Antimicrobial Susceptibility of Persister Biofilm Cells of Bacillus cereus and Pseudomonas fluorescens

Fernandes, Susana; Gomes, Inês B.; Sousa, Sérgio F.; Simões, Manuel

doi:10.3390/microorganisms10010160

Cited by 20 publications

(12 citation statements)

References 45 publications

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“…However, 6.4 log 10 CFU/mL have still been able to recover from the BAC MBC concentration, suggesting that a fraction of the dormant cells were able to resuscitate and regain culturability. Indeed, in the work of Fernandes et al [ 41 ], it was reported that P. fluorescens persister cells were also able to recover after biocide (BAC) removal and nutrient re-establishment. Although in that paper, persisters’ formation resulted from the BAC effects on 48 h old biofilm cells, and the contact time and concentration used were different from those of the present study, a similar trend was observed.…”

Section: Resultsmentioning

confidence: 99%

Pseudomonas fluorescens Cells’ Recovery after Exposure to BAC and DBNPA Biocides

2022

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A proper assessment of the effects of biocides on bacterial cells is key to the prevention of antimicrobial resistance and the implementation of suitable biocidal programmes. It is particularly relevant regarding the ability of dead-labelled cells to recover their functional processes once the biocide is removed. In the present work, we studied how Pseudomonas fluorescens cells previously exposed to different concentrations of BAC (benzalkonium chloride) and DBNPA (2,2-Dibromo-3-nitrilopropionamide) behave upon the restoration of optimum growth conditions. The following indicators were evaluated: culturability, membrane integrity, metabolic activity (resazurin), cellular energy (ATP), and cell structure and morphology (transmission electron microscopy (TEM)). The results demonstrated that cells previously labelled as ‘dead’ recovered to a greater extent in all indicators. Only cells previously exposed to BAC at 160 mg/L (concentration above the MBC) showed significant reductions on all the evaluated indicators. However, the obtained values were much higher than the ‘death’ thresholds found for the autoclaved cells. This suggests that cells exposed to this concentration take more time to rebuild their functional processes. The recovery of DBNPA-treated cells did not seem to be related to the biocide concentration. Finally, a reflection on what kind of cells were able to recover (remaining cells below the detection limit and/or dormant cells) is also presented.

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Section: Resultsmentioning

confidence: 99%

Pseudomonas fluorescens Cells’ Recovery after Exposure to BAC and DBNPA Biocides

2022

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“…Within their natural habitats, bacteria are usually organized in multi-layered biofilms, in which individual cells are often more resistant towards harsh environmental conditions such as cleaning and disinfection procedures [ 6 , 23 , 33 , 34 , 35 ]. However, current standards for the evaluation of disinfectants, and therefore recommended user concentrations, are based on efficacy testing against planktonic bacteria either in suspension or fixed to a surface, rather than against biofilms.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Biofilm Cultivation Models for Efficacy Testing of Disinfectants against Salmonella Typhimurium Biofilms

et al. 2023

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Within the European Union, Salmonella is frequently reported in food and feed products. A major route of transmission is upon contact with contaminated surfaces. In nature, bacteria such as Salmonella are often encountered in biofilms, where they are protected against antibiotics and disinfectants. Therefore, the removal and inactivation of biofilms is essential to ensure hygienic conditions. Currently, recommendations for disinfectant usage are based on results of efficacy testing against planktonic bacteria. There are no biofilm-specific standards for the efficacy testing of disinfectants against Salmonella. Here, we assessed three models for disinfectant efficacy testing on Salmonella Typhimurium biofilms. Achievable bacterial counts per biofilm, repeatability, and intra-laboratory reproducibility were analyzed. Biofilms of two Salmonella strains were grown on different surfaces and treated with glutaraldehyde or peracetic acid. Disinfectant efficacy was compared with results for planktonic Salmonella. All methods resulted in highly repeatable cell numbers per biofilm, with one assay showing variations of less than 1 log10 CFU in all experiments for both strains tested. Disinfectant concentrations required to inactivate biofilms were higher compared to planktonic cells. Differences were found between the biofilm methods regarding maximal achievable cell numbers, repeatability, and intra-laboratory reproducibility of results, which may be used to identify the most appropriate method in relation to application context. Developing a standardized protocol for testing disinfectant efficacy on biofilms will help identify conditions that are effective against biofilms.

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“…High cell density is required to have QS level impacting on cell signalling, gene expression and physiological changes in neighbouring cells [ 35 – 37 ]. (iv) Presence of persister cells which are metabolically inactive bacteria scattered through the biofilms, but different from the dormant bacterial cell population as a result, for example, of reduced access to nutrient or oxygen [ 38 , 39 ]. It has been suggested that these cells are responsible for biofilm regrowth following biocide exposure [ 38 , 39 ].…”

Section: Bacteria In Hydrated Biofilms Are More Resilient Than Plankt...mentioning

confidence: 99%

“…(iv) Presence of persister cells which are metabolically inactive bacteria scattered through the biofilms, but different from the dormant bacterial cell population as a result, for example, of reduced access to nutrient or oxygen [ 38 , 39 ]. It has been suggested that these cells are responsible for biofilm regrowth following biocide exposure [ 38 , 39 ]. (v) Extracellular enzymatic degradation of antimicrobials [ 40 ].…”

Section: Bacteria In Hydrated Biofilms Are More Resilient Than Plankt...mentioning

confidence: 99%

How biofilm changes our understanding of cleaning and disinfection

Maillard,

Centeleghe

2023

Antimicrob Resist Infect Control

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Biofilms are ubiquitous in healthcare settings. By nature, biofilms are less susceptible to antimicrobials and are associated with healthcare-associated infections (HAI). Resistance of biofilm to antimicrobials is multifactorial with the presence of a matrix composed of extracellular polymeric substances and eDNA, being a major contributing factor. The usual multispecies composition of environmental biofilms can also impact on antimicrobial efficacy. In healthcare settings, two main types of biofilms are present: hydrated biofilms, for example, in drains and parts of some medical devices and equipment, and environmental dry biofilms (DSB) on surfaces and possibly in medical devices. Biofilms act as a reservoir for pathogens including multi-drug resistant organisms and their elimination requires different approaches. The control of hydrated (drain) biofilms should be informed by a reduction or elimination of microbial bioburden together with measuring biofilm regrowth time. The control of DSB should be measured by a combination of a reduction or elimination in microbial bioburden on surfaces together with a decrease in bacterial transfer post-intervention. Failure to control biofilms increases the risk for HAI, but biofilms are not solely responsible for disinfection failure or shortcoming. The limited number of standardised biofilm efficacy tests is a hindrance for end users and manufacturers, whilst in Europe there are no approved standard protocols. Education of stakeholders about biofilms and ad hoc efficacy tests, often academic in nature, is thus paramount, to achieve a better control of biofilms in healthcare settings.

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Antimicrobial Susceptibility of Persister Biofilm Cells of Bacillus cereus and Pseudomonas fluorescens

Cited by 20 publications

References 45 publications

Pseudomonas fluorescens Cells’ Recovery after Exposure to BAC and DBNPA Biocides

Pseudomonas fluorescens Cells’ Recovery after Exposure to BAC and DBNPA Biocides

Evaluation of Biofilm Cultivation Models for Efficacy Testing of Disinfectants against Salmonella Typhimurium Biofilms

How biofilm changes our understanding of cleaning and disinfection

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