Irrigant divalent cation concentrations influence bacterial adhesion.
BACKGROUND
Surgical wounds are frequently contaminated by microbes, but rarely become infected if the bacterial burden is low, and irrigation is used to reduce contamination. Wound fluids are low in calcium and high in magnesium. We hypothesized that manipulating irrigant divalent cation concentrations might influence bacterial adhesion.


METHODS
Staphylococcus aureus, E. coli, and Pseudomonas aeruginosa were stained with fluorescent calcein AM before plating onto fibroblast monolayers, collagen I, or uncoated bacteriologic plastic. After 1 h, wells were washed with HEPES-buffered pH-balanced sterile water without or with 5 mM CaCl(2), 5 mM MgCl(2), or 1 mM EDTA+EGTA, and the remaining adherent bacteria were assayed fluorometrically.


RESULTS
Supplementing the irrigation with magnesium or chelators increased but calcium-supplemented irrigation reduced bacterial adhesion to collagen or fibroblasts. Nonspecific electrostatic bacterial adhesion to uncoated plastic was unaffected by calcium.


CONCLUSIONS
Bacterial adhesion to mammalian cells and matrix proteins is influenced by divalent cations, and pathogenic bacteria may be adapted to adhere under the low calcium high magnesium conditions in wounds. Although these results await confirmation for other bacteria, and in vivo validation and safety-testing, they suggest that supplementing wound irrigation with 5 mM CaCl(2) may reduce bacterial adhesion and subsequent wound infection.
Dass
Clarissa L
CL
Department of Surgery, Michigan State University and the John D Dingell VAMC, Lansing, MI 48912, USA.
Walsh
Mary F
MF
Seo
Sue
S
Shiratsuchi
Hiroe
H
Craig
David H
DH
Basson
Marc D
MD
D000818:Animals; D001422:Bacterial Adhesion / Q000187:drug effects*; D002118:Calcium / Q000494:pharmacology*; D002413:Cations, Divalent / Q000494:pharmacology*; D002460:Cell Line; D002614:Chelating Agents / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004926:Escherichia coli; D008274:Magnesium / Q000494:pharmacology*; D051379:Mice; D010969:Plastics; D011550:Pseudomonas aeruginosa; D013211:Staphylococcus aureus; D013530:Surgical Wound Infection / Q000517:prevention & control*; D007507:Therapeutic Irrigation
D002413:Cations, Divalent; D002614:Chelating Agents; D010969:Plastics; D004533:Egtazic Acid; D004492:Edetic Acid; D008274:Magnesium; D002118:Calcium