THE EFFECT OF ZINC ON MICROBIAL-GROWTH AND BACTERIAL KILLING BY CEFAZOLIN IN A STAPHYLOCOCCUS-AUREUS ABSCESS MILIEU

Microbial growth and antimicrobial bacterial killing are both diminish ed in abscesses. It was postulated that zinc depletion in abscesses, p erhaps secondary to a neutrophil protein resembling calprotectin, may be partly responsible for these effects. In a rabbit tissue-cage absce ss model, pooled abscess supernatant concentration of zinc was < 1.53 muM. The addition of 41.7 muM zinc had no effect on Staphylococcus aur eus growth or the bacterial killing effect of cefazolin in serum. In a bscess fluid supernatants, bacterial growth without antibiotic and bac terial killing by cefazolin were both enhanced by the addition of zinc . Fractionation of the abscess fluid with ultrafiltration membranes sh owed that these effects could be reproduced with the fraction between 30 and 50 kDa. These findings suggest that a protein in abscess fluid supernatants that resembles the neutrophil protein calprotectin may, t hrough its zinc binding effects, inhibit microbial growth within an ab scess but also inhibit the activity of bactericidal antibiotics.