Which of the following drug should not be used to treat Klebsiella infection?

Ampicillin It is active against all organisms sensitive to PnG; in addition, many gram-negative bacilli, e.g. H. influenzae, E. coli, Proteus, Salmonella and Shigella are inhibited. However, due to widespread use, many of these have developed resistance; usefulness of this antibiotic has decreased considerably. Ampicillin is more active than PnG for Streptoccus viridans and enterococci; equally active for pneumococci, gonococci and meningococci (penicillin.resistant strains are resistant to ampicillin as well); but less active against other gram-positive cocci. Penicillinase producing Staph. are not affected, as are other gram-negative bacilli, such as Pseudomonas, Klebsiella, indole positive Proteus and anaerobes like Bacteroides fragilis ESSENTIALS OF MEDICAL PHARMACOLOGYU K.D.TRIPATHI SIXTH EDITION PAGE NO:700