title: Short communication: comparison of virulence factors in Klebsiella pneumoniae strains associated with multiple or single cases of mastitis.
abstract: Klebsiella pneumoniae mastitis in dairy cattle is generally due to an opportunistic infection from the environment, resulting in large heterogeneity among mastitis-causing strains within a herd. However, in mastitis outbreaks in 4 herds, several strains of K. pneumoniae were identified as the cause of infection in multiple cows, suggesting increased ability to either cause disease or evade host defenses. In this study, differences in capsule formation and immune evasion were compared in 5 pairs of K. pneumoniae strains, where one strain in each pair was associated with multiple cases of mastitis and the other with a single case of mastitis. Production of capsular polysaccharide, ability to evade killing by polymorphonuclear neutrophilic leukocytes (PMNL), and the relationship between the 2 were evaluated for each strain grown in broth or milk. Growth of isolates in skim milk increased capsule size and ability to evade killing by PMNL, depending on strain type. Specifically, strains associated with multiple cases of mastitis had increased capsule size in skim milk. Strains associated with single cases of mastitis were better able to evade killing by PMNL when grown in skim milk. Our results, although preliminary, suggest that the 2 groups of strains may constitute different subpopulations of K. pneumoniae. However, our findings do not indicate that capsule or evasions of killing by PMNL explain increased mastitis outbreaks with Klebsiella. Further work will explain the enhanced ability of some strains to cause mastitis in dairy cows.
authors.affiliation: Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061. Electronic address: isisk@vt.edu.
authors.forename: I
authors.initials: I
authors.lastname: Kanevsky-Mullarky
authors.affiliation: Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061.
authors.forename: A J
authors.initials: AJ
authors.lastname: Nedrow
authors.affiliation: Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061.
authors.forename: S
authors.initials: S
authors.lastname: Garst
authors.affiliation: Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061.
authors.forename: W
authors.initials: W
authors.lastname: Wark
authors.affiliation: Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061.
authors.forename: M
authors.initials: M
authors.lastname: Dickenson
authors.affiliation: Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061.
authors.forename: C S
authors.initials: CS
authors.lastname: Petersson-Wolfe
authors.affiliation: Quality Milk Production Services, Cornell University, 240 Farrier Road, Ithaca, NY 14853.
authors.forename: R N
authors.initials: RN
authors.lastname: Zadoks
mesh_terms: D000818:Animals; D002417:Cattle; D004196:Disease Outbreaks / Q000662:veterinary*; D005260:Female; D007710:Klebsiella Infections / Q000662:veterinary; D007711:Klebsiella pneumoniae / Q000472:pathogenicity* / Q000502:physiology*; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D009518:New York / Q000453:epidemiology; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D037521:Virulence Factors
keywords: Klebsiella pneumoniae; bovine mastitis; capsule; neutrophil