Bacterial adhesion and growth reduction by novel rubber-derived oligomers

Abstract

In the medical field, attached bacteria can cause infections associated with catheters, incisions, burns, and medical implants especially in immunocompromised patients. The problem is exacerbated by the fact that attached bacteria are ∼1000 times more resistant to antibiotics than planktonic cells. The rapid spread of antibiotic resistance in these and other organisms has led to a significant need to find new methods for preventing bacterial attachment. The goal of this research was to evaluate the effectiveness of novel polymer coatings to prevent the attachment of three medically relevant bacteria. Tests were conducted with Pseudomonas aeruginosa, Staphylococcus epidermidis, and Staphylococcus aureus for oligomers derived from modifications of natural rubber (cis 1,4-polyisoprene). The different oligomers were: PP04, with no quaternary ammonium (QA); MV067, one QA; PP06, three QA groups. In almost all experiments, cell attachment was inhibited to various extents as long as the oligomers were used. PP06 was the most effective as it decreased the planktonic cell numbers by at least 50% for all bacteria. Differences between species sensitivity were also observed. P. aeruginosa was the most resistant bacteria tested, S. aureus, the most sensitive. Further experiments are required to understand the full extent and mode of the antimicrobial properties of these surfaces.

Keywords: Antibacterial; Polyisoprene; Pseudomonas aeruginosa; Rubber; Staphylococcus aureus; Staphylococcus epidermidis.

Fig. 1

Structure of the natural rubber derived oligomers PP04, MV067, and PP06. Darocur 1173 was used as a photoinitiator and HDDA (hexanedioldiacrylate) as a reactive diluant.

Fig. 2

Growth curves of S. aureus, S. epidermidis and P. aeruginosa in TSB. Error bars, standard error (n = 3).

Fig. 3

Protocol 1 (see Table 1.A.): (A). P. aeruginosa on the surface. (B). P. aeruginosa in the medium. (C). S. aureus on the surface. (D). S. aureus in the medium. (E). S. epidermidis on the surface. (F). S. epidermidis in the medium. The average of each experimental value was divided by the average control value and plotted. *p < .05, **p < .01 compared to control values.

Fig. 4

Protocol 2 (see Table 1B): (A) P. aeruginosa on the surface. (B) P. aeruginosa in the medium. (C) S. aureus on the surface. (D) S. aureus in the medium. (E) S. epidermidis on the surface. (F) S. epidermidis in the medium. The average of each experimental value was divided by the average control value and plotted. *p < .05, **p < .01 compared to control values.