Effect of parenteral nutrition solutions on biofilm formation of coagulase-negative Staphylococci: An experimental study

Abstract

Objectives: In our study we investigated the effects of parenteral nutrition (PN) solutions on Coagulase negative staphylococci (CoNS) biofilm production. Materials and methods: Thirty nine CoNS strains isolated from hemocultures and a reference strain (ATCC 12228 Staphylococcus epidermidis) were included. Bacterial dilutions were made in Tryptic Soy Broth (TSB). The experimental mediums were 1. Glucose, 2. Amino acid, 3. Lipid, 4. Glucose+ Amino acid+ lipid, 5. Glucose+ Amino acid, 6. Glucose+ Lipid, 7. Amino acid+ Lipid, and 8. Control (TSB). Biofilm formation was evaluated by “quantitative microdilution plaque test”. The values greater than cut off value are considered as positive. Biofilm positivity was divided into 3 groups (mild, moderate and intensive) and all other strains under cutoff value were accepted as negative. The numbers of biofilm positive strains derived from 1-7. mediums were compared with each other, and with the results of control. Results: The three-component PN solution and two component PN solutions containing glucose+ lipid and amino acid+ lipid were found to increase the biofilm production activity of CoNS when compared to the control group. Slime positivity in medium 1 and 2 was lower than control significantly, in medium 4, 6, and 7 slime positivity was higher considerably. The indifferent results were obtained within the mediums 1, 2, 3 and within the mediums 4, 5, 6, and 7. Conclusions: In our study, it was found that, glucose, amino acid and lipid solutions which were building structures of PN decreased the biofilm production when used solitary. However use of the compounds increased the biofilm production. Therefore, we can conclude that PN solutions given as mixtures in routine practice increase the risk of catheter infection.