Community-associated Strains Research Articles

Epidemics of Community-Associated Methicillin-Resistant Staphylococcus aureus in the United States: A Meta-Analysis

Staphylococcus aureus is the most frequent cause of skin and soft tissue infections in humans. Methicillin-resistant strains of S. aureus (MRSA) that emerged in the 1960s presented a relatively limited public health threat until the 1990s, when novel community-associated (CA-) MRSA strains began circulating. CA-MRSA infections are now common, resulting in serious and sometimes fatal infections in otherwise healthy people. Although some have suggested that there is an epidemic of CA-MRSA in the U.S., the origins, extent, and geographic variability of CA-MRSA infections are not known. We present a meta-analysis of published studies that included trend data from a single site or region, and derive summary epidemic curves of CA-MRSA spread over time. Our analysis reveals a dramatic increase in infections over the past two decades, with CA-MRSA strains now endemic at unprecedented levels in many US regions. This increase has not been geographically homogeneous, and appears to have occurred earlier in children than adults.

A comparison of clinical outcomes between healthcare-associated infections due to community-associated methicillin-resistantStaphylococcus aureusstrains and healthcare-associated methicillin-resistantS. aureusstrains

There are limited data examining whether outcomes of methicillin-resistant Staphylococcus aureus (MRSA) healthcare-associated infections (HAIs) are worse when caused by community-associated (CA) strains compared to HA strains. We reviewed all patients' charts at our institution from 1999 to 2009 that had MRSA first isolated only after 72 h of hospitalization (n=724). Of these, 384 patients had a MRSA-HAI according to CDC criteria. Treatment failure was similar in those infected with a phenotypically CA-MRSA strain compared to a phenotypically HA-MRSA strain (23% vs. 15%, P=0.10) as was 30-day mortality (16% vs. 19%, P=0.57). Independent risk factors associated with (P<0.05) treatment failure were higher Charlson Comorbidity Index, higher APACHE II score, and no anti-MRSA treatment. These factors were also associated with 30-day mortality, as were female gender, older age, MRSA bloodstream infection, MRSA pneumonia, and HIV. Our findings suggest that clinical and host factors, not MRSA strain type, predict treatment failure and death in hospitalized patients with MRSA-HAIs.

Methicillin-resistant Staphylococcus aureus nasal carriage among patients receiving hemodialysis in Taiwan: prevalence rate, molecular characterization and de-colonization

BackgroundStaphylococcus aureus, particularly methicillin resistant (MRSA), is a common pathogen among patients receiving hemodialysis. To evaluate nasal carriage, molecular characterization and effectiveness of decolonization of MRSA among patients receiving hemodialysis in Taiwan, we conducted this study.MethodsFrom January to June 2011, two nasal samplings with a 3-month interval were obtained from patients undergoing hemodialysis in a medical center (CGMH), and in a local hospital (YMH) and sent for detection of MRSA. For MRSA carriers, decolonization procedures were administered. All patients in CGMH were observed if MRSA infections occurred during the study period.ResultsA total of 529 nasal specimens (265 from CGMH and 264 from YMH) were collected from 296 patients (161 from CGMH and 135 from YMH). 233 patients participated in both surveys. Average one-time point MRSA carriage rate was 3.8%, and the rate was up to 6.9% for those with two-time point surveys. No additional significant factor for MRSA carriage was identified. Seventy percent of the 20 colonizing MRSA isolates, though categorized as healthcare-associated strains epidemiologically, shared common molecular characteristics of the local community-associated strains. Only one of the 20 MRSA-colonized patients failed decolonization and had persistent colonization, while without any intervention, 17 (61%) of 28 patients with methicillin-sensitive S. aureus colonization in the first survey had persistent colonization of a genetically indistinguishable strain. Within the study period, two patients (1.24%) in CGMH, one with MRSA colonization (9.1%), developed MRSA infection.ConclusionA substantial proportion of patients receiving hemodialysis in Taiwan had MRSA colonization, mostly genetically community strains. Decolonization procedures may effectively eliminate MRSA colonization and might reduce subsequent MRSA infection in these patients.

Prevalence and Characteristics of Staphylococcus aureus in Connecticut Swine and Swine Farmers

This study explores the characteristics of Staphylococcus aureus (S. aureus) in swine and their human handlers in a convenience sample of 35 farms in Connecticut. Husbandry practices are clearly different from better-known concentrated animal feeding operations (CAFOs) with less intensive rearing conditions. Nasal samples were collected from 263 pigs and nine humans on 35 farms during the 2010 rearing season. Samples were analysed using established microbiology methods, and resulting methicillin-sensitive (MSSA) and resistant (MRSA) isolates were typed by pulsed-field gel electrophoresis (PFGE) and spa typing. PCR was used to detect the presence of the Panton-Valentine Leukocidin (PVL) gene, a cytotoxin usually associated with CA-MRSA infection. A farm assessment form and questionnaire were used to obtain the information about husbandry practices and human exposure risk, respectively. Staphylococcus aureus colonized swine and humans were found in 51% (18/35) of the farms sampled at a rate of 30% (85/259) and 22% (2/9), respectively. Eight pigs and two humans were MRSA positive on five farms. MRSA in swine was related to healthcare-associated (HA), community-associated (CA) or livestock-associated (LA) MRSA strains, whereas humans were colonized with HA-MRSA. On the basis of spa typing, there was evidence of human-animal transmission thereby signifying humanosis/reverse zoonoses. The PVL gene was found in 88% (7/8) of MRSA swine isolates, the first time this gene has been seen in colonized pigs sampled on US farm. MSSA isolates belonged to six spa types: t337 (41%), t034 (12%), t334 (12%), t4529 (12%), t8760 (18%) and t1166 (6%) including LA strains. This is the first time spa type t8760 has been reported and the only MSSA with the PVL gene. In summary, MRSA including LA strains (LA-MRSA) can be found on small farms with different husbandry practices from CAFOs, suggesting that preventive measures for zoonotic MRSA infection should address a range of animal production.

In Vitro Susceptibilities and Molecular Analysis of Vancomycin-Intermediate and Vancomycin-Resistant Staphylococcus aureus Isolates

There is increasing frequency of vancomycin-intermediate and -resistant Staphylococcus aureus (VISA and VRSA) isolates identified in clinical practice. There are limited reports evaluating susceptibility patterns and molecular characteristics of these strains. Laboratory analysis was performed on 13 VRSA and 33 VISA isolates, including susceptibility testing by broth microdilution, detection of Panton-Valentine leukocidin (PVL) genes, arginine catabolic mobile element (ACME), and staphylococcal cassette chromosome mec typing using polymerase chain reaction. Strain typing using pulsed-field gel electrophoresis (PFGE) was performed on VRSA isolates. Telavancin, linezolid, tigecycline, and minocycline were active against >90% of VISA isolates, while >90% of VRSA isolates were susceptible to ceftaroline, daptomycin, linezolid, minocyline, tigecycline, rifampin, and trimethoprim/sulfamethoxazole. There were no VISA or VRSA isolates that carried PVL genes or ACME, and most strains (69.8%) were staphylococcal cassette chromosome mec type II. VRSA isolates were predominantly related to USA100 (53.8%) and none were related to USA300 or USA400. A large number of available antimicrobial agents retain very good in vitro activity against VRSA and VISA isolates. The present isolates appear to be derived from healthcare-associated strains based on the absence of features associated with community-associated strains, and VRSA isolates are polyclonal by PFGE.

National prevalence of methicillin-resistant Staphylococcus aureus in inpatients at United States health care facilities, 2010

Methicillin-resistant Staphylococcus aureus (MRSA) remains one of the most prevalent multidrug-resistant organisms causing health care-associated infections. Limited data are available about how the prevalence of MRSA has changed over the past several years and what MRSA prevention practices have been implemented since the 2006 Association for Professionals in Infection Control and Epidemiology, Inc, MRSA survey. We conducted a national prevalence survey of MRSA colonization or infection in inpatients at US health care facilities. The survey was developed, received institutional review board approval, and then was distributed to all US Association for Professionals in Infection Control and Epidemiology, Inc, members. Members were asked to complete the survey on 1 day during the period August 1 to December 30, 2010, reporting the number of inpatients with MRSA infection or colonization and facility- and patient-specific information. Personnel at 590 facilities indicated a state and responded to the survey. All states were represented, except for Alaska and Washington, DC (mean, 12 facilities per state; range, 1-38). Respondents reported 4,476 MRSA-colonized/infected patients in 67,412 inpatients; the overall MRSA prevalence rate was 66.4 per 1,000 inpatients (25.3 infections and 41.1 colonizations per 1,000 inpatients). Active surveillance testing was conducted by 75.7% of the respondents; 39.6% used nonselective media, 37.2% used selective media, and 23.3% used polymerase chain reaction. Detailed data were provided on 3,176 MRSA-colonized/infected patients. Of those in whom colonization/infection status was reported (1,908/3,086 [61.8%] were MRSA colonized and 1,778/3,086 [38.2%] were MRSA infected), most MRSA-colonized or infected patients (78.3%) were detected within 48 hours of admission; the most common site of infection was skin and soft tissue (42.9%); and, using the Centers for Disease Control and Prevention's definitions, approximately 50% would be classified as health care-associated infections. Our survey documents that the MRSA prevalence in 2010 is higher than that reported in our 2006 survey. However, the majority of facilities currently are performing active surveillance testing, and, compared with 2006, the rate of MRSA infection has decreased while the rate of MRSA colonization has increased. In addition, compared with 2006, the proportion of MRSA strains recovered from MRSA-colonized/infected patients that are health care-associated strains has deceased, and community-associated strains have increased.

Trends in antimicrobial resistance in intensive care units in the United States

Antimicrobial resistance and a paucity of new antimicrobial agents are ongoing challenges. This review focuses on the major epidemiologic trends and novel treatments, when available, for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus, Clostridium difficile, and multidrug-resistant Gram-negative bacilli in the United States during 2010-2011. MRSA bloodstream infection rates have declined, primarily due to interventions aimed at decreasing vascular catheter infections. The proportion of MRSA due to the community-associated strain USA300 continues to increase. Recent studies of active surveillance and contact isolation for MRSA prevention provide conflicting views of efficacy. Two novel treatments for recurrent C. difficile infection, monoclonal antibodies and fidaxomicin, show promising results. Antimicrobial resistance among Gram-negative bacilli has become widespread; extended-spectrum beta-lactamases are now commonly found among Escherichia coli causing community-acquired infections in the United States. Klebsiella pneumoniae carbapenemases have spread beyond the northeast, and the New Delhi metallo-beta-lactamase has been reported in multiple countries within a few years of its discovery. Antimicrobial resistance, particularly among Gram-negative bacilli, continues to increase at a rapid rate. Given the frequent transfer of patients between outpatient and acute care settings, as well as between different geographic regions, coordinated infection control interventions are warranted.

Heavy chain-only antibodies and tetravalent bispecific antibody neutralizing Staphylococcus aureus leukotoxins

Panton-Valentine leukocidin (PVL) is a pore-forming toxin associated with current outbreaks of community-associated methicillin-resistant strains and implicated directly in the pathophysiology of Staphylococcus aureus-related diseases. Humanized heavy chain-only antibodies (HCAb) were generated against S. aureus PVL from immunized transgenic mice to neutralize toxin activity. The active form of PVL consists of the two components, LukS-PV and LukF-PV, which induce osmotic lysis following pore formation in host defense cells. One anti-LukS-PV HCAb, three anti-LukF-PV HCAbs with affinities in the nanomolar range, and one engineered tetravalent bispecific HCAb were tested in vitro and in vivo, and all prevented toxin binding and pore formation. Anti-LukS-PV HCAb also binds to γ-hemolysin C (HlgC) and inhibits HlgC/HlgB pore formation. Experiments in vivo in a toxin-induced rabbit endophthalmitis model showed that these HCAbs inhibit inflammatory reactions and tissue destruction, with the tetravalent bispecific HCAb performing best. Our findings show the therapeutic potential of HCAbs, and in particular, bispecific antibodies.

Clinical and Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus among Patients in an Ambulatory Hemodialysis Center

To describe the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) carriage and transmission in an ambulatory hemodialysis population. Prospective cohort study. Outpatient hemodialysis facility affiliated with a large academic medical center. Of the 170 facility patients, 103 (61%) participated in the study. Swab specimens of the nares, axillae, and vascular access site were collected from participants weekly for 3 weeks and then monthly for 5 months. Demographic and clinical data were collected monthly for 12 months. Molecular analysis of MRSA isolates was performed. The baseline MRSA carriage prevalence was 12%. Factors associated with MRSA carriage included a history of MRSA; failed renal transplantation; hospital admission within 6 months; and receipt of a first-generation cephalosporin, cefepime, or vancomycin. Six subjects acquired MRSA after enrollment (incidence, 1.2 per 100 patient-months at-risk; overall prevalence, 18%). Molecular analysis suggested that transmission occurred within the facility. The incidence of MRSA infection among carriers was 1.76 per 100 patient-months. Community-associated strains (ie, USA300) were isolated from 28% of carriers and at least 25% of infections. The prevalence of MRSA carriage and the incidence of infection among carriers were high among ambulatory hemodialysis patients, and community-associated MRSA was responsible for a large portion of the MRSA burden. A relatively high rate of MRSA acquisition was observed, with indirect evidence of intrafacility transmission. Additional studies are needed to confirm these findings and to identify effective and feasible methods to prevent MRSA transmission and infection among hemodialysis patients.

Meticillin-resistant Staphylococcus aureus in a harbour seal (Phoca vitulina)

METICILLIN-resistant Staphylococcus aureus (MRSA) is an important zoonosis that has increased in prevalence over the past decade, with up to 2 per cent of human beings acting as carriers, posing...

Methicillin-Resistant Staphylococcus aureus in Northeastern Scotland in 2003 to 2007: Evolving Strain Distribution and Resistance Patterns

This study explored strain distribution and resistance patterns of methicillin-resistant Staphylococcus aureus (MRSA) over a 5-year period in northeastern Scotland. We noted a shift in the relative rates of epidemic strains and an increase in community-associated strains. Use of oral antibiotics to eradicate throat carriage may have contributed to trimethoprim resistance, which was observed to increase 10-fold.

Ketamine inhibits tumor necrosis factor secretion by RAW264.7 murine macrophages stimulated with antibiotic-exposed strains of community-associated, methicillin-resistant Staphylococcus aureus

BackgroundInfections caused by community-associated strains of methicillin-resistant Staphylococcus aureus (CA-MRSA) are associated with a marked and prolonged host inflammatory response. In a sepsis simulation model, we tested whether the anesthetic ketamine inhibits the macrophage TNF response to antibiotic-exposed CA-MRSA bacteria via its antagonism of N-methyl-D-aspartate (NMDA) receptors. RAW264.7 cells were stimulated for 18 hrs with 105 to 107 CFU/mL inocula of either of two prototypical CA-MRSA isolates, USA300 strain LAC and USA400 strain MW2, in the presence of either vancomycin or daptomycin. One hour before bacterial stimulation, ketamine was added with or without MK-801 (dizocilpine, a chemically unrelated non-competitive NMDA receptor antagonist), APV (D-2-amino-5-phosphono-valerate, a competitive NMDA receptor antagonist), NMDA, or combinations of these agents. Supernatants were collected and assayed for TNF concentration by ELISA.ResultsRAW264.7 cells exposed to either LAC or MW2 in the presence of daptomycin secreted less TNF than in the presence of vancomycin. The addition of ketamine inhibited macrophage TNF secretion after stimulation with either of the CA-MRSA isolates (LAC, MW2) in the presence of either antibiotic. The NMDA inhibitors, MK-801 and APV, also suppressed macrophage TNF secretion after stimulation with either of the antibiotic-exposed CA-MRSA isolates, and the effect was not additive or synergistic with ketamine. The addition of NMDA substrate augmented TNF secretion in response to the CA-MRSA bacteria, and the addition of APV suppressed the effect of NMDA in a dose-dependent fashion.ConclusionsKetamine inhibits TNF secretion by MRSA-stimulated RAW264.7 macrophages and the mechanism likely involves NMDA receptor antagonism. These findings may have therapeutic significance in MRSA sepsis.

A Case of Acute Cholecystitis Caused by Methicillin‐Resistant Staphylococcus aureus in an Immunocompromised Patient

Although infections with Staphylococcus aureus can implicate multiple organ systems, involvement of the biliary tract is rare. A case of acute cholecystitis and bacteremia with methicillin-resistant S aureus (MRSA) in a patient with HIV infection is presented. The MRSA isolate was found to be a community-associated strain. The present case highlights the invasive nature of staphylococcal infections and the emerging importance of community-associated MRSA strains.

Escherichia coli O25b-ST131: a pandemic, multiresistant, community-associated strain

Escherichia coli sequence type 131 (ST131) is a worldwide pandemic clone, causing predominantly community-onset antimicrobial-resistant infection. Its pandemic spread was identified in 2008 by utilizing multilocus sequence typing (MLST) of CTX-M-15 extended-spectrum β-lactamase-producing E. coli from three continents. Subsequent research has confirmed the worldwide prevalence of ST131 harbouring a broad range of virulence and resistance genes on a transferable plasmid. A high prevalence of the clone (∼30%-60%) has been identified amongst fluoroquinolone-resistant E. coli. In addition, it potentially harbours a variety of β-lactamase genes; most often, these include CTX-M family β-lactamases, and, less frequently, TEM, SHV and CMY β-lactamases. Our knowledge of ST131's geographical distribution is incomplete. A broad distribution has been demonstrated amongst antimicrobial-resistant E. coli from human infection in Europe (particularly the UK), North America, Canada, Japan and Korea. High rates are suggested from limited data in Asia, the Middle East and Africa. The clone has also been detected in companion animals, non-companion animals and foods. The clinical spectrum of disease described is similar to that for other E. coli, with urinary tract infection predominant. This can range from cystitis to life-threatening sepsis. Infection occurs in humans of all ages. Therapy must be tailored to the antimicrobial resistance phenotype of the infecting isolate and the site of infection. Phenotypic detection of the ST131 clone is not possible and DNA-based techniques, including MLST and PCR, are described.

Molecular analysis of 2 cases of methicillin-resistant Staphylococcus aureus cholecystitis and a review of the literature

We present 2 cases of methicillin-resistant Staphylococcus aureus (MRSA) acalculous cholecystitis and review the literature. We performed pulsed field gel electrophoresis, typing of the staphylococcal cassette chromosome mec element, and Panton–Valentine leukocidin testing on the isolates. One each was closely related to USA100 and USA300, indicating that both healthcare- and community-associated strains may cause MRSA cholecystitis.

Resistencia de Staphylococcus aureus a los antibióticos en un hospital de la orinoquia colombiana

ObjectiveAnalyze the antimicrobial resistance patterns of Staphylococcus aureus at a hospital in Villavicencio, Colombia from 2005 to 2009. DesignRetrospective cohort study Setting: Villavicencio Departamental Hospital, a second and third level care center Targetpopulation: Patients’ microbiological records showing positive strains for S. aureus were analyzed. InterventionsNone VariableMethicillin resistance OutcomesAntimicrobial resistance ResultsNine hundred and seventy six strains of S. aureus were isolated from 29,451 microbiological screened samples, and their antimicrobial resistance pattern was analyzed by standard micro-dilution broth tests. 49.6% strains were resistant to methicillin, and their co-resistance was higher mainly to gentamycin (25%), ciprofloxacin (25.1%), clindamycin (29.4%) and erythromycin (31.0), but lower to trimethoprim/sulfamethoxazole (11.8%). Although co-resistance to vancomycin was supposed to be low, some intermediate range and resistant isolates were found, but this statement cannot be established because they were not confirmed at a referenced laboratory. Tetracycline resistance was high even for methicillin sensitive stains. No resistance to linezolid was identified. Resistance to tigecycline was not evaluated. ConclusionsS. aureus resistance to methicillin is also common at the target hospital in the Colombian Orinoco region. Co-resistance is higher particularly to gentamycin, ciprofloxacin and clindamycin in methicillin resistant strains. High sensitivity to these antimicrobials is evidenced when S. aureus is also sensitive to methicillin. Some findings related to sensitivity to ciprofloxacin and clindamycin in the presence of methicillin resistance suggest the possibility of community-associated strains in Villavicencio as well as in other Colombian cities. This possibility deserves further confirmatory research.

Prevalence and Characteristics of Staphylococcus aureus Colonization among Healthcare Professionals in an Urban Teaching Hospital

To determine the prevalence of asymptomatic carriage of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) among healthcare professionals (HCPs) who experience varying degrees of exposure to ambulatory patients and to genetically characterize isolates. This single-center, cross-sectional study enrolled 256 staff from the intensive care units, emergency department, and prehospital services of an urban tertiary care university hospital in 2008. Occupational histories and nasal samples for S. aureus cultures were obtained. S. aureus isolates were genetically characterized with the use of spa typing and screened for mecA. MRSA isolates underwent further characterization. S. aureus was isolated from 112 of 256 (43.8%) HCPs, including 30 of 52 (57.7%) paramedics, 51 of 124 (41.1%) nurses, 11 of 28 (39.3%) clerical workers, and 20 of 52 (38.5%) physicians. MRSA was isolated from 17 (6.6%) HCPs, including 1 (1.9%) paramedic, 13 (10.5%) nurses, 1 (3.6%) clerical worker, and 2 (3.8%) physicians. Among S. aureus isolates, 15.2% were MRSA. MRSA prevalence was 9.6% (12/125) in emergency department workers, 5.1% (4/79) in intensive care unit workers, and 1.9% (1/52) in emergency medical services workers. Compared with paramedics, who had the lowest prevalence of methicillin resistance among S. aureus isolates (1 of 30 [3.3%] isolates), nurses, who had the highest prevalence (13 of 51 [25.4%] isolates), had an odds ratio of 9.92 (95% confidence interval, 1.32-435.86; P = .02) for methicillin resistance. Analysis of 15 MRSA isolates revealed 7 USA100 strains, 6 USA300 strains, 1 USA800 strain, and 1 EMRSA-15 strain. All USA300 strains were isolated from emergency department personnel. The observed prevalence of S. aureus and MRSA colonization among HCPs exceeds previously reported prevalences in the general population. The proportion of community-associated MRSA among all MRSA in this colonized HCP cohort reflects the distribution of the USA300 community-associated strain observed increasingly among US hospitalized patients.

Antimicrobial Susceptibilities of Health Care-Associated and Community-Associated Strains of Methicillin-Resistant Staphylococcus aureus from Hospitalized Patients in Canada, 1995 to 2008

We determined the in vitro antimicrobial susceptibilities of 7,942 methicillin-resistant Staphylococcus aureus (MRSA) isolates obtained from patients hospitalized in 48 Canadian hospitals from 1995 to 2008. Regional variations in susceptibilities were identified. The dissemination of community-associated strains in Canada appears to have contributed to increased susceptibility of MRSA to several non-beta-lactam antimicrobial agents in the past decade. Reduced susceptibility to glycopeptides was not identified.

Prediction of vancomycin pharmacodynamics in children with invasive methicillin-resistant Staphylococcus aureus infections: A Monte Carlo simulation

Background: Due to the emergence of community-associated strains, the prevalence of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections has increased substantially in pediatric patients. A vancomycin AUC 0–24/MIC index >400 best predicts treatment outcomes for invasive MRSA infection in adults. Data on whether recommended vancomycin doses in children achieve this break point are lacking. Objective: This study aimed to assess the likelihood that currently recommended vancomycin doses in children achieve AUC 0–24/MIC >400. Methods: Vancomycin AUC 0–24/MIC predictions were conducted across a range of dosages (40–70 mg/kg/d) using a Monte Carlo simulation (n = 5000). AUC 0–24 was calculated as daily dose divided by vancomycin clearance, and daily dose was fixed for a given simulation. Three literature-reported estimates in children were used to define vancomycin clearance and its variance. For the MIC distribution of MRSA isolates, susceptibility data were obtained from the University of California, San Francisco Children's Hospital, San Francisco, California (n = 180; 40% ≤0.5 mg/L; 59% = 1 mg/L; and 1% = 2 mg/L). Results: Using the recommended empiric dosage of 40 mg/kg/d, 58% to 66% of children were predicted to achieve AUC 0–24/MIC >400. Increasing the vancomycin dosage to 60 mg/kg/d substantially increased the likelihood (88%–98%) of achieving this pharmacodynamic target. On sensitivity analysis, a dosage of 40 mg/kg/d was more strongly influenced by small changes in MIC compared with 60 mg/kg/d. Conclusions: Recommended empiric vancomycin dosing in children (40 mg/kg/d) was not predicted to consistently achieve the pharmacodynamic target of AUC 0–24/MIC >400 for invasive MRSA infections. A vancomycin dosage of 60 mg/kg/d was predicted to optimize achievement of this target in children.

Outbreak of Skin Infections in College Football Team Members Due to an Unusual Strain of Community-Acquired Methicillin-Susceptible Staphylococcus aureus

We report a skin and soft-tissue infection outbreak among football team members due to a USA300 methicillin-susceptible Staphylococcus aureus (MRSA) strain with genes coding for Panton-Valentine leukocidin and the arginine catabolic mobile element. We postulate that the strain is a community-associated USA300 MRSA strain that lost methicillin resistance but retained important virulence factors.