TABLE 3.

Antimicrobial susceptibility comparison between the H. influenzae study group isolated in 2007 and the control group isolated in 1997

ParameterNo. of isolates (%) for:% ChangeFisher exact test
2007 (109)1997 (88)OR (95% CI)Pd
Amoxicillin resistance (MIC ≥ 4 μg/ml)33 (30.2)34 (38.6)-8.40.69 (0.38-1.25)0.23
β-Lactamase-positive isolates19 (17.4)29 (32.9)-15.50.43 (0.22-0.83)0.01
Amoxicillin resistance in β-lactamase-negative isolates14 (12.8)5 (5.7)+7.11.99 (0.68-5.85)0.31
Amoxicillin, MIC ≥ 2 μg/mla26 (28.9)8 (13.6)+15.32.60 (1.08-6.20)0.04
Amoxicillin, MIC ≥ 32 μg/mlb15 (78.9)29 (100)-21.12.45 (1.02-5.90)0.04
Amoxicillin-clavulanic acid, MIC = 2 to 4 μg/mlc25 (27.8)8 (13.6)+14.20.05 (0.003-1.16)0.02
gBLNAS60 (55)43 (48.9)+6.11.30 (0.73-2.25)0.40
gBLPAR16 (14.7)17 (19.3)-4-.60.72 (0.34-1.52)0.44
gBLNAR30 (27.5)16 (18.2)+9.31.71 (0.86-3.40)0.13
gBLPACR3 (2.8)12 (13.6)-15.40.13 (0.036-0.45)0.0004
Azithromycin, MIC = 2 to 8 μg/ml95 (87.2)58 (66)+21.23.50 (1.72-7.20)0.0005
Trimethoprim-sulfamethoxazole, MIC ≥ 4 μg/ml38 (34.9)44 (50)-15.10.53 (0.30-0.95)0.04
Trimethoprim-sulfamethoxazole and amoxicillin simultaneous resistance16 (14.7)23 (26.1)-11.40.49 (0.24-1.00)0.04
  • a This values includes intermediate and resistant isolates (9). Total β-lactamase-negative isolates: 90 in 2007 and 59 in 1997.

  • b Total β-lactamase-positive isolates: 19 in 2007 and 29 in 1997.

  • c Total β-lactamase-negative isolates: 90 in 2007 and 59 in 1997.

  • d Significant values are indicated in boldface.