Shubhangi Bhende

In Vitro Antimicrobial Activity of Oxidized Regenerated Cellulose Against Antibiotic-Resistant Microorganisms

BACKGROUND The emergence of multi-drug resistant microorganisms presents a critical problem for patients undergoing surgery. Acidic pH, which is produced by oxidized regenerated cellulose (ORC), is a broad-spectrum physiological detriment to survival of microorganisms known to cause surgical infections. The purpose of this study was to examine the antimicrobial effect of ORC against antibiotic-resistant organisms. METHODS ORC products were challenged with ATCC reference strains and clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE), vancomycin-resistant Enterococcus (VRE), penicillin-resistant Streptococcus pneumoniae (PRSP), and non-resistant ATCC strains of S. aureus and Pseudomonas aeruginosa. Samples of three ORC products (SURGICEL absorbable hemostat, SURGICEL Fibrillar absorbable hemostat, and SURGICEL NU-KNIT absorbable hemostat and identified, respectively, as ORC-R, ORC-F, and ORC-N for this study) were inoculated with challenge organisms in nutrient broth to produce a weight to volume ratio of 15 mg ORC/mL. Plate counts were performed at 0, 1, 6, and 24 h. RESULTS Antimicrobial activity was seen with all three ORC products against the challenge organisms. Data indicate that antibiotic-resistant microorganisms remain susceptible to the antimicrobial activity of ORC. In testing with nine of 10 bacteria, including four antibiotic-resistant clinical isolates (VRE, MRSA, and PRSP) three-log or greater reductions were seen at 24-h exposure. One ATCC strain of VRE demonstrated some level of resistance to the acidic pH effect. ORC-N showed a three-log reduction with this organism, whereas the reductions with ORC-R and ORC-F were less than one log. CONCLUSION Since low pH affects a relatively broad-spectrum of bacteria and does not act in a mechanism-specific manner, as do antibiotics, antibiotic-resistant strains of bacteria are unlikely to resist the ORC pH effect. Results of this in vitro assessment support the hypothesis that the antimicrobial activity of ORC is effective against antibiotic-resistant microorganisms.

In Vitro Assessment of Microbial Barrier Properties of Dermabond® Topical Skin Adhesive

BACKGROUND Several different techniques are used for wound closure. Cyanoacrylate tissue adhesives are less invasive and easy to apply, and the cosmetic results are comparable to or better than the conventional methods for wound repair. The purpose of this study is to demonstrate that Dermabond Topical Skin Adhesive, 2-octylcyanoacrylate (a registered trademark of Ethicon) is an effective barrier against the penetration of microorganisms in an in vitro model. MATERIALS AND METHODS Octylcyanoacrylate adhesive was evaluated in vitro as a barrier to microbial penetration using a strike through test. Agar media containing pH sensitive dye was used. The dye changed color in the presence of acidic microbial metabolic products. Octylcyanoacrylate adhesive was applied to the agar surface to form uniformly thick films. A total of 300 single layered films and an additional 300 triple layered films were evaluated. A 10-microL aliquot of inoculum containing at least 1x10(3) cfu was applied to the surface of each film. Plates were incubated at 37 degrees C for 72 h and were observed for growth and color change every 24 h during the incubation period. RESULTS A series of binomial calculations were performed, varying the level of effectiveness of the test and the level of statistical confidence. Of the 600 test articles evaluated, 598 retained their patency at the end of 72 h. One individual test film was invalidated due to extrinsic contamination. The data presented indicated that octylcyanoacrylate tissue adhesive provided a barrier to microbial penetration with 95% confidence of 99% efficacy for 72 h in this in vitro model. CONCLUSION The results of these in vitro experiments supported the hypothesis that octylcyanoacrylate tissue adhesive is an effective barrier to microbial penetration by gram-positive and gram-negative motile and nonmotile species.

In vitro assessment of chlorhexidine gluconate-impregnated polyurethane foam antimicrobial dressing using zone of inhibition assays.

OBJECTIVE To evaluate an antimicrobial dressing consisting of hydrophilic polyurethane foam with chlorhexidine gluconate for activity against several antibiotic-resistant clinical isolates as well as American Type Culture Collection reference strains using zone of inhibition assays. METHODS Sterile foam samples with chlorhexidine gluconate and untreated controls were transferred onto inoculated agar plates. Plates were incubated at 35 degrees C to 37 degrees C for 24 hours and examined for zones of inhibition around the foam samples. RESULTS Polyurethane foam with chlorhexidine gluconate showed antimicrobial activity in vitro against all of the challenge organisms including antibiotic-resistant clinical isolates. CONCLUSION The data from this in vitro study support the hypothesis that polyurethane foam with chlorhexidine gluconate has an antimicrobial effect against antibiotic-resistant Staphylococcus and Enterococcus species, as well as Candida species.