Article

The role of bacterial biofilms in chronic infections

Københavns Universitet, København N, Denmark.
APMIS. Supplementum 05/2013; 121(136):1-58. DOI: 10.1111/apm.12099
Source: PubMed

ABSTRACT Acute infections caused by pathogenic bacteria have been studied extensively for well over 100 years. These infections killed millions of people in previous centuries, but they have been combated effectively by the development of modern vaccines, antibiotics and infection control measures. Most research into bacterial pathogenesis has focused on acute infections, but these diseases have now been supplemented by a new category of chronic infections caused by bacteria growing in slime-enclosed aggregates known as biofilms. Biofilm infections, such as pneumonia in cystic fibrosis patients, chronic wounds, chronic otitis media and implant- and catheter-associated infections, affect millions of people in the developed world each year and many deaths occur as a consequence. In general, bacteria have two life forms during growth and proliferation. In one form, the bacteria exist as single, independent cells (planktonic) whereas in the other form, bacteria are organized into sessile aggregates. The latter form is commonly referred to as the biofilm growth phenotype. Acute infections are assumed to involve planktonic bacteria, which are generally treatable with antibiotics, although successful treatment depends on accurate and fast diagnosis. However, in cases where the bacteria succeed in forming a biofilm within the human host, the infection often turns out to be untreatable and will develop into a chronic state. The important hallmarks of chronic biofilm-based infections are extreme resistance to antibiotics and many other conventional antimicrobial agents, and an extreme capacity for evading the host defences. In this thesis, I will assemble the current knowledge on biofilms with an emphasis on chronic infections, guidelines for diagnosis and treatment of these infections, before relating this to my previous research into the area of biofilms. I will present evidence to support a view that the biofilm lifestyle dominates chronic bacterial infections, where bacterial aggregation is the default mode, and that subsequent biofilm development progresses by adaptation to nutritional and environmental conditions. I will make a series of correlations to highlight the most important aspects of biofilms from my perspective, and to determine what can be deduced from the past decades of biofilm research. I will try to bridge in vitro and in vivo research and propose methods for studying biofilms based on this knowledge. I will compare how bacterial biofilms exist in stable ecological habitats and opportunistically in unstable ecological habitats, such as infections. Bacteria have a similar lifestyle (the biofilm) in both habitats, but the fight for survival and supremacy is different. On the basis of this comparison, I will hypothesize how chronic biofilm infections are initiated and how bacteria live together in these infections. Finally, I will discuss different aspects of biofilm infection diagnosis. Hopefully, this survey of current knowledge and my proposed guidelines will provide the basis and inspiration for more research, improved diagnostics, and treatments for well-known biofilm infections and any that may be identified in the future.

5 Followers
 · 
161 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: ABSTRACT The biostimulative effect of low-level laser therapy (LLLT) in tissues has been noted in reference to the treatment of various diseases but little information exists on its effectiveness on chronic wounds and biofilm. The scope of this review was to identify literature reporting on LLLT alone, without photodynamic agents, as an antimicrobial/antibiofilm technology and determine its effects on wound healing. Overall the beneficial effects of LLLT in promoting wound healing in animal and human studies has been demonstrated. However, the lack of credible studies using reproducible models and light dosimetry restricts the analysis of current data. Efforts must be addressed to standardize phototherapy procedures as well as to develop suitable in vitro and in vivo biofilm models to test LLLT efficacy in promoting biofilm eradication and wound healing.
    Future Microbiology 02/2015; 10(2):255-72. DOI:10.2217/fmb.14.109 · 3.82 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Dental plaque is a biofilm that causes dental caries, gingivitis and periodontitis. Most of the studies in antibacterial coatings have been conducted by in vitro single-species biofilm formation but oral biofilm involves more than 500 different bacterial species that are able to interact. Therefore, new studies are focused on in vitro multispecies biofilm model that mimic in vivo biofilms. The aim of the present work was to study different antibacterial coatings onto titanium surfaces, and evaluate the in vitro antimicrobial properties of the surfaces on two different bacterial species and an oral biofilm. Lactate dehydrogenase assay determined that treated samples did not affect fibroblast viability. In addition, the viability of microorganisms on modified samples was evaluated by LIVE/DEAD BackLight bacterial viability kit. Although a decrease in viable bacteria onto treated samples was obtained, the results showed differences in effectiveness when single-biofilm and oral plaque were tested. It confirms, as we expected, the distinct sensitivities that bacterial strains have. Thus, this multispecies biofilms model holds a great potential to assess antibacterial properties onto samples for dental purposes.
    ACS Applied Materials & Interfaces 03/2015; DOI:10.1021/acsami.5b00402 · 5.90 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 1. Wstęp Problem zakażeń okołowszczepowych, zwanych rów nież zakażeniami związanymi z biomateriałem (BAIs – Biomaterial Associated Infections) nie został do końca poznany. Tytan, współcześnie stosowany w implantowanych wyrobach medycznych, w porówna-niu z innymi materiałami takimi jak lateks, poli(chlorek winylu) (PVC), teflon czy stal nierdzewna, wykazuje najmniejszą podatność na adhezję bakterii [21, 24, 99]. Ponadto unikatowa cecha tego pierwiastka sprawia, że materiały tytanowe mogą uzyskać funkcjonalne połą-czenie z żywą tkanką kostną w procesie zwanym osteo-integracją [16, 32]. Jednym z czynników, które mogą zakłócić ten proces jest kolonizacja powierzchni przez bakterie inicjujące rozwój zakażenia [42, 57]. Powsta-nie stanu zapalnego zapoczątkowuje proces resorpcji tkanki kostnej wokół wszczepu. Tym samym zaburzona zostaje stabilizacja wszczepu prowadząc do jego oblu-zowania na skutek mikro-ruchów. Postępująca rucho-mość implantu upośledza prawidłowe przenoszenie sił mechanicznych, co w konsekwencji prowadzi do jego utraty [11, 12]. Zakażenia okołowszczepowe mogą być przyczyną nieprawidłowego zrostu lub braku zrostu odłamów kostnych, zapalenia skóry lub błon śluzowych, zakażeń systemowych, wydłużenia czasu hospitalizacji i obniżenia jakości życia pacjenta [103]. Dodatkowo, zakażenia te niosą ryzyko groźnych dla życia powikłań na skutek bakteriemii u pacjentów poddanych leczeniu immunosupresyjnemu bądź z wszczepionymi sztucz-nymi zastawkami serca [37, 60]. Zakażenia okołowszczepowe są inicjowane przez drobnoustroje, które przyłączając się do powierzchni implantu żyją w postaci biofilmu [56]. Procedury lecznicze obejmujące chirurgiczne oczyszczenie po-wierzchni implantu oraz antybiotykoterapię (miejs-cową bądź ogólnoustrojową) nie zawsze są skuteczne [107, 110]. Przyczyną tego zjawiska jest fakt, że bakterie żyjące w biofilmie wykazują prawie 1000-krotnie wyż-szą oporność na większość środków bakteriobójczych niż formy planktonowe tych samych szczepów bak terii [29, 80]. Dodatkową przyczyną małej skuteczności antybiotykoterapii jest fakt, że penetracja leku do tka-nek zmienionych zapalnie, niedotlenionych, niekiedy martwiczych, jest znacznie obniżona [27]. Bakterie odpowiedzialne za większość zakażeń okołowszczepo-wych należą do gatunków oportunistycznych, co ma bezpośredni związek z faktem, że tkanki w okolicy oko-łowszczepowej charakteryzują się obniżoną odpornoś-cią na zakażenie. Strefa ta nazywana jest locus minoris Abstract: Bacterial infections accompanying implanted medical devices create serious clinical problems. Using titanium implants may reduce the rate of there infections. Physicochemical properties of titanium allow using it as implantable biomaterial to maintain osseointegration, phenomenon described as " biological and functional connection of the implant with the living bone ". One of the most important factors which can affect osseointegration is bacterial colonization of the implant surface and development of Biomaterial Associated Infection (BAI). Impaired osseointegration can increase the risk of subsequent loosening due to micromotion. BAI's in orthopaedics and maxillofacial surgery are serious complications, which ultimately lead to osteomyelitis with consequent devastating effects on bone and surrounding soft tissues. Implant associated infections are caused by microorganisms which adhere to the implant surface and then live clustered together in a highly hydrated extracellular matrix attached to the surface, known as bacterial biofilm. Simple debridement procedures with retention of prosthesis and chemotherapy with antimicrobial agents are the treatments not always effective against infections already established.
    Postepy Mikrobiologii 01/2014; 53(2):123-134. · 0.27 Impact Factor

Preview

Download
4 Downloads