In Vitro and In Vivo Testing of Microbe Growth on Antimicrobial Nursing Scrubs

Around 5% to 10% of hospitalized patients develop a hospital-acquired infection (HAI). Scrubs are a potential vector of HAIs. To compare the antimicrobial characteristics of scrubs with and without an antimicrobial fabric coating, as tested in the laboratory (in vitro) and hospital (in vivo) environments. Two protocols were conducted to address the purpose. The in vitro protocol was a laboratory study that involved observing the microbe growth after inoculating coated and uncoated scrub fabric swatches with S. aureus and then processing them in moist and dry environments. The in vivo protocol was a clinical trial that measured microbe growth on coated and uncoated scrubs prior to and following nursing staff completing a 12-hr shift on an acute care unit, as measured by colony forming units (CFUs). For high-humidity environments, the in vitro study indicated that swatches treated with an antimicrobial coating exhibited minimal microbe growth, while untreated swatches exhibited significant microbe growth. For low-humidity environments, coated and uncoated swatches were all found to exhibit minimal microbe growth. In the in vivo study, the CFUs increased on scrubs worn by nurses over a 12-hr shift with no significant difference in CFUs for coated and uncoated scrubs. For bacteria in a warm and moist environment, the antimicrobial coating was found to be important for inhibiting growth. For bacteria in a warm and dry environment, both coated and uncoated fabrics performed similarly as measured at 24 hr, with minimal bacterial growth observed. In a hospital environment, microbe growth was observed, but no significant difference was detected when comparing coated and uncoated scrubs. This may have been due to the short time between exposure and culturing the scrubs for analysis immediately at the end of the shift not allowing for enough time to kill or inhibit growth. Contact time between the bacteria and scrub fabric (coated or uncoated) in the in vivo study more directly correlated with the 0-hr observations for the in vitro study, suggesting that the ineffectiveness of the treated scrubs in the clinical results may be due in part to short residence times before collection.