Molecular Characterization of Methicillin-Resistant Coagulase-Negative Staphylococci from a Neonatal Intensive Care Unit

Bogado, Isabel E; Limansky, Adriana S.; Sutich, Emma; Marchiaro, Patricia; Marzi, Marta Mónica; Putero, Juan; Viale, Alejandro M.

doi:10.1086/502083

Cited by 18 publications

(13 citation statements)

References 17 publications

(14 reference statements)

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“…This large genetic variability is in accordance with previous studies conducted on the genetic diversity of S. epidermidis in the hospital environment and/or in the community (27)(28)(29). However, these two distinct populations were found to be phylogenetically related, as MLST (a typing method designed to study long-term global epidemiology and population structure) revealed that all but three STs (ST73 and two new STs, close to ST19 and ST86, respectively) clustered into a unique CC that corresponds to the major CC, CC7 (previously CC2), described by Miragaia and coworkers (8,29).…”

Section: Discussionsupporting

confidence: 92%

Comparative Epidemiology of Staphylococcus epidermidis Isolates from Patients with Catheter-Related Bacteremia and from Healthy Volunteers

et al. 2013

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Staphylococcus epidermidis is a major cause of catheter-related bloodstream infections (CRBSIs). Recent studies suggested the existence of well-adapted, highly resistant, hospital-associated S. epidermidis clones. The molecular epidemiology of S. epidermidis in Belgian hospitals and the Belgian community has not been explored yet. We compared a set of 33 S. epidermidis isolates causing CRBSI in hospitalized patients with a set of 33 commensal S. epidermidis isolates. The factors analyzed included resistance to antibiotics and genetic diversity as determined by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and SCCmec typing. Additionally, the presence of virulence-associated mobile genetic elements, the ica operon and the arginine catabolic mobile element (ACME), was assessed and compared against clinical data. CRBSI S. epidermidis isolates were significantly resistant to more antibiotics than commensal S. epidermidis isolates. The two populations studied were very diverse and genetically distinct as only 23% of the 37 PFGE types observed were harbored by both CRBSI and commensal isolates. ACME was found in 76% of S. epidermidis strains, regardless of their origin, while the ica operon was significantly more prevalent in CRBSI isolates than in commensal isolates (P < 0.05). Nine patients presented a clinically severe CRBSI, eight cases of which were due to an ica-positive multiresistant isolate belonging to sequence type 2 (ST2) or ST54. S. epidermidis isolates causing CRBSI were more resistant and more often ica positive than commensal S. epidermidis isolates, which were genetically heterogeneous and susceptible to the majority of antibiotics tested. Clinically severe CRBSIs were due to isolates belonging to two closely related MLST types, ST2 and ST54.

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Section: Discussionsupporting

confidence: 92%

Comparative Epidemiology of Staphylococcus epidermidis Isolates from Patients with Catheter-Related Bacteremia and from Healthy Volunteers

et al. 2013

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“…This was observed not only in studies involving isolates from diverse geographic or clinical origins (27,29,45) but also in collections which originated from the same hospital (6) and even in a single intensive care unit (2). Variations in the pulsed-field gel electrophoresis (PFGE) macrorestriction pattern were even detected among isolates recovered from the same infection site of a single patient (10,43,48).…”

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confidence: 92%

“…Molecular typing of nosocomial S. epidermidis strains by several typing methods has shown considerable diversity within the S. epidermidis population (2,5,10,11,25,27,29). This was observed not only in studies involving isolates from diverse geographic or clinical origins (27,29,45) but also in collections which originated from the same hospital (6) and even in a single intensive care unit (2).…”

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confidence: 99%

Inferring a Population Structure for Staphylococcus epidermidis from Multilocus Sequence Typing Data

et al. 2007

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Despite its importance as a human pathogen, information on population structure and global epidemiology of Staphylococcus epidermidis is scarce and the relative importance of the mechanisms contributing to clonal diversification is unknown. In this study, we addressed these issues by analyzing a representative collection of S. epidermidis isolates from diverse geographic and clinical origins using multilocus sequence typing (MLST). Additionally, we characterized the mobile element (SCCmec) carrying the genetic determinant of methicillin resistance. The 217 S. epidermidis isolates from our collection were split by MLST into 74 types, suggesting a high level of genetic diversity. Analysis of MLST data using the eBURST algorithm revealed the existence of nine epidemic clonal lineages that were disseminated worldwide. One single clonal lineage (clonal complex 2) comprised 74% of the isolates, whereas the remaining isolates were clustered into 8 minor clonal lineages and 13 singletons. According to our evolutionary model, SCCmec was acquired at least 56 times by S. epidermidis. Although geographic dissemination of S. epidermidis strains and the value of the index of association between the alleles, 0.2898 (P < 0.05), support the clonality of S. epidermidis species, examination of the sequence changes at MLST loci during clonal diversification showed that recombination gives rise to new alleles approximately twice as frequently as point mutations. We suggest that S. epidermidis has a population with an epidemic structure, in which nine clones have emerged upon a recombining background and evolved quickly through frequent transfer of genetic mobile elements, including SCCmec.

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“…The most widely used method for characterizing S. epidermidis isolates is pulsed-field gel electrophoresis (PFGE), which has mainly been deployed to address short-term epidemiology issues. The molecular characterization of nosocomial S. epidermidis isolates by PFGE has revealed considerable genetic diversity within the population (1,6,11,25,31). Despite the diversity that has been observed, PFGE has been used to track the dissemination of particular S. epidermidis strains between different patients (27), wards (47), and hospitals (35), thus providing a valuable tool for the control of S. epidermidis infections in clinical settings.…”

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confidence: 99%

Comparison of Molecular Typing Methods for Characterization of Staphylococcus epidermidis : Proposal for Clone Definition

et al. 2008

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In the present study we give some direction on the selection of the most appropriate typing method(s) to be used for the characterization of Staphylococcus epidermidis, in view of the most recent findings on the evolution, population structure, and epidemiology of this species. In order to achieve this aim, quantitative assessment of the correlation of the results of three typing methods-pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and staphylococcal chromosomal cassette mec (SCCmec) typing, which target different regions of the chromosome that evolve at different rates-was performed. In order to evaluate the discriminatory ability and the strength and direction of the correlation of the different typing methods, Simpson's index of diversity (SID), the adjusted Rand coefficient (AR), and the Wallace coefficient (W) were calculated. PFGE was the most discriminatory method (SID ‫؍‬ 99%), followed by MLST (SID ‫؍‬ 90%) and SCCmec typing (SID ‫؍‬ 75%). The values of AR and W (0.10 < AR < 0.30; 0.50 < W < 0.75) indicated that the partition of the same isolate collection by PFGE, MLST, and SCCmec typing provided results that had only a poor correlation with each other. However, the information provided by the combination of PFGE and SCCmec enabled the prediction of the results obtained by MLST at the level of the clonal complex with a high degree of precision (W > 0.90). We propose that clones of S. epidermidis be defined by the combination of the PFGE type followed by the SCCmec type, which provides reliable information on the short-term epidemiology and the ability to predict with consistency long-term clonal evolution.In recent years, the development and extensive use of molecular typing methods based on the direct analysis of genomic polymorphisms have greatly improved the understanding of the evolutionary history, population dynamics, and patterns of dissemination of bacteria (14,37,38).The basic principle of epidemiological typing is that isolates of an infectious agent that belong to the same chain of transmission are clonally related; that is, they descend from a common ancestor. During their evolutionary history, isolates within a given species diversify through point mutations, recombination, or the acquisition/deletion of mobile genetic elements, giving rise to extensive genomic and phenotypic diversity. Since the rates for mutation, recombination, and transfer of mobile elements as well as environmental pressures vary from species to species, the typing method selected and the threshold of marker similarity used to define a clone need to be adjusted to the species under investigation. Furthermore, space and time also need to be considered when the optimal epidemiological markers are selected. Ideally, typing methods should be reproducible and stable; should have a high discriminatory power and epidemiological concordance; should be versatile, easy to perform, easy to interpret; and should be cost-effective and time effective.Staphylococcus epidermidis is one of the most impor...

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Molecular Characterization of Methicillin-Resistant Coagulase-Negative Staphylococci from a Neonatal Intensive Care Unit

Cited by 18 publications

References 17 publications

Comparative Epidemiology of Staphylococcus epidermidis Isolates from Patients with Catheter-Related Bacteremia and from Healthy Volunteers

Comparative Epidemiology of Staphylococcus epidermidis Isolates from Patients with Catheter-Related Bacteremia and from Healthy Volunteers

Inferring a Population Structure for Staphylococcus epidermidis from Multilocus Sequence Typing Data

Comparison of Molecular Typing Methods for Characterization of Staphylococcus epidermidis : Proposal for Clone Definition

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