RESUMO
The role of biofilm in implant infections and the genetic control of its production are still giving rise to great interest and controversial new results are continuing to emerge from widespread investigations. Bacteria embedded in biofilms are more resistant to most antibiotics. Hypotheses regarding the mechanisms of antibiotic multi-resistance in biofilm are brought to light, including the onset of persister cells during the attachment of bacteria to implant surfaces.This 2008 special issue ''Focus on Implant Infections'', presents new strategies for combating biofilm infections,such as the use of staphylococcal quorum-sensing inhibitors or the ''bioelectric effect'': the phenomenon by which electric current can enhance the activity of some antimicrobial agents against bacteria in biofilms.
Assuntos
Anti-Infecciosos/uso terapêutico , Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Infecções Relacionadas à Prótese/tratamento farmacológico , Biofilmes/crescimento & desenvolvimento , Farmacorresistência Bacteriana , Eletricidade , Humanos , Testes de Sensibilidade Microbiana , Infecções Relacionadas à Prótese/microbiologia , Percepção de Quorum/efeitos dos fármacosRESUMO
Orthopedic implants may fail owing to different reasons: poor osseointegration at the tissue-implant interface, generation of wear debris, stress and strain imbalance between implant and surrounding tissues, and infections. To ensure success in orthopedics, implant materials must not evoke an undesirable inflammatory response, they must be habitable by bone-forming cells (favoring adhesion of osteoblasts), hinder formation of soft connective tissue (hindering adhesion of fibroblasts), and be anti-infective (discouraging bacterial adhesion). Recent studies have suggested that nanophase materials have a better efficacy as bone implants in favoring osseointegration compared to conventional orthopedic implant materials. This minireview discusses studies on nanophase materials as bone implants, focusing on the effect of these materials in inhibiting bacterial adhesion for the prevention of implant infections.
Assuntos
Antibacterianos/uso terapêutico , Aderência Bacteriana/efeitos dos fármacos , Substitutos Ósseos , Materiais Revestidos Biocompatíveis , Nanoestruturas , Procedimentos Ortopédicos/instrumentação , Próteses e Implantes/efeitos adversos , Infecções Relacionadas à Prótese/prevenção & controle , Animais , Humanos , Osseointegração , Desenho de Prótese , Falha de Prótese , Infecções Relacionadas à Prótese/etiologia , Infecções Relacionadas à Prótese/microbiologiaRESUMO
The Alpha-like protein (Alp) family, repeat-containing surface proteins once thought to be important adhesion factors confined to pathogenic streptococci and enterococci, is broader than previously known. Analysis of the annotated microbial genomes has identified new potential members of the Alp family not only in other Gram- positive opportunistic pathogens but also in commensal microflora of the human gut and the skin. This finding has highlighted the importance of genome sequencing projects for unraveling in greater detail lateral gene transfer events involving virulence factors between pathogens and commensals. These should receive constant attention not only as part of infectious disease prevention programs, but also in the food and biotechnology industries.
Assuntos
Adesinas Bacterianas/metabolismo , Aderência Bacteriana , Trato Gastrointestinal/microbiologia , Fatores de Virulência/metabolismo , Adesinas Bacterianas/genética , Animais , Aderência Bacteriana/genética , Bases de Dados Genéticas , Evolução Molecular , Transferência Genética Horizontal , Genoma Bacteriano , Humanos , Mutação , Fatores de Virulência/genéticaRESUMO
Implant-related infections are broadly recognized as one of the most serious and devastating complications associated with the use of biomaterials in medical practice. The growing interest and need for the development of implant materials with reduced susceptibility to microbial colonization and biofilm formation has necessitated the development of a series of in vitro and in vivo models for evaluation and preclinical testing. Current technologies provide these investigations with an ample choice of qualitative and quantitative techniques for an accurate assessment of the bioactivity and anti-infective efficacy of any new compound or device. These tests are typically performed using a reference bacterial strain designated as the test or reference strain. Recent molecular epidemiological studies have identified the complex clonal nature of most prevalent etiological agents implicated in implant-associated infections. New information which is continually emerging on the identity and the characteristics of both sporadic and epidemic clones must be considered when selecting a reference. A new emerging requirement is that the strain should be representative of the clones causing clinically relevant infections; they should, therefore, belong to the most prevalent epidemic clones rather than to sporadic ones, which may occur in only 1 out of 200 infections or even fewer. The correct choice of reference strain for preclinical tests is of crucial importance for the clinical significance of the achieved results. In this paper we report our experience and recommendations regarding this issue.
Assuntos
Anti-Infecciosos/uso terapêutico , Bactérias/efeitos dos fármacos , Materiais Revestidos Biocompatíveis , Teste de Materiais , Próteses e Implantes/efeitos adversos , Infecções Relacionadas à Prótese/prevenção & controle , Animais , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Bactérias/patogenicidade , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Farmacorresistência Bacteriana , Contaminação de Equipamentos , Genômica , Humanos , Controle de Infecções , Teste de Materiais/métodos , Epidemiologia Molecular , Desenho de Prótese , Infecções Relacionadas à Prótese/microbiologia , Reprodutibilidade dos TestesRESUMO
Photodynamic treatment (PDT) has been proposed as a new approach for inactivation of biofilms associated with medical devices that are resistant to chemical additives or biocides. In this study, we evaluated the antimicrobial activity of merocyanine 540 (MC 540), a photosensitizing dye that is used for purging malignant cells from autologous bone marrow grafts, against Staphylococcus epidermidis biofilms. Effect of the combined photodynamic action of MC 540 and 532 nm laser was investigated on the viability and structure of biofilms of two Staphylococcus epidermidis strains, RP62A and 1457. Significant inactivation of cells was observed when biofilms were exposed to MC 540 and laser simultaneously. The effect was found to be light dose-dependent but S. epidermidis 1457 biofilm proved to be slightly more susceptible than S. epidermidis RP62A biofilm. Furthermore, significant killing of both types of cells was attained even when a fixed light dose was delivered to the biofilms. Confocal laser scanning microscope (CLSM) analysis indicated damage to bacterial cell membranes in photodynamically treated biofilms, while disruption of PDT-treated biofilm was confirmed by scanning electron microscopy (SEM).
Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Lasers , Fármacos Fotossensibilizantes/farmacologia , Pirimidinonas/farmacologia , Staphylococcus epidermidis/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Membrana Celular/efeitos dos fármacos , Relação Dose-Resposta à Radiação , Microscopia Confocal , Microscopia Eletrônica de Varredura , Staphylococcus epidermidis/crescimento & desenvolvimentoRESUMO
Research on implant infections requires cooperative efforts and integration between basic and clinical expertises. An international group of women scientists is acting together in this field. The main research topics of the participants of this group are described. Formation of bacterial biofilms, antibiotic resistance and production of virulence factors like adhesins and toxins are investigated. New biomaterials, coatings and drugs designed to inhibit microbial adhesion are evaluated, and infection-resistant biomaterials are under study, such as a novel heparinizable polycarbonate-urethane (Bionate) or incorporation of diamino-diamide-diol (PIME) to reduce bacterial attachment. The correlation between biofilm production and the accessory-gene-regulator (agr) is investigated in Staphylococcus aureus. The ability to form biofilm has also been shown to be one of the important virulence factors of Enterococcus faecalis, favouring colonization of inert and biological surfaces. The study of quorum sensing has led to the discovery of a quorum sensing inhibitor termed RIP that suppresses staphylococcal biofilm and infections. The immune response and the local defence mechanisms of the host against implant-associated infections, activation and infiltration of immunocompetent cells into the sites of infection have been studied in patients with implant-associated osteomyelitis. Production of monoclonal antibodies (mAbs) as possible vaccines against the staphylococcal collagen-binding MSCRAMMs is in progress.
Assuntos
Antibacterianos/uso terapêutico , Vacinas Bacterianas , Pesquisa Biomédica , Próteses e Implantes/efeitos adversos , Infecções Relacionadas à Prótese/prevenção & controle , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Materiais Revestidos Biocompatíveis , Comportamento Cooperativo , Farmacorresistência Bacteriana , Feminino , Humanos , Controle de Infecções , Comunicação Interdisciplinar , Cooperação Internacional , Desenho de Prótese , Infecções Relacionadas à Prótese/microbiologia , Percepção de Quorum/efeitos dos fármacos , Fatores de Virulência/metabolismoRESUMO
The status of population density is communicated among bacteria by specific secreted molecules, called pheromones or autoinducers, and the control mechanism is called ""quorum-sensing"". Quorum-sensing systems regulate the expression of a panel of genes, allowing bacteria to adapt to modified environmental conditions at a high density of population. The two known different quorum systems are described as the LuxR-LuxI system in gram-negative bacteria, which uses an N-acyl-homoserine lactone (AHL) as signal, and the agr system in gram-positive bacteria, which uses a peptide-tiolactone as signal and the RNAIII as effector molecules. Both in gram-negative and in gram-positive bacteria, quorum-sensing systems regulate the expression of adhesion mechanisms (biofilm and adhesins) and virulence factors (toxins and exoenzymes) depending on population cell density. In gram-negative Pseudomonas aeruginosa, analogs of signaling molecules such as furanone analogs, are effective in attenuating bacterial virulence and controlling bacterial infections. In grampositive Staphylococcus aureus, the quorum-sensing RNAIII-inhibiting peptide (RIP), tested in vitro and in animal infection models, has been proved to inhibit virulence and prevent infections. Attenuation of bacterial virulence by quorum-sensing inhibitors, rather than by bactericidal or bacteriostatic drugs, is a highly attractive concept because these antibacterial agents are less likely to induce the development of bacterial resistance.
Assuntos
Bactérias/patogenicidade , Infecções Relacionadas à Prótese/microbiologia , Percepção de Quorum , Aliivibrio fischeri/patogenicidade , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Farmacorresistência Bacteriana , Humanos , Infecções Relacionadas à Prótese/tratamento farmacológico , Pseudomonas aeruginosa/patogenicidade , Percepção de Quorum/efeitos dos fármacos , Staphylococcus aureus/patogenicidade , VirulênciaRESUMO
Antibiotic treatment of infections associated with the use of indwelling medical devices in ageing and/or severely ill patients represents a significant healthcare problem due to the difficulty of treating such infections and to the various collateral effects that may be observed following the often aggressive therapy. We summarize some effects of antibiotics on the expression of virulence factors of the microorganisms which cause such infections. These effects, particularly those resulting in a stimulation of bacterial virulence, might be usefully included among the other well-known collateral effects of antibiotic therapy.
Assuntos
Antibacterianos/uso terapêutico , Bactérias/efeitos dos fármacos , Infecções Bacterianas/tratamento farmacológico , Infecções Relacionadas à Prótese/tratamento farmacológico , Antibacterianos/efeitos adversos , Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Bactérias/patogenicidade , Infecções Bacterianas/microbiologia , Biofilmes/efeitos dos fármacos , Relação Dose-Resposta a Droga , Farmacorresistência Bacteriana , Humanos , Testes de Sensibilidade Microbiana , Infecções Relacionadas à Prótese/microbiologia , Virulência/efeitos dos fármacos , Fatores de Virulência/metabolismoRESUMO
Microorganisms universally attach to surfaces, resulting in biofilm formation. These biofilms entail a serious problem in daily clinical practice because of the great prevalence of implantable device-related infections. Differences in antibiotic activity against planktonic and sessile bacteria may relate to clinical failures in the treatment of biofilm-related infections (BRI). Bacteriophages have several characteristics that make them potentially attractive therapeutic agents in some selected clinical settings, like for example BRI. They are highly specific and very effective in lysing targeted bacteria, moreover, they appear to be safe for humans. Many studies have shown the potential of phages for the treatment of infectious diseases in plants and animals, including infections with highly drug-resistant bacteria. The therapeutic use of bacteriophages, possibly in combination with antibiotics, may be a valuable approach in BRI. However, many important questions still remain that must be addressed before phages can be endorsed for therapeutic use in humans.
Assuntos
Bacteriófago lambda , Biofilmes , Biotecnologia/métodos , Infecções Relacionadas à Prótese/prevenção & controle , Fagos de Staphylococcus , Staphylococcus aureus/virologia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Biofilmes/efeitos dos fármacos , Infecções Relacionadas à Prótese/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Vancomicina/farmacologia , Vancomicina/uso terapêuticoRESUMO
Staphylococcus aureus has emerged as a major cause of implant infections. It is known that it is able to produce several toxins that contribute to its armory of virulent weapons, but there are still no data on their prevalence among isolates recovered from biomaterial-centered infections. In this study, 200 Staphylococcus aureus isolates from infections related to different types of orthopedic implants (hip and knee arthroprostheses, internal and external fixation devices) were tested by polymerase chain reaction for the prevalence of genes encoding for leukotoxins. Although almost all isolates were positive for the ã-hemolysin gene (99%), none was positive for lukM. The leukotoxin genes lukE/lukD were found in 67% of isolates. The presence of lukE/lukD was significantly associated with that of Accessory Gene Regulatory locus agr II. The lukE/lukD-positive isolates were significantly more prevalent in the staphylococcal isolates from knee arthroprostheses than in the isolates from the other implant types. The genes encoding Panton-Valentine leukocidin components were detected in only one isolate that, curiously enough, was taken solely from a knee arthroprosthesis infection.
Assuntos
Proteínas de Bactérias/genética , Toxinas Bacterianas/genética , DNA Bacteriano/isolamento & purificação , Regulação Bacteriana da Expressão Gênica , Prótese Articular/efeitos adversos , Dispositivos de Fixação Ortopédica/efeitos adversos , Infecções Relacionadas à Prótese/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Proteínas de Bactérias/isolamento & purificação , Toxinas Bacterianas/isolamento & purificação , Exotoxinas/genética , Fixadores Externos/efeitos adversos , Proteínas Hemolisinas/genética , Prótese de Quadril/efeitos adversos , Humanos , Fixadores Internos/efeitos adversos , Prótese do Joelho/efeitos adversos , Leucocidinas/genética , Reação em Cadeia da Polimerase , Staphylococcus aureus/química , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/patogenicidade , Transativadores/genéticaRESUMO
Staphylococci have become the most common cause of nosocomial infections, especially in patients with predisposing factors such as indwelling or implanted foreign polymer bodies. The pathogenesis of foreign-body associated infections with S.aureus and S. epidermidis is mainly related to the ability of these bacteria to form thick, adherent multilayered biofilms. In a biofilm, staphylococci are protected against antibiotic treatment and attack from the immune system, thus making eradication of the infections problematic. This necessitates the discovery of novel prophylactic and therapeutic strategies to treat these infections. In this review, we provide an overview of staphylococcal biofilm components and discuss new possible approaches to controlling these persistent biofilm-dwelling bacteria.
Assuntos
Antibacterianos/uso terapêutico , Biofilmes/efeitos dos fármacos , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/prevenção & controle , Vacinas Antiestafilocócicas , Staphylococcus , Adesinas Bacterianas/imunologia , Antibacterianos/farmacologia , Anticorpos Antibacterianos/uso terapêutico , Aderência Bacteriana/efeitos dos fármacos , Proteínas de Bactérias/uso terapêutico , Glicosídeo Hidrolases/uso terapêutico , Humanos , Lisostafina/uso terapêutico , Polissacarídeos Bacterianos/imunologia , Percepção de Quorum/efeitos dos fármacos , Infecções Estafilocócicas/imunologia , Staphylococcus/efeitos dos fármacos , Staphylococcus/crescimento & desenvolvimento , Staphylococcus/imunologiaRESUMO
In recent years, a variety of new technologies have been proposed that allow rapid qualitative and quantitative microbiological analyses. In this paper we discuss the urgent needs for reliable and rapid microbiological analytical techniques in different applicative fields involving the research, production and medical application of implant materials, and the potential benefits derived from the use of new methods for rapid bacterial quantification. Current compendial methods are easy to perform and have gained confidence over their long period of use, but the supplemental use of new technologies could represent real breakthroughs whenever sensitive and rapid responses are urgently required and not met by the tests currently in use. Overall, the new microbiological methods require critical evaluation depending on their specific type of application and they may still not be thought of as totally substitutive, but they certainly exhibit considerable potential for different areas of biomaterials, as well as for advanced therapy medicinal and tissue engineering treatments.
Assuntos
Materiais Biocompatíveis/química , Teste de Materiais , Técnicas Microbiológicas , Técnicas de Diagnóstico Molecular , Próteses e Implantes/microbiologia , Desenho de Prótese , Infecções Relacionadas à Prótese/microbiologia , Materiais Biocompatíveis/uso terapêutico , Humanos , Infecções Relacionadas à Prótese/diagnóstico , Infecções Relacionadas à Prótese/prevenção & controle , Reprodutibilidade dos Testes , Propriedades de Superfície , Engenharia TecidualRESUMO
The synthesis of Ag nanoparticles from Ag+ has been investigated, with pectin acting both as reductant and coating.â¼100% Ag+ to Ag(0) one-pot conversion was obtained, yielding p-AgNP, i.e. an aqueous solution of pectin-coated spherical Ag nanoparticles (d=8.0±2.6nm), with a<1ppm concentration of free Ag+ cation. Despite the low free Ag+ concentration and low Ag+ release with time, the nature of the coating allows p-AgNP to exert excellent antibacterial and antibiofilm actions, comparable to those of ionic silver, tested on E. coli (Gram-) and S. epidermidis (Gram+) both on planctonic cells and on pre- and post-biofilm formation conditions. Moreover, p-AgNP were tested on fibroblasts: not only p-AgNP were found to be cytocompatible but also revealed capable of promoting fibroblasts proliferation and to be effective for wound healing on model cultures. The antibacterial activity and the wound healing ability of silver nanoparticles are two apparently irreconcilable properties, as the former usually requires a high sustained Ag+ release while the latter requires low Ag+ concentration. p-AgNP represents an excellent compromise between opposite requirements, candidating as an efficient medication for repairing wounds and/or to treat vulnerable surgical site tissues, including the pre-treatment of implants as an effective prophylaxis in implant surgery.
Assuntos
Antibacterianos/química , Biofilmes/efeitos dos fármacos , Nanopartículas Metálicas/química , Pectinas/química , Prata/química , Cicatrização/efeitos dos fármacos , Antibacterianos/farmacologia , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Humanos , Tamanho da Partícula , Pectinas/farmacologia , Plâncton/citologia , Plâncton/efeitos dos fármacos , Prata/farmacologia , Nitrato de Prata/farmacologia , Staphylococcus epidermidis/efeitos dos fármacos , Propriedades de SuperfícieRESUMO
There are numerous reports in the literature using animal models of osteomyelitis for investigating pathogenesis, diagnosis, and treatment of bone infections. Rabbits, rats, and dogs are commonly used animals, and, less frequently, chickens, guinea pigs, miniature pigs, goats, and sheep. Commonly used bones for creating local osteomyelitis include tibia, femur, and radius, and, less frequently, mandible and spine. When designing a specific model, one should consider which animal and which bone will be used, which route for inoculation (either local injection or systemically through vascular injection), which bacterial species and how many bacteria should be applied, if and what sclerosing agent, foreign body or implant should be employed, and if local trauma is needed. Basic methods of evaluation include clinical observation, radiography, microbiology, and histology.
Assuntos
Modelos Animais de Doenças , Osteomielite/patologia , Animais , Osteomielite/microbiologiaRESUMO
The possibility of biosurfaces with high or low adhesiveness for protein, bacteria or eukaryotic cells is discussed. At the interface surface object/biological milieu, biocompatibility, (no) bioadhesion and (no) biocontamination are shown to be correlated with physico-chemical surface characteristics. First consequence is the (no) possibility of biofilm formation. Substrates with low surface energy could interact only with hydrophobic biomolecules. On substrates with high surface energy, a water monolayer spontaneously formed. Modification of a surface by plasma techniques is a way for engineering biomaterials. Plasma techniques are dry processes and more suitable for biomedical applications. In the field of biomaterial medical devices, in hygienic prevention of nosocomial diseases, in food packaging, the use of substrates with a very hydrophilic character may help to prevent the proliferation of cells and bacteria. Such a technique is so efficient that antibiotic molecules are not necessary. Therefore, surface engineering is a tool for modifying and adapting materials to specific biological applications.
Assuntos
Engenharia Biomédica/métodos , Interações Hidrofóbicas e Hidrofílicas , Animais , Aderência Bacteriana , Materiais Biocompatíveis , Biofilmes , Adesão Celular , Humanos , Teste de Materiais/métodos , Microscopia Eletrônica de Varredura , Modelos Biológicos , Polímeros/química , Polímeros/metabolismo , Proteínas/análise , Propriedades de SuperfícieRESUMO
The production and the mechanism of action of exotoxins from Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa are presented. The attack to the immune host's defenses is the main virulence factor of opportunistic bacteria in implant infections, favoring the invasion and colonization of compromised periprosthesis tissues.
Assuntos
Infecções Bacterianas/microbiologia , Exotoxinas/metabolismo , Infecções Oportunistas/microbiologia , Infecções Relacionadas à Prótese/microbiologia , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/metabolismo , Pseudomonas aeruginosa/patogenicidade , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/metabolismo , Staphylococcus aureus/patogenicidade , Staphylococcus epidermidis/metabolismo , Staphylococcus epidermidis/patogenicidadeRESUMO
The vast use of prosthetic materials in medicine over the last decades has been accompanied by the appearance of new opportunistic pathogens previously considered incapable of causing infections with significant morbidity and/or mortality. In this regard, the genus Staphylococcus enlisting numerous species usually characterized by a saprophytic habit covers a special role. Apart from Staphylococcus aureus and Staphylococcus epidermidis, well known for their large prevalence in implant-related infections, a number of further staphylococcal species are progressively being indicated for their pathogenic potential. The increasing attention on these opportunistic bacteria is due to an ever growing number of clinical reports, which is also deriving from a more accurate identification of these species with currently available techniques. This synopsis intends to offer an overview on recently emerging coagulase-negative staphylococci (CoNS) as well as coagulase-positive/-variable staphylococci exhibiting distinct traits of virulence, pathogenicity, and epidemiologic impact depending among others on the medical field, the type of prosthetic device and its anatomic location.
Assuntos
Doenças Transmissíveis Emergentes/microbiologia , Infecções Relacionadas à Prótese/microbiologia , Infecções Estafilocócicas/epidemiologia , Humanos , VirulênciaRESUMO
In natural and man-made environments, microbial communities thrive as biofilms on living (e.g. tissue) and inanimate (e.g. plastic, metal, wood, mineral) surfaces. Biofilms are found in a wide range of aqueous habitats, including physiological fluids. Numerous types of microorganisms are able to colonize catheters, implants, prosthetics, and other medical devices manufactured from different metallic and non-metallic materials dwelling within a human body. The development of biofilm is facilitated by the production of extracellular polymeric substances (EPS). Biofilms formed on surfaces of metallic materials may alter interfacial electrochemical processes, which can lead to increased corrosion of the colonized substratum. Deterioration of metallic materials in the presence of a biofilm is termed biocorrosion or microbially-influenced corrosion (MIC). In the field of biomaterials, ""biocorrosion"" is commonly used when describing the effect of host tissue on the corrosion of implant metals and alloys. Therefore, to avoid confusion, we will here use the term MIC as a reference to biofilm-influenced corrosion. It is important to realise that although most metals are prone to microbial colonization, i.e. to biofouling, this does not imply that they are susceptible to MIC. For example, a metal such as titanium, accumulates biofilm, however, it still demonstrates excellent resistance against MIC. Corrosion is, by definition, an electrochemical process, therefore, electrochemical techniques are frequently employed to determine and measure the rate of abiotic, as well as biologically driven corrosion reactions. This communication addresses the use of electrochemical techniques for monitoring (i) biofilm formation on and (ii) MIC of implant metals and alloys.
Assuntos
Biofilmes/crescimento & desenvolvimento , Metais/química , Infecções Relacionadas à Prótese/microbiologia , Corrosão , Eletroquímica , Microscopia Eletrônica de Varredura , Infecções Relacionadas à Prótese/prevenção & controleRESUMO
In recent years the progress in the field of nanotechnologies has offered new possibilities to control the superficial features of implant materials down to a nanoscale level. Several studies have therefore tried to explore the effects of nanostructured biomaterial surfaces on the behavior of eukaryotic cells. However, nanotopography could exert an influence also on the behavior of prokaryotic cells, with relevant implications concerning the susceptibility of implant surfaces to infection. Aim of this study was to examine the behavior of Staphylococcus aureus on polyethylene terephthalate (PET) surfaces either cylindrically nanostructured (PET-N) or flat ion-etched (PET-F), and on tissue culture-grade polystyrene (PS). Microbial adherence was assessed by chemiluminometry under 4 different conditions: (a) bacteria suspended in MEM medium, (b) bacteria in MEM supplemented with 10% fetal bovine serum (FBS), (c) test surfaces preconditioned in FBS, and (d) post-exposure of colonised surfaces to serum-supplemented MEM. Under all circumstances, PET-F and PET-N specimens showed identical bacterial adhesion properties. In the absence of serum, all 3 test materials showed a very high adhesivity to microbial cells and both PET surfaces exhibited greater adhesion than PS. On the contrary, the presence of 10% serum in solution significantly affected cell behavior: the number of microbial cells on all surfaces was drastically reduced, and the adhesion properties of PET surfaces with respect to PS were reversed, with PET being less adhesive. Overall, the specific cylindrical nanostructures created on PET did not significantly influence microbial behavior. Ongoing studies are verifying whether other nanotopographies with different geometry could have more substantial effects.
Assuntos
Aderência Bacteriana/fisiologia , Staphylococcus aureus/fisiologia , Materiais Biocompatíveis , Contagem de Colônia Microbiana , Meios de Cultura , Meios de Cultura Livres de Soro , Medições Luminescentes , Teste de Materiais , Nanopartículas , Nanotecnologia , Polietilenotereftalatos , Poliestirenos , Propriedades de SuperfícieRESUMO
Several species belonging to Staphylococcus genus (non Sau/ non Sep species) exhibit increasing abilities as opportunistic pathogens in colonisation of periprosthesis tissues. Here we report on antibiotic resistance of 193 strains, belonging to non Sau/ non Sep species, consecutively collected from orthopedic implant infections in a period of about 40 months. The 193 strains (representing 17% of all staphylococci isolated) were analysed for their antibiotic resistance to 16 different drugs. Five species turned out more prevalent, ranging from 1 to 5%: S. hominis (4.2%), S. haemolyticus (3.7%), S. capitis (2.7%), S. warneri (2.6%), and S. cohnii (1.6%). Among these, the prevalence of antibiotic resistance to penicillins was similar, ranging from 51% to 66%. Conversely, significant differences were observed for all the remaining antibiotics. For S. haemolyticus the resistances to oxacillin and imipenem, the four aminoglycosides and erythromycin were at least twice that of the other three species which were compared. S. warneri was on the contrary the species with the lowest occurrence of resistant strains. Ten species appeared only rarely at the infection sites: S. lugdunensis, S. caprae, S. equorum, S. intermedius, S. xylosus, S. simulans, S. saprophyticus, S. pasteuri, S. sciuri, and S. schleiferi. The behaviours of these species, often resistant to penicillins, were individually analysed. Differences in both the frequencies and the panels of antibiotic resistances observed among the non Sau/ non Sep species: i) suggest that horizontal spreading of resistance factors, if acting, was not sufficient per se to level their bio-diversities; ii) highlight and confirm the worrisome appearance within the Staphylococcus genus of emerging ""new pathogens"", not homogeneous for their virulence and antibiotic resistance prevalence, which deserve to be recognised and treated individually.