Table 1.
Overview of the prepared novel antimicrobially coated sutures.
Fig 1.
Zone of inhibition assay for five bacterial species over 48 hours.
Zones of inhibition in millimeter for each coating type at 22 μg/cm drug content (CL22, CP22, OL22, OP22) on sutures. Test strains used were S. aureus, MRSA, S. epidermidis, E. faecalis and E. coli after A) 24 hours and B) 48 hours test period.
Fig 2.
SEM pictures prior to bacterial exposure to inspect coating quality and suture integrity (magnification 200x).
Left: Chlorhexidine- and octenidine-coated sutures for the lowest and highest drug concentrations used. Chlorhexidine sutures (CL11, CL33, CP11, and CP33) and octenidine-coated sutures (OL11, OL33, OP11, and OP33) are shown for laurate or palmitate carriers. Commercial antimicrobial sutures Vicryl® Plus (VP). Right: Reference sutures without antimicrobial drugs. Plain PGA suture material Gunze used for preparations (G) and commercially available resorbable sutures PGA Resorba® (R) and Vicryl® (V). Furthermore, sutures coated solely with fatty acid lauric acid (LA80), or palmitic acid (PA80) were investigated. Images are representative of three numbers of fields from three suture replicates.
Fig 3.
SEM pictures following bacterial exposure of coated sutures to visualize adhered bacteria and estimate their number semi-quantitatively (magnification 2,500x).
Sutures were incubated in S.aureus suspension at 1.3 x 108 cfu/ml for 3 hours. Left: Novel antimicrobially coated sutures are shown for the lowest and highest drug concentrations at 11μg/cm and 33μg/cm, respectively. Chlorhexidine-coated sutures (CL11, CL33, CP11, and CP33) and octenidine-coated sutures (OL11, OL33, OP11, and OP33) depicted for laurate or palmitate carriers. The commercial antimicrobial triclosan reference Vicryl® Plus (VP) is also shown in the last row. Right: Suture references without antimicrobial substances (G, R, LA80, PA80, and V). Adhered bacteria were exemplarily marked with an asterisk (*). Images are representative of three numbers of fields from three suture replicates.
Fig 4.
Numbers of adhered S. aureus colonies on sutures’ surfaces per cm sample after 3 hours of incubation in on average 1.3 x 108 cfu/ml bacterial suspension.
Viably adhered numbers of bacteria and their reductions compared to uncoated Gunze (G) suture. Left (up to dashed line): Sutures coated with antimicrobial substances, such as chlorhexidine-laurate (CL), chlorhexidine-palmitate (CP), octenidine-laurate (OL), and octenidine-palmitate (OP) each with the drug concentration 11, 22, and 33 μg/cm. Novel coated sutures were also compared to commercially available triclosan-containing Vicryl® Plus (VP) suture. Right: Groups of sutures without active antimicrobial agents, uncoated Gunze (G), coated with fatty acids (PA80, LA80) and commercially available common resorbable sutures (V: Vicryl®, R: PGA Resorba®). Significance levels are p<0.05 (*), p<0.01 (**) and p<0.001 (***); n.s.: not significant, n.a.: not applicable.
Fig 5.
Numbers of viable bacteria in suspension incubated for 3 hours with novel antimicrobial sutures.
An initial S. aureus concentration of 1.3 x 108 cfu/ml was used for bacterial suspensions. Chlorhexidine- or octenidine-coated sutures showed a strong inhibition of pathogens in the surrounding suspensions. The triclosan-coated suture Vicryl® Plus (VP) and the uncoated Gunze suture (G) were used as controls. Fatty acid-coated sutures (PA80, LA80) and commercial sutures without any drug content (V: Vicryl®, R: PGA Resorba®) were tested within the non-antimicrobial suture group. Significance levels are p<0.05 (*), p<0.01 (**) and p<0.001 (***); n.s.: not significant, n.a.: not applicable.
Table 2.
Evaluation of the novel antimicrobial sutures using chlorhexidine or octenidine at 11 μg/cm drug compared to commercial triclosan-containing Vicryl® Plus.
Table 3.
Rating levels used for comparative antimicrobial suture evaluation.