Mohamad R. Taha, BSA1 and Stephen K. Tyring, MD, PhD, MBA2,3

1School of Medicine, Texas A&M University Health Science Center, Bryan, TX, USA
2Center for Clinical Studies, Webster, TX USA
3Dermatology Department, University of Texas Health and Sciences Center at Houston, Houston, TX, USA

Conflict of interest: The authors declare that there are no conflicts of interest.
Funding sources: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Abstract:
A biofilm is a diverse community of microorganisms enclosed in an extracellular matrix. Although this organization of cells exists naturally in healthy skin, it is also involved in the pathogenesis of multiple skin disorders, such as acne and atopic dermatitis. Because biofilms provide microorganisms with a survival advantage and increased resistance to traditional antibiotics, they can be very difficult to treat, particularly when the goal is to also preserve the natural skin microbiota. This review aims to provide an overview of the role of biofilms in various dermatological diseases, as well as the conventional and newly developed therapies that can be used in their treatment.

Keywords: acne, atopic dermatitis, biofilms, dermal fillers, hidradenitis suppurativa, onychomycosis, chronic wounds

Introduction

Biofilms are a collection of microbial cells encased in a polymeric substance matrix.1,2 Biofilms can range in population from tens of cells to hundreds of thousands, and can encompass multiple species of organisms.3 The first step in its formation involves the attachment of the microorganism to a living or abiotic surface.3 The cells can then begin secreting extracellular components of the matrix, including polysaccharides, DNA, proteins, and lipids.3,4 This is followed by a maturation stage, with the formation of a stable, three-dimensional community that allows for the movement of nutrients and signaling particles within the biofilm.5

Biofilms provide cells with increased protection from desiccation, chemical perturbation, and invasion from other microorganisms.6 They can also reduce the susceptibility of bacteria to antibiotics by up to 1000 fold, due to reduced antibiotic penetration and the presence of metabolically dormant, antibiotic resistant persister cells, which can recolonize the biofilm following antibiotic administration.7 Biofilms can also alter the growth kinetics of bacteria, where cells deeper within the polymer are in a stationary phase of growth, which β‐lactam antibiotics are less effective against.7 These factors provide bacteria and certain species of fungi with a survival advantage compared to organisms in the planktonic state, which is the free floating state of microorganisms.3

Acne

The pathogenesis of acne is complex, involving inflammation of the pilosebaceous unit, as well as hyperkeratinization, androgen induced increase in sebum, and colonization of the follicle by Cutibacterium acnes (C. acnes).8,9 The C. acnes genome was shown to encode genes for the synthesis of extracellular polysaccharides, an essential component of biofilms.3 In one study, over 50% of antibiotic treated patients were found to be colonized with erythromycin and clindamycin resistant strains, and over 20% of them had tetracycline resistant acne.8 Biofilms are one factor for this increased resistance to antibiotics observed in patients with severe acne.8 For example, in vitro studies showed that significantly higher concentrations of cefamandole, ciprofloxacin, and vancomycin were needed to inhibit C. acnes biofilms compared to free floating bacteria.8 In another study, C. acnes biofilms were less sensitive compared to planktonic bacteria to a range of antimicrobials, such as 0.5% minocycline, 1% clindamycin, 0.5% erythromycin, 0.3% doxycycline, 0.5% oxytetracycline and 2.5-5% benzoyl peroxide.8

One hypothesis for the pathogenesis of acne is the formation of the comedone, which is a collection of keratin and sebum in the pilosebaceous unit caused by the hyperproliferation of keratinocytes in the follicular lining.9 Biofilms are thought to increase the cohesiveness between keratinocytes, which promotes the formation of the comedone and enables C. acnes to strongly attach itself to the follicular epithelium.9 Following the hyperproliferation of keratinocytes, the comedone grows with debris and releases its immunogenic contents into the surrounding dermis.9 As a result, proinflammatory cytokines can infiltrate the pilosebaceous unit and promote the development of inflamed pustules and papules seen in acne.9

In addition to certain antibiotics and antimicrobial peptides, agents that can specifically target biofilms in acne include surfactants such as rhamnolipids, which are produced by Pseudomonas aeruginosa (P. aeruginosa) and can dysregulate biofilms by creating central hollow cavities.9,10 Surfactants can also be used to weaken the adhesion of biofilms to surfaces and promote their dispersal.11 Quorum sensing (QS) plays an important role in the formation and maintenance of biofilms.11 By altering microbial gene expression, they can promote the transformation from the planktonic state into a sessile form.11 The use of QS inhibitors such as azithromycin, bergamottin, usnic acid, quercetin, and ellagic acid may help inhibit C. acnes virulence factors and biofilm formation.9,10 Moreover, dispersin B and deoxyribonuclease (DNase) can be employed to degrade biofilm proteins, while metal chelators can be used to bind to magnesium and calcium in the outer cell wall, which disrupts the stability of the biofilm.10 Nitric oxide generating agents can also be used to decrease intracellular cyclic dimeric guanosine monophosphate levels, which leads to a favoring of the planktonic state over the formation of biofilm.10 Finally, bacteriophage therapy specifically directed against C. acnes, has proved to be successful in the animal model and is an exciting new therapy that has been studied more extensively in other diseases such as meningitis, but not in the treatment of skin conditions.10

Atopic Dermatitis

Atopic dermatitis (AD) is present in 10% of children and 7% of adults in the United States. Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) are the two most commonly found bacteria in AD lesions, and are also known to form biofilms12-14 In a study of 40 patients with AD, 93% of biopsied lesions contained staphylococci, with 85% being strong producers of biofilms.15 Bacteria naturally colonize the epidermis, forming biofilms between squamous epithelial cells even in healthy skin.12 In AD however, S. aureus and other pathogens enhance inflammation and weaken the skin barrier.12,13,16 Although staphylococci natrally colonize the skin, those associated with biofilms have only been found in AD lesions.12 Moreover, S. aureus can cause keratinocytes to undergo apoptosis when present as biofilms but not in the planktonic state.12 This is significant to the pathogenesis of AD, as damaged keratinocytes release double-stranded RNA (dsRNA), which initiates the toll-like receptor (TLR)-3-mediated secretion of thymic stromal lymphopoietin (TSLP), a cytokine that causes a strong itch response.12 TSLP also activates dermal dendritic cells and recruits T helper 2 cells, which subsequently produce interleukin (IL)-4 and IL-13, leading to the inhibition of adenosine monophosphate (AMP) and further weakening immunity against pathogens.12 Bacterial biofilms can also result in the blockage of eccrine sweat glands and ducts, causing further inflammation or potentially inducing the inflammation and pruritus observed in AD.12,17

Traditional treatment of AD does not typically involve the use of antibiotics due to their insufficient specificity and risk of promoting antibiotic resistant bacteria.18 In terms of reducing inflammation in AD, a major goal of treatment is the improvement of dysbiosis, which involves reducing the population of S. aureus.18 Sodium hypochlorite bleach baths are helpful for improving clinical AD symptoms by limiting bacterial colonization and restoring skin surface microbiome. In vitro and in vivo investigations have provided evidence of efficacy, with one study demonstrating significant anti-staphylococcal and anti-biofilm activity when used at a concentration of 0.02% compared to the standard recommendation of 0.005%.18,19 There is also evidence supporting the topical use of farnesol and xylitol in supressing the formation of biofilms.14,20 Additionally, use of emollients can improve skin hydration and decrease pH, which may play a role in preventing S. aureus proliferation, with some studies suggesting a decreased incidence of AD in susceptible individuals after consistent emollient use.19 One of the novel treatments currently being developed to specifically target S. aureus in AD lesions is Staphefekt™, an engineered bacteriophage endolysin with bactericidal activity towards S. aureus.18 Other potential new therapies include synthetic antimicrobial peptides that target staphylococci as well as their biofilms, and omiganan, an indolicidin analog was found to improve microbial dysbiosis as well as clinical scores in phase II trials in the treatment of AD lesions.18 Finally, dupilumab and ultraviolet-B (UVB) therapy also exhibited efficacy in decreasing S. aureus colonization, while increasing the bacterial diversity in AD patients.18

Wounds

Wounds are particularly susceptible to the formation of biofilms due to the absence of the protective covering of the skin.21 S. aureus, P. aeruginosa, and the Clostridiales family are among the most common biofilm-forming bacteria found in wound infections.4,22 In chronic wounds, the healing process is impaired due to multiple factors that result in a constant state of inflammation.23,24 These wounds are characterized by the presence of proinflammatory cytokines such as tumor necrosis factor alpha and IL-1 alpha.23 One element that contributes to this state of chronic inflammation and recruits inflammatory cells is biofilm formation in the initial wound.23,25 These inflammatory cells then secrete proteases and reactive oxygen species that delay the healing process.23 In some cases, extensive use of antimicrobials, particularly in doses under the minimum inhibitory concentrations required for the infectious agent, promotes biofilm formation.4

Debridement is essential in the initial management of chronic wounds, including the removal of necrotic tissue and biofilms.23,26 This should be followed by the administration of antimicrobials such as polyhexamethylene biguanide, acetic acid, and iodine.23 Silver and hypochlorous acid have also shown therapeutic potential against biofilms when tested in vitro, exhibiting bactericidal activity against multiple microorganisms, including Pseudomonas and Staphylococcus.27 Low-frequency ultrasound, lasers, and photodynamic therapy are also potential options for biofilm breakdown.20

Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disorder characterized by painful nodules, abscesses and pus-discharging sinus tracts or fistulas known as tunnels.28,29 Microscopic analysis of HS lesions typically reveals inflammatory infiltrates that can partially be explained by the presence of biofilms in most cases of HS.28 This is particularly evident in the late stages of HS pathogenesis.30 Although HS is not an infectious disease itself, some studies have demonstrated the presence of slow-growing microbial agents.28,31 One study of the microbiome of sinus tracts in patients with moderate to severe HS found that they were predominantly colonized by anaerobic species, such as Prevotella and Porphyromonas.30 The deposition of intradermal corneocytes and hair fragments provides a suitable environment for the formation of biofilm by commensal bacteria.28 This is supported by the consistent detection of anaerobic species in HS lesions, which can grow in the anoxic environment created by deep-seated HS nodules, dilated hair follicles, and sinus tracts.28 In one study, 67% of sampled HS lesions contained biofilms.28 Moreover, the difficulty in detecting these pathogens using traditional culturing techniques, which identify the planktonic state of bacteria, may be due to the presence of biofilms, especially in chronic lesions.28

Conventional treatment of HS lesions continues to be tetracyclines, while second-line therapy involves a combination of clindamycin and rifampicin, which work synergistically and reduce risks of antibiotic resistance.30 However, when administered as monotherapy, 65.7% and 69.3% of bacterial cultures from HS patients were found to be resistant to clindamycin and rifampicin, respectively.30 Dapsone can also be used as a third-line treatment in mild to moderate HS, however, evidence supporting its use is weak.30,32 Other therapeutic options include metronidazole or ertapenem in severe cases, with the latter exhibiting resistance rates of less than 1%.30 Patients with HS often experience flare ups of the disease, which can also be partially attributed to biofilm formation.28,33

Dermal Fillers

Injectable dermal fillers are the second most common nonsurgical cosmetic procedure performed in the United States.17 Adverse effects include erythema and nodules, which although heavily disputed, have recently been attributed to biofilm formation.17,34 Conventional treatment of these side effects can involve the use of steroids, though when used at high doses can worsen the infection and symptoms.17,34 In one study that investigated the role of dermal fillers in biofilm formation, the presence of as few as 40 bacteria was enough to cause infection.35 Bacterial colonies in human skin contain up to 105 bacteria, which make them a potential source of needle contamination during skin penetration if proper precautions are not taken.35

Treatment of dermal filler biofilms includes broad-spectrum antibiotics such as ciprofloxacin, amoxicillin or clarithromycin.36 Dermal fillers composed of hyaluronic acid, one of the most common substances used in fillers, should also be treated with hyaluronidase.36 This serves to lyse the gel and remove the mechanical support of the biofilm.36 5-fluorouracil, laser lyses, and surgical resection can also be employed in more severe, treatment-resistant cases.17,36 Importantly, the conventional use of steroids, non-steroidal anti-inflammatory drugs, and antihistamines should be avoided.17,36

Onychomycosis

Onychomycosis is a fungal infection of the nails that is associated with the formation of biofilms.37-39 It is typically therapy resistant and relapses are common.37 Trichophyton rubrum, Trichophyton mentagrophytes and the Candida family are all fungi that can cause onychomycosis, and are also potentially capable of producing biofilms.4 These biofilms are hypothesized to be responsible for the treatment resistance and infection recurrence observed in onychomycosis.38 Multiple studies of patients with onychomycosis support the formation of fungal biofilms in vitro and ex vivo.38 Amphotericin B and echinocandins are usually effective in clearing free existing fungi as well as biofilms, especially when combined with biofilm-targeted treatments such as cationic antimicrobial peptides and antibody-guided alpha radiation.37 Antibody-mediated inhibition of matrix polysaccharides has been found to prevent biofilm formation in Cryptococcus neoformans.40 Other biofilm-specific therapies being investigated aim to inhibit the extracellular matrix or matrix polysaccharides and increase antifungal penetration, including gentian violet, DNases, and quorum-sensing molecules.37

Table 1. Summary of mechanisms of some agents used in the treatment of biofilms and related dermatological conditions.

Conclusion

The skin is colonized by a wide variety of microorganisms, which can aggregate and form biofilms.3,41 In some conditions, these biofilms can play a significant role in the pathogenesis of multiple skin diseases such as acne, atopic dermatitis, and hidradenitis suppurativa.8,12,28 With the growing concern of antibiotic resistance in dermatology, it is essential to consider the role of biofilms in the treatment of cutaneous disorders.42,43 Recently developed treatments, such as bacteriophage therapy, that have been used extensively in other fields of medicine but not yet in dermatology, should also be investigated for their utility in the management of skin conditions.10

References



  1. Donlan RM. Biofilms: microbial life on surfaces. Emerg Infect Dis. 2002 Sep;8(9):881-90.

  2. Zhao A, Sun J, Liu Y. Understanding bacterial biofilms: From definition to treatment strategies. Front Cell Infect Microbiol. 2023 Apr 6;13.

  3. Brandwein M, Steinberg D, Meshner S. Microbial biofilms and the human skin microbiome. NPJ Biofilms Microbiomes. 2016 Nov 23;2(1):3.

  4. Vlassova N, Han A, Zenilman JM, et al. New horizons for cutaneous microbiology: the role of biofilms in dermatological disease. Br J Dermatol. 2011 Oct;165(4):751-9.

  5. Yin W, Wang Y, Liu L, et al. Biofilms: the microbial “protective clothing” in extreme environments. Int J Mol Sci. 2019 Jul 12;20(14):3423.

  6. Yan J, Bassler BL. Surviving as a community: antibiotic tolerance and persistence in bacterial biofilms. Cell Host Microbe. 2019 Jul;26(1):15-21.

  7. Hughes G, Webber MA. Novel approaches to the treatment of bacterial biofilm infections. Br J Pharmacol. 2017 Jul 2;174(14):2237-46.

  8. Coenye T, Spittaels KJ, Achermann Y. The role of biofilm formation in the pathogenesis and antimicrobial susceptibility of Cutibacterium acnes. Biofilm. 2022 Dec;4:100063.

  9. Gowda A, Burkhart CG. Virulent acne biofilms offer insight into novel therapeutic options. Open Dermatol J. 2018 Sep 28;12(1):80-5.

  10. Burkhart CG. Assessment of Cutibacterium acnes: acne biofilm, comedones, and future treatments for acne. Open Dermatol J. 2024 Feb 29;18(1).

  11. Shahid A, Rasool M, Akhter N, et al. Innovative strategies for the control of biofilm formation in clinical settings [Internet]. In: Bacterial Biofilms. IntechOpen; 2020. Available from: http://dx.doi.org/10.5772/intechopen.89310

  12. Gonzalez T, Biagini Myers JM, Herr AB, et al. Staphylococcal biofilms in atopic dermatitis. Curr Allergy Asthma Rep. 2017 Dec 23;17(12):81.

  13. Di Domenico EG, Cavallo I, Bordignon V, et al. Inflammatory cytokines and biofilm production sustain Staphylococcus aureus outgrowth and persistence: a pivotal interplay in the pathogenesis of atopic dermatitis. Sci Rep. 2018 Jun 28;8(1):9573.

  14. Nusbaum AG, Kirsner RS, Charles CA. Biofilms in dermatology. Skin Therapy Lett. 2012 Jul;17(7):1-5.

  15. Allen HB, Vaze ND, Choi C, et al. The presence and impact of biofilm-producing Staphylococci in atopic dermatitis. JAMA Dermatol. 2014 Mar 1;150(3):260.

  16. Di Domenico EG, Cavallo I, Capitanio B, et al. Staphylococcus aureus and the cutaneous microbiota biofilms in the pathogenesis of atopic dermatitis. Microorganisms. 2019 Aug 29;7(9):301.

  17. Kravvas G, Veitch D, Al-Niaimi F. The increasing relevance of biofilms in common dermatological conditions. J Dermatolog Treat. 2018 Mar;29(2):202-7.

  18. Blicharz L, Rudnicka L, Czuwara J, et al. The influence of microbiome dysbiosis and bacterial biofilms on epidermal barrier function in atopic dermatitis—an update. Int J Mol Sci. 2021 Aug 5;22(16):8403.

  19. Demessant-Flavigny AL, Connétable S, Kerob D, et al. Skin microbiome dysbiosis and the role of Staphylococcus aureus in atopic dermatitis in adults and children: a narrative review. J Eur Acad Dermatol Venereol. 2023 Jun;37(Suppl 5):3-17.

  20. Vaishnavi KV, Safar L, Devi K. Biofilm in dermatology. J Skin Sex Transm Dis. 2019 Apr 22;1(1):3-7.

  21. Percival SL, McCarty SM, Lipsky B. Biofilms and wounds: an overview of the evidence. Adv Wound Care (New Rochelle). 2015 Jul 1;4(7):373-81.

  22. Darvishi S, Tavakoli S, Kharaziha M, et al. Advances in the sensing and treatment of wound biofilms. Angew Chem Int Ed Engl. 2022 Mar 21; 61(13):e202112218.

  23. Bjarnsholt T, Eberlein T, Malone M, et al. Management of wound biofilm made easy. London: Wounds International 2017; 8(2). Available from: www.woundsinternational.com

  24. Diban F, Di Lodovico S, Di Fermo P, et al. Biofilms in chronic wound infections: innovative antimicrobial approaches using the in vitro Lubbock chronic wound biofilm model. Int J Mol Sci. 2023 Jan 5;24(2):1004.

  25. Clinton A, Carter T. Chronic wound biofilms: pathogenesis and potential therapies. Lab Med. 2015 Nov 1;46(4):277-84.

  26. Weigelt MA, McNamara SA, Sanchez D, et al. Evidence-based review of antibiofilm agents for wound care. Adv Wound Care (New Rochelle). 2021 Jan 1;10(1):13-23.

  27. Sen CK, Roy S, Mathew-Steiner SS, et al. Biofilm management in wound care. Plast Reconstr Surg. 2021 Aug 27;148(2):275e-88e.

  28. Ring HC, Bay L, Nilsson M, et al. Bacterial biofilm in chronic lesions of hidradenitis suppurativa. Br J Dermatol. 2017 Apr;176(4):993-1000.

  29. Sabat R, Jemec GBE, Matusiak Ł, et al. Hidradenitis suppurativa. Nat Rev Dis Primers. 2020 Mar 12;6(1):18.

  30. Huynh FD, Damiani G, Bunick CG. Rethinking hidradenitis suppurativa management: insights into bacterial interactions and treatment evolution. Antibiotics. 2024 Mar 17;13(3):268.

  31. Wark KJL, Cains GD. The microbiome in hidradenitis suppurativa: a review. Dermatol Ther (Heidelb). 2021 Feb 26;11(1):39-52.

  32. Rabindranathnambi A, Jeevankumar B. Dapsone in hidradenitis suppurativa: a systematic review. Dermatol Ther (Heidelb). 2022 Feb 8;12(2):285-93.

  33. Kathju S, Lasko LA, Stoodley P. Considering hidradenitis suppurativa as a bacterial biofilm disease. FEMS Immunol Med Microbiol. 2012 Jul;65(2):385-9.

  34. Haneke E. Managing complications of fillers: rare and not-so-rare. J Cutan Aesthet Surg. 2015;8(4):198.

  35. Alhede M, Er Ö, Eickhardt S, et al. Bacterial biofilm formation and treatment in soft tissue fillers. Pathog Dis. 2014 Apr;70(3):339-46.

  36. Dumitraşcu DI, Georgescu AV. The management of biofilm formation after hyaluronic acid gel filler injections: a review. Clujul Med. 2013;86(3):192-5.

  37. Gupta AK, Daigle D, Carviel JL. The role of biofilms in onychomycosis. J Am Acad Dermatol. 2016 Jun;74(6):1241-6.

  38. Gupta AK, Foley KA. Evidence for biofilms in onychomycosis. G Ital Dermatol Venereol. 2019 Feb;154(1):50-5.

  39. Gupta AK, Carviel J, Shear NH. Antibiofilm treatment for onychomycosis and chronic fungal infections. Skin Appendage Disord. 2018 Aug;4(3):136-40.

  40. Gupta AK, Daigle D, Carviel JL. The role of biofilms in onychomycosis. J Am Acad Dermatol. 2016 Jun;74(6):1241-6.

  41. Byrd AL, Belkaid Y, Segre JA. The human skin microbiome. Nat Rev Microbiol. 2018 Mar 15;16(3):143-55.

  42. Harkins CP, McAleer MA, Bennett D, et al. The widespread use of topical antimicrobials enriches for resistance in Staphylococcus aureus isolated from patients with atopic dermatitis. Br J Dermatol. 2018 Oct;179(4):951-8.

  43. Dessinioti C, Katsambas A. Antibiotics and antimicrobial resistance in acne: epidemiological trends and clinical practice considerations. Yale J Biol Med. 2022 Dec;95(4):429-43.


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