Staphylococcus aureus dry-surface biofilms are more resistant to heat treatment than traditional hydrated biofilms

Almatroudi, Ahmad; Tahir, Shamaila; Hu, Honghua; Chowdhury, Durdana; Gosbell, Iain B; Jensen, Slade O.; Whiteley, Greg S.; Deva, Anand K.; Glasbey, Trevor; Vickery, Karen

doi:10.1016/j.jhin.2017.09.007

Cited by 64 publications

(68 citation statements)

References 29 publications

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“…Antibiotics have been reported to have reduced permeability in biofilm and the concentration of these agents against biofilms are estimated to be 1,000 times more than that required for planktonic cells. 28 Our present study indicated that the same concentration of phage would suffice for efficient activity on planktonic cells, as well as on biofilms.…”

Section: Discussionsupporting

confidence: 52%

Isolation, Characterization, and Comparison of Efficiencies of Bacteriophages to Reduce Planktonic and Biofilm-Associated Staphylococcus aureus

Rai

Vittal

Raj

2020

Journal of Health and Allied Sciences NU

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Introduction In the present era, wherein occurrence of antimicrobial resistance compounded with biofilms in disease conditions has rendered present antibiotic therapy ineffective, the need for alternative strategies to treat bacterial infections has brought bacteriophages to the forefront. The antimicrobial activity of phages is often determined by a viable cell reduction assay which focuses only on planktonic forms. The physiology of an organism in biofilm differs from those that are planktonic; hence, there is a need to evaluate the activity of phages both on planktonic forms, as well as on biofilms, to select candidate therapeutic phages. Methods Bacteriophages for Staphylococcus aureus were isolated from environmental samples and characterized based on growth kinetics and DNA fingerprint patterns. Activity of isolated phages on planktonic forms was determined by viable count reduction assay. Phage ability to prevent biofilm formation and ability to disperse formed biofilms were performed in 96-well microtiter plates and biofilm estimated by crystal violet assay. Results Four bacteriophages designated, that is, P3, PD1, PE1, and PE2, were isolated and characterized. Planktonic cells of S. aureus were found to be sensitive to phages PD1, PE1, and PE2. Phages PD1 and PE2 were efficient in preventing biofilm formation and phages PD1, PE1, and P3 were efficient in dispersing formed biofilms. Conclusion The ability of some phages to disperse biofilms effectively, while unable to show the same efficiency on planktonic cells, indicates that viable count reduction assay alone may not be a sufficient tool to imply bactericidal activity of bacteriophages, especially while trying to eradicate biofilms.

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Section: Discussionsupporting

confidence: 52%

Isolation, Characterization, and Comparison of Efficiencies of Bacteriophages to Reduce Planktonic and Biofilm-Associated Staphylococcus aureus

Rai

Vittal

Raj

2020

Journal of Health and Allied Sciences NU

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“…However, a study on the efficacy of hypochlorite against DSB found that this semi-dehydrated biofilm was more tolerant to hypochlorite than hydrated biofilm [11]. The water content of hydrated S. aureus biofilm grown in the CDC bioreactor is 90%, whilst that of DSB is 61% [21]. This lower water content, in combination with the thicker extracellular polymeric substances (EPS), may result in lower diffusion of biocides and hence contribute to biocide tolerance.…”

Section: Discussionmentioning

confidence: 99%

Effect of disinfectant formulation and organic soil on the efficacy of oxidizing disinfectants against biofilms

Chowdhury

Rahman

et al. 2019

Journal of Hospital Infection

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Background: Biofilms that develop on dry surfaces in the healthcare environment have increased tolerance to disinfectants. This study compared the activity of formulated oxidizing disinfectants with products containing active ingredients against Staphylococcus aureus dry-surface biofilm (DSB) alone. Methods: DSB was grown in the CDC bioreactor with alternating cycles of hydration and dehydration. Disinfectant efficacy was tested before and after treatment with neutral detergent for 30 s, and in the presence or absence of standardized soil. Biofilms were treated for 5 min with peracetic acid (Surfex and Proxitane), hydrogen peroxide (Oxivir and 6% H 2 O 2 solution) and chlorine (Chlorclean and sodium dichloroisocyanurate tablets). Residual biofilm viability and mass were determined by plate culture and protein assay, respectively. Findings: Biofilm viability was reduced by 2.8 log 10 for the chlorine-based products and by 2 log 10 for Proxitane, but these products failed to kill any biofilm in the presence of soil. In contrast, Surfex completely inactivated biofilm (6.3 log 10 reduction in titre) in the presence of soil. H 2 O 2 products had little effect against DSB. Biofilm mass removed in the presence and absence of soil was <30% by chlorine and approximately 65% by Surfex. Detergent treatment prior to disinfection had no effect. Conclusion: The additives in fully formulated disinfectants can act synergistically with active ingredients, and thus increase biofilm killing whilst decreasing the adverse effect of soil. It is suggested that purchasing officers should seek efficacy testing results, and consider whether efficacy testing has been conducted in the presence of biological soil and/or biofilm.

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“…While there is currently no standard for testing bactericidal efficacy of disinfectants against DSB [37], we elected to use the EPA's minimum six log 10 standard of wet surface biofilms as our model validation standard. A six log 10 density of DSB was achieved for S. aureus and P. aeruginosa.…”

Section: A Minimum Six Log 10 Density Of Dsb For Disinfectant Efficacmentioning

confidence: 99%

“…With regards to disinfectant efficacy testing against DSB, developing S. aureus and P. aeruginosa biofilms at near room temperatures could provide a more robust and challenging scenario for disinfectant efficacy testing and subsequent product registration with the EPA. Moreover, DSB are more tolerant to disinfection than wet surface biofilms [26,37]. While our study successfully developed a rapid in vitro model for growing DSB, it is limited in that multi-species biofilms were not studied to better mimic the real-world use of disinfectants.…”

Section: Mean Log 10 Densities For Dsb Explained By Epsmentioning

confidence: 99%

“…The tolerance to antimicrobial disinfectants has been principally associated with EPS, which can shield underlying cells from direct contact with antimicrobials [35,36]. Compared to wet surface biofilms, dry surface bacterial biofilms can be more tolerant to disinfection procedures [26,37]. However, while there is an official method for testing the bactericidal efficacy of disinfectants against wet surface biofilms [38], a comparable method for developing DSB for disinfectant efficacy testing in vitro has not been extensively developed.…”

Section: Introductionmentioning

confidence: 99%

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A rapid model for developing dry surface biofilms of Staphylococcus aureus and Pseudomonas aeruginosa for in vitro disinfectant efficacy testing

Nkemngong

Voorn

Li³

et al. 2020

Antimicrob Resist Infect Control

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Background: Bacterial biofilms persistent on dry environmental surfaces in healthcare facilities play an important role in the occurrence of healthcare associated infections (HAI). Compared to wet surface biofilms and planktonic bacteria, dry surface biofilms (DSB) are more tolerant to disinfection. However, there is no official method for developing DSB for in vitro disinfectant efficacy testing. The objectives of this study were to (i) develop an in vitro model of DSB of S. aureus and P. aeruginosa for disinfectant efficacy testing and (ii) investigate the effect of drying times and temperatures on DSB development. We hypothesized that a minimum six log 10 density of DSB could be achieved on glass coupons by desiccating wet surface biofilms near room temperatures. We also hypothesized that a DSB produced by the model in this study will be encased in extracellular polymeric substances (EPS). Methods: S. aureus ATCC-6538 and P. aeruginosa ATCC-15442 wet surface biofilms were grown on glass coupons following EPA MLB SOP MB-19. A DSB model was developed by drying coupons in an incubator and viable bacteria were recovered following a modified version of EPA MLB SOP MB-20. Scanning electron microscopy was used to confirm the EPS presence on DSB. Results: Overall, a minimum of six mean log 10 densities of DSB for disinfectant efficacy were recovered per coupon after drying at different temperatures and drying times. Regardless of strain, temperature and dry time, 86% of coupons with DSB were confirmed to have EPS. Conclusion: A rapid model for developing DSB with characteristic EPS was developed for disinfectant efficacy testing against DSB.

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Staphylococcus aureus dry-surface biofilms are more resistant to heat treatment than traditional hydrated biofilms

Cited by 64 publications

References 29 publications

Isolation, Characterization, and Comparison of Efficiencies of Bacteriophages to Reduce Planktonic and Biofilm-Associated Staphylococcus aureus

Isolation, Characterization, and Comparison of Efficiencies of Bacteriophages to Reduce Planktonic and Biofilm-Associated Staphylococcus aureus

Effect of disinfectant formulation and organic soil on the efficacy of oxidizing disinfectants against biofilms

A rapid model for developing dry surface biofilms of Staphylococcus aureus and Pseudomonas aeruginosa for in vitro disinfectant efficacy testing

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