An average of 106 cfu/ml was ascertained in this solution using a densitometer. The suspension was filled into the inner lumina of all tubes.
Excess fluid was removed after one hour of contamination at room temperature and the fully sealed tubes incubated for 24 h at 37°C. Segments (5 mm) were then excised from each tube and vortexed for 30 s in a neutralizing solution containing 5 ml of 0.9% saline and a combination of 3% saponin, 3% tween 80, 0.1% histidine and 0.1% cysteine for OCT inactivation. A series of 10-fold dilutions were made from each sample fluid and pipetted onto Mueller-Hinton/McConkey agar. Each dilution step was repeated in triplicate. After incubation at 37°C for 24 hours, the numbers of Enzalutamide order colonies were counted and analysed. Reprocessing procedures S. aureus contaminated tubes were cleaned chemically with glutaraldehyde (2%) 5 times each and then re-contaminated. Manual brushing was added for LY294002 price the second reprocessing procedure. P. aeruginosa contaminated tubes were reprocessed mechanically and chemically 5 times between contamination procedures (Table 1). Statistical analysis The number of pathogens was calculated as mean cfu ± standard deviation (SD) and presented in groups. The experiments were repeated in quadruplicate for 24 hours. A one-sided t-test was used to determine statistical significant differences. A p-value
of < 0.05 was considered statistically significant. Acknowledgements We are much obliged to Heimomed for
granting the article-processing charge and for supplying the coated and uncoated tracheotomy tubes. Electronic supplementary material Additional file 1: Overview of bacterial colonization on coated versus uncoated tracheotomy tubes. The table illustrate the bacterial colonization on all 16 polymer tracheotomy tubes after contamination with S. aureus or P. aeruginosa at different experimental time points (T1, T2, and T3). (XLS 30 KB) References 1. Gonzalez C, Rubio M, Romero-Vivas J, Gonzales M, Picazo JJ: Bacteremic pneumonia due to Staphylococcus aureus : a comparison of disease caused by methicillin-resistant and methicillin-susceptible organisms. Int J Infect Dis 1999, 29:1171–1177. 2. Rello J, Diaz E: Pneumonia in the Tolmetin intensive care unit. Crit Care Med 2003, 31:2544–2551.CrossRefPubMed 3. Adair CG, Gorman SP, Feron BM, Byers LM, Jones DS, Goldsmith CE, Moore JE, Kerr JR, Curran MD, Hogg G, Webb CH, McCarthy GJ, Milligan KR: Implications of endotracheal tube biofilm for ventilator associated pneumonia. Intensive Care Med 1990, 25:1072–1076.CrossRef 4. Adair CG, Gorman SP, O’Neill FP, McClurg B, Goldsmith EC, Webb CH: Selective decontamination of the digestive tract does not prevent the formation of microbial biofilm on endotracheal tubes. J Antimicrob Chemother 1993, 31:689–697.CrossRefPubMed 5. Jansen B: New concepts in the prevention of polymer-associated foreign body infections. Zentralbl Bakteriol 1990, 272:401–410.PubMed 6.