Which of the following are ineffective against gram negative bacteria?

Vancomycin is a glycopeptide antibiotic used in the prophylaxis and treatment of infections caused by Gram-positive bacteria. Cefixine is an oral third generation cephalosporin antibiotic. It has good activity for gram-negatives. Metroridozole is highly active against gram-negative anaerobic bacteria, such as B. fragilis, and gram-positive anaerobic bacteria, such as C. difficile. Gentamicin is an aminoglycoside antibiotic, used to treat many types of bacterial infections, paicularly those caused by Gram-negative organisms.