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Table 3 Proportion of S. pneumoniae and H. influenzae isolates with reduced susceptibility to antibiotics, determined by minimum inhibitory concentration (MIC)

From: Streptococcus pneumoniae and Haemophilus influenzae in paediatric meningitis patients at Goroka General Hospital, Papua New Guinea: serotype distribution and antimicrobial susceptibility in the pre-vaccine era

  Number tested Intermediate resistant Resistant Median MIC RS isolates
S. pneumoniae (n = 180)    
 Penicillin 177 NA 38 (21.5 %) 0.25
 Cotrimoxazole 176 8 (4.5 %) 7 (4.0 %) 2/38
 Tetracycline 96 0 (0 %) 4 (4.2 %) 24
 Chloramphenicol 176 NA 4 (2.3 %) 16
 Ceftriaxone 124 1 (0.8 %) 0 (0 %) 1
 Erythromycin 94 0 (0 %) 0 (0 %) NA
H. influenzae (n = 165)    
 Ampicillin 162 8 (4.9 %) 46 (28.4 %) 4
 Chloramphenicol 162 NA 51 (31.5 %) 16
 Cotrimoxazole 162 8 (4.9 %) 55 (34.0 %) >32/608
  1. CLSI breakpoints (μg/ml) for resistance (R) and intermediate resistance (IR) [18]
  2. S. pneumoniae: penicillin R ≥0.12; cotrimoxazole IR =1/19–2/38, R ≥4/76; tetracycline IR =4, R ≥8; chloramphenicol R ≥8; ceftriaxone IR =1, R ≥2; erythromycin IR =0.5, R ≥1
  3. H. influenzae: ampicillin IR =2, R ≥4; chloramphenicol IR =4, R ≥8; cotrimoxazole; IR =1/19–2/38, R ≥4/76
  4. RS reduced susceptibility (intermediate resistance and resistance)