Preliminary Efficacy Testing of the Disinfectant MicrobeCare XLP for Potential Use in Military Operational...

A safe, easy-to-use, permanently bonded antiseptic that does not require post-exposure bioload reduction but maintains effectiveness over time would have far-reaching implications across multiple industries. Health care is one such arena, particularly in austere military settings where resources are at a premium. MicrobeCare XLP (MicrobeCare, Buffalo Grove, IL, USA) is a commercially available spray-on agent that is advertised to covalently bond to surfaces and provide a long-lasting antimicrobial coating inhospitable to >99.99% of surface microorganisms. A pilot study was devised to gather baseline data regarding product efficacy and laboratory parameters before consideration of extended investigations and military utilization. The product manufacturer recommends bioload reductions before product application, following product application, and after each pathogenic exposure. To investigate the product's efficacy in circumstances more closely simulating a military operational setting in which post-pathogenic exposure bioload reduction would not be possible, this step was deliberately excluded from the test sequences.

Using autoclaved surgical forceps, growth of Staphylococcus aureus and Acinetobacter baumannii was evaluated in a controlled manner under multiple conditions. Test variations included duration of submersion in the MicrobeCare XLP solution and air-drying and a second autoclave sterilization. Control and treated forceps were exposed to a bacterial suspension and air-dried before being submerged in sterile saline and vortex mixed. The saline solution was serially diluted and plated on tryptic soy agar (TSA) II plates. Plates were incubated for 24 h and bacterial colony-forming units (CFU)/mL were counted.

Statistical significance was defined according to the American Society for Testing and Materials (ASTM) International passing criteria of 3 Log10 or 99.9% reduction of microorganisms. Additionally, p-values were calculated using two-tailed unpaired two-sample t-tests with unequal variance with a threshold of 0.05. In the S. aureus tests, none of the reduction calculations met the ASTM International passing criteria. In addition, the difference between the means of the colony counts in the MicrobeCare XLP-treated forceps and untreated control forceps was not statistically significant (p-value 0.109). Conversely, in the A. baumannii tests, each of the percent reduction calculations met the ASTM International passing criteria; the difference between the means of the colony counts in the treatment and control groups was statistically significant (p-value 0.008).

In these independent tests, MicrobeCare XLP effectively prevented growth of A. baumannii but had unpredictable results suppressing S. aureus. These results may relate to inherent properties of the bacteria or autoclave exposure, although the manufacturer asserts that the coating withstands such degradation. Additional testing could be performed using a broader range of microorganisms and exposure to varying conditions including other sterilization methods.