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1.
PLoS Pathog ; 17(2): e1009304, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33544760

RESUMEN

S. epidermidis is a substantial component of the human skin microbiota, but also one of the major causes of nosocomial infection in the context of implanted medical devices. We here aimed to advance the understanding of S. epidermidis genotypes and phenotypes conducive to infection establishment. Furthermore, we investigate the adaptation of individual clonal lines to the infection lifestyle based on the detailed analysis of individual S. epidermidis populations of 23 patients suffering from prosthetic joint infection. Analysis of invasive and colonizing S. epidermidis provided evidence that invasive S. epidermidis are characterized by infection-supporting phenotypes (e.g. increased biofilm formation, growth in nutrient poor media and antibiotic resistance), as well as specific genetic traits. The discriminating gene loci were almost exclusively assigned to the mobilome. Here, in addition to IS256 and SCCmec, chromosomally integrated phages was identified for the first time. These phenotypic and genotypic features were more likely present in isolates belonging to sequence type (ST) 2. By comparing seven patient-matched nasal and invasive S. epidermidis isolates belonging to identical genetic lineages, infection-associated phenotypic and genotypic changes were documented. Besides increased biofilm production, the invasive isolates were characterized by better growth in nutrient-poor media and reduced hemolysis. By examining several colonies grown in parallel from each infection, evidence for genetic within-host population heterogeneity was obtained. Importantly, subpopulations carrying IS insertions in agrC, mutations in the acetate kinase (AckA) and deletions in the SCCmec element emerged in several infections. In summary, these results shed light on the multifactorial processes of infection adaptation and demonstrate how S. epidermidis is able to flexibly repurpose and edit factors important for colonization to facilitate survival in hostile infection environments.

2.
J Med Microbiol ; 70(3)2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33492206

RESUMEN

Introduction. Staphylococcus epidermidis is predominant in implant-associated infections due to its capability to form biofilms. It can deploy several strategies for biofilm development using either polysaccharide intercellular adhesin (PIA), extracellular DNA (eDNA) and/or proteins, such as the extracellular matrix-binding protein (Embp).Hypothesis/Gap Statement. We hypothesize that the dichotomic regulation of S. epidermidis adhesins is linked to whether it is inside a host or not, and that in vitro biofilm investigations in laboratory media may not reflect actual biofilms in vivo.Aim. We address the importance of PIA and Embp in biofilm grown in 'humanized' media to understand if these components play different roles in biofilm formation under conditions where bacteria can incorporate host proteins in the biofilm matrix.Methodology. S. epidermidis 1585 WT (deficient in icaADBC), and derivative strains that either lack embp, express embp from an inducible promotor, or express icaADBC from a plasmid, were cultivated in standard laboratory media, or in media with human plasma or serum. The amount, structure, elasticity and antimicrobial penetration of biofilms was quantified to describe structural differences caused by the different matrix components and growth conditions. Finally, we quantified the initiation of biofilms as suspended aggregates in response to host factors to determine how quickly the cells aggregate in response to the host environment and reach a size that protects them from phagocytosis.Results. S. epidermidis 1585 required polysaccharides to form biofilm in laboratory media. However, these observations were not representative of the biofilm phenotype in the presence of human plasma. If human plasma were present, polysaccharides and Embp were redundant for biofilm formation. Biofilms formed in human plasma were loosely attached and existed mostly as suspended aggregates. Aggregation occurred after 2 h of exposing cells to plasma or serum. Despite stark differences in the amount and composition of biofilms formed by polysaccharide-producing and Embp-producing strains in different media, there were no differences in vancomycin penetration or susceptibility.Conclusion. We suggest that the assumed importance of polysaccharides for biofilm formation is an artefact from studying biofilms in laboratory media void of human matrix components. The cell-cell aggregation of S. epidermidis can be activated by host factors without relying on either of the major adhesins, PIA and Embp, indicating a need to revisit the basic question of how S. epidermidis deploys self-produced and host-derived matrix components to form antibiotic-tolerant biofilms in vivo.


Asunto(s)
Adhesinas Bacterianas/metabolismo , Proteínas Bacterianas/metabolismo , Biopelículas/crecimiento & desarrollo , Polisacáridos Bacterianos/metabolismo , Infecciones Estafilocócicas/microbiología , Staphylococcus epidermidis/fisiología , Adhesión Bacteriana , Regulación Bacteriana de la Expresión Génica , Humanos
3.
mBio ; 11(5)2020 10 20.
Artículo en Inglés | MEDLINE | ID: mdl-33082256

RESUMEN

Although it is normally an innocuous part of the human skin microbiota, Staphylococcus epidermidis has emerged as a major nosocomial pathogen, and implanted foreign materials are an essential risk factor for the development of an infection. The extraordinary efficiency of S. epidermidis to colonize artificial surfaces is particularly related to the ability to form biofilms. Biofilm formation itself critically depends on stable pathogen binding to extracellular host matrix components, e.g. fibronectin (Fn), covering inserted devices in vast amounts. Extracellular matrix binding protein (Embp) and its subdomains referred to as the F-repeat and the FG-repeat are critical for adherence of S. epidermidis to surface-immobilized Fn. Embp-Fn interactions preferentially occur with surface-bound, but not folded, globular Fn via binding to the F3 domain. High-resolution structure analysis of F- and FG-repeats revealed that both repeats are composed of two tightly connected triple α-helix bundles, exhibiting an elongated but rather rigid structural organization in solution. Both F- and FG-repeat possess Fn-binding capacity via interactions with type III subdomain FN12, involving residues within the C and F ß-sheet. FN12 essentially supports stability of the globular Fn state, and thus these findings reasonably explain why Embp-mediated interaction of S. epidermidis necessitates Fn surface immobilization. Thus, Embp employs an uncharacterized bacterial Fn-binding mechanism to promote staphylococcal adherence.IMPORTANCE Staphylococcus epidermidis is a leading pathogen in implant-associated hospital infections. The pathogenesis critically depends on bacterial binding to ECM components, specifically fibronectin (Fn). The cell surface-localized, 1-MDa extracellular matrix binding protein (Embp) is essentially characterized by 10 F- and 40 FG-repeats. These repetitive units, each characterized by two α-helical bundles, organize themselves in a rigid, elongated form. Embp binds preferentially to surface-localized but not soluble Fn, with both F- and FG-repeats being sufficient for Fn binding and resulting bacterial adherence. Binding preferentially involves Fn type III domain, specifically residues of FN12 ß-sheets C and F. Both play key role in stabilizing the globular Fn conformation, explaining the necessity of Fn surface immobilization for a subsequent interaction with Embp. In comparison to many other bacterial Fn-binding proteins using the Fn N terminus, Embp employs a previously undescribed mechanism supporting the adhesion of S. epidermidis to surface-immobilized Fn.

4.
Acta Orthop ; 89(5): 580-584, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29947288

RESUMEN

Background and purpose - Cutibacterium acnes, formerly known as Propionibacterium acnes, is often isolated from deep tissues of the shoulder. It is recognized as an important causative agent of foreign-material associated infections. However, the incidence and significance of its detection in tissues from patients without clinical evidence for infection is unclear. We assessed the incidence of C. acnes colonization of osteosynthesis material in asymptomatic patients, and evaluated the short-term outcome in relation to the microbiological findings. Patients and methods - We microbiologically analyzed osteosynthesis material of 34 asymptomatic patients after surgery on the clavicle. Material obtained from 19 asymptomatic patients after osteosynthesis of the fibula served as a control group. Patients were clinically followed up for 3-24 months after removal of the osteosynthesis material. Results - Bacteria were recovered from devices in 29 of 34 patients from the clavicle group. 27 of 29 positive samples grew C. acnes. Isolation of C. acnes was more common in male than in female patients. No bacterial growth was observed on foreign material from patients in the fibula group. All patients remained asymptomatic at follow-up. Interpretation - Growth of C. acnes is common on osteosynthesis material of the shoulder, especially in males. Samples were positive irrespective of clinical signs of infection. Therefore, detection of C. acnes in this clinical setting is of questionable clinical significance. The high positivity rate in asymptomatic patients discourages routine sampling of material in cases without clinical evidence for infection.


Asunto(s)
Placas Óseas/microbiología , Fijación Interna de Fracturas/instrumentación , Propionibacterium acnes/aislamiento & purificación , Fracturas del Hombro/cirugía , Articulación del Hombro/microbiología , Adulto , Anciano , Tornillos Óseos/microbiología , Clavícula/lesiones , Clavícula/cirugía , Remoción de Dispositivos , Contaminación de Equipos , Femenino , Peroné/lesiones , Peroné/cirugía , Estudios de Seguimiento , Fijación Interna de Fracturas/métodos , Humanos , Masculino , Persona de Mediana Edad , Propionibacterium acnes/crecimiento & desarrollo , Articulación del Hombro/cirugía , Adulto Joven
5.
Diagn Microbiol Infect Dis ; 89(4): 253-257, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28974396

RESUMEN

Given constantly high or even rising incidences of both colonization and infection with vancomycin-resistant enterococci (VRE), timely and accurate identification of carriers in high-risk patient populations is of evident clinical importance. In this study, a two-tier approach consisting of PCR-based screening and cultural confirmation of positive results is compared to the conventional approach solely based on culture on selective media. The 2-tier strategy was highly consistent with the conventional approach, and was found to possess high sensitivity and specificity (93.1% and 100%, respectively). The introduction of the PCR-based combined VRE screening approach significantly (P<0.0001) reduced median overall time to result by 44.3hours. The effect was found to be most pronounced in VRE negative samples. Positive vanA PCR was highly consistent with culture (PPV: 92.0%, 95% CI: 72.5-98.6%, NPV: 99.6%, 95% CI: 98.9-99.6%), thus allowing for preliminary reporting of VRE detection. In contrast, a vanB positive PCR does not allow for preliminary reporting (PPV: 58.5%, 95% CI: 44.2-71.6%, NPV: 99.8%, 95% CI: 99.2-100%). The introduction of a molecular assay for rapid detection of VRE from rectal swabs combined with cultural confirmation proved to be reliable and time saving, especially in a setting of low VRE prevalence and predominance of vanA positive strains.


Asunto(s)
Técnicas de Tipificación Bacteriana , Infecciones por Bacterias Grampositivas/diagnóstico , Enterococos Resistentes a la Vancomicina/aislamiento & purificación , Proteínas Bacterianas/genética , Ligasas de Carbono-Oxígeno/genética , Medios de Cultivo/química , Humanos , Reacción en Cadena de la Polimerasa , Recto/microbiología , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Enterococos Resistentes a la Vancomicina/clasificación
6.
J Antimicrob Chemother ; 72(9): 2483-2488, 2017 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-28637339

RESUMEN

Background: Avibactam is a novel broad-range ß-lactamase inhibitor active against Ambler class A (including ESBL and KPC) and some Ambler class C and D (e.g. OXA-48) enzymes. We here report on the emergence of ceftazidime/avibactam resistance in clinical, multiresistant, OXA-48 and CTX-M-14-producing Klebsiella pneumoniae isolate DT12 during ceftazidime/avibactam treatment. Methods and results: Comparative whole-genome sequence analysis identified two SNPs in the CTX-M-14-encoding gene leading to two amino acid changes (P170S and T264I). Compared with WT CTX-M-14, expression of the CTX-M-14Δ170Δ264 isoform in Escherichia coli led to a >64- and 16-fold increase in ceftazidime and ceftazidime/avibactam MICs, respectively, functionally linking the observed SNPs and elevated MICs. The mutated CTX-M-14 isoform exhibited augmented ceftazidime hydrolytic activity, which was a reasonable cause for impaired susceptibility to avibactam inhibition. The P170S exchange in CTX-M-14 was found in association with elevated ceftazidime/avibactam MICs for independent K. pneumoniae isolates, but was not sufficient for full resistance. Apparently, additional CTX-M-independent mechanisms contribute to ceftazidime/avibactam resistance in K. pneumoniae DT12. Conclusions: This study on the molecular basis of ceftazidime/avibactam resistance in clinical K. pneumoniae emerging in vivo underscores the need for continuous monitoring of ceftazidime/avibactam susceptibility during therapy. Despite sustained inhibition of OXA-48, rapid development of CTX-M-14 isoforms exhibiting augmented ceftazidime hydrolytic activity may limit the usefulness of ceftazidime/avibactam monotherapies in infections caused by isolates carrying blaCTX-M-14 and blaOXA-48.


Asunto(s)
Antibacterianos/farmacología , Compuestos de Azabiciclo/farmacología , Ceftazidima/farmacología , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/genética , Compuestos de Azabiciclo/administración & dosificación , Compuestos de Azabiciclo/uso terapéutico , Ceftazidima/administración & dosificación , Ceftazidima/uso terapéutico , Combinación de Medicamentos , Farmacorresistencia Bacteriana Múltiple , Genoma Bacteriano , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Infecciones por Klebsiella/tratamiento farmacológico , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/aislamiento & purificación , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Inhibidores de beta-Lactamasas/farmacología
7.
Mol Microbiol ; 103(5): 860-874, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-27997732

RESUMEN

The otherwise harmless skin inhabitant Staphylococcus epidermidis is a major cause of healthcare-associated medical device infections. The species' selective pathogenic potential depends on its production of surface adherent biofilms. The Cell wall-anchored protein Aap promotes biofilm formation in S. epidermidis, independently from the polysaccharide intercellular adhesin PIA. Aap requires proteolytic cleavage to act as an intercellular adhesin. Whether and which staphylococcal proteases account for Aap processing is yet unknown. Here, evidence is provided that in PIA-negative S. epidermidis 1457Δica, the metalloprotease SepA is required for Aap-dependent S. epidermidis biofilm formation in static and dynamic biofilm models. qRT-PCR and protease activity assays demonstrated that under standard growth conditions, sepA is repressed by the global regulator SarA. Inactivation of sarA increased SepA production, and in turn augmented biofilm formation. Genetic and biochemical analyses demonstrated that SepA-related induction of biofilm accumulation resulted from enhanced Aap processing. Studies using recombinant proteins demonstrated that SepA is able to cleave the A domain of Aap at residue 335 and between the A and B domains at residue 601. This study identifies the mechanism behind Aap-mediated biofilm maturation, and also demonstrates a novel role for a secreted staphylococcal protease as a requirement for the development of a biofilm.


Asunto(s)
Proteínas Bacterianas/metabolismo , Biopelículas/crecimiento & desarrollo , Metaloendopeptidasas/metabolismo , Procesamiento Proteico-Postraduccional , Staphylococcus epidermidis/enzimología , Staphylococcus epidermidis/fisiología , Adhesinas Bacterianas/metabolismo , Adhesión Bacteriana , Polisacáridos Bacterianos/metabolismo , Unión Proteica , Staphylococcus epidermidis/química , Staphylococcus epidermidis/genética
9.
Int J Med Microbiol ; 306(6): 471-8, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27292911

RESUMEN

Biofilm-associated Staphylococcus epidermidis implant infections are notoriously reluctant to antibiotic treatment. Here we studied the effect of sub-inhibitory concentrations of penicillin, oxacillin, vancomycin, daptomycin, linezolid and tigecycline on S. epidermidis 1585 biofilm formation, expression of extracellular matrix binding protein (Embp) and potential implications for S. epidermidis - macrophage interactions. Penicillin, vancomycin, daptomycin, and linezolid had no biofilm augmenting effect at any of the concentrations tested. In contrast, at sub-inhibitory concentrations tigecycline and oxacillin exhibited significant biofilm inducing activity. In S. epidermidis 1585, SarA is a negative regulator of giant 1 MDa Embp, and down regulation of sarA induces Embp-dependent assembly of a multi-layered biofilm architecture. Dot blot immune assays, confocal laser scanning microscopy, and qPCR showed that under biofilm inducing conditions, tigecycline augmented embp expression compared to the control grown without antibiotics. Conversely, expression of regulator sarA was suppressed, suggesting that tigecycline exerts its effects on embp expression through SarA. Tigecycline failed to induce biofilm formation in embp transposon mutant 1585-M135, proving that under these conditions Embp up-regulation is necessary for biofilm accumulation. As a functional consequence, tigecycline induced biofilm formation significantly impaired the up-take of S. epidermidis by mouse macrophage-like cell line J774A.1. Our data provide novel evidence for the molecular basis of antibiotic induced biofilm formation, a phenotype associated with inherently increased antimicrobial tolerance. While this could explain failure of antimicrobial therapies, persistence of S. epidermidis infections in the presence of sub-inhibitory antimicrobials is additionally propelled by biofilm-related impairment of macrophage-mediated pathogen eradication.


Asunto(s)
Antibacterianos/metabolismo , Proteínas Bacterianas/biosíntesis , Biopelículas/crecimiento & desarrollo , Proteínas Portadoras/biosíntesis , Evasión Inmune , Minociclina/análogos & derivados , Staphylococcus epidermidis/efectos de los fármacos , Staphylococcus epidermidis/fisiología , Animales , Proteínas Bacterianas/genética , Proteínas Portadoras/genética , Línea Celular , Perfilación de la Expresión Génica , Humanos , Immunoblotting , Macrófagos/microbiología , Ratones , Microscopía Confocal , Minociclina/metabolismo , Fagocitosis , Reacción en Cadena en Tiempo Real de la Polimerasa , Staphylococcus epidermidis/inmunología , Staphylococcus epidermidis/metabolismo , Tigeciclina , Transactivadores/biosíntesis , Transactivadores/genética
10.
Int J Med Microbiol ; 305(8): 902-9, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26454536

RESUMEN

Infections due to vancomycin-resistant enterococci (VRE) are of significant importance in high-risk populations, and daptomycin is a bactericidal antibiotic to treat multidrug-resistant VRE in these patients. The emergence of daptomycin non-susceptibility invasive VRE during daptomycin therapy is a major clinical issue. Here the hypothesis was tested that systemic daptomycin therapy also induces the emergence of daptomycin non-susceptible (DNS-) isolates in colonizing VRE populations. 11 vancomycin-resistant Enterococcus faecium strain pairs recovered from rectal swabs were available for analysis. All initial isolates exhibited daptomycin MICs within the wild type MIC distribution of E. faecium (MIC≤4 mg/L). In follow-up isolates from five patients a 4-16-fold daptomycin MIC increase was detected. All patients carrying DNS-VRE received daptomycin (14-28 days) at 4 mg/kg body weight, while two patients in whom no DNS-VRE emerged were only treated with daptomycin for 1 and 4 days, respectively. Comparative whole genome sequencing identified DNS-VRE-specific single nucleotide polymorphisms (SNP), including mutations in cardiolipin synthase (Cls), and additional SNPs in independent genes potentially relevant for the DNS phenotype. Mutations within cls were also identified in three additional, colonizing DNS-VRE. Of these, at least one strain was transmitted within the hospital. In none of the VRE isolates tested, pre-existing or de novo mutations in the liaFSR operon were detected. This is the first report documenting the emergence of DNS-VRE in colonizing strains during daptomycin treatment, putting the patient at risk for subsequent DNS-VRE infections and priming the spread of DNS-VRE within the hospital environment.


Asunto(s)
Antibacterianos/farmacología , Daptomicina/farmacología , Tolerancia a Medicamentos , Enterococcus faecium/efectos de los fármacos , Enterococos Resistentes a la Vancomicina/efectos de los fármacos , Antibacterianos/uso terapéutico , ADN Bacteriano/química , ADN Bacteriano/genética , Daptomicina/uso terapéutico , Enterococcus faecium/aislamiento & purificación , Heces/microbiología , Genoma Bacteriano , Infecciones por Bacterias Grampositivas/microbiología , Humanos , Pruebas de Sensibilidad Microbiana , Polimorfismo de Nucleótido Simple , Enterococos Resistentes a la Vancomicina/aislamiento & purificación
11.
PLoS Pathog ; 11(3): e1004735, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25799153

RESUMEN

Virulence of the nosocomial pathogen Staphylococcus epidermidis is crucially linked to formation of adherent biofilms on artificial surfaces. Biofilm assembly is significantly fostered by production of a bacteria derived extracellular matrix. However, the matrix composition, spatial organization, and relevance of specific molecular interactions for integration of bacterial cells into the multilayered biofilm community are not fully understood. Here we report on the function of novel 18 kDa Small basic protein (Sbp) that was isolated from S. epidermidis biofilm matrix preparations by an affinity chromatographic approach. Sbp accumulates within the biofilm matrix, being preferentially deposited at the biofilm-substratum interface. Analysis of Sbp-negative S. epidermidis mutants demonstrated the importance of Sbp for sustained colonization of abiotic surfaces, but also epithelial cells. In addition, Sbp promotes assembly of S. epidermidis cell aggregates and establishment of multilayered biofilms by influencing polysaccharide intercellular-adhesin (PIA) and accumulation associated protein (Aap) mediated intercellular aggregation. While inactivation of Sbp indirectly resulted in reduced PIA-synthesis and biofilm formation, Sbp serves as an essential ligand during Aap domain-B mediated biofilm accumulation. Our data support the conclusion that Sbp serves as an S. epidermidis biofilm scaffold protein that significantly contributes to key steps of surface colonization. Sbp-negative S. epidermidis mutants showed no attenuated virulence in a mouse catheter infection model. Nevertheless, the high prevalence of sbp in commensal and invasive S. epidermidis populations suggests that Sbp plays a significant role as a co-factor during both multi-factorial commensal colonization and infection of artificial surfaces.


Asunto(s)
Adhesión Bacteriana/fisiología , Biopelículas/crecimiento & desarrollo , Proteínas de Unión Periplasmáticas/metabolismo , Staphylococcus epidermidis/fisiología , Animales , Ratones , Proteínas de Unión Periplasmáticas/genética
12.
Artículo en Inglés | MEDLINE | ID: mdl-25741476

RESUMEN

Staphylococcus epidermidis is a usually harmless commensal bacterium highly abundant on the human skin. Under defined predisposing conditions, most importantly implantation of a medical device, S. epidermidis, however, can switch from a colonizing to an invasive life style. The emergence of S. epidermidis as an opportunistic pathogen is closely linked to the biofilm forming capability of the species. During the past decades, tremendous advance regarding our understanding of molecular mechanisms contributing to surface colonization has been made, and detailed information is available for several factors active during the primary attachment, accumulative or dispersal phase of biofilm formation. A picture evolved in which distinct factors, though appearing to be redundantly organized, take over specific and exclusive functions during biofilm development. In this review, these mechanisms are described in molecular detail, with a highlight on recent insights into multi-functional S. epidermidis cell surface proteins contributing to surface adherence and intercellular adhesion. The integration of distinct biofilm-promoting factors into regulatory networks is summarized, with an emphasis on mechanism that could allow S. epidermidis to flexibly adapt to changing environmental conditions present during colonizing or invasive life-styles.


Asunto(s)
Biopelículas , Infecciones Estafilocócicas/microbiología , Staphylococcus epidermidis/fisiología , Animales , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Humanos , Staphylococcus epidermidis/genética
13.
Infect Immun ; 83(1): 214-26, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25332125

RESUMEN

Biofilm formation is the primary virulence factor of Staphylococcus epidermidis. S. epidermidis biofilms preferentially form on abiotic surfaces and may contain multiple matrix components, including proteins such as accumulation-associated protein (Aap). Following proteolytic cleavage of the A domain, which has been shown to enhance binding to host cells, B domain homotypic interactions support cell accumulation and biofilm formation. To further define the contribution of Aap to biofilm formation and infection, we constructed an aap allelic replacement mutant and an icaADBC aap double mutant. When subjected to fluid shear, strains deficient in Aap production produced significantly less biofilm than Aap-positive strains. To examine the in vivo relevance of our findings, we modified our previously described rat jugular catheter model and validated the importance of immunosuppression and the presence of a foreign body to the establishment of infection. The use of our allelic replacement mutants in the model revealed a significant decrease in bacterial recovery from the catheter and the blood in the absence of Aap, regardless of the production of polysaccharide intercellular adhesin (PIA), a well-characterized, robust matrix molecule. Complementation of the aap mutant with full-length Aap (containing the A domain), but not the B domain alone, increased initial attachment to microtiter plates, as did in trans expression of the A domain in adhesion-deficient Staphylococcus carnosus. These results demonstrate Aap contributes to S. epidermidis infection, which may in part be due to A domain-mediated attachment to abiotic surfaces.


Asunto(s)
Proteínas Bacterianas/metabolismo , Biopelículas/crecimiento & desarrollo , Infecciones Relacionadas con Catéteres/microbiología , Infecciones Estafilocócicas/microbiología , Staphylococcus epidermidis/fisiología , Factores de Virulencia/metabolismo , Animales , Proteínas Bacterianas/genética , Modelos Animales de Enfermedad , Eliminación de Gen , Prueba de Complementación Genética , Masculino , Datos de Secuencia Molecular , Ratas Sprague-Dawley , Análisis de Secuencia de ADN , Staphylococcus epidermidis/metabolismo , Factores de Virulencia/genética
14.
J Bacteriol ; 196(19): 3482-93, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25070736

RESUMEN

Staphylococcus epidermidis is an opportunistic pathogen that is one of the leading causes of medical device infections. Global regulators like the agr quorum-sensing system in this pathogen have received a limited amount of attention, leaving important questions unanswered. There are three agr types in S. epidermidis strains, but only one of the autoinducing peptide (AIP) signals has been identified (AIP-I), and cross talk between agr systems has not been tested. We structurally characterized all three AIP types using mass spectrometry and discovered that the AIP-II and AIP-III signals are 12 residues in length, making them the largest staphylococcal AIPs identified to date. S. epidermidis agr reporter strains were developed for each system, and we determined that cross-inhibitory interactions occur between the agr type I and II systems and between the agr type I and III systems. In contrast, no cross talk was observed between the type II and III systems. To further understand the outputs of the S. epidermidis agr system, an RNAIII mutant was constructed, and microarray studies revealed that exoenzymes (Ecp protease and Geh lipase) and low-molecular-weight toxins were downregulated in the mutant. Follow-up analysis of Ecp confirmed the RNAIII is required to induce protease activity and that agr cross talk modulates Ecp activity in a manner that mirrors the agr reporter results. Finally, we demonstrated that the agr system enhances skin colonization by S. epidermidis using a porcine model. This work expands our knowledge of S. epidermidis agr system function and will aid future studies on cell-cell communication in this important opportunistic pathogen.


Asunto(s)
Proteínas Bacterianas/metabolismo , Péptidos Cíclicos/metabolismo , Percepción de Quorum , Infecciones Estafilocócicas/microbiología , Staphylococcus epidermidis/fisiología , Animales , Proteínas Bacterianas/genética , Regulación Bacteriana de la Expresión Génica , Humanos , Péptidos Cíclicos/genética , Staphylococcus epidermidis/genética , Staphylococcus epidermidis/crecimiento & desarrollo , Porcinos
15.
Mol Microbiol ; 86(2): 394-410, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22957858

RESUMEN

Biofilm formation is essential for Staphylococcus epidermidis pathogenicity in implant-associated infections. Nonetheless, large proportions of invasive Staphylococcus epidermidis isolates fail to form a biofilm in vitro. We here tested the hypothesis that this apparent paradox is related to the existence of superimposed regulatory systems suppressing a multicellular biofilm life style in vitro. Transposon mutagenesis of clinical significant but biofilm-negative S. epidermidis 1585 was used to isolate a biofilm positive mutant carrying a Tn917 insertion in sarA, chief regulator of staphylococcal virulence. Genetic analysis revealed that inactivation of sarA induced biofilm formation via overexpression of the giant 1 MDa extracellular matrix binding protein (Embp), serving as an intercellular adhesin. In addition to Embp, increased extracellular DNA (eDNA) release significantly contributed to biofilm formation in mutant 1585ΔsarA. Increased eDNA amounts indirectly resulted from upregulation of metalloprotease SepA, leading to boosted processing of autolysin AtlE, in turn inducing augmented autolysis and release of eDNA. Hence, this study identifies sarA as a negative regulator of Embp- and eDNA-dependent biofilm formation. Given the importance of SarA as a positive regulator of polysaccharide mediated cell aggregation, the regulator enables S. epidermidis to switch between mechanisms of biofilm formation, ensuring S. epidermidis adaptation to hostile environments.


Asunto(s)
Adhesinas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Bacteriólisis , Biopelículas , ADN Bacteriano/metabolismo , Regulación hacia Abajo , Regulación Bacteriana de la Expresión Génica , Staphylococcus epidermidis/fisiología , Transactivadores/metabolismo , Adhesinas Bacterianas/metabolismo , Proteínas Bacterianas/genética , ADN Bacteriano/genética , Humanos , Staphylococcus epidermidis/genética , Transactivadores/genética
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