Table 3.

In vitro activity of the antimicrobial agents against isolates of S. pneumoniae classified by penicillin susceptibility profile

Penicillin susceptibility profileAntimicrobial agentaMIC90No. (%) of isolates that were:
SusceptibleIntermediateResistant
Susceptible (n = 839)Amoxicillin0.03839 (100)0 (0)0 (0)
Amoxiclavb0.03839 (100)0 (0)0 (0)
Cefaclorc≤1805 (95.9)30 (3.6)4 (0.5)
Cefuroxime axetilc≤0.25838 (99.8)0 (0)1 (0.2)
Cefiximec, d0.5
Cefotaxime≤0.25837 (99.8)2 (0.2)0 (0)
Erythromycin8747 (89.0)0 (0)92 (11.0)
Clarithromycin4748 (89.2)0 (0)91 (10.8)
Azithromycin8725 (86.4)22 (2.6)92 (10.9)
Ciprofloxacind249 (5.8)
Intermediate (n = 479)Amoxicillin2464 (96.9)11 (2.3)4 (0.8)
Amoxiclavb2463 (96.7)13 (2.7)3 (0.6)
Cefaclor3287 (18.2)58 (12.1)334 (69.7)
Cefuroxime axetil4170 (35.5)136 (28.4)173 (36.1)
Cefiximed4
Cefotaxime1408 (85.2)66 (13.8)5 (1.0)
Erythromycin≥64203 (42.4)0 (0)276 (57.6)
Clarithromycin≥64203 (42.4)3 (0.6)273 (57.0)
Azithromycin≥64191 (39.9)15 (3.1)273 (57.0)
Ciprofloxacind239 (8.1)
Resistant (n= 366)Amoxicillin8216 (59.0)68 (18.6)82 (22.4)
Amoxiclavb8220 (60.1)62 (16.9)84 (22.9)
Cefaclor≥641 (0.3)2 (0.5)363 (99.2)
Cefuroxime axetil80 (0)11 (3.0)355 (97.0)
Cefiximed≥8
Cefotaxime242 (11.5)214 (58.5)110 (30.0)
Erythromycin≥64146 (39.9)0 (0)220 (60.1)
Clarithromycin≥64146 (39.9)0 (0)220 (60.1)
Azithromycin≥64146 (39.9)0 (0)220 (60.1)
Ciprofloxacind232 (8.7)
  • a See Table 1, footnote a.

  • b See Table 1, footnote b.

  • c NCCLS recommendations state that a pneumococcal isolate that is susceptible to penicillin can be considered susceptible to cefaclor, cefixime, and cefuroxime.

  • d See Table 1, footnote c.