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Table 2 Rates of resistance to various antibacterials among Streptococcus pneumoniae isolates collected during Years 1–4 (2000–2004) of the PROTEKT US study

From: Trends in antibacterial resistance among Streptococcus pneumoniae isolated in the USA: update from PROTEKT US Years 1–4

Antibacterial Year 1 (n = 10,103) Year 2 (n = 10,012) Year 3 (n = 10,886) Year 4 (n = 8,494)
Penicillin     
   MIC50/MIC90 (μg/mL) 0.06/4 0.06/2 ≤ 0.03/2 ≤ 0.03/2
   MIC range (μg/mL) 0.06–16 0.06–16 ≤ 0.03–16 ≤ 0.03–16
   Resistant (% of isolates) 26.3 21.2 20.2 16.5
   Intermediate (% of isolates) 12.5 14.2 15.3 20.0
Amoxicillin-clavulanate     
   MIC50/MIC90 (μg/mL) ≤ 0.12/2 ≤ 0.12/2 ≤ 0.12/2 ≤ 0.12/2
   MIC range (μg/mL) ≤ 0.12-≥ 8 ≤ 0.12-≥ 8 ≤ 0.12-≥ 8 ≤ 0.12-≥ 8
   Resistant (% of isolates) 4.4 3.5 4.0 4.1
Cefuroxime axetil     
   MIC50/MIC90 (μg/mL) ≤ 0.12/8 ≤ 0.12/8 0.25/8 0.25/4
   MIC range (μg/mL) ≤ 0.12-≥ 16 ≤ 0.12-≥ 16 0.25-≥ 16 ≤ 0.12-≥ 16
   Resistant (% of isolates) 28.8 24.1 23.0 20.4
Erythromycin     
   MIC50/MIC90 (μg/mL) 0.12/16 ≤ 0.06/16 0.12/64 ≤ 0.06/256
   MIC range (μg/mL) ≤ 0.06-≥ 256 ≤ 0.06-≥ 256 ≤ 0.06-≥ 256 ≤ 0.06-≥ 256
   Resistant (% of isolates) 31.0 27.9 29.2 29.1
Clarithromycin     
   MIC50/MIC90 (μg/mL) 0.06/16 ≤ 0.03/16 ≤ 0.03/32 ≤ 0.03/128
   MIC range (μg/mL) ≤ 0.03-≥ 256 ≤ 0.03-≥ 256 ≤ 0.03-≥ 256 ≤ 0.03-≥ 256
   Resistant (% of isolates) 30.7 27.5 28.7 28.9
Azithromycin     
   MIC50/MIC90 (μg/mL) 0.12/32 0.12/32 0.12/≥ 256 0.12/256
   MIC range (μg/mL) ≤ 0.03-≥ 256 ≤ 0.03-≥ 256 ≤ 0.03-≥ 256 ≤ 0.03-≥ 256
   Resistant (% of isolates) 31.0 27.7 28.9 28.9
Telithromycin     
   MIC50/MIC90 (μg/mL) ≤ 0.015/0.5 ≤ 0.015/0.25 ≤ 0.015/0.5 ≤ 0.015/0.5
   MIC range (μg/mL) ≤ 0.015–8 ≤ 0.015–4 ≤ 0.015–4 ≤ 0.015-≥ 4
   Resistant (% of isolates) 0.04 0.02 0.01 0.01
Levofloxacin     
   MIC50/MIC90 (μg/mL) 1/1 1/1 1/1 1/1
   MIC range (μg/mL) ≤ 0.12–128 ≤ 0.12-≥ 256 ≤ 0.12–128 ≤ 0.12-≥ 256
   Resistant (% of isolates) 0.8 1.1 0.8 1.0
Tetracycline     
   MIC50/MIC90 (μg/mL) 0.25/≥ 8 0.25/≥ 8 0.25/≥ 8 0.25/≥ 8
   MIC range (μg/mL) ≤ 0.06-≥ 8 ≤ 0.06-≥ 8 ≤ 0.06-≥ 8 ≤ 0.06-≥ 8
   Resistant (% of isolates) 15.9 14.9 14.8 14.6
Trimethoprim-sulfamethoxazole     
   MIC50/MIC90 (μg/mL) ≤ 0.25/≥ 8 ≤ 0.25/≥ 8 ≤ 0.25/≥ 8 ≤ 0.25/≥ 8
   MIC range (μg/mL) ≤ 0.25-≥ 8 ≤ 0.25-≥ 8 ≤ 0.25-≥ 8 ≤ 0.25≥ 8
   Resistant (% of isolates) 33.9 28.2 26.8 24.1
  1. MIC, minimum inhibitory concentration.