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Early identification of methicillin-resistant Staphylococcus aureus (MRSA) dominant clones involved in infection and initiation of adequate infection control measures are essential to limit MRSA spread and understand MRSA population dynamics. In this study we evaluated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) for the automated discrimination of the major MRSA lineages (clonal complexes, CC) identified in our hospital during a 20-year period (1990-2009). A collection of 82 well-characterized MRSA isolates belonging to the four main CCs (CC5, CC8, CC22 and CC398) was split into a reference set (n = 36) and a validation set (n = 46) to generate pattern recognition models using the ClinProTools software for the identification of MALDI-TOF/MS biomarker peaks. The supervised neural network (SNN) model showed the best performance compared with two other models, with sensitivity and specificity values of 100% and 99.11%, respectively. Eleven peaks (m/z range: 3278-6592) with the highest separation power were identified and used to differentiate all four CCs. Validation of the SNN model using ClinProTools resulted in a positive predictive value (PPV) of 99.6%. The specific contribution of each peak to the model was used to generate subtyping reference signatures for automated subtyping using the BioTyper software, which successfully classified MRSA isolates into their corresponding CCs with a PPV of 98.9%. In conclusion, we find this novel automated MALDI-TOF/MS approach to be a promising, powerful and reliable tool for S. aureus typing., (Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

We analyzed 91 samples of high-touch surfaces obtained within the first hour after daily cleaning in intensive care unit rooms occupied with patients with multidrug-resistant organisms (MDROs). We determined that 22% of high-touch surfaces in rooms with methicillin-resistant Staphylococcus aureus patients and 5% of high-touch surfaces in rooms with multiresistant Pseudomonas aeruginosa patients were colonized with the same strain as the patient. We postulated that textile cleaning wipes could be contaminated with MDROs and may contribute to its spreading within the room., (Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Colonization by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has been found to be markedly more common in HIV-infected individuals in the USA. Studies evaluating the prevalence MRSA colonization in HIV-infected populations in Europe are scarce. The aim of this study was to investigate the prevalence of MRSA colonization in a cohort of HIV-infected patients in Barcelona, Spain., Methods: Nasal and pharyngeal S. aureus carriage was assessed in a random sample of 190 patients from an outpatient HIV clinic. Nasal and pharyngeal swab specimens were obtained for staphylococcal culture from 190 and 110 patients respectively. All MRSA isolates were screened for Panton-Valentine leukocidin (PVL) genes by PCR. Molecular characterization of MRSA isolates was performed by multilocus sequence typing. Data related to HIV infection, healthcare exposure, and previously described risk factors for MRSA were collected from medical records and a questionnaire administered to each patient., Results: The patients' characteristics were as follows: male, 83 %; median (IQR) age, 45 (39-49) years; intravenous drug users, 39 %; men who have sex with men, 32 %; heterosexual, 26 %; CD4 count, 528/μL (IQR 351-740); on antiretroviral therapy, 96 %; and undetectable plasma viral load, 80 %. Sixty-five patients (34 %) were colonized by S. aureus. MRSA colonization was found in 1 % and 2 % of nasal and pharyngeal samples respectively. No PVL positive MRSA strains were detected and all the MRSA isolates belonged to typical hospital-acquired clones., Conclusions: Our data suggest that CA-MRSA colonization is not currently a problem in HIV-infected individuals in our area.

There is increasing concern regarding the association between certain methicillin-resistant Staphylococcus aureus (MRSA) genotypes and poor clinical outcome. To assess this issue, a large cohort of 579 subjects with MRSA bacteraemia was prospectively followed from June 2008 to December 2009, in 21 hospitals in Spain. Epidemiology, clinical data, therapy, and outcome were recorded. All MRSA strains were analysed in a central laboratory. Presence of a haematogenous seeding infection was the dependent variable in an adjusted logistic regression model. Of the 579 patients included in the study, 84 (15%) had haematogenous seeding infections. Microdilution vancomycin median MIC (IQR) was 0.73 (0.38-3) mg/L. Most MRSA isolates (n = 371; 67%) belonged to Clonal Complex 5 (CC5) and carried an SCCmec element type IV and agr type 2. Isolates belonging to ST8-agr1-SCCmecIV, ST22-agr1-SCCmecIV and ST228-agr2-SCCmecI--a single locus variant of ST5--accounted for 8%, 9% and 9% of the isolates, respectively. After adjusting by clinical variables, any of the clones was associated with increased risk of haematogenous seeding infections. Higher vancomycin MIC was not identified as an independent risk factor, either. In contrast, persistent bacteraemia (OR 4.2; 2.3-7.8) and non-nosocomial acquisition (3.0; 1.7-5.6) were associated with increased risk., (© 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.)

Mortality related to methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) remains high, despite changes in the epidemiology. To analyze the current predictive factors for mortality we conducted a prospective study in a large cohort of patients with MRSA-BSI from 21 Spanish hospitals. Epidemiology, clinical data, therapy and outcome were recorded. All MRSA strains were analysed, including susceptibility to antibiotics and molecular characterization. Vancomycin MICs (V-MIC) were tested by the E-test and microdilution methods. Time until death was the dependent variable in a Cox regression analysis. Overall, 579 episodes were included. Acquisition was nosocomial in 59% and vascular catheter was the most frequent source (38%). A dominant PFGE genotype was found in 368 (67%) isolates, which belonged to Clonal Complex (CC)5 and carried SCCmecIV and agr2. Microdilution V-MIC50 and V-MIC90 were 0.7 and 1.0 mg/L, respectively. Initial therapy was appropriate in 66% of episodes. Overall mortality was observed in 179 (32%) episodes. The Cox-regression analysis identified age >70 years (HR 1.88), previous fatal disease (HR 2.16), Pitt score >1 (HR 3.45), high-risk source (HR 1.85) and inappropriate initial treatment (HR 1.39) as independent predictive factors for mortality. CC5 and CC22 (HR 0.52 and 0.45) were associated with significantly lower mortality rates than CC8. V-MIC ≥1.5 did not have a significant impact on mortality, regardless of the method used to assess it., (© 2012 The Authors Clinical Microbiology and Infection © 2012 European Society of Clinical Microbiology and Infectious Diseases.)

Methicillin-resistant Staphylococcus aureus (MRSA) is highly prevalent in Spanish hospitals and community long-term-care facilities (LTCFs). This longitudinal study was performed in community LTCFs to determine whether MRSA colonization is associated with MRSA infections and overall mortality. Nasal and decubitus ulcer cultures were performed every 6 months for an 18-month period on 178 MRSA-colonized residents (86 490 patient-days) and 196 non-MRSA carriers (97 470 patient-days). Fourteen residents developed MRSA infections and 10 of these were skin and soft tissue infections. Two patients with respiratory infections required hospitalization. The incidence rate of MRSA infection was 0·12/1000 patient-days in MRSA carriers and 0·05/1000 patient-days in non-carriers (P=0·46). No difference in MRSA infection rate was found according to the duration of MRSA colonization (P=0·69). The mortality rate was 20·8% in colonized residents and 16·8% in non-carriers; four residents with MRSA infection died. Overall mortality was statistically similar in both cohorts. Our results suggest that despite a high prevalence of MRSA colonization in LTCFs, MRSA infections are neither frequent nor severe while colonized residents remain at the facility. The epidemiological impact of an MRSA reservoir is more relevant than the clinical impact of this colonization for an individual resident and supports current recommendations to control MRSA spread in community LTCFs.

Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) is a cause of concern in health systems all over the world, due to the high incidence rates and the associated undesirable outcomes. In our tertiary 900-bed university hospital, all episodes of MRSA-BSI have been prospectively followed up since the identification of the first episode in 1990. We conducted the current study to report changes in the epidemiology of MRSA-BSI over the 19-year period between 1990 and 2008, comparing 4 periods (1990-1994, 1995-1999, 2000-2004, and 2005-2008). Overall, 524 patients developed MRSA-BSI. Cumulative incidence was 10.0 episodes/100,000 patient days (range, 1.3-17.4). Although no trend in the incidence rate was observed between the 4 consecutive periods, significant upward trends in patient age and comorbidities, health care acquisition, and non-intravascular catheter source were all identified (p < 0.05). While the Iberian clone (ST247/SCCmecI) was dominant during the first and second periods, almost all the strains isolated in the subsequent periods belonged to Clonal Complex 5 (ST125/SCCmecIV and ST228/SCCmecI). A significant downward trend in vancomycin geometric minimum inhibitory concentration (MIC) was also observed from 2.04 mg/L to 0.88 mg/L, coinciding with the clonal replacement and the reduction in the hospital vancomycin prescription. Therefore, no MRSA vancomycin MIC creep was observed since higher MICs were associated with strains belonging to the Iberian clone. Glycopeptides were the most frequently used antibiotics for MRSA-BSI during all 4 periods. No differences in MRSA-BSI outcomes were found, and the mortality rate at 30 days was close to 29% in each of the 4 periods. In conclusion, we identified significant changes in demographic and clinical characteristics and in the molecular epidemiology of MRSA-BSI during the study period, but found no significant trends in cumulative incidence or in overall mortality rate.

The spread of meticillin-resistant Staphylococcus aureus (MRSA) is a major problem for both acute care hospitals and among residents in long term care facilities (LTCFs). We performed a cohort study to assess the natural history of MRSA colonisation in LTCF residents. Two cohorts of residents (231 MRSA carriers and 196 non-carriers) were followed up for an 18 month period, with cultures of nasal and decubitus ulcers performed every six months. In the MRSA carrier cohort, 110 (47.8%) residents had persistent MRSA colonisation for six months or longer, 44 (19.0%) had transient colonisation and nine (3.9%) were intermittently colonised. No risk factors for persistent MRSA colonisation could be determined. The annual incidence of MRSA acquisition was around 20% [95% confidence interval (CI): 14.3-25.5]. Antibiotic treatment was independently associated with MRSA acquisition (odds ratio: 2.27; 95% CI: 1.05-4.88; P=0.03). Just two clones were distinguishable by pulsed-field gel electrophoresis and multilocus sequence typing: CC5-MRSA IV, which is widely disseminated in Spanish hospitals, and ST22-MRSA IV. This study adds to the knowledge of the epidemiology of MRSA in community LTCFs, which are important components of long term care in Spain., (Copyright © 2010 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.)

Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains are no longer limited to acute-care hospitals but have now spread to other healthcare settings such as long-term-care facilities (LTCFs), in most of which they are endemic. In Europe, few studies have addressed the MRSA situation in LTCFs. A cross-sectional study to determine MRSA prevalence and factors associated with S. aureus carriage in community LTCF residents is reported here. Nasal and decubitus ulcer cultures were performed for residents of nine community LTCFs. Residents were classified as MRSA carriers, methicillin-susceptible S. aureus carriers and non-carriers. Overall, 1377 nasal swabs and 82 decubitus ulcer cultures were performed. MRSA was isolated from 15.5% and 59.0% of the former and latter, respectively. The prevalence of MRSA colonization was 16.8% (95% CI  14.9–18.8), varying from 6.7% to 35.8% (p <0.001) among LTCFs. Several independent variables were related to MRSA colonization. It is noteworthy that residents in an LTCF with fewer than 150 beds had at least a two-fold higher probability of being MRSA carriers. Modifiable factors were medical devices, decubitus ulcers and previous antibiotic treatment. An age of 85 years or older, a Charlson index ≥2 and transfer from an acute-care facility were non-modifiable factors also related to MRSA colonization. A high MRSA prevalence among residents in community LTCFs in Spain, with great variability among facilities, was found. The factors identified as being associated with MRSA colonization could be prevented by the implementation of several measures. Control strategies need to be coordinated between LTCFs and acute-care hospitals. [ABSTRACT FROM AUTHOR]