Do we really need to coat the novel silicone intranasal splints with antibiotics?

Abstract

Purpose

The novel silicone intranasal splints are suggested to resist biofilm formation due to their surface characteristics. We aimed to ascertain the necessity of coating these splints with antibiotics to prevent splint associated infections, in vitro.

Materials and methods

Pieces of Doyle II airway nasal splints made of medical grade silicone were divided into two test groups, treated with either (i) 0.2% nitrofurazone solution or (ii) 0.2% nitrofurazone containing ointment, and a control group, treated with (iii) 0.9% saline. Splint pieces were then incubated with Staphylococcus aureus solutions at 37 °C for 48 and 96 h. Following this, the splint pieces were incubated in 20 ml Mueller Hinton agar and appearing colonies were counted.

Results

Following 48and 96 h of incubation, the colonization rates in the saline group were significantly higher than the nitrofurazone ointment group (p < 0.001). The colonization rates in the liquid nitrofurazone group were significantly lower in comparison to the nitrofurazone ointment group (p < 0.001 and p = 0.019 respectively).

Conclusions

The method of coating the splints with antibiotic was superior to using uncoated splints in terms of preventing S. aureus colonization. The rather smooth surfaces of the splints were insufficient to block bacterial colonization and coating them with antibiotics seems to be beneficial for the prevention of infections.

1 Introduction

Following endonasal surgery, various nasal packing materials are being used to control epistaxis, prevent synechia and haematoma formation and support the skeleton of the nose . When compared with other types of packing materials, rubber or silicone intranasal splints were found to be superior in maintaining the functions of the eustachian tube, protecting the components of the mucociliary unit and providing the necessary support for the dorsum of the nose . Some authors even suggested the routine usage of the intranasal septal splints following a sinonasal operation . Despite this, in the literature, severe pain, vestibulitis and infections including toxic shock syndrome associated with the use of intranasal splints were reported .

In an attempt to prevent infections and provide lubrication, it was proposed that coating these splints with antibiotic ointments would be useful . On the other hand, despite the previously existing literature, some authors insisted that it was unnecessary to use antibiotic ointments or antibiotic soaked gauze packings along with the splints . Moreover, in the recent years, novel splints made of medical grade silicone were reported to have a smoother surface topography with a higher resistance to bacterial adhesion in comparison to their predecessors. The texture and surface properties of these silicone splints were found to be significantly effective in the prevention of biofilm formation . To the best of our knowledge, debates still exist regarding the use of ‘coated’ versus ‘uncoated’ intranasal splints following sinonasal surgery.

The authors of the present study aimed to compare the antibiotic coated splints with uncoated ones in terms of bacterial colonization in vitro and ascertain the necessity of coating these splints with antibiotics. The results were analyzed for statistical significance and implications of the findings were discussed using the existing literature.

2 Materials and methods

Doyle II airway nasal splints made of medical grade silicone were used in this study. Pieces of septal splints measuring 4 × 4 mm were prepared using a scalpel and all pieces were sterilized using ethylene oxide before the experiment. Splint pieces were divided into two test groups and a control group. Each group was also divided into ‘a’ and ‘b’ subgroups, each containing ten splint pieces (n = 60) ( Table 1 ). The first group was the control group and the splints in the control group were immersed in saline (0.9% NaCl) solution. Nitrofurazone ointment was used to coat the splints in the second group. Nitrofurazone solution (0.2%) bath was used to immerse the splints in the third group. The immersion or coating procedure was applied to each sample with an exposure time of 30 min and the splints were transferred into the sterile tubes.

Table 1

Distribution of experimental and control groups.

Group 1a: (n = 10): 0.9% saline treated splint pieces (Control group) (48 h) ^a

Group 1b: (n = 10): 0.9% saline treated splint pieces (Control group) (96 h) ^a

Group 2a: (n = 10): 0.2% nitrofurazone ointment coated splint pieces (48 h) ^a

Group 2b: (n = 10): 0.2% nitrofurazone ointment coated splint pieces (96 h) ^a

Group 3a: (n = 10): 0.2% nitrofurazone solution treated splint pieces (48 h) ^a

Group 3b: (n = 10): 0.2% nitrofurazone solution treated splint pieces (96 h) ^a

a Duration of incubation in Staphylococcus aureus solution.

Solutions of Staphylococcus aureus ATCC 29213, in phosphate buffered saline (PBS), with a concentration of 105 CFU/ml were prepared. Each sterile tube containing the prepared splint pieces were filled with 3 ml of this bacterial solution. The pieces were incubated with this solution for either 48 or 96 h in concordance with the experimental design (subgroups a = 48 h and b = 96 h). After the incubation period, to remove the unattached or planktonic bacteria, PBS in the tubes was discharged and washed 3 times with sterile PBS . After rinsing, the splint pieces were placed in 20 ml Mueller Hinton agar (BD, USA) which was prepared in autoclave and cooled to 45 °C. Splint pieces and agar medium were mixed in the vortex mixer and placed into 150 mm diameter Petri boxes. After their solidification, the Petri boxes were incubated at 37 °C for 24 h. This procedure was applied to each piece separately. Colonies were counted and appraised.

Data were evaluated statistically using Statistical Package for the Social Sciences (version 18.0; SPSS Inc., Chicago, IL, USA). All the statistical analyses were evaluated within a 95% two-sided confidence interval (CI). Descriptive statistics were calculated (mean, standard deviation). For comparing subgroups, Kruskal Wallis and Mann Whitney U tests were used. For analyzing the qualitative data Chi Square and Wilcoxon Signed Rank tests were used. A p value < 0.05 was accepted as statistically significant.