1440. Prolonged Antimicrobial Durability of a Sodium Mercaptoethane Sulfonate (MeSNA) + Minocycline (M) + Rifampin (R) Combination in an In Situ Melting, Bioabsorbable Wrap for Preventing Tissue Expander Infections Following Breast Reconstruction Surgeries
Session: Poster Abstract Session: HAI: Surgical Site Infections
Friday, October 28, 2016
Room: Poster Hall
Background: Tissue expanders (TE) used in breast reconstruction following cancer surgery have reported infection rates ranging from 2.5-24%. Most of these infections occur within 90 days of TE insertion and hypothesized to be caused by post-operative colonization of the TEs. The common practice of peri-operatively irrigating surgical pockets with low-viscosity antibiotic solutions provides ineffective transient prophylaxis. We previously reported a novel method for prolonging prophylaxis via application of solid film (wrap) containing M/R at implantation that subsequently liquefied in situ (at 37⁰C) to a viscous fluid. Here we tested further addition of the cytoprotective agent, MeSNA, previously shown to reduce fibrous capsule formation around TE implants in animals, to the M/R wrap for its ability to further enhance antimicrobial durability in an in vitro model.

Methods: Antimicrobial gelatin-based wraps were formed containing no antibiotic, M (0.1%)/R (0.05%), MesNA (5%), and M (0.1%)/R (0.05%)/MeSNA (5%). One-cm diameter silicone disks cut from TEs were covered with wraps. The disks were incubated with 5x105 CFU/ml clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and multi-drug resistant Pseudomonas aeruginosa (MDR-PA) in broth containing physiologic concentrations of collagenase. The inoculum was replaced weekly with fresh inoculum for 2 weeks. Each week disks were harvested and adherent organisms enumerated.

Results: Control silicone disks and no-antibiotic gelatin-wrapped disks yielded about 5x104 cfu/disc of adherent bacteria for each challenge organism. Wraps containing M/R completely inhibited all challenge organisms from attaching to the silicone at 1 week (p<0.001), but breakthrough occurred at week 2 for MDR-PA (at a level of 5x103 CFU/mL). The 5% MeSNA wraps did not inhibit adherence of MRSA or MDR-PA, but M/R/MeSNA wraps completely inhibited attachment of both challenge organisms for 2 weeks (p<0.001). Incorporation of MeSNA visibly decreased the rate of enzymatic dissolution of the wraps.

Conclusion: Addition of MeSNA (the MeSNA/M/R combination) enhanced the durability of antimicrobial efficacy of the M/R antimicrobial wrap against MDR-PA in a physiologic in vitro model.

Joel Rosenblatt, PhD1, Ruth Reitzel, MS2, George M. Viola, MD, MPH3, Jesse Selber, MD4 and Issam Raad, MD, FIDSA, FSHEA2, (1)1515 Holcombe - Suite FCT12.6030, UT MD Anderson Cancer Center, Houston, TX, (2)Infectious Diseases, Infection Control & Employee Health, University of Texas MD Anderson Cancer Center, Houston, TX, (3)The University of Texas MD Anderson Cancer Center, Houston, TX, (4)University of Texas MD Anderson Cancer Center, Houston, TX

Disclosures:

J. Rosenblatt, the University of Texas MD Anderson Cancer Center: Inventor of the Caprylic Acid - Glycerol Trinitrate Combination Technology and Shareholder , licensed by Novel Anti-Infective Technologies, LLC in which UTMDACC, Dr. Raad and Dr. Rosenblatt are shareholders. and Licensing agreement or royalty

R. Reitzel, None

G. M. Viola, None

J. Selber, None

I. Raad, Merck: Grant Investigator , Grant recipient
Pfizer: Speaker's Bureau , Speaker honorarium
Allergan: Grant Investigator , Grant recipient

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