Comparison of Staphylococcus aureus Isolates from Bovine and Human Skin, Milking Equipment, and Bovine Milk by Phage Typing, Pulsed-Field Gel Electrophoresis, and Binary Typing

Abstract

Staphylococcus aureus isolates (n ‫؍‬ 225) from bovine teat skin, human skin, milking equipment, and bovine milk were fingerprinted by pulsed-field gel electrophoresis (PFGE). Strains were compared to assess the role of skin and milking equipment as sources of S. aureus mastitis. PFGE of SmaI-digested genomic DNA identified 24 main types and 17 subtypes among isolates from 43 herds and discriminated between isolates from bovine teat skin and milk. Earlier, phage typing (L. K. Fox, M. Gershmann, D. D. Hancock, and C. T. Hutton, Cornell Vet. 81:183-193, 1991) had failed to discriminate between isolates from skin and milk. Skin isolates from humans belonged to the same pulsotypes as skin isolates from cows. Milking equipment harbored strains from skin as well as strains from milk. We conclude that S. aureus strains from skin and from milk can both be transmitted via the milking machine, but that skin strains are not an important source of intramammary S. aureus infections in dairy cows. A subset of 142 isolates was characterized by binary typing with DNA probes developed for typing of human S. aureus. Typeability and overall concordance with epidemiological data were lower for binary typing than for PFGE while discriminatory powers were similar. Within several PFGE types, binary typing discriminated between main types and subtypes and between isolates from different herds or sources. Thus, binary typing is not suitable as replacement for PFGE but may be useful in combination with PFGE to refine strain differentiation.

Staphylococcus aureus host specificity: comparative genomics of human versus animal isolates by multi-strain microarray

“…Our results suggest that there may be relatively few conserved differences between S. aureus from humans and animals, and fewer than had been previously suggested. This is despite the fact that most bovine and human S. aureus appear relatively host specific for colonization and pathogenicity (Kapur et al, 1995;Zadoks et al, 2002, Jørgensen et al, 2005.…”

“…A variety of methods, such as multilocus enzyme electrophoresis (MLEE), random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR), restriction fragment length polymorphism (RFLP), pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) have been used in epidemiological investigations of human and farm animal staphylococci (Kapur et al, 1995;Fitzgerald et al, 1997;Zadoks et al, 2000Zadoks et al, , 2002Smith et al, 2005;Jørgensen et al, 2005). Many of the studies are in agreement with the general concept of host specialization among S. aureus isolates.…”

Characterization of Dutch Staphylococcus aureus from bovine mastitis using a Multiple Locus Variable Number Tandem Repeat Analysis

“…Transfer of antibiotic resistance from human to animal isolates or the other way around has been a major concern (Pesavento et al, 2007;Zadoks et al, 2002). Host specificity of clones may reduce the chance that human-derived antibiotic-resistant S. aureus isolates are transmitted to cattle, although bovine mastitis may occasionally be caused by human-derived isolates.…”

“…The sources of bovine mastitis cases mostly are from bovine origin, but S. aureus originating from the farmer are another important source (Zadoks et al, 2002). In 2005 it was reported that each year at least 25% of all milking cows in The Netherlands suffer from clinical mastitis which is not only due to S. aureus (32%) as a causative agent (Lam, 2005).…”

Characterization of 26 Isolates of Staphylococcus Aureus, Predominantly from Dairy Sheep, Using Four Different Techniques of Molecular Epidemiology

“…14 However, because PFGE still provides more information due to its high discriminatory power, it remains the technique of choice for typing bacteria in longitudinal studies. 11,19,20 Clearly, MLST and PFGE are the most powerful techniques for high-precision epidemiological typing when episodes of animal to animal transmission need to be fully investigated. Moreover, MLST is an adequate technique for generating genetic profiles of a large number of isolates, especially when comparing large international strain collections.…”