Methicillin-resistant Staphylococcus Aureus Soft Tissue Infections Research Articles

Methicillin-Resistant Staphylococcus aureus Eradication and Decolonization in Children Study (Part 2): Patient- and Parent-Centered Outcomes of Decolonization.

BackgroundSkin and soft tissue infections (SSTIs) due to community-acquired methicillin-resistant Staphylococcus aureus (MRSA) can lead to a number of significant known medical outcomes including hospitalization, surgical procedures such as incision and drainage (I&D), and the need for decolonization procedures to remove the bacteria from the skin and nose and prevent recurrent infection. Little research has been done to understand patient and caregiver-centered outcomes associated with the successful treatment of MRSA infection.ObjectiveThis study aimed to uncover MRSA decolonization outcomes that are important to patients and their parents in order to create a set of prototype measures for use in the MRSA Eradication and Decolonization in Children (MEDiC) study.MethodsA 4-hour, human-centered design (HCD) workshop was held with 5 adolescents (aged 10-18 years) who had experienced an I&D procedure and 11 parents of children who had experienced an I&D procedure. The workshop explored the patient and family experience with skin infection to uncover patient-centered outcomes of MRSA treatment. The research team analyzed the audio and artifacts created during the workshop and coded for thematic similarity. The final themes represent patient-centered outcome domains to be measured in the MEDiC comparative effectiveness trial.ResultsThe workshop identified 9 outcomes of importance to patients and their parents: fewer MRSA outbreaks, improved emotional health, improved self-perception, decreased social stigma, increased amount of free time, increased control over free time, fewer days of school or work missed, decreased physical pain and discomfort, and decreased financial burden.ConclusionsThis study represents an innovative HCD approach to engaging patients and families with lived experience with MRSA SSTIs in the study design and trial development to determine meaningful patient-centered outcomes. We were able to identify 9 major recurrent themes. These themes were used to develop the primary and secondary outcome measures for MEDiC, a prospectively enrolling comparative effectiveness trial.Trial RegistrationClinicalTrials.gov NCT02127658; https://clinicaltrials.gov/ct2/show/NCT02127658

Diagnostic accuracy of methicillin-resistant Staphylococcus aureus nasal colonization to predict methicillin-resistant S aureus soft tissue infections

Nasal methicillin-resistant Staphylococcus aureus (MRSA) testing at admission to the hospital was found to have a positive likelihood ratio of 8.5 and a negative likelihood ratio of 0.41 for predicting MRSA soft tissue infections. The clinical utility of this test depends on the prevalence of MRSA infection. In high prevalence populations, nasal MRSA is useful to rule in MRSA infections. In low prevalence populations it may be useful to rule out infections.

Fingernail Carriage of Methicillin-Resistant Staphylococcus aureus and Possible Correlation with Soft Tissue Infections in Children.

Community-associated methicillin-resistant Staphylococcus aureus (MRSA) is a growing problem in the pediatric population, causing many soft tissue infections. This study was designed to examine fingernail carriage of MRSA in children and their caregivers as a possible link to community-associated MRSA soft tissue infections in children. We documented the prevalence of MRSA under the fingernails of children and the caregivers of pediatric patients with soft tissue infections and compared the prevalence with MRSA under the fingernails of children and the caregivers of children with no history of soft tissue infections. Children with soft tissue infections and their caregivers (50 subjects) had three fingernails of each hand swabbed and plated and these were compared with a control group of children and their caregivers (150 subjects) who had no history of MRSA or soft tissue infection. Caregivers and children in the study group were more likely than caregivers and the children in the control group to have MRSA under their fingernails (P < 0.05). Soft tissue infections in the study group were found most commonly in the diapering area (66%). MRSA carriage was evident under the fingernails of children and caregivers. Caregivers and their children who have soft tissue infections are more likely to have MRSA growth under fingernails than caregivers or their children who have no history of MRSA or soft tissue infections. Our study suggests that caregivers could be contributing to soft tissue infections in their children.

Duration of Colonization and Determinants of Earlier Clearance of Colonization With Methicillin-Resistant Staphylococcus aureus.

The duration of colonization and factors associated with clearance of methicillin-resistant Staphylococcus aureus (MRSA) after community-onset MRSA skin and soft-tissue infection (SSTI) remain unclear. We conducted a prospective cohort study of patients with acute MRSA SSTI presenting to 5 adult and pediatric academic hospitals from 1 January 2010 through 31 December 2012. Index patients and household members performed self-sampling for MRSA colonization every 2 weeks for 6 months. Clearance of colonization was defined as negative MRSA surveillance cultures during 2 consecutive sampling periods. A Cox proportional hazards regression model was developed to identify determinants of clearance of colonization. Two hundred forty-three index patients were included. The median duration of MRSA colonization after SSTI diagnosis was 21 days (95% confidence interval [CI], 19-24), and 19.8% never cleared colonization. Treatment of the SSTI with clindamycin was associated with earlier clearance (hazard ratio [HR], 1.72; 95% CI, 1.28-2.30; P < .001). Older age (HR, 0.99; 95% CI, .98-1.00; P = .01) was associated with longer duration of colonization. There was a borderline significant association between increased number of household members colonized with MRSA and later clearance of colonization in the index patient (HR, 0.85; 95% CI, .71-1.01; P = .06). With a systematic, regular sampling protocol, duration of MRSA colonization was noted to be shorter than previously reported, although 19.8% of patients remained colonized at 6 months. The association between clindamycin and shorter duration of colonization after MRSA SSTI suggests a possible role for the antibiotic selected for treatment of MRSA infection.

Frequent use of chlorhexidine-based body wash associated with a reduction in methicillin-resistant Staphylococcus aureus nasal colonization among military trainees.

In a field-based trial among military trainees, personal hygiene measures, including chlorhexidine (CHG) body wash, did not prevent overall and methicillin-resistant Staphylococcus aureus (MRSA) skin and soft-tissue infections (SSTI). We conducted a secondary analysis of anterior nares cultures obtained during the trial to evaluate the impact of hygiene measures on Staphylococcus aureus colonization. A cluster-randomized trial for SSTI prevention was conducted among U.S. Army infantry trainees from May 2010 to January 2012. There were three study groups with incrementally increasing education- and hygiene-based components: standard (S), enhanced standard (ES), and CHG. Anterior nares cultures were obtained from participants to determine the prevalence of S. aureus colonization. A total of 1,706 participants (469 S, 597 ES, and 640 CHG) without SSTI were included in the colonization analysis. Of those randomized to the CHG group, 360 (56.3%) reported frequent use of body wash. Frequent use of body wash had no effect on overall S. aureus colonization (53.3% versus 56.8% among infrequent/nonusers; P=0.25). MRSA colonization prevalence was marginally lower among frequent users (2.5% versus 4.7%; P=0.07). In multivariable analysis, the odds of MRSA colonization were lower among frequent users (odds ratio [OR], 0.36; 95% confidence interval [CI], 0.16 to 0.77). This CHG-associated reduction was not observed when comparing colonization with USA300 to that with non-USA300 types (OR, 0.59; 95% CI, 0.06 to 5.76). Frequent use of CHG body wash was associated with a reduction in MRSA nasal colonization among high-risk military trainees. Topical chlorhexidine may contribute to MRSA SSTI prevention by reducing colonization. However, further studies evaluating the pathogenesis of SSTI are needed. (This study has been registered at ClinicalTrials.gov under registration no. NCT01105767).

Neutrophil crawling in capillaries; a novel immune response to Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA), particularly the USA300 strain, is a highly virulent pathogen responsible for an increasing number of skin and soft tissue infections globally. Furthermore, MRSA-induced soft tissue infections can rapidly progress into life-threatening conditions, such as sepsis and necrotizing fasciitis. The importance of neutrophils in these devastating soft tissue infections remains ambiguous, partly because of our incomplete understanding of their behaviour. Spinning disk confocal microscopy was used to visualize the behaviour of GR1-labelled neutrophils in subcutaneous tissue in response to GFP-expressing MRSA attached to a foreign particle (agarose bead). We observed significant directional neutrophil recruitment towards the S. aureus agarose bead but not a control agarose bead. A significant increase in neutrophil crawling within the capillaries surrounding the infectious nidus was noted, with impaired capillary perfusion in these vessels and increased parenchymal cell death. No neutrophils were able to emigrate from capillaries. The crawling within these capillaries was mediated by the β2 and α4 integrins and blocking these integrins 2 hours post infection eliminated neutrophil crawling, improved capillary perfusion, reduced cell death and reduced lesion size. Blocking prior to infection increased pathology. Neutrophil crawling within capillaries during MRSA soft tissue infections, while potentially contributing to walling off or preventing early dissemination of the pathogen, resulted in impaired perfusion and increased tissue injury with time.

Recurrent MRSA Skin Infections in Atopic Dermatitis

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of recurrent skin and soft tissue infections. For patients with atopic dermatitis, recurrent skin infections with MRSA often lead to eczema exacerbation. There currently is no standard practice in the prevention of recurrent MRSA soft tissue infections in the general and the atopic dermatitis populations. The current article reviews recent data on S aureus decolonization treatments for the prevention of recurrent MRSA soft tissue infections in the community setting.

Reversion of Methicillin-ResistantStaphylococcus aureusSkin Infections to Methicillin-Susceptible Isolates

The rise of methicillin-resistant Staphylococcus aureus (MRSA) infections in the outpatient setting has led to a growing trend of empirical antibiotic treatment for MRSA. The limited oral antibiotics available and the growing resistance to these antibiotics make this a controversial practice. To determine the frequency of patients with MRSA skin and soft-tissue infections (SSTIs) reverting to methicillin-susceptible Staphylococcus aureus (MSSA) positivity. Retrospective medical record review of inpatients and outpatients from our university hospital and clinics between January 1, 2000, and December 31, 2010. Patients in our institutional microbiological database were included if they had a MRSA-positive SSTI and subsequent culture-proven S aureus SSTI more than 1 month later. No sociodemographic restrictions were applied. A sample of at least 200 patients meeting the above criteria was desired. The database was sorted by ascending medical record number, with the first 1681 patients' medical records reviewed. Of these, 215 patients met our criteria. Whether a patient remained MRSA positive in subsequent SSTIs or reverted to MSSA-positive infections. Of the total 215 patients, 64 (29.8%) had at least 1 incident of MSSA reversion, and 55 (25.6%) reverted to MSSA infections for the remainder of the study. We assessed various factors that might increase or decrease the likelihood of reversion. The presence of an invasive device was the only factor to demonstrate a statistically significant risk (relative risk, 1.20; 95% CI, 1.02-1.41; P = .03) toward remaining MRSA positive in subsequent infections. Patients with MRSA SSTIs demonstrated the ability to revert to subsequent MSSA SSTIs with a significant frequency. Further study regarding MRSA risk factors and their effects on subsequent infections would be valuable in guiding empirical treatment. Reculturing new infections in previously MRSA-positive patients is a prudent management strategy as we recognize that susceptibilities of the S aureus organisms change.

Trends and Factors Associated with Initial and Recurrent Methicillin-ResistantStaphylococcus aureus(MRSA) Skin and Soft-Tissue Infections among HIV-Infected Persons

Factors associated with initial methicillin-resistant Staphylococcus aureus (MRSA) skin and soft-tissue infections (SSTIs) and their recurrence have not been fully elucidated among HIV-infected persons. We retrospectively evaluated a large cohort of HIV-infected patients from 1993 to 2010 for culture-proven MRSA SSTIs. Separate logistic regression models evaluated factors associated with initial and recurrent infections. Of the 794 patients, 63 (8%) developed an initial infection (19.8 infections/1000 person years [PY]); risk factors included CD4 count <500 cells/mm(3) and HIV RNA level ≥400 copies/mL (P < .01), US Centers for Disease Control and Prevention (CDC) stage C versus A/B (P < .01), and injection drug use (IDU, P < .01). In all, 27% developed recurrence (206 infections/1000 PY); risk factors included hospital admission (P = .02). Minocycline for treatment of the initial infection was associated with an 80% decreased odds for recurrence (P = .03). HIV control and avoidance of IDU may be useful in reducing rates of MRSA SSTIs among HIV-infected persons.

Hospitalization of paediatric patients for methicillin-resistant Staphylococcus aureus skin and soft-tissue infection, 1998–2006

Hospital discharge reports have provided data for studies of methicillin-resistant Staphylococcus aureus (MRSA) skin and soft-tissue infection (SSTI) studies. This analysis determined the sensitivity and positive predictive value of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code combinations to calculate hospitalization incidence rates, representativeness of a set of three ICD-9-CM codes to define MRSA SSTI, and hospitalization incidence rate trends for paediatric MRSA SSTIs in Los Angeles County (LAC). Using 133 cases from 31 hospitals, we found that the set of three ICD-9-CM codes used to define laboratory-confirmed cases had one of the highest positive predictive values (49%). There was no difference in age and race between those categorized using three codes vs. other code combinations. A dramatic increase in paediatric MRSA SSTI cases occurred in LAC during 1998-2006. We conclude that this combination of codes may be used to determine the rise of MRSA SSTIs in paediatric populations.

Increasing incidence of methicillin-resistant Staphylococcus aureus skin and soft-tissue infections: reconsideration of empiric antimicrobial therapy

Background Community-acquired methicillin-resistant Staphylococcus aureus (MRSA) rates are at an all time high. MRSA rates as high as 60% have been reported in patients presenting with skin and soft-tissue infections (SSTIs). Our objectives were to (1) examine the incidence of MRSA over a 7-year period in surgical patients with SSTIs, (2) examine the choice of empiric antibiotic therapy, and (3) evaluate the vancomycin minimum inhibitory concentration (MIC) in MRSA isolates. Methods The medical records of all patients who underwent operative debridement of SSTIs from 2000 to 2006 were retrospectively reviewed. Demographic data such as age, race, and gender as well as co-morbid risk factors were collected. Preoperative American Society of Anesthesiologists (ASA) score, temperature, WBC, creatinine, HgbA1c, albumin, and empiric antimicrobial of choice were also included. Microbiology of all operative cultures was recorded. Available vancomycin MIC data were collected. All data are presented as mean ± standard error of the mean. A chi-square test was used for statistical analysis. Results From 2000 to 2006, 288 patients with operative debridement for SSTIs were identified. The mean age was 54 ± 11 years. Fifty-two percent of patients had diabetes mellitus, 55% were tobacco users, 34% alcohol users, and 23% had hepatitis C. The mean temperature at presentation was 99.2° ± 1.5°F. The mean white blood cell count was 13.8 ± .9. The mean HgbA1c was 8.6 ± 2.5. The mean body mass index was 30.1 ± 8. Sixty-seven percent of patients had an ASA ≥ 3. There was a significant increase in MRSA SSTIs in 2006 (77%) compared with 2000 (34%, P < .001). Correspondingly, there was a significant increase in empiric administration of vancomycin in 2006 (93%) compared with 2000 (18%, P < .001). The examination of vancomycin MIC shows a shift for MRSA isolates over this time period (MIC ≤ = .5 μg/mL, 62%, MIC = 1 μg/mL, 7%, and MIC = 2 μg/mL, 31%). Conclusion Our study shows a significant and ongoing increase in the incidence of MRSA in patients with SSTIs. Empiric coverage with an MRSA antimicrobial should be used as first-line therapy. However, given the observed increase in vancomycin MIC, alternative MRSA antimicrobials should be considered.

Community-Onset Methicillin-Resistant Staphylococcus aureus Skin and Soft-Tissue Infections: Impact of Antimicrobial Therapy on Outcome

Conflicting data exist on the role of antimicrobial therapy for the treatment of uncomplicated community-onset methicillin-resistant Staphylococcus aureus (MRSA) skin and soft-tissue infections (SSTIs). We performed a retrospective cohort study of 492 adult patients with 531 independent episodes of community-onset MRSA SSTIs, which consisted of abscesses, furuncles/carbuncles, and cellulitis, at 2 tertiary care medical centers. The purpose of the study was to determine the impact of active antimicrobial therapy (i.e., the use of an agent to which the organism is susceptible) and other potential risk factors on the outcome for patients with uncomplicated community-onset MRSA SSTIs. Treatment failure was the primary outcome of interest and was defined as worsening signs of infection associated with microbiological and/or therapeutic indicators of an unsuccessful outcome. Bivariate analyses and logistic regression analyses were preformed to determine predictors of treatment failure. An incision and drainage procedure was performed for the majority of patients. Treatment failure occurred in 45 (8%) of 531 episodes of community-onset MRSA SSTI. Therapy was successful for 296 (95%) of 312 patients who received an active antibiotic, compared with 190 (87%) of 219 of those who did not (P=.001 in bivariate analysis). Use of an inactive antimicrobial agent was an independent predictor of treatment failure on logistic regression analysis (adjusted odds ratio, 2.80; 95% confidence interval, 1.26-6.22; P=.01). Our findings suggest that certain patients with SSTIs that are likely caused by MRSA would benefit from treatment with an antimicrobial agent with activity against this organism.

Geographic information system localization of community-acquired MRSA soft tissue abscesses

Background Soft tissue infections with methicillin-resistant Staphylococcus aureus (MRSA) pose an ever-increasing risk to children in the community. Although historically these infections were limited to children with prolonged hospitalization, the authors have seen an increase in community-acquired infections in children without identifiable risk factors. The goal of this study is to determine the incidence of truly community-acquired MRSA soft tissue infections in our community and geographically map regions of increased risk. Methods After obtaining the institutional review board's approval, a retrospective chart review was conducted on 195 patients records who underwent an incision and drainage of soft tissue infections from January 1, 2000, to December 31, 2003. Thirteen patients were excluded from the study because no cultures were taken at the time of incision and drainage. Results The most common organism isolated from wound culture was S aureus, 40% (73/182), of which 45% (33/73) were MRSA. Eighty-one percent (27/33) of MRSA infections were in Springfield, 1 of 18 towns represented in the patient population. Geographic information system analysis identified a significant MRSA cluster 1.96 km in diameter within the city of Springfield. Conclusions Geography proved to be a significant risk factor for presenting with MRSA infection. Geographic maps of antibiotic resistance can be used to guide physician antibiotic selection before culture results are available. This has significant implications for the health care provider in proper antibiotic selection within the community.

An epidemic of methicillin-resistant Staphylococcus aureus soft tissue infections among medically underserved patients.

A high prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in soft tissue infections presents a treatment challenge. Retrospective analysis. The San Francisco General Hospital Integrated Soft Tissue Infection (ISIS) Clinic. Patients treated at the ISIS Clinic from July 1, 2000, to June 30, 2003. Information on patient demographics, surgical procedures, microbiologic studies, and antibiotic treatments was obtained for all patients treated in the ISIS Clinic. Microbial data and antibiotic susceptibility pattern of S aureus, treatment outcome, and antibiotic prescribed were analyzed for all evaluable patients. The ISIS Clinic treated 6156 unique patients for 12,012 episodes of infection. In this cohort, 5164 (84%) were either homeless or had no health insurance. More than half of the patients (58%) were injection drug users, but most had only 1 prior visit to the clinic (62%). Patients underwent a surgical procedure 7707 times (64%). Of the 837 positive cultures obtained, S aureus was recovered 695 times (83%), and 525 (63%) of the cultures contained MRSA. Therefore, a full 76% of all S aureus isolated was MRSA. In a subset analysis of 622 cultures collected prospectively from consecutive patients, 282 (45%) grew organisms, of which 256 (91%) were S aureus. MRSA represented 59% of all S aureus isolated. Homelessness and injection drug use were risk factors for infection by S aureus and MRSA. In another subgroup of patients with soft tissue infections that required admission to the hospital, MRSA was recovered from the cultures in 149 patients. In these patients with MRSA, 44 (30%) only received a beta-lactam antibiotic, inactive against MRSA, and had full resolution of their infection. The prevalence of MRSA soft tissue infections in the medically underserved ISIS Clinic cohort is extremely high. The transmission of the MRSA seems to be in the community. Antibiotic therapy directed at MRSA may not be needed in a large number of patients with these soft tissue infections. Studies to identify the source and cause of this MRSA outbreak are urgently needed. Clinical trials to examine the need for antibiotic therapy in soft tissue infections should be conducted.

Serum inhibitory and bactericidal activity against methicillin-resistant Staphylococcus aureus in volunteers receiving novobiocin and rifampin alone and in combination

The combination of novobiocin and rifampin is effective in eliminating colonization due to methicillin-resistant Staphylococcus aureus (MRSA) and in treating experimental MRSA soft tissue infections. To evaluate novobiocin, rifampin, and the combination of the two agents for potential oral therapy in patients with MRSA infections, we measured the serum inhibitory and bactericidal activity from four volunteers against 20 MRSA strains obtained from seven different institutions. When Stratton-Reller methods employing 50% human serum were used to perform the assay, rifampin produced peak mean serum inhibitory titers of 1:40, whereas novobiocin alone produced essentially no inhibitory activity. The combination of novobiocin plus rifampin had similar inhibitory activity as rifampin alone. The bactericidal titers produced by the three regimens were significantly less than inhibitory titers. In additional studies, involving serum from five volunteers tested against seven representative strains, peak mean serum inhibitory activity of novobiocin was 1:232 when Mueller-Hinton broth was used as the diluent compared with <1:2 when 50% human serum was used. We conclude that despite the high degree of activity of novobiocin in broth, its activity against MRSA in serum is minimal, probably related to the high degree of protein binding of that antibiotic.