Cefixime is a third generation cephalosporin, while cefaclor is a second generation cephalosporin, which is the biggest difference between these two cephalosporins. Usually, the second generation oral cephalosporins, with cefaclor as the typical representative, mainly inhibit the synthesis of bacterial cell wall and bactericidal effect, and have the effect of killing most of Gram-positive cocci and Gram-negative bacilli, but the effect of Gram-negative bacilli is stronger than the third generation cephalosporins, and the effect of Gram-positive cocci is smaller than the third generation cephalosporins. Therefore, cefixime is a third-generation cephalosporin, and this type of drug is usually highly stable to the β-lactamase produced by Gram-positive bacilli, so this drug is an enzyme-resistant cephalosporin.