Duke:

The two abstract below may be of some significant help in explaining
why you want to rinse with Bactorban (Mupirocin) and why you think it
might be effective..
Good luck,

Michael

1: Laryngoscope. 2007 Dec 3 [Epub ahead of print]Click here to read
Links
   In Vitro Activity of Mupirocin on Clinical Isolates of
Staphylococcus aureus and its Potential Implications in Chronic
Rhinosinusitis.
   Ha KR, Psaltis AJ, Butcher AR, Wormald PJ, Tan LW.

   From the Department of Surgery-Otorhinolaryngology Head and Neck
Surgery (k.r.h., a.j.p., p.-j.w., l.w.t.), The University of Adelaide,
Adelaide, South Australia; and the Department of Microbiology
(a.r.b.), The Queen Elizabeth Hospital, Adelaide, South Australia.

   BACKGROUND:: It has been postulated that bacterial biofilms are
involved in the pathogenesis of chronic rhinosinusitis (CRS). Biofilms
present on sinus mucosa are difficult to eradicate with conventional
antibiotic therapy and are thought to provide a nidus for recurrent
infection. Topical delivery of antibiotics via nasal irrigation may
present a way of delivering high concentrations of antibiofilm agents
with potentially low systemic absorption and side effects. This study
investigates the effectiveness of mupirocin and two other antibiotics,
ciprofloxacin and vancomycin, on established in vitro biofilms of
Staphylococcus aureus isolated from patients with CRS. METHODS:: S.
aureus American Type Culture Collection 25923 and 12 clinical isolates
were investigated for their ability to form biofilms in an in vitro
setting using a 96 well microtiter crystal violet (CV) plate assay and
confocal scanning laser microscopy (CSLM). Antimicrobial
susceptibility tests to determine minimum inhibitory concentrations
were performed on planktonic and biofilm forming strains. In addition,
established biofilms were subjected to the antimicrobial agents at a
twofold dilution series. A CV analysis of biofilm mass was performed
after 1 and 24 hours of treatment, and minimum biofilm inhibition
concentrations at 50% (MIB50) and 90% (MIB90) biofilm inhibition were
recorded. RESULTS:: With use of a 96-well microtiter plate CV assay, 8
of the 12 clinical isolates formed mature biofilms after 8 days of
culture. These results correlated with findings from CSLM analysis of
in vitro biofilms grown on Permanox chamber slides. Increased
antimicrobial resistance was observed in the biofilm isolates when
compared with planktonic counterparts. Mupirocin was capable of
reducing biofilm mass by greater than 90% at concentrations of 125 mug/
mL or less in all S. aureus isolates. Ciprofloxacin and vancomycin
were largely ineffective in attaining MIB90 concentrations within safe
dosage ranges. CONCLUSIONS:: The topical application of mupirocin via
nasal irrigation may be useful in eliminating S. aureus biofilms
present on the sinus mucosa of patients with CRS and may offer an
additional treatment to patients with recalcitrant sinusitis.

   PMID: 18090864 [PubMed - as supplied by publisher]

1: Am J Rhinol. 2007 Mar-Apr;21(2):149-53.Click here to read Links
   Effectiveness of topical antibiotics on Staphylococcus aureus
biofilm in vitro.
   Desrosiers M, Bendouah Z, Barbeau J.

   Department of Otolaryngology-Head and Neck Surgery, University of
Montreal, Montreal, Canada. desrosiers_martin@hotmail.com

   BACKGROUND: In vitro biofilm-producing capacity in isolates of
Staphylococcus aureus and Pseudomonas aeruginosa collected from the
sinus cavities after endoscopic sinus surgery (ESS) are associated
with a poor outcome in patients with chronic rhinosinusitis (CRS).
However, conventional oral antibiotic therapy is frequently
ineffective in eradicating bacteria in the biofilm form. Increasing
the concentration of antibiotics may offer a means of countering this
resistance. The aim of this study was to determine the in vitro
activity of moxifloxacin (MOXI) against S. aureus in biofilm form
(recovered from patients with CRS at least 1 year post-ESS). METHOD:
This study was performed in a research microbiology laboratory, where
five isolates of S. aureus with known biofilm-forming capacity were
cultured in Tryptic Soy Broth 0.5% glucose in 96-well plates at 37
degrees C for 24 hours. After visual confirmation of biofilm
formation, plates were incubated in phosphate-buffered saline (PBS) or
with MOXI at concentrations of 0.1x, Ix, 100x, and 1000x minimal
inhibitory concentration (MIC) for an additional 24 hours. Biofilm
from 3 wells of each concentration were collected and sonicated and
the number of viable bacteria was determined by serial dilution and
plating. RESULTS: After incubation, the number of viable bacteria was
similar for nontreated and MOXI-treated biofilms at MIC and sub-MIC
levels. However, MOXI at 1000x (0.1-0.2 mg/mL) gave a 2 to 2.5 log
reduction in number of viable bacteria. CONCLUSION: In vitro results
show that increased concentrations of antibiotics, easily attainable
in topical solutions, are effective in killing bacteria in bacterial
biofilms. This suggests a role for topical antibiotic therapies in the
treatment of biofilm infections.

   PMID: 17424869 [PubMed - indexed for MEDLINE]