RESUMEN
In hospitals, sinks act as reservoirs for bacterial pathogens. To assess the extent of splashing, fluorescein dye was added to four hospital sinks previously involved in pathogen dispersal to the environment and/or transmission to patients, and one sink that was not. Applying dye to the p-trap or tailpiece did not result in any fluorescent droplets outside of the drain. When applied to the drain, droplets were found in all but one wash basin, and this was more common in the absence of a drain plug. Sink design considerations to install drain plugs, reduce dripping and offset the tap may help to prevent transmission from drains.
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Infección Hospitalaria , Infección Hospitalaria/microbiología , Hospitales , HumanosRESUMEN
BACKGROUND: An altered immune response against Staphylococcus aureus might contribute to inflammation and barrier damage in atopic dermatitis (AD). OBJECTIVES: To profile IgG antibodies against 55 S. aureus antigens in sera of children with mild-to-severe AD and to evaluate the association between IgG levels and disease severity. METHODS: In this cross-sectional study, we included children with AD from two interventional study cohorts, the Shared Medical Appointment (SMA) cohort (n = 131) and the older DAVOS cohort (n = 76). AD severity was assessed using the Self-Administered Eczema Area and Severity Index (SA-EASI) and levels of thymus and activation-regulated chemokine (TARC) in serum. IgG antibody levels against 55 S. aureus antigens were quantified simultaneously using a Luminex assay. Pair-wise correlations were calculated between the 55 IgG levels using the Spearman rank correlation test. Linear regression analysis was performed to test for associations between 55 IgG levels and SA-EASI and TARC, adjusting for age, sex and S. aureus colonization. RESULTS: In the SMA cohort, 16 antigens were associated with SA-EASI and 12 with TARC (10 overlapping antigens; P-values 0·001-0·044). The associated IgG antibodies targeted mainly secreted proteins with immunomodulatory functions. In the DAVOS study, IgG levels against only four and one S. aureus antigen(s) were associated with SA-EASI and TARC, respectively (no overlap). CONCLUSIONS: In young children, severity of AD is associated with an IgG response directed against S. aureus antigens with mainly immunomodulatory functions. These findings encourage further evaluation of the role of S. aureus in the pathogenesis of AD.
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Dermatitis Atópica/inmunología , Inmunoglobulina G/metabolismo , Infecciones Estafilocócicas/inmunología , Staphylococcus aureus/inmunología , Adolescente , Anticuerpos Antibacterianos/metabolismo , Antígenos Bacterianos/metabolismo , Niño , Preescolar , Estudios Transversales , Femenino , Humanos , Inmunoglobulina G/inmunología , Lactante , Recién Nacido , MasculinoRESUMEN
Fifteen percent of all methicillin-resistant Staphylococcus aureus (MRSA) clonal complex 398 (CC398) human carriers detected in The Netherlands had not been in direct contact with pigs or veal calves. To ensure low MRSA prevalence, it is important to investigate the likely origin of this MRSA of unknown origin (MUO). Recently, it was shown that CC398 strains originating from humans and animals differ in the presence of specific mobile genetic elements (MGEs). We hypothesized that determining these specific MGEs in MUO isolates and comparing them with a set of CC398 isolates of various known origin might provide clues to their origin. MUO CC398 isolates were compared to MRSA CC398 isolates obtained from humans with known risk factors, a MRSA CC398 outbreak isolate, livestock associated (LA) MRSA CC398 isolates from pigs, horses, chickens, and veal calves, and five methicillin-susceptible Staphylococcus aureus (MSSA) CC398 isolates of known human origin. All strains were spa typed, and the presence or absence of, scn, chp, φ3 int, φ6 int, φ7 int, rep7, rep27, and cadDX was determined by PCRs. The MRSA CC398 in humans, MUO, or MRSA of known origin (MKO) resembled MRSA CC398 as found in pigs and not MSSA CC398 as found in humans. The distinct human MSSA CC398 spa type, t571, was not present among our MRSA CC398 strains; MRSA CC398 was tetracycline resistant and carried no φ3 bacteriophage with scn and chp. We showed by simple PCR means that human MUO CC398 carriers carried MRSA from livestock origin, suggestive of indirect transmission. Although the exact transmission route remains unknown, direct human-to-human transmission remains a possibility as well.
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Staphylococcus aureus Resistente a Meticilina/genética , Infecciones Estafilocócicas/transmisión , Infecciones Estafilocócicas/veterinaria , Animales , Bovinos , Pollos , Estudios de Cohortes , Caballos , Humanos , Incidencia , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , PorcinosRESUMEN
Due to molecular mimicry, Campylobacter jejuni lipo-oligosaccharides can induce a cross-reactive antibody response to nerve gangliosides, which leads to Guillain-Barré syndrome (GBS). Cross-reactive antibodies to ganglioside GQ1b are strongly associated with oculomotor weakness in GBS and its variant, Miller Fisher syndrome (MFS). Antigen recognition is a crucial first step in the induction of a cross-reactive antibody response, and it has been shown that GQ1b-like epitopes expressed on the surface of C. jejuni are recognized by sialic acid-binding immunoglobulin-like lectin-7 (Siglec-7). We aimed to determine the epitope specificity of C. jejuni binding to Siglec-7, and correlate the outcome to disease symptoms in GBS and MFS patients. Using a well-defined GBS/MFS-associated C. jejuni strain collection, which included three sialic acid knockout strains, we found that Siglec-7 exclusively binds to C. jejuni strains that express terminal disialylated ganglioside mimics. When serological and diagnostic patient records were correlated with the Siglec-7-binding properties, we observed an association between Siglec-7 binding and the presence of anti-GQ1b antibodies in patient serum. In addition, Siglec-7 binding was associated with oculomotor weakness in GBS and MFS patients. Lipo-oligosaccharide-specific binding of C. jejuni to Siglec-7 may be an initiating event in immune recognition and presentation, and lead to anti-GQ1b antibody production and the development of ocular weakness in GBS or MFS.
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Antígenos Bacterianos/metabolismo , Antígenos de Diferenciación Mielomonocítica/metabolismo , Autoanticuerpos/sangre , Campylobacter jejuni/química , Campylobacter jejuni/patogenicidad , Síndrome de Guillain-Barré/patología , Lectinas/metabolismo , Ácidos Siálicos/metabolismo , Campylobacter jejuni/genética , Técnicas de Inactivación de Genes , Síndrome de Guillain-Barré/inmunología , Humanos , Músculos Oculomotores/fisiopatología , Unión ProteicaRESUMEN
Staphylococcus aureus (S. aureus) colonizes the anterior nares in part of the population and the persistent carrier state is associated with increased infection risk. Knowledge concerning the determinants of S. aureus nasal carriage is limited. Previously, we found that glucocorticoid receptor polymorphisms influence carrier risk, suggesting involvement of glucocorticoids. Our aim was to study long-term cortisol levels in non-carriers, intermittent, and persistent carriers of S. aureus. We hypothesized that cortisol levels are higher in carriers, since cortisol-induced immune suppression would enhance S. aureus colonization. We determined nasal carrier state and long-term hair cortisol levels in 72 healthy subjects. Nasal swabs were collected twice with an interval of 2 weeks. Cortisol levels were determined in hair segments of 3 cm, which corresponds to a period of roughly 3 months. Of all 72 participants, 38 were non-carriers, 10 were intermittent carriers, and 24 were persistent carriers of S. aureus. Cortisol levels did not differ between these carrier groups (p=0.638). Long-term cortisol levels are not associated with S. aureus nasal carriage.
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Cabello/química , Hidrocortisona/análisis , Mucosa Nasal/microbiología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/aislamiento & purificación , Adulto , Portador Sano/microbiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Cavidad Nasal/microbiología , Polimorfismo de Nucleótido Simple , Receptores de Glucocorticoides/genética , Infecciones Estafilocócicas/epidemiología , Staphylococcus aureus/patogenicidad , Factores de TiempoRESUMEN
The Netherlands is known for its low methicillin-resistant Staphylococcus aureus (MRSA) prevalence. Yet MRSA with no link to established Dutch risk factors for acquisition, MRSA of unknown origin (MUO), has now emerged and hampers early detection and control by active screening upon hospital admittance. We assessed the magnitude of the problem and determined the differences between MUO and MRSA of known origin (MKO) for CC398 and non-CC398. National MRSA Surveillance data (2008-2009) were analysed for epidemiological determinants and genotypic characteristics (Panton-Valentine leukocidin, spa). A quarter (24%) of the 5545 MRSA isolates registered were MUO, i.e. not from defined risk groups. There are two genotypic MUO groups: CC398 MUO (352; 26%) and non-CC398 MUO (998; 74%). CC398 MUO needs further investigation because it could suggest spread, not by direct contact with livestock (pigs, veal calves), but through the community. Non-CC398 MUO is less likely to be from a nursing home than non-CC398 MKO (relative risk 0.55; 95% CI 0.42-0.72) and Panton-Valentine leukocidin positivity was more frequent in non-CC398 MUO than MKO (relative risk 1.19; 95% CI 1.11-1.29). Exact transmission routes and risk factors for non-CC398 as CC398 MUO remain undefined.
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Enfermedades Transmisibles Emergentes/epidemiología , Enfermedades Transmisibles Emergentes/microbiología , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Toxinas Bacterianas/genética , Infecciones Comunitarias Adquiridas/epidemiología , Infecciones Comunitarias Adquiridas/microbiología , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Exotoxinas/genética , Femenino , Genotipo , Humanos , Leucocidinas/genética , Masculino , Staphylococcus aureus Resistente a Meticilina/clasificación , Staphylococcus aureus Resistente a Meticilina/genética , Persona de Mediana Edad , Tipificación Molecular , Países Bajos/epidemiología , Adulto JovenRESUMEN
It remains largely unknown which factors determine the clinical outcome of human metapneumovirus (HMPV) infections. The aim of the present study was to analyse whether exposure to bacterial pathogens can influence HMPV infections. From 57 children, serum samples and colonization data for Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Streptococcus pneumoniae were collected at 1.5, 6, 14 and 24 months of age. Seroconversion rates to HMPV were determined and related to bacterial carriage. Frequent nasopharyngeal carriage (≥2 times in the first 2 years of life) of S. pneumoniae, but not of the other three pathogens, was associated with increased seroconversion rates of infants to HMPV at the age of 2 years (frequently vs. less exposed, 93% vs. 59%; p <0.05). Subsequently, the susceptibility of well-differentiated normal human bronchial epithelial cells (wd-NHBE) pre-incubated with bacterial pathogens to in vitro HMPV infection was evaluated. Pre-incubation of wd-NHBE with S. pneumoniae resulted in increased susceptibility to infection with HMPV-enhanced green fluorescent protein (EGFP), as determined by enumeration of EGFP-positive cells. This was not the case for cells pre-incubated with H. influenzae, M. catarrhalis on S. aureus. We conclude that exposure to S. pneumoniae can modulate HMPV infection.
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Anticuerpos Antivirales/sangre , Portador Sano , Susceptibilidad a Enfermedades , Metapneumovirus/aislamiento & purificación , Infecciones por Paramyxoviridae/epidemiología , Infecciones Neumocócicas/complicaciones , Streptococcus pneumoniae/patogenicidad , Preescolar , Haemophilus influenzae/aislamiento & purificación , Haemophilus influenzae/patogenicidad , Humanos , Lactante , Metapneumovirus/inmunología , Moraxella catarrhalis/aislamiento & purificación , Moraxella catarrhalis/patogenicidad , Nasofaringe/microbiología , Infecciones por Paramyxoviridae/inmunología , Infecciones por Paramyxoviridae/virología , Staphylococcus aureus/aislamiento & purificación , Staphylococcus aureus/patogenicidad , Streptococcus pneumoniae/aislamiento & purificaciónRESUMEN
Presently, several pneumococcal proteins are being evaluated as potential vaccine candidates. Here, we gather novel insights in the immunogenicity of PLY, PsaA, PspA, PspC, NanA, Hyl, PpmA, SlrA, Eno, IgA1-protease, PdBD, BVH-3, SP1003, SP1633, SP1651, SP0189 and SP0376. We developed a multiplex bead-based immunoassay (xMAP(®) Technology, Luminex Corporation) to simultaneously quantify antibodies against these 17 pneumococcal proteins in serum. The median fluorescence intensity (MFI) values obtained for human pooled serum with the multiplex assay were between 82% and 111% (median 94%) of those obtained with the singleplex assays. For IgG, the coefficient of variation (CV) in serum ranged from 2% to 9%, for IgA, the CV ranged from 3% to 14% and for IgM, the CV ranged from 11% to 15%. Using this immunoassay, we showed that anti-pneumococcal antibody levels exhibited extensive inter-individual variability in young children suffering from invasive pneumococcal disease. All proteins, including the proteins with, as yet, unknown function, were immunogenic. In conclusion, the multiplex Streptococcus pneumoniae immunoassay based on proteins is reproducible. This assay can be used to monitor anti-S. pneumoniae antibody responses in a material- and time-saving manner.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Proteínas Bacterianas/inmunología , Infecciones Neumocócicas/inmunología , Streptococcus pneumoniae/inmunología , Proteínas Bacterianas/genética , Niño , Preescolar , Citometría de Flujo , Humanos , Inmunoensayo/métodos , Inmunoglobulina A/sangre , Inmunoglobulina G/sangre , Meningitis Neumocócica/inmunología , Meningitis Neumocócica/microbiología , Infecciones Neumocócicas/microbiología , Polisacáridos Bacterianos/genética , Polisacáridos Bacterianos/inmunología , Reproducibilidad de los ResultadosRESUMEN
The Staphylococcus aureus immune evasion cluster (IEC), located on ß-haemolysin-converting bacteriophages (ßC-Φs), encodes the immune-modulating proteins chemotaxis inhibitory protein, staphylococcal complement inhibitor (SCIN), staphylococcal enterotoxin A and staphylokinase. Its precise role in S. aureus colonization is unclear. We studied the presence of the IEC-carrying bacteriophages in human and animal S. aureus isolates, using PCR for the gene encoding SCIN (scn). Human isolates were obtained by collecting serial nasal swabs from 21 persistent carriers. S. aureus strains from 19 (90%) persistent carriers contained an IEC that was present and indistinguishable in 95% of cases at all five sampling moments over a 3-month period. Of the 77 infectious animal strains included in the study, only 26 strains (34%) were IEC-positive. Integration of these IEC-positive strains into an amplified fragment length polymorphism genotype database showed that 24 of 53 (45%) strains were human-associated and only two of 24 (8%) were 'true' animal isolates (p < 0.001). The high prevalence and stability of IEC-carrying ßC-Φs in human strains suggested a role for these ßC-Φs in human nasal colonization. To test this hypothesis, 23 volunteers were colonized artificially with S. aureus strain NCTC 8325-4 with or without the IEC type B-carrying ßC-Φ13. Intranasal survival was monitored for 28 days after inoculation. The strain harbouring ßC-Φ13 was eliminated significantly faster (median 4 days; range 1-14 days) than the strain without ßC-Φ13 (median 14 days; range 2-28 days; p 0.011). In conclusion, although IEC-carrying ßC-Φs are highly prevalent among human colonizing S. aureus strains, they are not essential in the first stages of S. aureus nasal colonization.
Asunto(s)
Genes Virales , Evasión Inmune/genética , Mucosa Nasal/microbiología , Infecciones Estafilocócicas/virología , Fagos de Staphylococcus/genética , Staphylococcus aureus/virología , Adulto , Animales , Proteínas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Recuento de Colonia Microbiana , Enterotoxinas/genética , Femenino , Proteínas Hemolisinas/metabolismo , Humanos , Masculino , Metaloendopeptidasas/genética , Persona de Mediana Edad , Familia de Multigenes , Mascotas , Esfingomielina Fosfodiesterasa/metabolismo , Staphylococcus aureus/genética , Staphylococcus aureus/aislamiento & purificación , Adulto JovenRESUMEN
Expanding knowledge on the humoral immune response in Staphylococcus aureus-infected patients is a mandatory step in the development of vaccines and immunotherapies. Here, we present novel insights into the antibody responses following S. aureus bacteremia. Fifteen bacteremic patients were followed extensively from diagnosis onwards (median 29 days, range 9-74). S. aureus strains (median 3, range 1-6) and serial serum samples (median 16, range 6-27) were collected. Strains were genotyped by pulsed-field gel electrophoresis (PFGE) and genes encoding 19 staphylococcal proteins were detected by polymerase chain reaction (PCR). The levels of IgG, IgA, and IgM directed to these proteins were determined using bead-based flow cytometry. All strains isolated from individual patients were PFGE-identical. The genes encoding clumping factor (Clf) A, ClfB, and iron-responsive surface-determinant (Isd) A were detected in all isolates. Antigen-specific IgG levels increased more frequently than IgA or IgM levels. In individual patients, different proteins induced an immune response and the dynamics clearly differed. Anti-ClfB, anti-IsdH, and anti-fibronectin-binding protein A IgG levels increased in 7 of 13 adult patients (p < 0.05). The anti-IsdA IgG level increased in 12 patients (initial to peak level: 1.13-10.72 fold; p < 0.01). Peak level was reached 7-37 days after diagnosis. In a bacteremic 5-day-old newborn, antistaphylococcal IgG levels declined from diagnosis onwards. In conclusion, each bacteremic patient develops a unique immune response directed to different staphylococcal proteins. Therefore, vaccines should be based on multiple components. IsdA is immunogenic and, therefore, produced in nearly all bacteremic patients. This suggests that IsdA might be a useful component of a multivalent staphylococcal vaccine.
Asunto(s)
Bacteriemia/inmunología , Infecciones Estafilocócicas/inmunología , Staphylococcus aureus/inmunología , Adulto , Anciano , Anticuerpos Antibacterianos/sangre , Anticuerpos Antibacterianos/inmunología , Bacteriemia/microbiología , Preescolar , Análisis por Conglomerados , Electroforesis en Gel de Campo Pulsado , Femenino , Humanos , Inmunidad Humoral/inmunología , Isotipos de Inmunoglobulinas/sangre , Isotipos de Inmunoglobulinas/inmunología , Recién Nacido , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/genética , Estadísticas no Paramétricas , Virulencia/genéticaRESUMEN
In order to develop novel antistaphylococcal strategies, understanding the determinants of carriage and how humans respond to Staphylococcus aureus exposure is essential. Here, the primary S. aureus-specific humoral immune response and its association with nasal colonization was studied in young children. Sera from 57 colonized or non-colonized children, serially collected at birth and at 6, 14 and 24 months, were analysed for IgG, IgA and IgM binding to 19 staphylococcal proteins, using flow cytometry-based technology. The antibody responses showed extensive inter-individual variability. On average, the levels of antistaphylococcal IgA and IgM increased from birth until the age of 2 years (p <0.05), whereas the levels of IgG decreased (p <0.001). Placentally transferred maternal IgG did not protect against colonization. In colonized children, IgG and IgA levels for a number of proteins were higher than in non-colonized children. At both 14 and 24 months, the levels of IgG against chemotaxis inhibitory protein of S. aureus (at 24 months; median fluorescence intensity, 4928 vs. 24, p <0.05), extracellular fibrinogen-binding protein (987 vs. 604, p <0.05), and iron-responsive surface determinant H (62 vs. 5, p <0.05) were significantly higher in colonized children. The levels of IgA against CHIPS, IsdH and IsdA were higher (p <0.05). Therefore, CHIPS, Efb, IsdA and IsdH seem to play a role in nasal colonization of young children.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Portador Sano/inmunología , Mucosa Nasal/microbiología , Infecciones Estafilocócicas/inmunología , Staphylococcus aureus/inmunología , Factores de Edad , Antígenos Bacterianos/inmunología , Proteínas Bacterianas/inmunología , Portador Sano/microbiología , Preescolar , Proteínas Inactivadoras de Complemento/inmunología , Citometría de Flujo/métodos , Humanos , Inmunidad Materno-Adquirida , Inmunoglobulina A/sangre , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Lactante , Recién Nacido , Receptores de Superficie Celular/inmunología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/aislamiento & purificaciónRESUMEN
Micro-evolutionary analysis of 70 ST398 isolates by pulsed-field gel electrophoresis (PFGE) using Cfr9I revealed three sub-clones with abundant inter- and intra-sub-clone heterogeneity in spa- and SCCmec-types. In addition, we developed two specific PCRs for the detection of Staphylococcus aureus sequence type 398 (ST 398) isolates with 100% specificity and high sensitivity.
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Técnicas de Tipificación Bacteriana/métodos , Evolución Molecular , Reacción en Cadena de la Polimerasa/métodos , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/veterinaria , Staphylococcus aureus/clasificación , Staphylococcus aureus/genética , Animales , Análisis por Conglomerados , Dermatoglifia del ADN , ADN Bacteriano/genética , Electroforesis en Gel de Campo Pulsado , Genotipo , Humanos , Resistencia a la Meticilina , Sensibilidad y Especificidad , Staphylococcus aureus/aislamiento & purificaciónRESUMEN
At the Veterinary Microbiological Diagnostic Center, the Netherlands, the percentage of methicillin-resistant Staphylococcus aureus (MRSA) isolates found in equine clinical samples increased from 0% in 2002 to 37% in 2008. MRSA of spa-type t064, belonging to MLST ST8 and spa-types t011 and t2123, both belonging to the livestock-associated MLST ST398, predominated. During an outbreak of post-surgical MRSA infections in horses at a veterinary teaching hospital in 2006/2007, MRSA isolates of spa-type t2123 were cultured from 7 horses and 4/61 personnel which indicated zoonotic transmission. After intervention the outbreak stopped. However, another outbreak occurred in 2008, where 17 equine MRSA isolates of spa-type t011 (n=12), t2123 (n=4), and t064 (n=1) were found. This time, 16/170 personnel were positive for MRSA with spa-type t011 (n=11) and t2123 (n=5). Personnel in close contact with horses were more often MRSA-positive (15/106) than those without (1/64). Screening of horses upon admission showed that 9.3% were MRSA-positive predominantly with spa-type t011. Weekly cross-sectional sampling of all hospitalized horses for 5 weeks showed that 42% of the horses were MRSA-positive at least once, again predominantly with spa-type t011, which suggests that nosocomial transmission took place. Fifty-three percent of the environmental samples were MRSA-positive, including samples from students' and staff members' rooms, and all were spa-type t011. This indicates that humans contribute to spreading the organism. Culturing of samples employing high-salt pre-enrichment performed better than a comparable method without pre-enrichment. Our results show that nosocomial transmission occurs in equine clinics and suggests that personnel play a role in the transmission.
Asunto(s)
Brotes de Enfermedades , Enfermedades de los Caballos/epidemiología , Enfermedades de los Caballos/microbiología , Staphylococcus aureus Resistente a Meticilina/patogenicidad , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Animales , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Brotes de Enfermedades/estadística & datos numéricos , Caballos , Humanos , Staphylococcus aureus Resistente a Meticilina/clasificación , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificaciónRESUMEN
In a household setting within a residential care facility for visually and intellectually disabled people, a resident (index case) was diagnosed with dermal abscesses caused by a methicillin-resistant Staphylococcus aureus (MRSA) which was non-typeable by standard pulsed-field gel electrophoresis. All residents and staff in contact with the index case (a total of 200 people) were screened for MRSA.
Asunto(s)
Brotes de Enfermedades/prevención & control , Brotes de Enfermedades/estadística & datos numéricos , Resistencia a la Meticilina , Instituciones Residenciales/estadística & datos numéricos , Medición de Riesgo/métodos , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/prevención & control , Humanos , Incidencia , Países Bajos/epidemiología , Vigilancia de la Población , Factores de RiesgoRESUMEN
Staphylococcus aureus staphylococcal cassette chromosome mec type IV (SSCmec IV) is associated with virulent community-acquired methicillin-resistant Staphylococcus aureus (MRSA) and frequent horizontal transfer among staphylococci. To gain insight into the mechanism of transfer, we studied the ccrA/B type 2 recombinase-mediated excision of SCCmec IV (n = 5 strains) and SCCmec II (n = 2). In SCCmec IV- but not SCCmec II-containing strains, spontaneous excision of the cassette was observed. Introduction of ccrA/B type 2 recombinase genes under control of an S. aureus bacterial phage promoter in the different strains yielded excision of SCCmec II and multiple excision variants of SCCmec IV. Sequencing of the alternatively excised products in SCCmec IV strains identified a 100-bp shortened SCCmec' variant and a 5,877-bp, conserved SCC-like element that lacks mecA and ccrA/B recombinases. Excision of the SCC-like element in wild-type S. aureus was dependent on the presence of SCCmec. The element could be excised separately or as part of a novel composite cassette together with SCCmec. The relative abundance of and variety in SCCmec IV excisions may contribute to the frequency of horizontal transfer and genetic plasticity in SCCmec IV MRSA strains.
Asunto(s)
Antibacterianos/farmacología , Cromosomas Bacterianos , Variación Genética , Resistencia a la Meticilina/genética , Meticilina/farmacología , Staphylococcus aureus/genética , Transferencia de Gen Horizontal , Genes Bacterianos , Modelos Genéticos , Recombinasas/metabolismo , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/clasificación , Staphylococcus aureus/efectos de los fármacosRESUMEN
Recently we described a novel bacteriophage-encoded pathogenicity island in Staphylococcus aureus that harbors a number of virulence factors that are all involved in the evasion of innate immunity. Here we describe a mechanism by which staphylokinase (SAK), frequently present on this pathogenicity island, interferes with innate immune defenses: SAK is anti-opsonic. By activating human plasminogen (PLG) into plasmin (PL) at the bacterial surface, it creates bacterium-bound serine protease activity that leads to degradation of two major opsonins: human immunoglobulin G (IgG) and human C3b. Incubation of opsonized bacteria with PLG and SAK resulted in removal of anti-staphylococcal IgGs and C3b from the bacterial surface. In phagocytosis assays this proved to be a very efficient mechanism to reduce the opsonic activity of human IgG and serum. The fact that SAK activates human PLG at the bacterial surface and removes IgG as well as C3b makes this protein a unique anti-opsonic molecule.
Asunto(s)
Metaloendopeptidasas/fisiología , Proteínas Opsoninas/metabolismo , Staphylococcus aureus/enzimología , Complemento C3b/inmunología , Complemento C3b/metabolismo , Activación Enzimática , Fibrinolisina , Humanos , Inmunoglobulina G/sangre , Inmunoglobulina G/metabolismo , Proteínas Opsoninas/sangre , Plasminógeno/metabolismo , Unión Proteica , Staphylococcus aureus/patogenicidadRESUMEN
The presence of sequences related to the agr of Staphylococcus aureus was demonstrated in Staphylococcus epidermidis by agr-specific PCR, and Southern blot. The agr-like locus of S. epidermidis A086 was cloned and sequenced. An overall homology of 68% was found between the agr locus from S. epidermidis and S. aureus. The agr locus from S. epidermidis was organized similar to those from S. aureus and S. lugdunensis. The putative RNAII molecule contains four open reading frames, agr A, B, C and D. AgrA was a response regulator. AgrB showed homology with transducer and translocase molecules. AgrC is expected to act as a histidine protein kinase in which a leucine zipper is present. AgrD is presumably processed into an autoinducer peptide. The putative RNAIII molecule contained an open reading frame encoding a putative 26 amino acid (aa) polypeptide, which differed in 3 aa from the RNAIII encoded delta-toxin of S. aureus. Kinetic studies showed that the production of this RNAIII was elevated during the post-exponential phase. delta-Toxin activity was demonstrated for 21 of 23 tested S. epidermidis strains. Kinetic studies of the production of delta-toxin showed that the toxin was produced during the post-exponential phase. Sequencing of S. epidermidis A097, which showed a delayed agr-response, revealed a truncated AgrC lacking the histidine kinase domain. These data indicate that an agr-like locus is active in S. epidermidis during the post-exponential phase.
Asunto(s)
Proteínas Bacterianas/genética , Toxinas Bacterianas/genética , Genes Bacterianos/genética , Staphylococcus epidermidis/genética , Transactivadores , Factores de Transcripción/genética , Secuencia de Aminoácidos , Toxinas Bacterianas/biosíntesis , Clonación Molecular , Genes Reguladores/genética , Datos de Secuencia Molecular , Sistemas de Lectura Abierta/genética , ARN Bacteriano/genética , ARN Mensajero/genética , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Staphylococcus aureus/genética , Staphylococcus epidermidis/metabolismo , Staphylococcus epidermidis/patogenicidadRESUMEN
Methicillin-resistant isolates of Staphylococcus aureus (MRSA) were divided on the basis of their epidemiologic behaviour into two subgroups, epidemic MRSA (EMRSA) and sporadic MRSA (SMRSA) strains. An existing adherence assay was modified to determine differences in adherence properties between these two groups of MRSA, and the influence of culture conditions on the adherence of SMRSA and EMRSA strains to plastic, human collagen I (HuCol I) and pharyngeal carcinoma Detroit 562 cells (D562) was determined. In-vitro parameters, such as culture medium, growth temperature and growth phase of the bacterium, influenced the adherence of MRSA strains to plastic significantly. Even more pronounced differences in adherence due to changes in growth conditions and growth phase of the bacteria were found for the adherence of MRSA strains to HuCol I. Growth phase had a significant effect on the adherence of MRSA strains to the pharyngeal carcinoma cells D562. However, the study did not find conditions which made it possible to distinguish EMRSA from SMRSA strains. These data show that extrapolation of in-vitro data concerning adherence of MRSA strains to in-vivo conditions should be treated with caution.
Asunto(s)
Adhesión Bacteriana , Resistencia a la Meticilina , Staphylococcus aureus/patogenicidad , Colágeno/metabolismo , Medios de Cultivo , Humanos , Neoplasias Faríngeas , Plásticos/metabolismo , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/crecimiento & desarrollo , Temperatura , Células Tumorales CultivadasRESUMEN
Forty strains of methicillin-resistant Staphylococcus aureus (MRSA) were divided on the basis of their epidemiologic behavior into two subgroups, sporadic MRSA (SMRSA) and epidemic MRSA (EMRSA) strains. The strains were examined for binding of 125I-labelled fibronectin, vitronectin, collagen, Fc fragments of immunoglobulin G, and fibrinogen. A significant difference between EMRSA and SMRSA strains was found for binding of 125I-labelled fibrinogen and for Fc fragments of immunoglobulin G, (P < 0.05). No significant difference in the binding of 125I-labelled fibronectin and collagen was found between EMRSA and SMRSA strains. The binding of 125I-labelled vitronectin to MRSA strains was found to be aspecific. Capsular serotypes of the strains were determined with monoclonal antibodies against capsular types 5 and 8. Strains could be divided into the following four groups: types 5, 8, and 5/8 and nontypeable. More nontypeable strains were found in the EMRSA group (66.6%). Significantly more EMRSA strains (79%) than SMRSA strains (44%) produced alpha-toxin (P < 0.025). Logistic regression analysis using a combination of the parameters 125I-labelled immunoglobulin G binding, capsular type, and alpha-toxin production predicted the epidemic character with a sensitivity of 83% and a specificity of 75%.