A fluorescent method for assessing the antimicrobial efficacy of disinfectant against Escherichia coli ATCC 35218 biofilm

Abstract

In this study, a versatile method was developed to assess biocide efficacy against Escherichia coli biofilm growth on carriers made of five different materials. The glucuronidase activity of live E. coli on a fluorogenic substrate (4-methylumbellyferyl-beta-D-glucuronide, MUG) was used as a viability test. Fluorescence emissions from cellular suspensions of E. coli in the test range displayed a linear response with a MUG concentration of 10 microg ml(-1). A glucuronidase activity curve with cellular suspensions of E. coli calculated as colony-forming units per milliliter showed a good correlation (0.9487 and 0.917 for 1 and 18 h of incubation, respectively), with counts obtained from biofilm containing this organism; E. coli cultures in suspension were used as standard. Three agents commonly used as disinfectants, sodium hypochlorite, hydrogen peroxide, and ethanol, were tested at use concentrations and at one-half and decimal dilutions. At decimal dilutions, ethanol at 70% proved to be the least active disinfectant on E. coli biofilm. Unlike other methods, our method permits the testing of disinfectant efficacy against biofilm growth on different materials. In preliminary assays, glass, polyvinyl chloride, polypropylene, polycarbonate, and silicon were tested. Because they gave the lowest E. coli counts after 24 and 48 h, glass and polypropylene were the two materials to which biofilm adhered least strongly.

Damage of Candida albicans blastoconidia exposed to biocides

“…At present, we have only limited information on the mechanism of action of disinfectants and antiseptics against pathogenic fungi 2–4,8 . Also, only a few studies have been conducted to elucidate the bactericidal mechanism of biocides 3,9–13 . These researchers described similar damage in the fine structure of bacterial cells that were exposed to biocides 1,3 …”

“…[2][3][4]8 Also, only a few studies have been conducted to elucidate the bactericidal mechanism of biocides. 3,[9][10][11][12][13] These researchers described similar damage in the fine structure of bacterial cells that were exposed to biocides. 1,3 The blastoconidia of the strains C. albicans 24 (Lc-LYS -0.02%, Lc-ILS -20%) and C. albicans 28 (Lc-LYS 0.32%, Lc-ILS 80%) exhibited diversified susceptibility to LYS and ILS and the reason of this difference is still not understood.…”

New Device for High-Throughput Viability Screening of Flow Biofilms

“…However, there are other possibilities. For example, the LIVE/DEAD stain is accurate for determination of viability where the level of killing is high, which is often the goal of HTP screening; another possibility is to use a fluorogenic substrate, such as 4-methylumbellyferyl-␤-D-glucuronide (28), to measure biofilm metabolic activity. The BioFlux device is also likely to be useful in HTP screening of other biofilm parameters.…”

“…Methods have been developed for HTP screening of the viability of static biofilms (6,28,32,33), but there are no methods for HTP screening of flow biofilms. The latter biofilms are typically grown in flow cells, which have to be examined individually to determine viability and thus cannot be used for rapid screening.…”

Rapid detection of rRNA group I pseudomonads in contaminated metalworking fluids and biofilm formation by fluorescent in situ hybridization

“…Microorganisms growing within the biofilm are protected from the surrounding environment and are highly tolerant to different disinfection methods. Once established within the system, the biofilms also serve as continuous sources of contamination of MWFs (Mariscal et al 2007).…”