Table 3.

Contamination rates in each culture system for different patient groups

Patient groupNo. of specimens (% of total)% Contamination ina:Pc
460960LJ460 vs 960460 vs LJ960 vs LJ
Without cystic fibrosis2,382 (90.8)3.36.95.3<0.001<0.0010.021
With cystic fibrosisb 242 (9.2)24.816.914.50.0340.004NS
Total2,624 (100.0)5.37.96.2<0.0010.018NS
  • a Abbreviations: 460, BACTEC 460TB system; 960, BACTEC MGIT 960 system; LJ, LJ medium. For differences between patient groups, P < 0.001 .

  • b From 106 cystic fibrosis patients (95.0% of specimens were sputum samples).

  • c Abbreviations: NS, not significant; ND, not done.