Value of bedside plating of semiquantitative cultures for diagnosis of central venous catheter-related infections in ICU patients.

We compared semiquantitative central venous catheter tip cultures plated at the bedside with those cultured in the laboratory, to determine if bedside plating provides a significantly better yield. Paired segments of 197 catheter tips from 92 surgical and medical ICU patients were evaluated prospectively. A total of 31 catheter tip cultures were positive for > or = 15 organisms per agar plate, with 10 of these being simultaneously positive at the bedside and in the laboratory. Cultures were exclusively positive in 18 cases plated immediately at the bedside, whereas laboratory plating resulted in only 3 exclusively positive cases. This discrepancy was statistically significant (p < 0.005). Compared with bedside plating, the sensitivity and specificity of sending catheters to the laboratory were 36 percent and 98 percent, respectively. These results indicate that the practice of sending central venous catheter tips to the laboratory for routine culture should be reconsidered in favor of bedside plating.