly for Lactococcus spp. As a result, the incidence of Lactococcus spp. on the farm may have been historically underreported and consequently little is known about the clinical importance of this genus as a mastitis pathogen. We used molecular genetic identification methods to accurately differentiate 60 environmental streptococci and streptococci-like bacteria isolated from cows with high somatic cell count and chronic intramammary infection (IMI; >2 somatic cell scores above 4) among 5 geographically distinct farms in New York and Minnesota that exhibited an observed increase in IMI. These isolates were phenotypically identified as Streptococcus uberis and Streptococcus spp. Genetic methods identified 42 isolates (70%) as Lactococcus lactis ssp. lactis, including all 10 isolates originally phenotypically identified as Streptococcus uberis. Antibiotic inhibition testing of all Lc. lactis ssp. lactis showed that 7 isolates were resistant to tetracycline. In the present study, a predominance of Lc. lactis ssp. lactis was identified in association with chronic, clinical bovine IMI among all 5 farms and characterized antimicrobial resistance for treatment therapies. Routine use by mastitis testing labs of molecular identification methods for environmental streptococci and streptococci-like bacteria can further define the role and prevalence of Lc. lactis ssp. lactis in association with bovine IMI and may lead to more targeted therapies., (Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)
- Published
- 2014
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