Cross contamination of blood cultures associated with a multiple use venting device

Aim - To investigate cross contamination of blood cultures associated with multiple use venting devices, which are widely used in clinical microbiolog y laboratories to reduce labour costs. Methods - Systematic analysis of 13880 blood culture results in a large tea ching hospital where multiple use venting devices were employed. Results - Nine series of potential cross contamination were identified in a 12 month period. Four series involved coagulase negative staphylococci and were unlikely to represent true cross contamination. Five series involved blood cultures which had significant bacterial growth at the time of ventin g. Conclusions - Multiple use venting del vices can be associated with cross c ontamination of blood cultures. This may result from contamination of the i nternal lumen of the venting device which is not exposed to the biocide. Me dical microbiologists should consider the possibility of cross contaminatio n associated with venting procedures when interpreting blood culture result s. Further development of multiple use venting devices is required to reduc e the risk of cross contamination of cultures.