Posts filed under ‘Resistencia bacteriana’

Do Staphylococcus epidermidis Genetic Clusters Predict Isolation Sources?

Journal of Clinical Microbiology July 2016 V.54 N.7 P.1711-1719

Isaiah Tolo, Jonathan C. Thomas, Rebecca S. B. Fischer, Eric L. Brown, Barry M. Gray, and D. Ashley Robinson

aDepartment of Microbiology and Immunology, University of Mississippi Medical Center, Jackson, Mississippi, USA

bDepartment of Biology, University of Bolton, Bolton, United Kingdom

cCenter for Infectious Disease, University of Texas Health Science Center, Houston, Texas, USA

dDepartment of Pediatrics, University of Illinois College of Medicine at Peoria, Peoria, Illinois, USA

Staphylococcus epidermidis is a ubiquitous colonizer of human skin and a common cause of medical device-associated infections. The extent to which the population genetic structure of S. epidermidis distinguishes commensal from pathogenic isolates is unclear. Previously, Bayesian clustering of 437 multilocus sequence types (STs) in the international database revealed a population structure of six genetic clusters (GCs) that may reflect the species’ ecology. Here, we first verified the presence of six GCs, including two (GC3 and GC5) with significant admixture, in an updated database of 578 STs. Next, a single nucleotide polymorphism (SNP) assay was developed that accurately assigned 545 (94%) of 578 STs to GCs. Finally, the hypothesis that GCs could distinguish isolation sources was tested by SNP typing and GC assignment of 154 isolates from hospital patients with bacteremia and those with blood culture contaminants and from nonhospital carriage. GC5 was isolated almost exclusively from hospital sources. GC1 and GC6 were isolated from all sources but were overrepresented in isolates from nonhospital and infection sources, respectively. GC2, GC3, and GC4 were relatively rare in this collection. No association was detected between fdh-positive isolates (GC2 and GC4) and nonhospital sources. Using a machine learning algorithm, GCs predicted hospital and nonhospital sources with 80% accuracy and predicted infection and contaminant sources with 45% accuracy, which was comparable to the results seen with a combination of five genetic markers (icaA, IS256, sesD [bhp], mecA, and arginine catabolic mobile element [ACME]). Thus, analysis of population structure with subgenomic data shows the distinction of hospital and nonhospital sources and the near-inseparability of sources within a hospital.


June 24, 2016 at 2:01 pm

Significance of Staphylococcus epidermidis in Health Care-Associated Infections, from Contaminant to Clinically Relevant Pathogen: This Is a Wake-Up Call!

Journal of Clinical Microbiology July 2016 V.54 N.7 P.1679-1681

Micael Widerström

Department of Clinical Microbiology, Infectious Diseases, Unit of Research, Education and Development-Östersund, Umeå University, Umeå, Sweden

Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, have been recognized as an important cause of health care-associated infections. Concurrently, S. epidermidis is a common contaminant in clinical cultures, which poses a diagnostic challenge. An article in this issue of Journal of Clinical Microbiology (I. Tolo, J. C. Thomas, R. S. B. Fischer, E. L. Brown, B. M. Gray, and D. A. Robinson, J Clin Microbiol 54:1711–1719, 2015, describes a rapid single nucleotide polymorphism-based assay for distinguishing between S. epidermidis isolates from hospital and nonhospital sources, which represents an important contribution to the characterization and understanding of S. epidermidis health care-associated infections.


June 24, 2016 at 1:59 pm

Escherichia coli Harboring mcr-1 and blaCTX-M on a Novel IncF Plasmid: First report of 2 mcr-1 in the USA

Antimicrob. Agents Chemother. May 26, 2016

Patrick McGann1#*, Erik Snesrud1*, Rosslyn Maybank1 , Brendan Corey1 , Ana C. Ong1 3 , Robert Clifford1, Mary Hinkle1 , Timothy Whitman2 , Emil Lesho1 , and Kurt E. Schaecher3# 4

1 5 Multidrug-resistant Organism Repository and Surveillance Network, Walter Reed Army

6 Institute of Research, Silver Spring, Maryland, USA.

2 7 Department of Infectious Diseases, Walter Reed National Military Medical Center, MD, USA .

3 8 Department of Pathology, Walter Reed National Military Medical Center, MD, USA.

Patrick Mc Gann, PhD Walter Reed Army Institute of Research, 2S35 Silver Spring, Maryland 20910, USA Phone: (301) 319 9912 Email:

The recent discovery of a plasmid-borne colistin resistance gene, mcr-1, heralds the emergence of truly pan-drug resistant bacteria (1). The gene has been found primarily in Escherichia coli, but has also been identified in other members of the Enterobacteriaceae from human, animal, food and environmental samples on every continent (2-5). In response to this threat, starting in May 2016, all extended-spectrum β-lactamase (ESBL)-producing E.coli clinical isolates submitted to the clinical microbiology laboratory at the Walter Reed National Military Medical Center (WRNMMC) were tested for resistance to colistin by E-test. Herein we report the presence of mcr-1 in an E. coli cultured from a patient with a urinary tract infection (UTI) in the United States….


May 30, 2016 at 8:38 am

Neisseria gonorrhoeae Resistant to Ceftriaxone and Cefixime, Argentina

Emerging Infectious Diseases June 2016 V.22 N.6


To the Editor:

Antimicrobial resistance in Neisseria gonorrhoeae is increasing globally. In recent years, gonococcal strains with resistance to the extended-spectrum cephalosporin (ESC) ceftriaxone have been reported from many countries (1). In South America, 7 ceftriaxone-resistant strains (MICs >0.25 μg/mL) were reported from Brazil in 2007; however, these isolates have not been characterized (2). Emergence of cephalosporin-resistant gonorrhea would substantially limit treatment options and represent a major public health concern. We report an N. gonorrhoeae isolate in Argentina that was resistant to ceftriaxone and cefixime…..



2016-06 Neisseria gonorrhoeae Resistant to Ceftriaxone and Cefixime, Argentina EID

May 21, 2016 at 10:45 am

Rapid Detection of Polymyxin Resistance in Enterobacteriaceae

Emerging Infectious Diseases June 2016 V.22 N.6

Patrice Nordmann, Aurélie Jayol, and Laurent Poirel

University of Fribourg, Fribourg, Switzerland

For identification of polymyxin resistance in Enterobacteriaceae, we developed a rapid test that detects glucose metabolization associated with bacterial growth in the presence of a defined concentration of colistin or polymyxin B. Formation of acid metabolites is evidenced by a color change (orange to yellow) of a pH indicator (red phenol). To evaluate the test, we used bacterial colonies of 135 isolates expressing various mechanisms of colistin resistance (intrinsic, chromosomally encoded, and plasmid-mediated MCR-1) and 65 colistin-susceptible isolates. Sensitivity and specificity were 99.3% and 95.4%, respectively, compared with the standard broth microdilution method. This new test is inexpensive, easy to perform, sensitive, specific, and can be completed in <2 hours. It could be useful in countries facing endemic spread of carbapenemase producers and for which polymyxins are last-resort drugs.


May 21, 2016 at 10:41 am

High MICs for Vancomycin and Daptomycin and Complicated Catheter-Related Bloodstream Infections with Methicillin-Sensitive Staphylococcus aureus

Emerging Infectious Diseases June 2016 V.22 N.6

Rafael San-Juan, Esther Viedma, Fernando Chaves, Antonio Lalueza, Jesús Fortún, Elena Loza, Miquel Pujol, Carmen Ardanuy, Isabel Morales, Marina de Cueto, Elena Resino-Foz, Alejandra Morales-Cartagena, Alicia Rico, María P. Romero, María Ángeles Orellana, Francisco López-Medrano, Mario Fernández-Ruiz, and José María Aguado

University Hospital–Research Institute 12 de Octubre, Madrid, Spain (R. San-Juan, E. Viedma, F. Chaves, A. Lalueza, E. Resino-Foz, A. Morales-Cartagena, M.Á. Orellana, F. López-Medrano, M. Fernández-Ruiz, J. María Aguado); Hospital Universitario Ramón y Cajal, Madrid (J. Fortún, E. Loza); University Hospital–Bellvitge Institute for Biomedical Research, Barcelona, Spain (M. Pujol, C. Ardanuy); Hospital Universitario Virgen de la Macarena, Seville, Spain (I. Morales, M. de Cueto); Hospital Universitario La Paz, Madrid (A. Rico, M.P. Romero)

We investigated the prognostic role of high MICs for antistaphylococcal agents in patients with methicillin-sensitive Staphylococcus aureus catheter-related bloodstream infection (MSSA CRBSI). We prospectively reviewed 83 episodes from 5 centers in Spain during April 2011–June 2014 that had optimized clinical management and analyzed the relationship between E-test MICs for vancomycin, daptomycin, oxacillin, and linezolid and development of complicated bacteremia by using multivariate analysis. Complicated MSSA CRBSI occurred in 26 (31.3%) patients; MICs for vancomycin and daptomycin were higher in these patients (optimal cutoff values for predictive accuracy = 1.5 μg/mL and 0.5 μg/mL). High MICs for vancomycin (hazard ratio 2.4, 95% CI 1.2–5.5) and daptomycin (hazard ratio 2.4, 95% CI 1.1–5.9) were independent risk factors for development of complicated MSSA CRBSI. Our data suggest that patients with MSSA CRBSI caused by strains that have high MICs for vancomycin or daptomycin are at increased risk for complications.


May 20, 2016 at 3:39 pm

The Impact of Infectious Disease Specialist Consultation for Staphylococcus aureus Bloodstream Infections: A Systematic Review.

Open Forum Infect Dis. 2016 Mar 1;3(2):ofw048.

Paulsen J1, Solligård E2, Damås JK3, DeWan A4, Åsvold BO5, Bracken MB4.

Author information

1Centre ofMolecular Inflammation Research, Department of Cancer Research and Molecular Medicine; Department of Medicine, Levanger Hospital, Nord-Trøndelag Hospital Trust; Mid-Norway Sepsis Research Center, Norwegian University of Science and Technology, Trondheim.

2Departments ofCirculation and Medical Imaging; Mid-Norway Sepsis Research Center, Norwegian University of Science and Technology, Trondheim; Clinic of Anaesthesia and Intensive Care.

3Centre ofMolecular Inflammation Research, Department of Cancer Research and Molecular Medicine; Mid-Norway Sepsis Research Center, Norwegian University of Science and Technology, Trondheim; Departments ofInfectious Diseases.

4Department of Chronic Disease Epidemiology , Yale University School of Public Health , New Haven, Connecticut.

5Mid-Norway Sepsis Research Center, Norwegian University of Science and Technology, Trondheim; Public Health, Norwegian University of Science and Technology, Trondheim; Endocrinology, St Olavs Hospital, Trondheim University Hospital, Norway.


Staphylococcus aureus is a common cause of severe bloodstream infection. We performed a systematic review to assess whether consultation with infectious disease specialists decreased all-cause mortality or rate of complications of S aureus bloodstream infections.

The review also assessed parameters associated with the quality of management of the infection. We searched for eligible studies in PubMed, Embase, Scopus, and clinical as well as the references of included studies.

We identified 22 observational studies and 1 study protocol for a randomized trial. A meta-analysis was not performed because of the high risk of bias in the included studies. The outcomes are reported in a narrative review.

Most included studies reported survival benefit, in the adjusted analysis. Recommended management strategies were carried out significantly more often among patients seen by an infectious disease specialist.

Trials, such as cluster-randomized controlled trials, can more validly assess the studies at low risk of bias.



May 11, 2016 at 8:09 am

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