31. Which of the following may cause resistance to penicillin?

A. Impermeability of cell envelope
B. Production of β-lactamases by bacteria
C. Alteration or lack of penicillin-binding proteins
D. All of the above

32. The third-generation cephalosporin agent is

A. cefotaxime
B. cefoxitin
C. cephalothin
D. cephalexin

33. The penicillin-resistant to β-lactamases is

A. carbenicillin
B. cloxacillin
C. penicillin-G
D. ampicillin

34. The antibiotics not clinically useful for Pseudomonas aeruginosa infection is

A. aminoglycosides
B. ceftazidime
C. piperacillin
D. trimethoprim-sulphamethoxazole

35. Which of the following drugs may show plasmid-mediated resistance?

A. Nalidixic acid
B. Ampicillin
C. Rifampicin
D. Methicillin