Agboke, A. A. & C. O. Esimone 2011: Antimicrobial evaluation of the interaction between methanol extract of the lichen, Ramalina farinacea (Ramalinacea) and Ampicilin against clinical isolates of Staphylococcus aureus. - Journal of Medicinal Plant Research5(4): 644-648. [RLL List # 223 / Rec.# 32805] Abstract: Ampicillin is a member of the group of antibiotics called penicillin otherwise known as B-lactam drugs; it is a selective inhibitor of bacterial cell wall synthesis and therefore is active against growing bacteria. Ampicillin is one of the most widely prescribed antibiotics. It is considered as penicillin and is a close relative of amoxicillin. Unlike penicillin, ampicillin and amoxicillin can penetrate and prevent the growth of certain types of bacteria, called gram-negative bacteria. Ampicillin is used mainly to treat infections of the middle ear, sinuses, bladder, kidney, and uncomplicated gonorrhea. It is used intravenously to treat meningitis and other serious infections. The activities of this antibiotic were in some cases hindered by the b-lactamase producing resistant strains of Staphylococcus aureus. Antimicrobial interaction screening of the methanol extract with ampicillin, reveled that most of the combination ratio of methanol extract and ampicillin shows synergism while few were additive and no indifference and antagonism. This shows that in the treatment of infections of S. aureus the combination of the methanol extract of Lichen, Ramalina farinacea and ampicilin can be used together to enhance potency of the ampicilin in some cases of infection by S. aureus.