Methicillin-resistant Staphylococcus Aureus Disease Research Articles

Unintended Consequences of MRSA Infection: Empiric Non-MRSA Antibiotic Use and Resultant Clostridioides difficile Infection

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for the largest number of invasive infections due to a multidrug-resistant pathogen. Approximately 10% of hospitalized carriers will experience invasive MRSA disease in the year following discharge incurring antibiotic therapy beyond focused treatment of MRSA. Objective: We aimed to quantify the extent of non-MRSA empiric antibiotics incurred by MRSA infections and further assess the risk of Clostridioides difficile Infection (CDI) as a result of treatment of MRSA infection. Methods: The CLEAR Trial was a postdischarge randomized controlled trial of 2,121 MRSA carriers comparing MRSA education alone to education plus repeated decolonization that demonstrated a 30% reduction in MRSA infection and a 17% reduction in all-cause infection attributable to decolonization in the year following hospital discharge (Huang SS, NEJM 2019). We included all hospitalization outcomes due to MRSA infection in the CLEAR Trial with detailed medication administration records to quantify unintended consequences of MRSA infection related to empiric non-MRSA antibiotic use and resultant CDI. Full-text medical records were reviewed with a standardized abstraction form to collect inpatient administered antibiotics and hospital-associated CDI. Results: In total,154 hospitalizations due to MRSA infection with a mean length-of-stay of 10.6 days were identified. During 25 hospitalizations (16.2%), patients received only anti-MRSA antibiotics. During the remaining 129 (83.8%) hospitalizations, patients received a mean of 1.6 distinct non-MRSA antibiotics totaling a mean of 6.6 days of therapy (DOT). Empiric non-MRSA therapy was given for 3.2 DOT before MRSA culture results became available and was continued for an additional 3.4 DOT afterward. Among all 849 non-MRSA DOT, the most common were due to piperacillin-tazobactam (293 DOT, 34.5%), levofloxacin (105 DOT, 12.4%), and metronidazole (93 DOT, 11.0%). Across all 154 hospitalizations, a mean of 5.5 non-MRSA DOT was calculated per MRSA hospitalization, with 6 CDI cases (3.9%) as a direct sequelae of empiric non-MRSA antibiotics provided for MRSA infection. Conclusions: Hospitalization for MRSA infection results in extensive non-MRSA empiric antibiotic therapy both before and after MRSA culture results are known. This antibiotic use is associated with a 3.9% risk of CDI that exceeds the national risk of acquiring CDI (3.2 per 1,000 admissions) by 12-fold during any hospital stay (Barrett ML, AHRQ 2018). The CLEAR Trial findings that postdischarge decolonization reduces MRSA infection and hospitalization by 30% suggests that decolonization may also reduce non-MRSA antibiotic use and CDI in this population.Funding: NoneDisclosures: None

Potential antimicrobial effect of plant essential oils and virulence genes expression in methicillin-resistant Staphylococcus aureus isolates.

Aim:This study aimed to investigate the antibacterial efficacy of eight commercially available essential oil (EO) blends and characterize the effect on the expression of some virulence genes against methicillin-resistant Staphylococcus aureus (MRSA).Materials and Methods:In vitro evaluation of the antimicrobial effects of oils against MRSA was performed using the disk diffusion method and by measuring the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The EOs (A-F) were contained (β-pinene, carvacrol, carvone, dimethyl trisulfide, linalool, limonene, menthol, monoterpene hydrocarbons, and thymol) in different amounts. In addition, a real-time polymerase chain reaction was also used to determine the gene expression of the virulence genes (intercellular adhesion cluster [ica]-9, ica-15, and RNA III) against MRSA (ATCC 43300) after treatment with selected oils.Results:Among the eight EOs evaluated, EO (D), (E), and (A) showed, in general, the greatest antimicrobial activity against MRSA. EO at 1/3 MIC has effectively down-regulated ica-9 and ica-15 of MRSA by 17.83 and 4.94 folds, respectively. Meanwhile, EO (A) has effectively down-regulated RNAIII by 3.74 folds. Our results indicated that some of the EOs exhibit promising antimicrobial effects against MRSA isolates. Moreover, the results of the analyzed virulence genes related to the pathogenicity of MRSA were down-regulated at the sub-MIC concentrations of EOs, indicated that EOs could be successfully used to suppress the virulence factors and, consequently, decreased the pathogenicity of MRSA.Conclusion:These encouraging results indicate that some of the EOs used in this study can be utilized as a natural antibiotic for the treatment of MRSA disease.

The role of international travel in the spread of methicillin-resistant Staphylococcus aureus.

Increasing international travel has facilitated the transmission of various multidrug-resistant bacteria-including methicillin-resistant Staphylococcus aureus (MRSA)-across continents. Individuals may acquire MRSA from the community, healthcare facilities, or even from animal exposure. Skin contact with colonized individuals, fomites, or animals during an overseas trip may result in either asymptomatic colonization or subsequent clinically significant MRSA disease. MRSA strains that harbor the Panton-Valentine leucocidin toxin are particularly associated with community transmission and may potentially have enhanced virulence resulting in serious skin and soft tissue infections or even necrotizing pneumonia. More importantly, secondary transmission events upon return from traveling have been documented, leading to potentially detrimental outbreaks within the community or the healthcare setting. We sought to review the existing literature relating to the role of various aspects of travel in the spread of MRSA. Risk factors for acquiring MRSA during travel together with the need for targeted screening of high-risk individuals will also be explored. Data for this article were identified via PubMed searches using a combination of search terms: "methicillin resistance," "MRSA," "livestock-associated MRSA," "community-associated MRSA," "travel," and "outbreak." The relevant articles were extensively perused to determine secondary sources of data. Our review of the current literature suggests that international travel plays a significant role in the transmission of MRSA, potentially contributing to the replacement of existing endemic MRSA with fitter and more transmissible strains. Therefore, selective and targeted screening of travelers with risk factors for MRSA colonization may be beneficial. Healthcare professionals and patients should be considered for screening if they were to return from endemic areas, with the former group decolonized before returning to patient care work, in order to reduce the transmission of MRSA to vulnerable patient populations.

Zero tolerance for healthcare-associated MRSA bacteraemia: is it realistic?

BackgroundThe term ‘zero tolerance’ has recently been applied to healthcare-associated infections, implying that such events are always preventable. This may not be the case for healthcare-associated infections such as methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia.MethodsWe combined information from an epidemiological investigation and bacterial whole-genome sequencing to evaluate a cluster of five MRSA bacteraemia episodes in four patients in a specialist hepatology unit.ResultsThe five MRSA bacteraemia isolates were highly related by multilocus sequence type (ST) (four isolates were ST22 and one isolate was a single-locus variant, ST2046). Whole-genome sequencing demonstrated unequivocally that the bacteraemia cases were unrelated. Placing the MRSA bacteraemia isolates within a local and global phylogenetic tree of MRSA ST22 genomes demonstrated that the five bacteraemia isolates were highly diverse. This was consistent with the acquisition and importation of MRSA from the wider referral network. Analysis of MRSA carriage and disease in patients within the hepatology service demonstrated a higher risk of both initial MRSA acquisition compared with the nephrology service and a higher risk of progression from MRSA carriage to bacteraemia, compared with patients in nephrology or geriatric services. A root cause analysis failed to reveal any mechanism by which three of five MRSA bacteraemia episodes could have been prevented.ConclusionsThis study illustrates the complex nature of MRSA carriage and bacteraemia in patients in a specialized hepatology unit. Despite numerous ongoing interventions to prevent MRSA bacteraemia in healthcare settings, these are unlikely to result in a zero incidence in referral centres that treat highly complex patients.

Methicillin-resistant Staphylococcus aureus colonization and disease severity in atopic dermatitis: a cross-sectional study from South India.

Colonization by methicillin-resistant Staphylococcus aureus (MRSA) in atopic dermatitis is little studied but has therapeutic implications. It may have a role in disease severity given the additional virulence factors associated. Our aims were to record the proportion of patients with MRSA colonization in atopic dermatitis and to ascertain if any association exists between MRSA colonization and disease severity. An observational cross-sectional study involving children aged≤12 years with atopic dermatitis attending the outpatient department of Government Medical College, Kottayam was conducted. Socio-demographic data, exacerbating factors and risk factors for hospital care-associated MRSA were documented. Extent of atopic dermatitis was recorded using a standardized scale (Eczema Area Severity Index, EASI). Skin swabs were taken from anterior nares and the worst affected atopic dermatitis sites for culture and sensitivity. Of the 119 subjects recruited during the study period (November 2009-April 2011), Staphylococcus aureus was isolated from 110 (92.4%) patients and MRSA from 30 (25.21%) patients. A total of 18 patients with MRSA had risk factors for healthcare associated-MRSA. The patients whose cultures grew MRSA were found to have significantly higher EASI score when compared to those patients colonized with methicillin sensitive Staphylococcus aureus (P < 0.01). Presence of Staphylococcus aureus, early age of onset, presence of food allergies, seasonal exacerbation and inadequate breastfeeding did not seem to influence disease severity. There is a high degree of prevalence of MRSA (25.2%) in atopic dermatitis and presence of MRSA is associated with increased disease severity. Further studies are needed to validate these findings.

Does the Nose Know? An Update on MRSA Decolonization Strategies

Colonization with methicillin-resistant Staphylococcus aureus (MRSA) is an important step in the pathogenesis of active infection and is a key factor in the epidemiology of MRSA infection. Decolonization of patients found to have MRSA carriage may be of value in certain patient populations, especially those undergoing elective surgery. However, the most commonly used agent for decolonization, mupirocin, comes with a considerable risk of resistance if widely employed. Recent studies of other novel agents for decolonization show promise, but further research is necessary. This review focuses on the pathogenesis from MRSA colonization to infection, identifies the risk factors for colonization, and summarizes decolonization strategies, including novel approaches that may have a role in decreasing MRSA disease burden.

Virulence strategies of the dominant USA300 lineage of community-associated methicillin-resistantStaphylococcus aureus(CA-MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious threat to worldwide health. Historically, MRSA clones have strictly been associated with hospital settings, and most hospital-associated MRSA (HA-MRSA) disease resulted from a limited number of virulent clones. Recently, MRSA has spread into the community causing disease in otherwise healthy people with no discernible contact with healthcare environments. These community-associated MRSA clones (CA-MRSA) are phylogenetically distinct from traditional HA-MRSA clones, and CA-MRSA strains seem to exhibit hypervirulence and more efficient host : host transmission. Consequently, CA-MRSA clones belonging to the USA300 lineage have become dominant sources of MRSA infections in North America. The rise of this successful USA300 lineage represents an important step in the evolution of emerging pathogens and a great deal of effort has been exerted to understand how these clones evolved. Here, we review much of the recent literature aimed at illuminating the source of USA300 success and broadly categorize these findings into three main categories: newly acquired virulence genes, altered expression of common virulence determinants and alterations in protein sequence that increase fitness. We argue that none of these evolutionary events alone account for the success of USA300, but rather their combination may be responsible for the rise and spread of CA-MRSA.

Multicenter Evaluation of the LightCycler MRSA Advanced Test, the Xpert MRSA Assay, and MRSASelect Directly Plated Culture with Simulated Workflow Comparison for the Detection of Methicillin-Resistant Staphylococcus aureus in Nasal Swabs

Rapid detection of nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) followed by appropriate infection control procedures reduces MRSA infection and transmission. We compared the performance and workflow of two Food and Drug Administration-approved nucleic acid amplification assays, the LightCycler MRSA Advanced Test and the Xpert MRSA test, with those of directly plated culture (MRSASelect) using 1202 nasal swabs collected at three U.S. sites. The sensitivity of the LightCycler test (95.2%; 95% CI, 89.1% to 98.4%) and Xpert assay (99%; 95% CI, 94.8% to 100%) did not differ compared with that of culture; the specificity of the two assays was identical (95.5%; 95% CI, 94.1% to 96.7%) compared with culture. However, sequencing performed on 71 samples with discordant results among the three methods confirmed the presence of MRSA in 40% of samples that were positive by both molecular methods but negative by culture. Workflow analysis from all sites including batch runs revealed average hands-on sample preparation times of 1.40, 2.35, and 1.44 minutes per sample for the LightCycler, Xpert, and MRSASelect methods, respectively. Discrete event simulation analysis of workflow efficiencies revealed that the LightCycler test used less hands-on time for the assay when greater than eight batched samples were run. The high sensitivity and specificity, low hands-on time, and efficiency gains using batching capabilities make the LightCycler test suitable for rapid batch screening of MRSA colonization.

Editorial Commentary: Deconstructing the Veterans Affairs MRSA Prevention Bundle

During the 1970s and 1980s, methicillinresistant Staphylococcus aureus (MRSA) became endemic in hospitals worldwide [1]. By 2007, a large-scale epidemiological study determined that 94 000 cases of invasive MRSA disease and 19 000 MRSA-related in-hospital deaths occurred annually in the United States [2]. Using these estimates, an editorial suggested that the burden of MRSA deaths exceeded that of deaths due to human immunodeficiency virus or AIDS in the United States [3]. TheoptimalapproachtoMRSAprevention in hospital settings is debated [4, 5]. In general, 2 epidemiological approaches have been described: (1) “horizontal” programs that broadly attempt to reduce infections from all pathogens and (2) “vertical” programs that aim to eradicate a single pathogen [6]. Horizontal programs include hand hygiene improvement interventions and centralline association bloodstream infection (CLABSI) “bundles.” Vertical programs screen all or selected patients for MRSA colonization by obtaining a nares swab sample and place MRSA-colonized or MRSA-infected patients on contact precautions. Contact precautions include single-bed rooms and patient cohorting and require healthcare workers to wear gowns and gloves for all contacts. Some studies reported benefits of such screening programs [7], some reported benefits when screening was combined with decolonization [8], and some found screening and isolation to be ineffective [9, 10]. After a successful pilot study in the VA Pittsburgh Healthcare System, in August 2006 the Veterans Health Administration implemented a MRSA bundle in 17 US Department of Veterans Affairs (VA) medical centers [11]. The bundle included (1) admission, inhospital transfer, and discharge activesurveillance swab samples for MRSA; (2) contact precautions for patients known or found to be MRSA carriers; (3) efforts targeting improved hand hygiene; and (4) efforts encouraging culture change [12]. Importantly, and infrequently, mentioned in descriptions of the VA MRSA Initiative, support was also made available for a MRSA prevention coordinator at each site, who was responsible for coordinating implementation of the bundle. Thus, the VA bundle included 1 vertical intervention (swab samples and contact precautions) and 3 horizontal interventions (hand hygiene, culture change, and MRSA prevention coordinator). By October 2007 the bundle was implemented in all acute-care (except mental health) units in 150 of 153 VA medical centers. By most measures the VA MRSA Initiative was a success. From initiation to June 2010, healthcare-associated MRSA infections declined by 62% in intensive care units (ICUs) and by 45% in nonICUs. MRSA acquisition declined 17% in ICUs and 21% in non-ICU settings. Interestingly, a subset of hospitals reported healthcare-associated vancomycin-resistant enterococcal and Clostridium difficile infection rates. After the initiative, vancomycin-resistant enterococcal infections were eliminated in ICUs and declined by 73% in non-ICUs. C. difficile infections declined 61% in non-ICU settings, with no change in ICUs [12]. How do we explain the MRSA declines reported by the VA? A nationwide decline in MRSA seen during the study period [13] might have contributed to these in-hospital declines; however, MRSA positivity on admission was relatively flat during the study period, so any outside impact should have been negligible. Importantly, infections declined 2–3 times more than incident colonization, suggesting that factors other than surveillance swab samples and isolation played a role in reduced MRSA infections. Thus, it seems that one benefit of the bundle was to reduce Received 22 February 2012; accepted 24 February 2012; electronically published 4 April 2012. Correspondence: Eli N. Perencevich, MD, MS, CADRE, Iowa City VA Medical Center, 601 Hwy 6 W, Iowa City, IA 52246 (eli-perencevich@uiowa.edu). Clinical Infectious Diseases 2012;54(11):1621–3 © The Author 2012. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals. permissions@oup.com. DOI: 10.1093/cid/cis277

Complicated Skin and Skin Structure Infections

FigureLet’s discuss the emerging wound taxonomies and new Food and Drug Administration (FDA) guidelines used for testing the efficacy of antibiotics in treating patients with soft tissue infections. Consideration must be given to the health–related quality of life indicators for patients with extremity soft tissue infections who are taking antibiotics. New Classifications Complicated skin and skin structure infections are commonly known as cSSSIs. However, for research efficacy purposes, in 2010 the FDA introduced a new classification known as acute bacterial skin and skin structure infections (ABSSSIs).1 The FDA introduced the nomenclature of ABSSSIs to provide a structural anatomic and a systemic basis for evaluating the effectiveness of antibiotics in the treatment of soft tissue infections and wounds. The major clinical difference between the old nomenclature, cSSSIs, and the new ABSSSI nomenclature is a minimum surface area and the correlation of local and systemic indications of infection. The FDA designation of ABSSSI includes extensive cellulitis/erysipelas, wound infections, major cutaneous abscesses, infected burns accompanied by redness, edema, and/or induration of a minimum surface area of 75 sq cm, accompanied by lymph node enlargement or systemic symptoms such as fever 38° C (100.4° F) or greater.1 This classification will provide a basis for measuring the clinical effectiveness of new antibiotics. These particular wound outcome parameters can be followed with the precision of time sequential photography and real-time electronic medical records in a prospective manner. Although classifications and clinical taxonomies help clinicians make inferences about the effect of our treatment, we still need clinical guidelines that maintain the standard of care at the point of service. New Clinical Guidelines In February 2011, the Infectious Diseases Society of America published its first clinical practice guidelines for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in children and adults.2–4 The clinical practice guidelines address the management of clinical syndromes associated with MRSA disease, including skin and soft tissue infections. From a clinical epidemiological point of view, the most common pathogen associated with morbidity and mortality from ABSSSIs remains MRSA. “It is the predominant etiology of both healthcare-associated and community-associated infections.”3,4 It is the prevalent cause of skin infections among patients presenting to the emergency department2–4 and can also cause more serious, invasive infections that account for about 18,000 deaths in the United States per year.2–4 MRSA and streptococci continue to be the main organisms in skin and soft tissue infections. Streptococcal infections are associated with both community-acquired and healthcare-acquired infections and without early recognition; streptococcal ABSSSIs can progress to necrotizing fasciitis, in about 25% of the cases, leading to morbidity and mortality.5 A Cautionary Tale Do not indiscriminately prescribe antibiotics. Do not use them unless there is a very specific reason or a definite pathogen identified. If you use powerful antibiotics for the treatment of ABSSSIs, you must consider the acronym ADD: Age-drug interactions, Disease-drug interactions, and Drug-drug interactions. This mnemonic is a reminder that the prescription of antibiotics is a serious undertaking and that patient safety is paramount.FigureRichard “Sal” Salcido, MD

Is Universal Screening of Children for Nasal Methicillin-Resistant Staphylococcus aureus Colonization Necessary on Hospital Admission?

Methicillin-resistant Staphylococcus aureus (MRSA) infections have increased significantly over the last decade. Increased prevalence and concern for nosocomial spread has led many states to mandate screening for nasal MRSA carriage. In December 2007, our institution implemented universal surveillance of all admitted patients. Nasal MRSA colonization rates and the role of universal surveillance in prevention and control of MRSA transmission in pediatric wards is not well characterized. The objectives of our study were to determine the incidence of nasal MRSA colonization, the concordance between nasal MRSA colonization and culture-proven MRSA disease at admission, and the impact of universal surveillance on MRSA transmission among children admitted to our pediatric ward. Loyola University Medical Center is an academic center with a pediatric hospital within the larger hospital. Of the 123 pediatric beds, 34 are ward beds. All children admitted from December 1, 2007, through June 30, 2010, were screened for nasal MRSA colonization, using the Cepheid GeneXpert system (Cepheid), and they were identified through the Epic electronic medical record system (Epic Systems). Contact isolation precautions were instituted if a polymerase chain reaction test or a clinical culture was positive. Microbiology laboratory data were used to identify patients with a positive nasal screen or MRSA cultures. Data on hospitalization within the previous 12 months, presence of an indwelling device, and site of the positive MRSA culture were collected. Recent antibiotic use and family history of MRSA disease were not analyzed because these data could not be reliably ascertained from charts. Antimicrobial susceptibilities of MRSA clinical isolates against oxacillin, gentamicin, cefazolin, rifampin, tetracycline, clindamycin, erythromycin, trimethoprim-sulfamethoxazole, and vancomycin were recorded. Isolates were considered to be community-associated MRSA (CA-MRSA) if they were resistant only to b-lactams erythromycin. Resistance to other antibiotics tested was considered to indicate healthcareassociated MRSA (HA-MRSA). Infection control data were reviewed to determine nosocomial MRSA cases in the pediatric ward. Four thousand and eighty-four patients were admitted to the pediatric ward, and 3,934 were screened for nasal MRSA colonization during the study. Of these, 234 patients (5.7%) were colonized, and 99 had culture-proven MRSA disease (2.4%). MRSA nasal colonization and disease rates were uniform throughout the study period. MRSA colonization and disease were highest among young children; 8.4% of infants less than 1 year old were colonized versus 5.2% of children 1 or more years old ( ). MRSA disease was more P p .004 prevalent in children 5 years old and under, 3.6% versus 1% in those more than 5 years old ( ). The incidence of P ! .002 nasal colonization markedly decreased in older age groups (Table 1). Most pediatric patients with MRSA colonization or disease had no identifiable risk factors; 9% had an indwelling catheter, and 39% were hospitalized in the year before. Most positive MRSA cultures (89%) were from skin and soft tissue sites, and 84% were CA-MRSA. Bacteremia was noted in 5 patients, 3 of whom had concurrent osteomyelitis. Only 54% of patients admitted with MRSA disease had a positive nasal screen. The use of MRSA nasal colonization to predict MRSA disease on admission had a sensitivity of 54% and a specificity of 96%. The positive predictive value was 24%, and the negative predictive value was 99%. Nosocomial MRSA infections were infrequent in our pediatric ward. There were 2 cases in the 2 years before universal surveillance and 1 during universal surveillance. The overall cost of universal screening of pediatric ward patients for the institute for the study period was $204,200, at $50 per test. Nasal MRSA colonization rates vary by geographic area and have increased over the last decade from less than 1% to 10%. Nasal MRSA colonization rate in admitted children was 5.7%, which is similar to the rate in our adult population (∼7%). The majority of colonized or infected children had no risk factors for HA-MRSA (!60%). Skin and soft tissue infections, mainly due to CA-MRSA, comprised the bulk of MRSA disease. Concerns for nosocomial spread of CA-MRSA have led many states to mandate screening of hospitalized patients and to observe contact precautions of identified carriers. While absence of MRSA nasal colonization is highly predictive of absence of disease, we found poor concordance between

Enfermedad por Staphylococcus aureus resistente a meticilina en Panamá

Introduction Infections due to methicillin-resistant Staphylococcus aureus (MRSA) are increasing worldwide. The clinical spectrum of the disease ranges from nasal colonization to superficial and invasive infections. Objectives To describe the frequency, clinical characteristics and risk factors associated with MRSA disease in children under 15 years old. To establish the prevalence of colonization and antimicrobial susceptibility of isolates. Material and methods Retrospective study. Included subjects; aged 1 month to 15 years old treated in the Hospital del Niño in Panama with invasive or superficial infection by S. aureus in the period from June 1, 2009 to June 30, 2010. Carrier status was assessed by performing nasal swabs. Demographic, clinical features, treatment of disease and antimicrobial resistance patterns. Results A total of 146 subjects were collected with S.aureus infections, of which 8.9% (13/146) were infected by MRSA. Community-acquired MRSA accounted for 38.5% of the isolates. We did not identify any risk factors for developing MRSA infections. The prevalence of nasal carriage was 8.3%. The resistance rates to erythromycin and clindamycin were 15.4%. Conclusions The incidence of MRSA infections was low compared with other regions. We recommend active surveillance in order to establish measures to prevent nosocomial infections and treatment guidelines based on local epidemiological criteria.

Clinical Practice Guidelines by the Infectious Diseases Society of America for the Treatment of Methicillin-Resistant Staphylococcus aureus Infections in Adults and Children: Executive Summary

Evidence-based guidelines for the management of patients with methicillin-resistant Staphylococcus aureus (MRSA) infections were prepared by an Expert Panel of the Infectious Diseases Society of America (IDSA). The guidelines are intended for use by health care providers who care for adult and pediatric patients with MRSA infections. The guidelines discuss the management of a variety of clinical syndromes associated with MRSA disease, including skin and soft tissue infections (SSTI), bacteremia and endocarditis, pneumonia, bone and joint infections, and central nervous system (CNS) infections. Recommendations are provided regarding vancomycin dosing and monitoring, management of infections due to MRSA strains with reduced susceptibility to vancomycin, and vancomycin treatment failures.

Clinical Practice Guidelines by the Infectious Diseases Society of America for the Treatment of Methicillin-Resistant Staphylococcus aureus Infections in Adults and Children

Evidence-based guidelines for the management of patients with methicillin-resistant Staphylococcus aureus (MRSA) infections were prepared by an Expert Panel of the Infectious Diseases Society of America (IDSA). The guidelines are intended for use by health care providers who care for adult and pediatric patients with MRSA infections. The guidelines discuss the management of a variety of clinical syndromes associated with MRSA disease, including skin and soft tissue infections (SSTI), bacteremia and endocarditis, pneumonia, bone and joint infections, and central nervous system (CNS) infections. Recommendations are provided regarding vancomycin dosing and monitoring, management of infections due to MRSA strains with reduced susceptibility to vancomycin, and vancomycin treatment failures.

Clinical Importance of Purulence in Methicillin-Resistant Staphylococcus aureus Skin and Soft Tissue Infections

The so-called community-associated methicillin-resistant Staphylococcus aureus (MRSA) strains are more frequently susceptible to non-ss-lactam antibiotics (including clindamycin) than health care-associated MRSA strains. We assessed whether predictive clinical characteristics of presumptive MRSA infections can be identified to guide choice of empiric antibiotic therapy. A clinical syndrome was assigned to each inpatient and outpatient at the University of Chicago Medical Center with an MRSA infection in 2004 to 2005. Antimicrobial susceptibilities and molecular characteristics of MRSA isolates were assessed. Patients were stratified by lesion characteristics. Of MRSA isolates from 262 patients with purulent skin and soft tissue infections (SSTIs), 231 (88%) were susceptible to clindamycin, 253 (97%) contained staphylococcal chromosomal cassette mec (SCCmec) IV, and 245 (94%) contained Panton-Valentine leukocidin (pvl) genes, characteristics associated with community-associated MRSA strains. The presence of a purulent SSTI had a positive predictive value of 88% for a clindamycin-susceptible MRSA isolate. Among 87 isolates from a nonpurulent SSTI, 44% were susceptible to clindamycin and 34% contained pvl genes. In 179 invasive MRSA disease isolates, 33% were clindamycin-susceptible and 26% carried pvl genes. A purulent MRSA SSTI strongly predicted the presence of a clindamycin-susceptible MRSA isolate. Presence of the pvl genes was almost universal among MRSA isolates causing purulent SSTIs; this was less common in nonpurulent SSTIs and other clinical syndromes.

Implementation of a Universal Admission Surveillance and Decolonization Program for Methicillin-Resistant Staphylococcus aureus (MRSA) Reduces the Number of MRSA and Total Number of S. aureus Isolates Reported by the Clinical Laboratory

Our three-hospital system began active surveillance for methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization, with decolonization of positive patients, on all admissions starting 1 August 2005. A question not previously addressed is whether reduction of the incidence of MRSA disease would lower the total number of S. aureus clinical isolates recovered by the microbiology laboratory that are reported to health care providers. The decreases in the numbers of MRSA and total S. aureus clinical isolates for each year after August 2005 were highly statistically significant compared to the numbers in each of the prior 3 years (P < 0.0001).

Evaluating the potential public health impact of a Staphylococcus aureus vaccine through use of population-based surveillance for invasive methicillin-resistant S. aureus disease in the United States

We evaluated the potential effects of a hypothetical vaccine in preventing invasive methicillin-resistant Staphylococcus aureus (MRSA) disease in the United States. Using an active, population-based surveillance program, we estimated baseline disease rates in the United States and compared three distinct vaccination strategies which targeted adults ≥65 years of age, persons at risk for recurrent invasive infection, and patients at hospital discharge. The strategies were projected to reduce the burden of invasive MRSA disease by 12.1%, 13.9% and 17.6%, respectively; with the strategy of vaccinating both adults ≥65 years of age and all adults at hospital discharge having the greatest impact per dose. Our data suggest that availability of an effective S. aureus vaccine could result in substantial reductions in invasive MRSA disease incidence. As candidate vaccines are evaluated, these data will be important in determining the optimal vaccination strategy.

Health Care-Associated Infection Prevention and Control: Pharmacists' Role in Meeting National Patient Safety Goal 7

Health care-associated infections and antimicrobial resistance are continually increasing, with fewer drugs available for effective treatment. Potential benefits of infection control and antimicrobial stewardship programs include improvements in antibiotic use and conversion from intravenous (IV) to oral antibiotics and reductions in resistance and infection rates and length of hospital stay. NorthShore University HealthSystem in Evanston, Illinois, was the first large hospital system in North America that adopted universal inpatient surveillance for methicillin-resistant Staphylococcus aureus (MRSA). Results showed that nasal MRSA was a powerful predictor of MRSA disease and antibiotic resistance in other organisms. MRSA infections occurring up to 30 days posthospitalization decreased by approximately 70%. At the Hospital of Saint Raphael, a community teaching hospital in New Haven, Connecticut, an antimicrobial stewardship pilot program focused on automatic conversation from IV to oral antimicrobials and appropriate antimicrobial use. The percentage of patients receiving oral fluconazole increased from 63% to 77%; the percentage of those receiving oral linezolid increased from 54% to 71%. Total antibiotic use decreased by 6%. Based on the 60-day trial, potential cost savings were estimated as $874,000 annually, less the cost of a pharmacist's salary and benefits. Infection control and antimicrobial stewardship programs offer pharmacists new opportunities for helping improve patient safety and quality of care. Pharmacy-medical staff partnership, combined with support from microbiology, infection control, information technology, and hospital administration, is key to a successful program.

Recurrence of Skin and Soft Tissue Infection Caused by Methicillin-Resistant Staphylococcus aureus in a HIV Primary Care Clinic

Recurrence of Skin and Soft Tissue Infection Caused by Methicillin-Resistant Staphylococcus aureus in a HIV Primary Care Clinic

Risk Factors and Molecular Analysis of Panton-Valentine Leukocidin-Positive Methicillin-Resistant Staphylococcus aureus Colonization in Healthy Children

Nasal carriage of Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) is associated with community associated disease. The risk factors for and characteristics of PVL-positive MRSA colonization in the healthy pediatric population are not well understood. Anterior nares cultures were obtained from healthy children < or =14 years of age presenting for health maintenance visits or attending 1 of 8 kindergartens during a 3-year period. A case-control study and molecular typing studies were performed. A total of 131 (8.1%) of 1615 children had nares cultures positive for MRSA, and 25 (1.5%) were colonized with PVL-positive MRSA. Nasal colonization of PVL-positive MRSA was significantly higher in 2006 than in 2004 (2.8% versus 0.7%; P = 0.006). By multivariate analysis, antibiotic use during the past 12 months (odds ratio, 29.37; 95% confidence interval, 10.72-80.50; P < 0.001) was the major risk factor associated with PVL-positive MRSA colonization in healthy children. Comparison of hospital MRSA strains with the community colonization strains by antimicrobial susceptibility testing, macrolide-lincosamide-streptogramin resistance gene testing, staphylococcal cassette chromosome mec typing, exotoxin profiling, and pulsed-field gel electrophoresis typing revealed that clonal spread of PVL-positive MRSA distinct from clinical hospital strains contributed to the high PVL-positive MRSA burden in the community. Nasal PVL-positive MRSA colonization in healthy children with no relationship to the hospital setting has increased significantly in the past 3 years, suggesting that it may be a major factor in the emergence of community-acquired MRSA disease in Taiwan. Previous antibiotic use was associated with PVL-positive MRSA colonization.