Impaired mucosal healing and infection associated with Staphylococcus aureus after endoscopic sinus surgery

The effects of nitric oxide on Staphylococcus aureus biofilm growth and its implications in chronic rhinosinusitis

BACKGROUND

The relationship between sinonasal nitric oxide (NO) levels and the pathogenic organism Staphylococcus aureus is yet to be established. High NO levels measured in healthy sinuses likely contribute to maintenance of relative sterility. Lower concentrations such as is found in the sinuses of chronic rhinosinusitis (CRS) patients may decrease this effect. S. aureus in biofilm form has recently been implicated in recalcitrant CRS, its isolation predicting a higher risk of posttreatment reinfection. This in vitro study aims to characterize the changes in S. aureus biofilm formation when exposed to different NO levels mimicking the normal and diseased NO sinus concentrations reported in previous literature in an in vitro setting.

METHODS

S. aureus ATCC 25923 and 7 clinical isolates were cultured in biofilm form using the MBEC device and the established biofilms exposed to 1 to 1000 μM NO concentrations. Biofilms were visualized using Live/Dead Baclight stain and confocal scanning laser microscopy, and quantified using Comstat2, a biofilm quantification software.

RESULTS

Biofilm biomass decreases from an average of 0.105 to 0.057 μm(3) /μm(2) at higher NO concentrations (125-1000 μM), but is increased to 0.470 μm(3) /μm(2) at lower NO concentrations (0.9-2.0 μM). The average biomass at high vs low concentrations are statistically significant (p < 0.001).

CONCLUSION

S. aureus biofilm formation varies across exposure to different NO levels, with antibiofilm effects at higher concentrations, and enhanced biofilm formation at lower or subphysiologic concentrations. These results coincide with the often dualistic function of NO, and have implications in its future use in the treatment of CRS.

The impact of intraoperative saline irrigations on bacterial load within the maxillary sinus

BACKGROUND

Saline irrigations are routinely employed during endoscopic sinus surgery to remove mucous and debris from the sinus cavities. What is unknown is whether this results in a quantitative reduction in pathologic bacteria within the sinus mucosa. The objectives of this study were to quantify the amount of 5 different bacteria (Staphylococcus aureus, Haemophilus influenzae, Pseudomonas aeruginosa, coagulase-negative Staphylococcus (CNS), and Streptococcus pneumoniae) within the maxillary sinus and to determine the impact of saline irrigations on bacterial counts.

METHODS

Twenty patients with chronic rhinosinusitis were prospectively enrolled. After bilateral maxillary antrostomies, biopsies were taken of the maxillary sinus mucosa prior to any irrigation. In each patient, the left maxillary sinus was then irrigated with 250 cc of normal saline (NS) with a pressurized pulse-irrigation device and the right side was irrigated with 250 cc of NS using a 30-cc syringe attached to a curved suction tip. Repeat maxillary sinus mucosal biopsies were then taken from each side. Each biopsy was analyzed using quantitative polymerase chain reaction to determine the presence and amount of each of the bacteria.

RESULTS

Saline irrigations were found to significantly reduce the amount of S. aureus, P. aeruginosa, and S. pneumoniae found within the maxillary sinus mucosa. No difference was found for H. influenzae or CNS. No difference in bacterial load reduction was able to be shown between the pressurized saline flushes and manual saline rinse methods.

CONCLUSION

Intraoperative saline irrigations are able to significantly reduce the amount of potentially pathogenic bacteria within the diseased sinus mucosa.

Staphylococcus aureus biofilms: Nemesis of endoscopic sinus surgery

OBJECTIVES/HYPOTHESIS

Chronic rhinosinusitis (CRS) patients with biofilms have persistent postoperative symptoms, ongoing mucosal inflammation, and recurrent infections. Recent evidence suggests that biofilms of differing species confer varying disease profiles in CRS patients. We aimed to prospectively investigate the effects of Staphylococcus aureus, Pseudomonas aeruginosa, Haemophilus influenzae, and fungal biofilms on outcomes following endoscopic sinus surgery (ESS).

STUDY DESIGN

Prospective blinded study.

METHODS

In this prospective blinded study, 39 patients undergoing ESS for CRS assessed their symptoms preoperatively using internationally accepted standardized symptom scoring systems and quality-of-life measures (10-point visual analog scale, Sino-Nasal Outcome Test-20, global severity of CRS). Their sinonasal mucosa was graded (Lund-Kennedy scale) and extent of radiologic disease on computed tomography scans scored (Lund-McKay scale). Random sinonasal tissue samples were assessed for different bacterial species forming biofilms by using fluorescent in-situ hybridization and confocal laser microscopy. For 12 months after surgery, CRS symptoms, quality of life, and objective evidence of persisting disease were assessed by using the preoperative tools.

RESULTS

Different bacterial species combinations were found in 30 of 39 patients; 60% of these 30 biofilms were polymicrobial biofilms and 70% had S aureus biofilms. Preoperative nasendoscopy and radiologic disease severity were significantly worse in patients with multiple biofilms (P = .02 and P = .01, respectively), and they had worse postsurgery mucosal outcomes on endoscopy (P = .01) requiring significantly more postoperative visits (P = .04). Those with S aureus biofilms progressed poorly with their symptom scores and quality-of-life outcomes, with significant differences in nasendoscopy scores (P = .007).

CONCLUSIONS

S. aureus biofilms play a dominant role in negatively affecting outcomes of ESS with persisting postoperative symptoms, ongoing mucosal inflammation, and infections.

What is the origin of Staphylococcus aureus in the early postoperative sinonasal cavity?

BACKGROUND

Despite increasing evidence of a role for Staphylococcus aureus (S. aureus) biofilms in chronic rhinosinusitis (CRS), the origin of this organism in the postsurgical sinonasal cavity had been unclear. Recently, we suggested that the increased culture rate of S. aureus following endoscopic sinus surgery (ESS) may be related to biofilm activity. This study, therefore, was designed to evaluate the origin of early postoperative sinonasal S. aureus and assess the early postoperative outcomes in patients culture-positive for this organism.

METHODS

Twenty-nine patients undergoing ESS for medically-recalcitrant CRS were prospectively enrolled. A comprehensive intraoperative S. aureus screening protocol was followed for all patients (including swabs for culture and tissue for fluorescence in situ hybridization [FISH] S. aureus biofilm analysis); early postoperative management included endoscopically-guided swabs for culture in all patients.

RESULTS

Twenty of 29 (69.0%) patients cultured S. aureus postoperatively, of which 17 of 20 (85.0%) were screen-positive at surgery. Seven of 11 (63.6%) intraoperatively biofilm-positive but culture-negative patients progressed to culture S. aureus post-ESS. S. aureus culture was associated with selected poorer early post-ESS outcomes.

CONCLUSION

S. aureus persists in the sinonasal cavity despite ESS. The postoperative culture of sinonasal S. aureus in patients previously biofilm-positive but culture-negative may reflect the dynamic ability of S. aureus to adapt to the surgically-altered microenvironment with subsequent biofilm dispersal and release of planktonic clones.

Can bottle design prevent bacterial contamination of nasal irrigation devices?

BACKGROUND

Saline nasal irrigation is a mainstay in the medical management of chronic rhinosinusitis (CRS) with proven efficacy. However, bacterial contamination of irrigation bottles has recently been reported and this may contribute to recurrent infections. Sterilization is effective but could a change in bottle design obviate the need for regular sterilization?

METHODS

A total of 20 stable CRS patients were given a NasalCare® (Techworld Corporation, Inc., Downington, PA) irrigation bottle to use regularly for 1 week. This bottle incorporates a 1-way valve to prevent irrigant regurgitation. Swabs were taken from their sinonasal cavity and 3 sites on the bottle-nozzle, valve, and inner surface.

RESULTS

This study cultured a range of organisms from all sites of the bottle, including common CRS pathogens such as S. aureus, P. aeruginosa, and E. coli. Whereas the bottle's inner surface had the lowest bacterial recovery rate, the frequent culture of organisms at this site suggests a 1-way valve cannot completely prevent irrigant reflux. The high rate of organism detection at the nozzle and valve of the bottle is concerning, as bacteria at these sites may be transported to the nose during nasal douching.

CONCLUSION

Saline irrigation will continue to be an essential component of CRS management. However, despite employing a 1-way liquid valve in this study, nasal irrigation bottles can still become contaminated with bacteria. Thus, patient education, irrespective of bottle design, will be essential in preventing bacterial contamination of nasal irrigation devices. The results of our survey suggest this message is not getting across to our patients.

Prophylactic antibiotics in endoscopic sinus surgery: a short follow-up study

BACKGROUND

The study was designed to assess the usefulness of postoperative antibiotics in patients undergoing endoscopic sinus surgery (ESS).

METHODS

The effects of antibiotics in the postoperative period of ESS patients were evaluated in a prospective, randomized, double-blind, placebo-controlled study. Fifty patients were treated with amoxicillin/clavulanate for 2 weeks after ESS, while the other half received placebo. Preoperatively, the symptom, endoscopic, and CT scores were recorded. In the postoperative period, symptom and endoscopic scores were recorded on the 5th, 12th, 21st, and 30th days. In estimating the length of the blood crust formation episode, a Kaplan-Meier plot was used.

RESULTS

Seventy-five patients completed the study: forty in the antibiotic-treated group and thirty-five in the placebo group. On the 5th day, nasal obstruction and drainage were significantly better in the antibiotic-treated group. In addition, a statistically significant difference in the endoscopic scores was noted between the treatment and placebo groups on days 5 and 12.

CONCLUSION

The use of an antibiotic (amoxicillin/clavulanate) in the postoperative period is able to improve the outcome in the early blood crust healing phase: nasal obstruction and drainage are reduced and the endoscopic score objectively showed a faster recovery.

Different biofilms, different disease? A clinical outcomes study

OBJECTIVES/HYPOTHESIS

A potential role for biofilms in Chronic Rhinosinusitis (CRS) has been proposed, and the adverse impact they have on disease severity and postoperative outcomes has also been well described. Recent advances have allowed the species within the biofilms of CRS patients to be clearly characterized. This study investigates whether different biofilm species have different disease outcomes.

STUDY DESIGN

Retrospective review.

METHODS

Twenty-four patients with medically recalcitrant CRS undergoing Endoscopic Sinus Surgery (ESS), in whom we had previously characterized their biofilms using fluorescence in situ hybridization (FISH), were reviewed a median of 11 months after their surgery. They were evaluated for preoperative disease markers and evidence of on-going disease in the postoperative period.

RESULTS

Thirty-seven biofilms were identified in the 24 patients. Almost half had polymicrobial biofilms. The presence of polymicrobial, rather than single-species biofilms adversely affected preoperative disease severity but did not alter postsurgical outcome. Patients with single organism Haemophilus influenzae biofilms presented with mild disease symptomatically and radiologically and achieved normal mucosa a short time after their surgery. Conversely, patients with Staphlococcus aureus in their biofilm makeup had more severe disease and a more complicated postoperative course. The effect of Pseudomonas aeruginosa and fungal biofilms is less clear.

CONCLUSIONS

Different biofilm species are associated with different disease phenotypes. H. influenzae biofilms are typically found in patients with mild disease, whereas S. aureus is associated with a more severe, surgically recalcitrant pattern.