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The Antibacterial Resistance Leadership Group (ARLG) has prioritized infections caused by gram-positive bacteria as one of its core areas of emphasis. The ARLG Gram-positive Committee has focused on studies responding to 3 main identified research priorities: (1) investigation of strategies or therapies for infections predominantly caused by gram-positive bacteria, (2) evaluation of the efficacy of novel agents for infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci, and (3) optimization of dosing and duration of antimicrobial agents for gram-positive infections. Herein, we summarize ARLG accomplishments in gram-positive bacterial infection research, including studies aiming to (1) inform optimal vancomycin dosing, (2) determine the role of dalbavancin in MRSA bloodstream infection, (3) characterize enterococcal bloodstream infections, (4) demonstrate the benefits of short-course therapy for pediatric community-acquired pneumonia, (5) develop quality of life measures for use in clinical trials, and (6) advance understanding of the microbiome. Future studies will incorporate innovative methodologies with a focus on interventional clinical trials that have the potential to change clinical practice for difficult-to-treat infections, such as MRSA bloodstream infections., Competing Interests: Potential conflicts of interest. All authors report funding support from the ARLG of the NIH and the NIAID (UM1AI104681). S. B. D. reports grants or contracts paid to her institution from Gilead, Pfizer, F2G, Regeneron, Chan Zuckerberg Biohub, and NIAID/NIH; consulting fees paid directly to her from Genentech and Janssen/Johnson & Johnson (J&J); travel and meeting support from the Infectious Diseases Society of America (IDSA) to speak at IDWeek; a patent (US20100143379A1) for Mif agonists and antagonist and therapeutic uses thereof; a leadership role on the IDSA Antibacterial Resistance Committee, California Department of Public Health Hospital Acquired Infections Advisory Committee, and ARLG Innovations Group, Laboratory Center, Mentorship Committee, Gram-positive Committee, and Immunosuppressed Host Group; and payment directly to her for clinical events committee/adjudication committee participation from Shionogi, Basilea, and the Duke Clinical Research Institute.D. R. A. reports funding support from ContraFect and a leadership role on the ARLG Gram-positive Committee. A. B. reports funding support from the ARLG Early Faculty Seedling Award (NIAID UM1AI104681) and consulting fees from Roche. H. W. B. reports royalties from the Sanford Guide; consulting fees from the Sanford Guide, Antimicrobial Agents and Chemotherapy/American Society for Microbiology (ASM), and ID Clinics of North America/Elsevier; honoraria for Grand Rounds at Temple University; travel and meeting support for an IDWeek Lecture; membership as a voting member on the Presidential Advisory Council on Combating Antibiotic-Resistant Bacteria; and membership on the Board of Trustees at the College of the Holy Cross. B. C. reports grants or contracts paid to his institution from Moderna Vaccines and Merck Vaccines; royalties from UpToDate; consulting fees from Cowen Investments, Pfizer, Moderna, GSK, and Sanofi; payment as a medicolegal expert with multiple law firms; participation on the data and safety monitoring board (DSMB) or advisory board for Affinivax and GSK; and a leadership role as president of the Pediatric Infectious Diseases Society. S. E. C. reports grants or contracts paid to her institution from the Agency for Healthcare Research and Quality (AHRQ), the Centers for Disease Control and Prevention (CDC), the Patient-Centered Outcomes Research Institute, and the US Food and Drug Administration (FDA); consulting fees paid directly to her from the Duke Clinical Research Institute; participation on a DSMB for Debiopharm; and leadership roles as a board member of the National Foundation for Infectious Diseases and Globarl Antibiotic Research and Development Partnership North America (GARDP-NA). S. R. E. reports grants from the NIAID/NIH and De Gruyter (Editor-in-Chief for Statistical Communications in Infectious Diseases); royalties from Taylor & Francis; consulting fees from Genentech, AstraZeneca, Takeda, Microbiotix, J&J, Endologix, ChemoCentryx, Becton Dickinson, Atricure, Roviant, Neovasc, Nobel Pharma, Horizon, International Drug Development Institute (IDDI), SVB Leerink, Medtronic, Regeneron, Wake Forest University, Recor, Janssen, and IDDI; payments from Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION); meeting support from the FDA, Deming Conference on Applied Statistics, Clinical Trial Transformation Initiative, Council for International Organizations of Medical Sciences, International Chinese Statistical Association Applied Statistics Symposium, and Antimicrobial Resistance and Stewardship Conference; board member participation for the NIH, Breast International Group, University of Pennsylvania, Washington University, Duke University, Roche, Pfizer, Takeda, Akouos, Apellis, Teva, Vir, DayOneBio, Alexion, Tracon, Rakuten, AbbVie, Nuvelution, Clover, FHI Clinical, Lung Biotech, SAB Biopharm, Advantagene, Candel, and Novartis; and board positions with the American Statistical Association, Society for Clinical Trials, and Frontier Science Foundation. V. G. F. reports personal consulting fees from Novartis, Debiopharm, Genentech, Achaogen, Affinium, The Medicines Co, MedImmune, Bayer, Basilea, Affinergy, Janssen, ContraFect, Regeneron, Destiny, Amphliphi Biosciences, Integrated Biotherapeutics, C3J, Armata, Valanbio, Akagera, Aridis, Roche, and Pfizer; grants from NIH, MedImmune, Allergan, Pfizer, Advanced Liquid Logics, Theravance, Novartis, Merck, Medical Biosurfaces, Locus, Affinergy, ContraFect, Karius, Genentech, Regeneron, Deep Blue, Basilea, and Janssen; royalties from UpToDate; stock options from Valanbio and ArcBio; honoraria from the IDSA for his service as Associate Editor of Clinical Infectious Diseases; travel support from ContraFect to the 2019 European Congress of Clinical Microbiology and Infectious Diseases (ECCMID); and a sepsis diagnostics patent pending. S. A. F. reports grant or contracts from NIH (P50HD103525, U01AL116400, R21AI176063) and AHRQ (R01 HS024269), honoraria from ARLG, and provision of Clorox wipes for a clinical research study. B. J. K. reports grants from CDC and NIAID; honoraria from ARLG; and leadership roles in the CDC Microbiome Working Group, IDSA Journal Club, and ARLG. T. H. reports consulting fees from Tanabe-Mitsubishi Pharma and honoraria from Duke University and Cancer and Chemo Therapy. T. P. L. reports grants paid to his institution from Wockhardt; grants paid directly to him from Paratek, Cidara, Biofire Diagnostics, and Merck; payment directly to him for lectures from Shionogi, Ferring, Seres, and Melinta; consulting fees paid directly to him from AbbVie, Cidara Therapeutics, Ferring, ICPD, Genentech, J&J, Melinta, Merck, Roche, Shionogi, Spero, Venatrox, La Jolla, Seres, Paratek, GSK, and DoseMe; and payment for the development of educational presentations from the Mayo Clinic. L. G. M. reports grants or contracts from Merck, ContraFect, Paratek, Medline, and GSK. J. M. M. reports grants from Asociación Nacional de Investigación y Desarrollo, Fondo Nacional de Desarrollo Científico y Tecnológico FONDECYT (grant number 1211947). B. S. reports advisory board fees paid directly to him from Basilia. T. T. T. reports grants from NIH paid to her institution; travel and meeting support from IDSA; and a leadership role on the IDWeek Planning Committee and a role as a Gulf Coast Consortium Cluster Reviewer (both unpaid). N. A. T. reports grants from CDC and PDI, Inc; and consulting fees from Techspert. D. J. W. reports grants paid to his institution from CDC and NIH/NIAID; a leadership role on the IDSA Childhood Pneumonia Guidelines Committee; and receipt of equipment from bioMérieux for procalcitonin assays for an observational study. T. L. H. reports grants from Karius and NIH; royalties from UpToDate; consulting fees from Aridis, Pfizer, Lysovant, and Affinivax; and participation on a DSMB for the SNAP Trial and the advisory board for Basilea. C. A. A. reports grant funding to their institution from NIH/NIAID (1 Po1 AI152999, R01AI148342, R01 AI346337, T32 AI141349, K24 Ai121296, U19 AI44297, R01 AI150685, and R21 AI151536), MeMed Diagnostics Ltd, Entasis Therapeutics, Merck Pharmaceuticals, and Harris County Public Health; royalties paid to them from UpToDate; reimbursement from IDSA for attending IDWeek as a speaker and part of the organizing committee; reimbursement from ASM to attend ASM Microbe as a speaker; reimbursement from the Society for Healthcare Epidemiology of America (SHEA) to attend SHEA as a speaker; reimbursement from the European Society for Clinical Microbiology and Infectious Diseases to attend ECCMID as a speaker; reimbursement from Mérieux Foundation to attend ICARE course as faculty; reimbursement from Sociedad Chilea de Infectiologia, Sociedad Colombiana de Infectologia, Pan American Society for Infectious Diseases, and Brazilian Society for Infectious Diseases to attend the annual meeting and act as a speaker; was an unpaid participant on a DSMB with the World Health Organization and Antibacterial Pipeline Advisory Group; received payment for participation with the NIH Grant Review Study Sections; was a voluntary member of the board of directors of IDSA; and is the Editor-in-Chief of Antimicrobial Agents and Chemotherapy. B. E. M. reports royalties from UpToDate for online chapters; consulting fees from JRD, LLC (J&J), PPD Development, LP (GSK0 and Basilea Pharmaceutical International Ltd); participation on a DSMB with NIH Therapeutic and Prevention; and held the position of Governor of the Academy with the American Academy of Microbiology. C. L. reports grant payments to their institutions from NIAID/NIH (1R01AI151038-01) and Pfizer. M. H. S. reports advisory board fees from DoseMe; consulting fees from GSK and Entasis; and has an issued patent US10688195B2. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Staphylococcus aureus skin and soft tissue infections (SA-SSTIs) are common in healthcare and community settings, and recurrences occur at variable frequency, even after successful initial treatment. Knowing the exact burden and timing of recurrent disease is critical to planning and evaluating interventions to prevent recurrent SSTIs., Methods: In this retrospective study, SSTI cases in patients aged ≥18 years at 3 US medical centers (Columbia, Chicago, Vanderbilt) between 2006 and 2016 were analyzed according to a biennial cohort design. Index SSTIs (with or without key comorbidities), either microbiologically confirmed to be SA-SSTI or not microbiologically tested (NMT-SSTI), were recorded within 1 calendar year and followed up for 12 months for recurrent infections. The number of index cases, proportion of index cases with ≥1 recurrence(s), time to first recurrence, and number of recurrences were collected for both SA-SSTI and NMT-SSTI events., Results: In the most recent cohorts, 4755 SSTI cases were reported at Columbia, 2873 at Chicago, and 6433 at Vanderbilt. Of these, 452, 153, and 354 cases were confirmed to be due to S. aureus. Most cases were reported in patients without key comorbidities. Across centers, 16.4%-19.0% (SA-SSTI) and 11.0%-19.2% (NMT-SSTI) of index cases had ≥1 recurrence(s). In patients without key comorbidities, more than 60% of index SSTIs with recurrences had only 1 recurrence, half of which occurred in the first 3 months following primary infection., Conclusions: SA-SSTI recurrences are common among healthy adults and occur in at least 1 in 6 individuals during the 1 year following the primary event., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America.)

Background: Vancomycin is the most commonly administered antibiotic in hospitalized patients, but optimal exposure targets remain controversial. To clarify the therapeutic exposure range, this study evaluated the association between vancomycin exposure and outcomes in patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia., Methods: This was a prospective, multicenter (n = 14), observational study of 265 hospitalized adults with MRSA bacteremia treated with vancomycin. The primary outcome was treatment failure (TF), defined as 30-day mortality or persistent bacteremia ≥7 days. Secondary outcomes included acute kidney injury (AKI). The study was powered to compare TF between patients who achieved or did not achieve day 2 area under the curve to minimum inhibitory concentration (AUC/MIC) thresholds previously found to be associated with lower incidences of TF. The thresholds, analyzed separately as co-primary endpoints, were AUC/MIC by broth microdilution ≥650 and AUC/MIC by Etest ≥320., Results: Treatment failure and AKI occurred in 18% and 26% of patients, respectively. Achievement of the prespecified day 2 AUC/MIC thresholds was not associated with less TF. Alternative day 2 AUC/MIC thresholds associated with lower TF risks were not identified. A relationship between the day 2 AUC and AKI was observed. Patients with day 2 AUC ≤515 experienced the best global outcomes (no TF and no AKI)., Conclusions: Higher vancomycin exposures did not confer a lower TF risk but were associated with more AKI. The findings suggest that vancomycin dosing should be guided by the AUC and day 2 AUCs should be ≤515. As few patients had day 2 AUCs <400, further study is needed to define the lower bound of the therapeutic range., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

The purpose of this study was to determine if a decolonization regimen reduces the frequency of methicillin-resistant Staphylococcus aureus (MRSA) infections and if colonization isolates are genetically related to subsequent infectious strains. Trauma patients admitted to the intensive care unit with positive MRSA nasal swabs were randomized to either daily chlorhexidine gluconate (CHG) baths and mupirocin (MUP) ointment to the nares or soap and water baths and placebo ointment for five days. Nasal swabs performed at the end of treatment and invasive MRSA infections during the remaining hospitalization were compared with the original nasal isolate via polymerase chain reaction for genetic relatedness as well as CHG and MUP resistance genes. Six hundred and seventy-eight intensive care unit admissions were screened, and 92 (13.6%) had positive (+) MRSA nasal swabs over a 22-month period ending in 3/2014. After the five day treatment period, there were 13 (59.1%) +MRSA second nasal swabs for CHG + MUP and 9 (90%) for soap and water baths and placebo, P = 0.114. No isolates tested positive for the MUP or CHG resistance genes mupA and qacA/B but 7 of 20 (35%) contained smr. There were seven (31.8%) MRSA infections in the CHG group and six (60%) for soap, P = 0.244. All 13 patients with MRSA infections had the same MRSA isolate present in the original nasal swab. There was no difference in all-cause Gram-negative or positive infections for CHG versus soap, 12 (54.5%) versus 7 (70%), P = 0.467. CHG + MUP are ineffective in eradicating MRSA from the anterior nares but may reduce the incidence of infection. Subsequent invasive MRSA infections are typically caused by the endogenous colonization strain.

Objective: Athletes have a higher risk of infection with Staphylococcus aureus than the general population. Most studies in athletes have included primarily male contact sports participants and have not assessed S. aureus carriage over time. We aimed to examine the epidemiology and risk factors of S. aureus carriage in a cohort of male and female collegiate athletes., Study Design: We conducted a prospective cohort study of 377 varsity collegiate athletes from August 2008 to April 2010. A baseline questionnaire ascertained risk factors for colonization. Nasal and oropharyngeal swabs were obtained at enrollment and monthly thereafter to detect S. aureus colonization. The primary outcome was S. aureus colonization, both with methicillin-susceptible and methicillin-resistant S. aureus, as defined by bacterial culture and molecular confirmation. Secondary outcomes were time to colonization with S. aureus and carriage profile, defined as non-carrier, intermittent carrier, or persistent carrier., Results: Overall, 224 contact sports and 153 non-contact sports athletes were enrolled. Contact sports athletes had a higher risk of carrying S. aureus over time: They had higher odds of being colonized with MRSA (OR 2.36; 95 % CI 1.13-4.93) and they tended to carry S. aureus for longer periods of time (intermittent carriage OR 3.60; 95 % CI 2.02-6.40; persistent carriage OR 2.39; 95 % CI 1.21-4.72). Athletes engaged in contact sports also acquired S. aureus more quickly (HR 1.61; 95 % CI 1.02-2.55)., Conclusions: Staphylococcus aureus carriage was common in contact sports athletes. These findings suggest that efforts to prevent transmission of S. aureus among athletes should be focused on contact sports teams.

Background: Staphylococcus aureus is the leading cause of skin and soft tissue infections in the United States, and S. aureus colonization increases the risk of infection. Although athletes have a higher risk of infection with S. aureus than the general population, most studies in athletes have not assessed colonization., Methods: We conducted a prospective cohort study of Vanderbilt University varsity athletes from August 2008 to April 2010. We assessed nasal and oropharyngeal colonization with methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains by obtaining swabs at enrollment and monthly thereafter until the end of the study. The athletes were also monitored for skin and soft tissue infections., Results: We enrolled 377 athletes and trainers (224 in contact sports and 153 in noncontact sports). The total S. aureus colonization prevalence ranged from 34% to 62%, and for MRSA it ranged from 8% to 29%. The colonization rate in the summer was significantly higher than that in the winter (odds ratio for MRSA [ORMRSA], 1.70 [95% confidence interval (CI), 1.23-2.35]; ORMSSA, 1.38 [95% CI, 1.05-1.82]). Of 603 MRSA isolates, 75% carried the staphylococcal cassette chromosome mec (SCCmec) type IV, and 5% carried the genes encoding Panton-Valentine leukocidin. Nine symptomatic S. aureus infections occurred, 7 of which were between July and September., Conclusions: The S. aureus colonization rate is higher than previously reported and fluctuated over time in this prospective cohort of athletes. The higher colonization prevalence during summer might explain the infectious outbreak during the summer months and may represent a key intervention time for preventing S. aureus disease in athletes., (© The Author 2014. Published by Oxford University Press on behalf of the Pediatric Infectious Diseases Society. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Objective: The characteristics of staphylococcal skin and soft tissue infections (SSTIs) are poorly understood in northern South America and the Caribbean. The objectives of this study were to determine the frequency of methicillin resistance among Staphylococcus aureus isolates in an emergency department (ED) in Guyana and to identify specific molecular characteristics of these methicillin-resistant Staphylococcus aureus (MRSA) strains., Methods: This was a cross-sectional study conducted at the main teaching hospital in Georgetown, Guyana. Eligible subjects included patients of all ages with SSTIs with obtainable purulent material. Purulent material was cultured, and S. aureus isolates were evaluated for antibiotic susceptibilities by disc diffusion. Molecular characterisation of MRSA isolates included identification of SCCmec type, assignment of genetic relatedness by rep-PCR and determination of the presence of two exotoxins, Panton-Valentine Leukocidin (PVL) and LukAB., Results: Eighty-five samples were collected; of these, 47 grew S. aureus. 24 of the 47 S. aureus samples were MRSA (51%; 95% CI 37% to 65%), representing 28% of all samples. All MRSA isolates were SCCmec type IV, PVL positive, LukAB positive and were highly related to the current epidemic clone in the USA, USA300., Conclusions: Here, we demonstrate a clinically significant proportion of methicillin resistance in SSTI-associated staphylococcal isolates. Guyanese isolates were highly related to the most common community-associated strain seen in the USA, USA300. These results have important implications for empiric antibiotic therapy and infection control policies in Guyana and similar settings., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

We collected all Staphylococcus aureus isolates from the National Children's Hospital in Costa Rica to evaluate the prevalence and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA). Of 299 S. aureus isolates, 61% were MRSA. Most MRSA isolates (94.5%) carried SCCmec IV, and 45.6% carried Panton-Valentine leukocidin-encoding genes. The high prevalence of MRSA in this population highlights the need for improvement of antibiotic prescription and infection control measures.

Objective: The study aimed to assess whether maternal colonization with Staphylococcus aureus during pregnancy or at delivery was associated with infant staphylococcal colonization., Methods: For this prospective cohort study, women were enrolled at 34 to 37 weeks of gestation between 2007 and 2009. Nasal and vaginal swabs for culture were obtained at enrollment; nasal swabs were obtained from women and their infants at delivery and 2- and 4-month postbirth visits. Logistic regression was used to determine whether maternal colonization affected infant colonization., Results: Overall, 476 and 471 mother-infant dyads had complete data for analysis at enrollment and delivery, respectively. Maternal methicillin-resistant S aureus (MRSA) colonization occurred in 10% to 17% of mothers, with the highest prevalence at enrollment. Infant MRSA colonization peaked at 2 months of age, with 20.9% of infants colonized. Maternal staphylococcal colonization at enrollment increased the odds of infant staphylococcal colonization at birth (odds ratio; 95% confidence interval: 4.8; 2.4-9.5), hospital discharge (2.6; 1.3-5.0), at 2 months of life (2.7; 1.6-4.3), and at 4 months of life (2.0; 1.1-3.5). Similar results were observed for maternal staphylococcal colonization at delivery. Fifty maternal-infant dyads had concurrent MRSA colonization: 76% shared isolates of the same pulsed-field type, and 30% shared USA300 isolates. Only 2 infants developed staphylococcal disease., Conclusions: S aureus colonization (including MRSA) was extremely common in this cohort of maternal-infant pairs. Infants born to mothers with staphylococcal colonization were more likely to be colonized, and early postnatal acquisition appeared to be the primary mechanism.

Objective: To define the molecular epidemiology of colonization and disease-associated isolates of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA)., Design: Laboratory-based comparative study of clinical staphylococcal isolates., Methods: We analyzed 255 pediatric CA-MRSA isolates for molecular characteristics associated with colonization and disease. We used polymerase chain reaction to determine the presence of Panton-Valentine Leukocidin and the lantibiotic element, bsaB, and to characterize the staphylococcal cassette chromosome mec type and accessory gene regulator locus. Pulsed-field gel electrophoresis was used to determine genetic relatedness between strains., Results: A total of 150 isolates were obtained from patients with clinical disease (37 invasive infections, 113 noninvasive infections) and 105 from subjects with nasal colonization alone. Of 150 disease-associated isolates, 123 (82%) belonged to pulsed-field gel electrophoresis group USA300, whereas only 19 (18%) of 105 colonization isolates were of the USA300 lineage. Colonization isolates were less likely to possess staphylococcal cassette chromosome mec type IV, Panton-Valentine Leukocidin, or agr type 1 (P < 0.001)., Conclusions: Colonization strains of CA-MRSA in children differ significantly from those strains recovered from patients with staphylococcal infections. This suggests that only colonization with specific strain types, rather than methicillin-resistant Staphylococcus aureus colonization in general, increases the risk for CA-MRSA disease.

Objective: To determine the frequency and clinical importance of methicillin-resistant Staphylococcus aureus (MRSA) colonization in student athletes., Design: Prospective observational cohort study., Setting: A major university in the southeastern United States., Participants: Student athletes participating in the men's football and women's lacrosse programs (N = 126). Main Exposure Monthly assessment of S aureus nasal colonization., Main Outcome Measures: Trends in S aureus colonization over time and the occurrence of skin and soft tissue infections., Results: Methicillin-resistant S aureus nasal colonization varied significantly through the athletic season (4%-23%), peaking during times of highest athletic activity. This increase in colonization was not associated with the development of an outbreak of skin and soft tissue infections, and no single MRSA clone emerged as a dominant isolate., Conclusions: During the athletic season, there is a considerable burden of MRSA colonization in student athletes; however, colonization alone appears to be insufficient to trigger an outbreak of staphylococcal infections. A combination of distinct molecular characteristics in the organism and specific host factors may govern the development of staphylococcal disease.

Methicillin-resistant Staphylococcus aureus isolates with vancomycin minimal inhibitory concentrations (MICs) >or=1.5 microg/mL have been associated with poorer clinical outcomes and treatment failures in adults. We evaluated vancomycin MICs in 71 invasive pediatric community-acquired MRSA isolates from 2004 to 2008, using the E-test micromethod and the E-test macro-method. The modal MIC by micromethod was 1.5 microg/mL, and median vancomycin MICs did not increase over time.

This paper evaluates the ability to detect three forms of methicillin-resistant Staphylococcus aureus (MRSA) in a microfluidic system. The MRSA was prepared off-chip by varying levels of sample preparation: one containing purified genomic DNA, another containing the supernatant of a crude preparation using simple reagents, and a third through boiled culture preparation without any additional reagents. Polydimethylsiloxane (PDMS) microfluidic chips were fabricated using soft lithography and then bonded to a 22mmx22mmx0.1mm glass cover slip. A lid fabricated in a similar manner was used during compression to prevent bubble formation and evaporation in the stationary well-based chip. A miniature thermal cycler based on a resistive heater and a small fan were used to cycle through desired temperatures for polymerase chain reaction and fluorescent intensity measurements were taken at each cycle. Each form of template provided positive results utilizing the developed micro-PCR system (verified with gel electrophoresis). A serial dilution of the purified genomic DNA provided a standard curve with an efficiency of 1.77. The lowest concentration that provided clear positive results came from a 3microL sample containing 11.2pg of DNA. The ability to detect MRSA in a sample having undergone minimal sample preparation is a necessary step in the development of a point-of-care detection system capable of identifying infectious organisms.

Clinical samples from 250 pregnant women undergoing screening for rectovaginal group B streptococcus colonization were evaluated concurrently for the presence of methicillin-resistant Staphylococcus aureus (MRSA). Overall, S aureus was detected in 21.6% of the women; 53.7% of the isolates were MRSA. Despite a lack of risk factors for MRSA colonization, rectovaginal MRSA was detected in 10.4% of pregnant women in this study., (Copyright 2010 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.)

Background: The rate of vancomycin failure in patients with hospital-acquired pneumonia (HAP) caused by methicillin-resistant Staphylococcus aureus (MRSA) has exceeded 40% in several studies. This observation was attributed initially to the lack of weight-based dosing and targeting of lower trough concentrations. However, a subsequent study demonstrated no additional benefit in patients who achieved trough vancomycin concentrations >15 mg/L compared with patients with concentrations between 5 and 15 mg/L. We sought to identify contributors to vancomycin failure in patients with MRSA HAP., Methods: This was a retrospective study of patients in a surgical intensive care unit with MRSA HAP who received vancomycin between January 1, 2005, and July 31, 2007. Clinical outcomes, microbiological data, prior antibiotic exposure, ventilator days, co-morbidities, and demographics were compared in patients with clinical success and those with treatment failure. Their characteristics were compared using a two-sided Fisher exact test or Mann-Whitney U test, as appropriate for nominal or continuous data., Results: More patients in the treatment failure group had received one or more doses of vancomycin within 90 days leading up to MRSA HAP (84% vs. 47%; p = 0.04). In addition, the duration of prior vancomycin exposure was significantly longer among patients in the treatment failure group (6 vs. 0 days; p < 0.05). There were no statistically significant differences in the percentages of patients who achieved a vancomycin trough concentrations > or =15 mg/dL within the first 48 h (28% vs. 17%; p = 0.69), 72 h (44% vs. 39%; p = 1.0), or 96 h (56% vs. 44%; p = 0.74) after starting treatment. Patients in the failure group had a significantly higher overall mortality rate (32% vs. 0; p = 0.02)., Conclusions: These data suggest that patients who have recent exposure to vancomycin are at high risk for vancomycin failure and may benefit from an appropriate alternative when a diagnosis of MRSA HAP is made.

Purpose of Review: Staphylococcus aureus is an important pathogen, contributing to both pediatric and adult infections in the USA. In recent years, methicillin-resistant Staphylococcus aureus (MRSA) has become a source of public fear and outcry. In this article, we review facts and fiction of sinonasal MRSA., Recent Findings: Although the exact role of bacteria in chronic rhinosinusitis continues to be debated, the role of MRSA in these patients is even less apparent. When MRSA is involved, there are few to guide treatment. Oral, parenteral, and topical antibiotics are all used in the treatment of sinonasal MRSA. MRSA eradication has been advocated by some; however, there are few data to support the efficacy of eradication. Current treatment regimens by the authors are reviewed., Summary: There is much that is not known about the role of MRSA in sinonasal infection, and the impact of sinonasal MRSA on the health quality of the community also remains undefined. Treatment outlines are presented; however, with the current state of data, these treatment preferences lack a solid, evidence-based foundation that is favored. Future studies will lay the foundation for more rigorously supported treatment algorithms.

BackgroundUncomplicated skin abscesses are common, yet the appropriate management of the condition in the era of community-associated methicillin-resistant Staphylococcus aureus (MRSA) is unclear.MethodsWe conducted a multicenter, prospective, double-blind trial involving outpatient adults and children. Patients were stratified according to the presence of a surgically drainable abscess, abscess size, the number of sites of skin infection, and the presence of nonpurulent cellulitis. Participants with a skin abscess 5 cm or smaller in diameter were enrolled. After abscess incision and drainage, participants were randomly assigned to receive clindamycin, trimethoprim-sulfamethoxazole (TMP-SMX), or placebo for 10 days. The primary outcome was clinical cure 7 to 10 days after the end of treatment.ResultsWe enrolled 786 participants: 505 (64.2%) were adults and 281 (35.8%) were children. A total of 448 (57.0%) of the participants were male. S. aureus was isolated from 527 participants (67.0%), and MRSA was isolated from 388 (49.4%). Ten days after therapy in the intention-to-treat population, the cure rate among participants in the clindamycin group was similar to that in the TMP-SMX group (221 of 266 participants [83.1%] and 215 of 263 participants [81.7%], respectively; P=0.73), and the cure rate in each active-treatment group was higher than that in the placebo group (177 of 257 participants [68.9%], P

Staphylococcus aureus capsular polysaccharides (CP) are important virulence factors under evaluation as vaccine antigens. Clinical S. aureus isolates have the biosynthetic capability to express either CP5 or CP8 and an understanding of the relationship between CP genotype/phenotype and S. aureus epidemiology is valuable. Using whole genome sequencing, the clonal relatedness and CP genotype were evaluated for disease-associated S. aureus isolates selected from the Tigecycline Evaluation and Surveillance Trial (T.E.S.T) to represent different geographic regions in the United States (US) during 2004 and 2009–10. Thirteen prominent clonal complexes (CC) were identified, with CC5, 8, 30 and 45 representing >80% of disease isolates. CC5 and CC8 isolates were CP type 5 and, CC30 and CC45 isolates were CP type 8. Representative isolates from prevalent CC were susceptible to in vitro opsonophagocytic killing elicited by anti-CP antibodies, demonstrating that susceptibility to opsonic killing is not linked to the genetic lineage. However, as not all S. aureus isolates may express CP, isolates representing the diversity of disease isolates were assessed for CP production. While approximately 35% of isolates (primarily CC8) did not express CP in vitro, CP expression could be clearly demonstrated in vivo for 77% of a subset of these isolates (n = 20) despite the presence of mutations within the capsule operon. CP expression in vivo was also confirmed indirectly by measuring an increase in CP specific antibodies in mice infected with CP5 or CP8 isolates. Detection of antigen expression in vivo in relevant disease states is important to support the inclusion of these antigens in vaccines. Our findings confirm the validity of CP as vaccine targets and the potential of CP-based vaccines to contribute to S. aureus disease prevention. [ABSTRACT FROM AUTHOR]

The article presents a study comparing the effectiveness of clindamycin with trimethoprim-sulfamethoxazole (TMP-SMX) for the treatment of uncomplicated skin infections like abscesses and cellulitis. Topics covered include antibiotic regimens in the era of community-acquired methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible S. aureus (MSSA), and the adverse events.