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

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.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.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.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.