title: Short communication: Genotypic and phenotypic identification of environmental streptococci and association of Lactococcus lactis ssp. lactis with intramammary infections among different dairy farms.
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.
authors.affiliation: Cornell University, Animal Health Diagnostic Center, Quality Milk Production Services, Ithaca, NY 14853.
authors.forename: B
authors.initials: B
authors.lastname: Werner
authors.affiliation: Cornell University, Animal Health Diagnostic Center, Quality Milk Production Services, Ithaca, NY 14853; Università degli Studi di Milano, Dipartimento di Scienze Veterinarie per la Salute, la Produzione Animale e la Sicurezza Alimentare, Via Celoria 10 20133 Milan, Italy. Electronic address: pm389@cornell.edu.
authors.forename: P
authors.initials: P
authors.lastname: Moroni
authors.affiliation: Cornell University, Animal Health Diagnostic Center, Quality Milk Production Services, Ithaca, NY 14853.
authors.forename: G
authors.initials: G
authors.lastname: Gioia
authors.affiliation: University of Leon, Food Hygiene and Food Microbiology Department, Faculty of Veterinary Science, Campus Universitario Vegazana s/n. 24071-León, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Lavín-Alconero
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary and Animal Sciences, PMAS Arid Agriculture University Rawalpindi, Pakistan.
authors.forename: A
authors.initials: A
authors.lastname: Yousaf
authors.affiliation: Keseca Veterinary Clinic, Geneva, NY 14456.
authors.forename: M E
authors.initials: ME
authors.lastname: Charter
authors.affiliation: Keseca Veterinary Clinic, Geneva, NY 14456.
authors.forename: B Moslock
authors.initials: BM
authors.lastname: Carter
authors.affiliation: Northern Valley Dairy Production Medicine Center, MN 55964.
authors.forename: J
authors.initials: J
authors.lastname: Bennett
authors.affiliation: Cornell University, Animal Health Diagnostic Center, Quality Milk Production Services, Ithaca, NY 14853.
authors.forename: D V
authors.initials: DV
authors.lastname: Nydam
authors.affiliation: Cornell University, Animal Health Diagnostic Center, Quality Milk Production Services, Ithaca, NY 14853.
authors.forename: F
authors.initials: F
authors.lastname: Welcome
authors.affiliation: GD Animal Health, Arnsbergstraat 7, 7418 EZ Deventer, the Netherlands.
authors.forename: Y H
authors.initials: YH
authors.lastname: Schukken
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D015169:Colony Count, Microbial / Q000662:veterinary; D024881:Drug Resistance, Bacterial; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000150:complications / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D013294:Lactococcus lactis / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000382:microbiology*; D008910:Minnesota; D009518:New York; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013290:Streptococcal Infections / Q000150:complications / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D013291:Streptococcus / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents
keywords: Lactococcus lactis ssp. lactis identification; Streptococcus spp.; bovine intramammary infection; streptococci-like bacteria