Methicillin Resistant Staphylococcus aureus (MRSA)に対するBifidobacterium breveの抗菌活性と活性物質の精製

Abstract

The staphylococci, known to be members of the normal flora of the nose, are sometimes involved in chronic sinusitis. Recently, non-chemotherapeutic approaches have assumed importance in the treatment of chronic staphylococcal infections, since the rapid emergence of resistance to commonly-employed antimicrobial drugs has made it difficult to eradicate resistant staphylococci such as a methicillin resistant Staphylococcus aureus (MRSA) from the lesion. Thus, the present study was done to show the antimicrobial activity of Bifidobacterium breve to MRSA isolated from a patient with chronic sinusitis. Using MRSA resistant to acidic condition, MRSA could not survive after day 1 in the culture supernatant of B. breve, but in the control of 0.01 M phosphate-buffered saline containing tryptic soy broth of which pH was adjusted to 4.3, growth of MRSA was not affected. This anti-MRSA activity by the culture supernatants of B. breve is active only in the acidic condition under pH 4.5. But using tryptic soy soft agar containing 1% lactose, the activity was effective at pH 7.0. Purification of the active moiety from the culture supernatant of B. breve was done with ion exchange chromatography. Investigation of the main ingredient of the active moiety was done with the Anthron, Lowry, and Orcinol methods, and the absorption spectrum was calculated. The main component of the active moiety is considered to contain nucleotide and the molecular weight of the moiety will be around 8000. Our study is in progress to isolate the active moiety exhibiting anti-MRSA activity. Therefore it may be possible to apply this anti-MRSA activity of B. breve for clinical use in future.