Disinfectant Efficacy Against Dry Surface Biofilms of Staphylococcus Aureus and Pseudomonas Aeruginosa Is Product, Time Point and Strain Dependent

Abstract

Background: Globally, healthcare associated infections (HAI) are the most frequent adverse outcome in healthcare delivery. Although bacterial biofilms contribute significantly to the incidence of HAI, few studies have investigated the efficacy of common disinfectants against dry surface biofilms (DSB). The objective of this study was to evaluate the bactericidal efficacy of seven disinfectants against DSB of Staphylococcus aureus and Pseudomonas aeruginosa. We hypothesized that overall, hydrogen peroxides, sodium dichloro-s-triazinetrione and quaternary ammonium compounds plus alcohol disinfectants will be more bactericidal against DSB than quaternary ammonium. We also hypothesized that regardless of differences in product chemistries, higher bactericidal efficacies against DSB will be exhibited after 24 h of dehydration compared to 72 h.Methods: Wet surface biofilms of S. aureus and P. aeruginosa were grown following EPA-MLB-SOP-MB-19 and dehydrated for 24 h and 72 h to establish DSB. Seven EPA-registered disinfectants were tested against dehydrated DSB following EPA-MLB-SOP-MB-20. Results: Overall, quaternary ammonium plus alcohol, sodium dichloro-s-triazinetrione, and hydrogen peroxide products were more efficacious against DSB than quaternary ammoniums for both tested strains. While there was no significant difference in biofilm killing efficacies between 24 h and 72 h S. aureus biofilms, significantly higher log10 reductions were observed when products were challenged with 24 h P. aeruginosa DSB compared to 72 h P. aeruginosa DSB. Conclusion: Strain type, active ingredient class, and dry time significantly impact disinfectant efficacy against DSB of S. aureus or P. aeruginosa.

Dry surface biofilms in the food processing industry: An overview on surface characteristics, adhesion and biofilm formation, detection of biofilms, and dry sanitization methods

“…Challenges and future trends among dry sanitization methods for LMF processing industries DSBs are more tolerant to cleaning and sanitization procedures than traditional biofilms (Nkemngong et al, 2021). Therefore, there is an increased demand for alternative sanitization methods (alcohol, hot air, UV-C light, PL, O 3 , and CAP) to eliminate pathogens and spoilage in the food industry.…”

“…Another important aspect is the stress response, since it can favor attachment mechanisms and microorganism survival on dry surfaces, which may then develop tolerance to different stresses (Karash & Yahr, 2022; Wang et al., 2022). These include starvation, dehydration stress (Nkemngong et al., 2020), osmotic stress, acid stress (Aviles et al., 2013), physical stress (Nkemngong et al., 2021), as well as pH and heat stress (Almatroudi et al., 2018). Thus, some species may become persistent cells, since induced stress can produce adaptive responses, allowing them to grow and disseminate resistance (Du et al., 2018; Fisher et al., 2017).…”

“…In addition, biofilm eradication through using wet sanitizers is difficult to achieve (Flemming et al, 2016;Ledwoch et al, 2018;Nkemngong et al, 2021). Wet cleaning protocols and wet-dry cycles may hydrate surfaces and favor bacterial growth under dry stress.…”

“…Preventing microbial attachment requires frequent intervals among unit operations, for cleaning and sanitization (Li et al., 2021). In addition, biofilm eradication through using wet sanitizers is difficult to achieve (Flemming et al., 2016; Ledwoch et al., 2018; Nkemngong et al., 2021). Wet cleaning protocols and wet–dry cycles may hydrate surfaces and favor bacterial growth under dry stress.…”

“…Wet cleaning protocols and wet–dry cycles may hydrate surfaces and favor bacterial growth under dry stress. Enabling slow growth rates of microbial cells can lead to a viable‐but‐nonculturable state (VBNC state), or other forms of growth dormancy, such as persistent cells, which are multidrug tolerant subpopulations (Flemming et al., 2016; Nkemngong et al., 2021).…”