Comparative testing of disinfectant efficacy on planktonic bacteria and bacterial biofilms using a new assay based on kinetic analysis of metabolic activity

Abstract

Although bacterial biofilms are the predominant manner of bacterial colonization, most standard procedures for antimicrobial susceptibility testing and efficacy testing of disinfectants are adapted for application to planktonic bacteria. To our knowledge, this is the first study to use a newly developed microplate-based biofilm test system that uses kinetic analysis of the metabolic activity in biofilms, after disinfectant exposure, to evaluate disinfectant efficacy. Our study shows that findings obtained from disinfectant efficacy testing on planktonic bacteria cannot be extrapolated to predict disinfectant efficacy on bacterial biofilms of clinically relevant multidrug-resistant organisms.

Prevalence and Detection of qac Genes from Disinfectant-Resistant Staphylococcus aureus Isolated from Salon Tools in Ishaka Town, Bushenyi District of Uganda

“…Disinfectants susceptibility tests were done using the agar well diffusion method as described by Günther et al [ 26 ] with some modifications. The bacterial inocula were standardized with 0.5 McFarland standard solutions.…”

Biofilms in the Spotlight: Detection, Quantification, and Removal Methods

“…Different indicators of metabolic activity have been used to cover the different types of assays, one of which is XTT tetrazolium salt which, when converted to the strongly colored formazan, allows the metabolic activity of the cells forming the biofilm to be determined (Koban et al., ). Another indicator that can be used in this type of assay is resazurin, a blue dye that turns pink when it is reduced by the metabolically active cells within the biofilms (O'Brien et al., ), the measurement of which can be used to quantify the viability of the biofilm (Alonso, Cruces, Perez, Fernandez‐Cruz, & Guembe, ; Günther, Scherrer, Kaiser, DeRosa, & Mutters, ; Welch et al., ).…”

Ability of chlorhexidine, octenidine, polyhexanide and chloroxylenol to inhibit metabolism of biofilm-forming clinical multidrug-resistant organisms

“…Consistent application of standard infection control measures has been shown to reduce the likelihood of VRE infection in susceptible patients, resulting in the development of recommendations to adequately disinfect the environment (Mutters et al, 2013). In a study by Günther and colleagues, octenidine (OCT) and CHG inhibited MRSA within biofilms, but mupirocin, polyhexanide, and chloroxylenol did not show clinically relevant antimicrobial activity (Gunther et al, 2017b). The greatest bactericidal effects have been reported for CHG (log10 reduction of 9) (Gunther et al, 2017b).…”