Intracellular killing of mastitis pathogens by penethamate hydriodide following internalization into mammary epithelial cells

Abstract

Penethamate hydriodide was highly effective in killing Streptococcus uberis, Streptococcus dysgalactiae subsp. dysgalactiae and Staphylococcus aureus that internalized mammary epithelial cells. At higher concentrations (32 microg/mL to 32 mg/mL), killing rates ranged from 85% to 100%. At lower concentrations (0.032 microg/mL to 3.2 microg/mL), killing rates ranged from 0 to 80%. Results of this proof-of-concept study demonstrated that: (1) penethamate hydriodide is capable of entering mammary epithelial cells and killing intracellular mastitis pathogens without affecting mammary epithelial cell viability, (2) the in vitro model used is capable of quantifying the fate of mastitis pathogens internalized into mammary epithelial cells, and (3) this in vitro model can be used to determine the effectiveness of antibiotics at killing bacteria within the cytoplasm of mammary epithelial cells.

Knowledge gaps and research priorities inStaphylococcus aureusmastitis control

“…The intracellular location of S. aureus is a contributing factor to the problem of therapeutic failure. A commercially available antibiotic product has been shown to be able to kill S. aureus internalized in mammary epithelial cells in vitro, but its superior efficacy to cure chronic mastitis has not been established (Almeida, Patel, Friton, & Oliver, ). Another problem is that the intracellular staphylococci are not in a metabolic state of susceptibility to the antibiotic (Craven and Anderson, ).…”

“…Availability of typing methods, and whole-genome sequencing, may improve our knowledge of specific virulence traits or features that make these strains more difficult to cure. to be able to kill S. aureus internalized in mammary epithelial cells in vitro, but its superior efficacy to cure chronic mastitis has not been established (Almeida, Patel, Friton, & Oliver, 2007). Another problem is that the intracellular staphylococci are not in a metabolic state of susceptibility to the antibiotic (Craven and Anderson, 1980).…”

Staphylococcus aureus Phenol-Soluble Modulins Impair Interleukin Expression in Bovine Mammary Epithelial Cells

“…Adhesion assays were performed as described previously (29). Briefly, confluent monolayers of PS cells in 96-well plates (2.5 ϫ 10 5 cells/well) were incubated for 90 min with an S. aureus suspension at an MOI of 80:1.…”

Modulation of the inflammatory response of bovine mammary epithelial cells by cholecalciferol (vitamin D) during Staphylococcus aureus internalization

“…The predominant contagious pathogen responsible for mastitis in lactating cows is the Gram-positive bacterium S. aureus [18]. Mammary gland infections by S. aureus are frequently characterized by the ability of bacteria to colonize and internalize into udder cells (epithelial and endothelial cells), allowing their spreading and evasion of host defenses, decreasing the efficiency of antibiotic treatments, and thereby resulting in chronic infections [3,4,15]. Therefore, the development of methods for controlling bovine mastitis is desirable.…”