Predictive value of surveillance skin cultures in total-parenteral-nutrition-related infection

To assess the importance of skin flora in the pathogenesis of infection complicating total parenteral nutrition and the predictive value of positive skin cultures for the development of infection 54 patients, who received 59 courses of total parenteral nutrition, were followed up. Three times per week, at the time of dressing and line changes, the skin at the site of insertion of the cannula was swabbed for culture. Results of skin cultures were compared with results of semiquantitative culture of the proximal intravascular portion of the cannula. Infected patients were defined as those having cannula cultures with greater than or equal to 15 colonies or those with primary septicaemia. 21 of 59 courses (36%) were associated with positive skin cultures; 14 of these 21 courses were associated with cannula infection, 2 with bacteraemia or fungaemia, and 12 with local infection. 38 of 59 (64%) courses had sterile skin cultures; in none of these 38 patients did infection develop (p less than 0.001). Skin colonisation was associated with otherwise unexplained fever (11 of 21 with positive skin culture versus 5 of 38 with negative skin culture, p less than 0.001), inflammation at the insertion site (13 of 21 versus 10 of 38, p less than 0.05), and violations of line protocol (11 of 21 versus 10 of 38, p less than 0.05). The absence of any organism on the skin had a negative predictive value of 98%, whereas the presence of an organism on the skin had a positive predictive value of 61%. Skin culture thus seems able to identify which patients receiving parenteral nutrition are at high risk of infection.