Predictive value of surveillance skin and hub cultures in central venous catheters sepsis

In a prospective study of septic complications of central venous catheters used for total parenteral nutrition, daily surveillance catheter hub cultures and twice weekly skin cultures at the catheter entry site were evaluated for their predictive value for catheter sepsis, i.e. bacteraemia with an identical species as that recovered from the catheter tip, or catheters which grew greater than or equal to 15 cfus by a semiquantitative method and/or greater than or equal to 10(3) cfus by a quantitative method. Of 142 catheters studied, 29 were identified to have catheter sepsis. For these the sensitivity of the surveillance hub culture was 34.5% and the sensitivity of the skin culture was 37.9%. When either the hub or the skin culture result was considered as an indication of catheter sepsis, the sensitivity increased to 79.3%. The positive and negative predictive value of the combined result was 44.2% and 93.3% respectively. This study suggests that simultaneous hub and skin cultures are required for a satisfactory surveillance.