Bacterial interference among nasal inhabitants: eradication of Staphylococcus aureus from nasal cavities by artificial implantation of Corynebacterium sp

Abstract

To evaluate the role of normal flora in the nares in preventing Staphylococcus aureus colonization, we conducted a replacement study in vivo. Staphylococcus epidermidis (rate of colonization: 100%), various species of corynebacteria (52.5%) and S. aureus (25.%) were the major bacterial inhabitants in the nares of 156 healthy volunteers. The low incidence of S. aureus colonization in the carriers with corynebacteria (8.5%), compared to non-carriers (44. 5%) indicated the possibility of competition for survival between S. aureus and corynebacteria. To confirm this hypothesis, we artificially implanted a strain of Corynebacterium sp (API Coryne bioprofile; 5100304), denoted as Co304 into the nares of 17 S. aureus carriers. S. aureus was completely eradicated in 71% of carriers by up to 15 inoculations of Co304. However, similar doses of 0.9% NaCl or S. epidermidis into the nares of 10 volunteers did not eradicate S. aureus. No bacteriocin-like activity against S. aureus was detectable, even after mitomycin C stimulation of Co304. Thus Co304 interfered with S. aureus by a different mechanism to a bacteriocin-like activity.