Trends in US hospital admissions for skin and soft tissue infections

Factors associated with decision to hospitalize emergency department patients with skin and soft tissue infection

Introduction

Emergency department (ED) hospitalizations for skin and soft tissue infection (SSTI) have increased, while concern for costs has grown and outpatient parenteral antibiotic options have expanded. To identify opportunities to reduce admissions, we explored factors that influence the decision to hospitalize an ED patient with a SSTI.

Methods

We conducted a prospective study of adults presenting to 12 U.S. EDs with a SSTI in which physicians were surveyed as to reason(s) for admission, and clinical characteristics were correlated with disposition. We employed chi-square binary recursive partitioning to assess independent predictors of admission. Serious adverse events were recorded.

Results

Among 619 patients, median age was 38.7 years. The median duration of symptoms was 4.0 days, 96 (15.5%) had a history of fever, and 46 (7.5%) had failed treatment. Median maximal length of erythema was 4.0cm (IQR, 2.0–7.0). Upon presentation, 39 (6.3%) had temperature >38°C, 81 (13.1%) tachycardia, 35 (5.7%), tachypnea, and 5 (0.8%) hypotension; at the time of the ED disposition decision, these findings were present in 9 (1.5%), 11 (1.8%), 7 (1.1%), and 3 (0.5%) patients, respectively. Ninety-four patients (15.2%) were admitted, 3 (0.5%) to the intensive care unit (ICU). Common reasons for admission were need for intravenous antibiotics in 80 (85.1%; the only reason in 41.5%), surgery in 23 (24.5%), and underlying disease in 11 (11.7%). Hospitalization was significantly associated with the following factors in decreasing order of importance: history of fever (present in 43.6% of those admitted, and 10.5% discharged; maximal length of erythema >10cm (43.6%, 11.3%); history of failed treatment (16.1%, 6.0%); any co-morbidity (61.7%, 27.2%); and age >65 years (5.4%, 1.3%). Two patients required amputation and none had ICU transfer or died.

Conclusion

ED SSTI patients with fever, larger lesions, and co-morbidities tend to be hospitalized, almost all to non-critical areas and rarely do they suffer serious complications. The most common reason for admission is administration of intravenous antibiotics, which is frequently the only reason for hospitalization. With the increasing outpatient intravenous antibiotic therapy options, these results suggest that many hospitalized patients with SSTI could be managed safely and effectively as outpatients.

Hospitalist perspective on the treatment of skin and soft tissue infections

The prevalence of skin and soft tissue infections (SSTIs) has been increasing in the United States. These infections are associated with an increase in hospital admissions. Hospitalists play an increasingly important role in the management of these infections and need to use hospital resources efficiently and effectively. When available, observation units are useful for treating low-risk patients who do not require hospital admission. Imaging tools may help to exclude abscesses and necrotizing soft tissue infections; however, surgical exploration remains the principal means of diagnosing necrotizing soft tissue infections. The most common pathogens that cause SSTIs are streptococci and Staphylococcus aureus. Methicillin-resistant S aureus (MRSA) is a prevalent pathogen, and concerns are increasing regarding the unclear distinctions between community-acquired and hospital-acquired MRSA. Other less frequent pathogens that cause SSTIs include Enterococcus species, Escherichia coli, Klebsiella species, Enterobacter species, and Pseudomonas aeruginosa. Cephalexin and clindamycin are suitable options for infections caused by streptococcal species and methicillin-susceptible S aureus. The increasing resistance of S aureus and Streptococcus pyogenes to erythromycin limits its use in these infections, and better alternatives are available. Parenteral cefazolin, nafcillin, or oxacillin can be used in hospitalized patients with nonpurulent cellulitis caused by streptococci and methicillin-susceptible S aureus. When oral MRSA therapy is indicated, clindamycin, doxycycline, trimethoprim-sulfamethoxazole, or linezolid is appropriate. Vancomycin, linezolid, daptomycin, tigecycline, telavancin, and ceftaroline fosamil are intravenous options that should be used in MRSA infections that require patient hospitalization. In the treatment of patients with SSTIs, hospitalists are at the forefront of providing proper patient care that reduces hospital costs, duration of therapy, and therapeutic failures. This review updates guidelines on the management of SSTIs with a focus on infections caused by S aureus, particularly MRSA, and outlines the role of the hospitalist in the effective management of SSTIs.

Antibiotic prescribing practices in a multicenter cohort of patients hospitalized for acute bacterial skin and skin structure infection

OBJECTIVE

Hospitalizations for acute bacterial skin and skin structure infection (ABSSSI) are common. Optimizing antibiotic use for ABSSSIs requires an understanding of current management. The objective of this study was to evaluate antibiotic prescribing practices and factors affecting prescribing in a diverse group of hospitals.

DESIGN

Multicenter, retrospective cohort study.

SETTING

Seven community and academic hospitals.

METHODS

Children and adults hospitalized between June 2010 and May 2012 for cellulitis, wound infection, or cutaneous abscess were eligible. The primary endpoint was a composite of 2 prescribing practices representing potentially avoidable antibiotic exposure: (1) use of antibiotics with a broad spectrum of activity against gram-negative bacteria or (2) treatment duration greater than 10 days.

RESULTS

A total of 533 cases were included: 320 with nonpurulent cellulitis, 44 with wound infection or purulent cellulitis, and 169 with abscess. Of 492 cases with complete prescribing data, the primary endpoint occurred in 394 (80%) cases and varied significantly across hospitals (64%-97%; P < .001). By logistic regression, independent predictors of the primary endpoint included wound infection or purulent cellulitis (odds ratio [OR], 5.12 [95% confidence interval (CI)], 1.46-17.88), head or neck involvement (OR, 2.83 [95% CI, 1.17-6.82]), adult cases (OR, 2.20 [95% CI, 1.18-4.11]), and admission to a community hospital (OR, 1.90 [95% CI, 1.05-3.44]).

CONCLUSIONS

Among patients hospitalized for ABSSSI, use of antibiotics with broad gram-negative activity or treatment courses longer than 10 days were common. There may be substantial opportunity to reduce antibiotic exposure through shorter courses of therapy targeting gram-positive bacteria.

A national survey of skin infections, care behaviors and MRSA knowledge in the United States

A nationally representative sample of approximately 2000 individuals was surveyed to assess SSTI infections over their lifetime and then prospectively over six-months. Knowledge of MRSA, future likelihood to self-treat a SSTI and self-care behaviors was also queried. Chi square tests, linear and multinomial regression were used for analysis. About 50% of those with a reported history of a SSTI typical of MRSA had sought medical treatment. MRSA knowledge was low: 28% of respondents could describe MRSA. Use of protective self-care behaviors that may reduce transmission, such as covering a lesion, differed with knowledge of MRSA and socio-demographics. Those reporting a history of a MRSA-like SSTI were more likely to respond that they would self-treat than those without such a history (OR 2.05 95% CI 1.40, 3.01; p<0.001). Since half of respondents reported not seeking care for past lesions, incidence determined from clinical encounters would greatly underestimate true incidence. MRSA knowledge was not associated with seeking medical care, but was associated with self-care practices that may decrease transmission.

Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections: 2014 Update by the Infectious Diseases Society of America

A panel of national experts was convened by the Infectious Diseases Society of America (IDSA) to update the 2005 guidelines for the treatment of skin and soft tissue infections (SSTIs). The panel's recommendations were developed to be concordant with the recently published IDSA guidelines for the treatment of methicillin-resistant Staphylococcus aureus infections. The focus of this guideline is the diagnosis and appropriate treatment of diverse SSTIs ranging from minor superficial infections to life-threatening infections such as necrotizing fasciitis. In addition, because of an increasing number of immunocompromised hosts worldwide, the guideline addresses the wide array of SSTIs that occur in this population. These guidelines emphasize the importance of clinical skills in promptly diagnosing SSTIs, identifying the pathogen, and administering effective treatments in a timely fashion.

Risk factors for methicillin-resistant Staphylococcus aureus skin and soft-tissue infections in outpatients in Taiwan

Information on the risk factors for community-associated skin and soft-tissue infections (SSTIs) due to methicillin-resistant Staphylococcus aureus in Asian populations is scarce. To this end we performed a case-control study of patients treated at two hospital-affiliated outpatient clinics in Taiwan to determine potential risk factors for MRSA SSTIs. S. aureus was isolated from 39 of 100 eligible patients, and 74% were MRSA. Apart from resistance to clindamycin and erythromycin, most MRSA isolates were susceptible to appropriate antimicrobials. The significant risk factors identified by multivariate analysis for MRSA SSTIs were male gender (P = 0·09), nasal carriage of MRSA (P = 0·02), exposure to an individual who had surgery within a year before infection (P = 0·02), and antibiotic treatment for SSTI in the year before infection (P = 0·04). The identification of such factors may assist provision of appropriate treatment to patients with suspected S. aureus SSTIs particularly in Taiwan.

Incidence and cost of hospitalizations associated with Staphylococcus aureus skin and soft tissue infections in the United States from 2001 through 2009

BACKGROUND

The emergence of community-associated methicillin-resistant Staphylococcus aureus (SA) and its role in skin and soft tissue infections (SSTIs) accentuated the role of SA-SSTIs in hospitalizations.

METHODS

We used the Nationwide Inpatient Sample and Census Bureau data to quantify population-based incidence and associated cost for SA-SSTI hospitalizations.

RESULTS

SA-SSTI associated hospitalizations increased 123% from 160,811 to 358,212 between 2001 and 2009, and they represented an increasing share of SA- hospitalizations (39% to 51%). SA-SSTI incidence (per 100,000 people) doubled from 57 in 2001 to 117 in 2009 (p<0.01). A significant increase was observed in all age groups. Adults aged 75+ years and children 0-17 years experienced the lowest (27%) and highest (305%) incidence increase, respectively. However, the oldest age group still had the highest SA-SSTI hospitalization incidence across all study years. Total annual cost of SA-SSTI hospitalizations also increased and peaked in 2008 at $4.84 billion, a 44% increase from 2001. In 2009, the average associated cost of a SA-SSTI hospitalization was $11,622 (SE=$200).

CONCLUSION

There has been an increase in the incidence and associated cost of SA-SSTI hospitalizations in U.S.A. between 2001 and 2009, with the highest incidence increase seen in children 0-17 years. However, the greatest burden was still seen in the population over 75 years. By 2009, SSTI diagnoses were present in about half of all SA-hospitalizations.

Humanized tissue pharmacodynamics of cefazolin against commonly isolated pathogens in skin and skin structure infections

OBJECTIVES

The objective of this study was to assess the efficacy of humanized cefazolin tissue concentrations against methicillin-susceptible Staphylococcus aureus (MSSA) and Enterobacteriaceae in an in vitro pharmacodynamic model.

METHODS

Nine clinical isolates [five MSSA (cefazolin MIC range 0.5-2.0 mg/L), two Escherichia coli (cefazolin MICs 1.0 and 2.0 mg/L) and two Klebsiella pneumoniae (cefazolin MICs of 1.0 and 2.0 mg/L)] were evaluated with a starting inoculum (0 h) of 10(6) cfu/mL. Time-kill curves were built and the area under the bacterial killing and regrowth curve (AUBC) was calculated.

RESULTS

The starting inoculum had a mean ± SD of 6.3 ± 0.28 log10 cfu/mL. Cefazolin human simulated targets for peak, trough and half-life were 13.0 mg/L, 2.6 mg/L and 2.6 h, respectively. Control isolates grew to 8.5 ± 0.2 log10 cfu/mL. Against MSSA, cefazolin achieved a reduction from 0 h of -1.18 ± 0.67 and -3.58 ± 1.24 log10 cfu/mL, at 4 and 24 h, respectively. Cefazolin achieved a reduction in bacterial density of -3.45 ± 0.35 and -2.68 ± 0.99 log10 cfu/mL at 4 and 24 h, respectively, when tested against Enterobacteriaceae. No significant difference was observed when comparing AUBC based on MIC values. The rate of initial bacterial reduction of Enterobacteriaceae was rapid, with a decrease of >3 log10 cfu/mL by 4 h, while MSSA exhibited a gradual reduction in bacterial density over one dosing interval.

CONCLUSIONS

The observed antibacterial effects of cefazolin support its continued utility against susceptible S. aureus, E. coli and K. pneumoniae in skin and skin structure infections.

Cutaneous bacterial infections caused by Staphylococcus aureus and Streptococcus pyogenes in infants and children

Acute bacterial skin and skin structure infections (SSSIs) are among the most common bacterial infections in children. The medical burden of SSSIs, particularly abscesses, has increased nationwide since the emergence of community-acquired methicillin-resistant Staphylococcus aureus. SSSIs represent a wide spectrum of disease severity. Prompt recognition, timely institution of appropriate therapy, and judicious antimicrobial use optimize patient outcomes. For abscesses, incision and drainage are paramount and might avoid the need for antibiotic treatment in uncomplicated cases. If indicated, empiric antimicrobial therapy should target Streptococcus pyogenes for nonpurulent SSSIs, such as uncomplicated cellulitis, and S aureus for purulent SSSIs such as abscesses.

Ceftaroline fosamil for the treatment of acute bacterial skin and skin structure infections

Skin infections have traditionally been classified by the US FDA as uncomplicated and complicated. In August 2010, the FDA released a new guidance document for the development of drugs to treat acute bacterial skin and skin structure infections (ABSSSI) and this was updated in 2013. Several new issues were addressed and henceforth skin infections in clinical trials were termed ABSSSI. In the USA, the annual prevalence of methicillin-resistant Staphylococcus aureus-related skin infections have continuously increased from 32.7% in 1998 to 53.8% in 2007. Ceftaroline fosamil is the only cephalosporin approved in the USA for monotherapy treatment of ABSSSI including infections caused by methicillin-resistant S. aureus. The efficacy of ceftaroline fosamil was shown in the CANVAS clinical trials. The CANVAS Day-3 analyses met an earlier, primary efficacy time point requested by the FDA. Ceftaroline has minimal drug-drug interactions, is well tolerated and possesses the safety profile associated with the cephalosporin class.

Economic outcomes of inappropriate initial antibiotic treatment for complicated skin and soft tissue infections: a multicenter prospective observational study

This study examined economic outcomes associated with inappropriate initial antibiotic treatment (IIAT) in complicated skin and soft tissue infections using data from adults hospitalized and treated with intravenous antibiotic therapy. We specifically analyzed for the subsets of patients infected with methicillin-resistant Staphylococcus aureus (MRSA), with healthcare-associated (HCA) infections, or both. Data from 494 patients (HCA: 360; MRSA:175; MRSA + HCA: 129) showed the overall mean length of stay (LOS) was 7.4 days and 15.0% had the composite economic outcome of any subsequent hospital admissions, emergency department visits, or unscheduled visits related to the study infection. A total of 23.1% of patients had IIAT; after adjustments, these patients had longer LOS than patients without IIAT in the HCA cohort (marginal LOS = 1.39 days, P = 0.03) and the MRSA + HCA cohort (marginal LOS = 2.43 days, P = 0.01) and were significantly more likely to have the composite economic outcome in all study cohorts (odds ratio: overall = 1.79; HCA = 3.09; MRSA = 3.66; MRSA + HCA = 6.92; all P < 0.05).

Application of external drugs comprising silver compounds for the treatment of pyodermic patients

An external anti-bacterial therapy is selected for pyodermic patients empirically. Silver sulfathiazole has an evident anti-inflammatory and anti-microbial effect against a broad range of microorganisms. Goal of the study. To assess the efficacy, safety and tolerability of a cream comprising 2% silver sulfathiazole vs. 3% tetracycline ointment for the treatment of pyodermic patients. Materials and methods. The study involved 50 pyodermic patients (at the mean age of 23.5 ± 4.1 years) including 31 (62%) male and 19 (38%) female patients. The patients were divided into two groups: Group I (n = 35) used the cream comprising 2% silver sulfathiazole while Group II (n = 15) was administered 3% tetracycline ointment. All of the patients were assessed for clinical and microbiological efficacy of the therapy. Results. The average patient recovery time in Group I amounted to 8.7 ± 0.9 days and 13.1 ± 2.7 days in Group II (р < 0.01). As many as 33 patients (94.3%) achieved clinical recovery and 2 patients (5.7%) achieved improvement by Day 10 in Group I; in Group II, clinical recovery was observed in 8 patients (53.3%), improvement - in 3 patients (20%), and no effect - in 4 patients (26.7%). Conclusion. The external anti-bacterial monotherapy of pyodermic patients with the cream comprising 2% silver sulfathiazole is more efficient than treatment with 3% tetracycline ointment. High clinical and microbiological efficacy of the cream comprising 2% silver sulfathiazole makes it possible to recommend it for empirical treatment of pyodermic patients.

The impact of initial antibiotic therapy (linezolid, vancomycin, daptomycin) on hospital length of stay for complicated skin and soft tissue infections

Background

Empiric therapy of inpatient skin and soft tissue infections (SSTIs) generally require methicillin resistant Staphylococcus aureus (MRSA) coverage. Limited data are available to directly compare the effect of initial antibiotic choice on treatment outcomes and length of stay (LOS).

Objective

To assess potential differences in length of hospital stay when inpatients with complex skin and soft tissue infections (SSTIs) were initially treated with either vancomycin, linezolid, or daptomycin.

Methods

A retrospective review of 219 patients diagnosed with inpatient SSTI who received linezolid, vancomycin, or daptomycin for >48 hours was performed. Data collected included demographics, comorbidities, microbiologic/laboratory data, additional management (surgical, non-study antibiotics), hospital LOS, treatment outcome and morbidity/mortality.

Results

The three groups evaluated were linezolid (n = 45), vancomycin (n = 90) daptomycin (n = 84). There was no difference between the three groups with respect to gender, age, comorbidities, leukocytosis, fever, antibiotics prior to admission, site of infection culture results and surgical intervention. One death was recorded, not associated with diagnosis of SSTI. No significant difference in LOS was found (P = 0.525) between the 3 groups. The mean LOS in entire cohort was 4.5 days (SD ± 2.5); thirty patients had prolonged LOS for non-SSTI reasons; reanalyzing the data without these 30 patients did not produce any difference in the mean LOS between the 3 groups. Switching vancomycin just prior to discharge to facilitate outpatient therapy was common but did not impact LOS.

Conclusions

No difference was detected in hospital length of stay with respect to the initial choice of antibiotic (linezolid, vancomycin, or daptomycin) for SSTI. The three antibiotic regimens were equally effective in treating SSTIs as judged by LOS, irrespective of age, gender, comorbidities or baseline severity of SSTI. Given the large standard deviation in LOS, this result should be confirmed by larger studies.

Ceftaroline fosamil and treatment of acute bacterial skin and skin structure infections: CAPTURE study experience

The Clinical Assessment Program and TEFLARO Utilization Registry (CAPTURE) is a multicentre retrospective cohort study in the USA describing treatment of acute bacterial skin and skin structure infection (ABSSSI) with ceftaroline fosamil (CPT-F). Charts for review were chosen by random selection. Among 647 evaluable patients, 52% were obese, 46% had diabetes mellitus (DM), and 19% had peripheral vascular disease (PVD). Methicillin-resistant Staphylococcus aureus (MRSA) was recovered in 28% and methicillin-susceptible S. aureus (MSSA), 11%. Antibiotics were administered prior to CPT-F treatment in 80%, and concurrently in 39%. Clinical success overall was 85%; in patients with DM, 83%; with PVD, 76%; and in obese patients, 88%. Clinical success was ≥ 79% across all infection types; 81% for MRSA and 83% for MSSA; and 86% for ceftaroline monotherapy and 84% for concurrent therapy. These high clinical success rates support CPT-F as an effective treatment option for ABSSSI, including infections due to MRSA and patients with significant co-morbidities.

Monocytes loaded with indocyanine green as active homing contrast agents permit optical differentiation of infectious and non-infectious inflammation

Distinguishing cutaneous infection from sterile inflammation is a diagnostic challenge and currently relies upon subjective interpretation of clinical parameters, microbiological data, and nonspecific imaging. Assessing characteristic variations in leukocytic infiltration may provide more specific information. In this study, we demonstrate that homing of systemically administered monocytes tagged using indocyanine green (ICG), an FDA-approved near infrared dye, may be assessed non-invasively using clinically-applicable laser angiography systems to investigate cutaneous inflammatory processes. RAW 264.7 mouse monocytes co-incubated with ICG fluoresce brightly in the near infrared range. In vitro, the loaded cells retained the ability to chemotax toward monocyte chemotactic protein-1. Following intravascular injection of loaded cells into BALB/c mice with induced sterile inflammation (Complete Freund’s Adjuvant inoculation) or infection (Group A Streptococcus inoculation) of the hind limb, non-invasive whole animal imaging revealed local fluorescence at the inoculation site. There was significantly higher fluorescence of the inoculation site in the infection model than in the inflammation model as early as 2 hours after injection (p<0.05). Microscopic examination of bacterial inoculation site tissue revealed points of near infrared fluorescence, suggesting the presence of ICG-loaded cells. Development of a non-invasive technique to rapidly image inflammatory states without radiation may lead to new tools to distinguish infectious conditions from sterile inflammatory conditions at the bedside.

"Serious skin & soft tissue infections in rheumatoid arthritis patients taking anti-tumor necrosis factor alpha drugs: a nested case-control study"

Background

Anti-tumor necrosis factor alpha (anti-TNF) drugs are very effective for the treatment of rheumatoid arthritis but may increase the risk of serious bacterial infections. We assessed the association between the risk of serious skin and soft tissue infections (SSSTI) and the use of these agents in rheumatoid arthritis patients (RA).

Methods

We conducted a nested case–control study among rheumatoid arthritis patients in the Veterans Integrated Service Network 20 from 2000–2008. We identified rheumatoid arthritis patients with SSSTI, matched them to three sets of RA controls and used conditional logistic regression to compare the risk of SSSTI between patients treated and those not treated with an anti-TNF drug, after adjusting for known confounders and important covariates. Limited by the design, we could not assess (absolute) risk but only relative risk in terms of association.

Results

Among the 97 cases and 291 controls, 90 percent were male, 62 percent white, with a mean age of 63 years. Twenty percent received anti-TNF drugs during the study period. Thirty-nine percent of cases and 15 percent of controls died, (OR 3.5, 95% CI: 2.033, 6.11, p <0.01). Diabetes mellitus (37%), kidney disease (16%) and a history of skin infections (27%) were common among cases. Based on conditional logistic regression, anti-TNF use was not significantly associated with skin and soft tissue infections (OR 1.1, 95% CI: 0.61-2.03, p = 0.92). However, patients with diabetes mellitus (OR 2.5, 95% CI: 1.53-4.13, p = 0.01) or a prior history of skin infection (OR 5.7, 95% CI: 2.87-11.43, p <0.01) were more likely to have skin and soft tissue infections.

Conclusion

Use of anti-TNF therapy among RA patients was not associated with an increased risk of SSSTI, but patients with diabetes mellitus and those with a history of prior skin infection were significantly more likely to have SSSTI and mortality was higher among cases than controls in this veteran cohort.

Comparative analysis of empiric antimicrobial treatments for skin and soft tissue infections in newly hospitalized patients

PURPOSE

Intravenous vancomycin is the standard empiric treatment for complicated skin and soft tissue infections (SSTIs) due to its coverage against methicillin-resistant Staphylococcus aureus (MRSA). The objective of this study was to compare the hospital length of stay (LOS) between vancomycin-treated patients and patients receiving newer anti-MRSA agents. The study also aimed to identify factors associated with therapy change in patients receiving vancomycin on admission.

METHODS

Electronic medical records were used to conduct this retrospective cohort study. The LOS was compared among 5 groups of adult patients with admission diagnoses for SSTI who were initiated on linezolid, daptomycin, ceftaroline, tigecycline, or vancomycin. Survival analysis was used to identify factors associated with therapy change from vancomycin to another study medication.

RESULTS

Vancomycin was prescribed in 1046 (92%) admissions. Although none of the between-group differences in LOS reached statistical significance, there was a trend toward shorter LOS in vancomycin-treated patients compared to linezolid-treated patients (P = .059). Coagulopathy was independently associated with increased likelihood of therapy change from vancomycin (hazard ratio = 4.71; P <.001).

CONCLUSIONS

In the treatment of SSTI, newer agents result in LOS comparable to vancomycin. In patients initiated on vancomycin, therapy change was associated with longer LOS. Coagulopathy was independently associated with increased probability of therapy change.

Factors associated with high resource utilization in pediatric skin and soft tissue infection hospitalizations

OBJECTIVE

To describe factors associated with prolonged lengths of stay (LOS) and increased charges for pediatric skin and soft tissue infection (SSTI) hospitalizations.

METHODS

This study was a cross-sectional analysis of pediatric SSTI hospital discharges in 2009 within the Healthcare Cost and Utilization Project Kids' Inpatient Database. Outcomes were prolonged LOS (>75th percentile) and increased hospital charges (>75th percentile). Multivariate logistic regression controlling for patient and hospital level factors was conducted for 2009 data to assess associations among variables.

RESULTS

The 75th percentile for LOS was 3 days. Infants had higher odds of prolonged LOS than other age groups (<1 year: 1; 1-4 years: 0.70 [95% confidence interval (CI): 0.64-0.76]; 5-12 years: 0.69 [95% CI: 0.63-0.76]; 13-18 years: 1.01 [95% CI: 0.91-1.10]), as did all minority groups compared with white subjects (black subjects: 1.23 [95% CI: 1.09-1.38]; Hispanic subjects: 1.33 [95% CI: 1.20-1.47]; and other races: 1.30 [95% CI: 1.12-1.50]). Public payers compared with private payers (odds ratio: 1.17 [95% CI: 1.10-1.26]) also had increased odds of prolonged LOS. The 75th percentile for charges was $14 317. The adolescent-aged category had higher odds of charges >75th percentile compared with the age category <1 year (odds ratio: 1.54 [95% CI: 1.36-1.74]). All racial/ethnic minorities had higher odds of charges >75th percentile compared with white subjects (black subjects: 1.38 [95% CI: 1.17-1.62]; Hispanic subjects: 1.90 [95% CI: 1.59-2.26]; and other races: 1.26 [95% CI: 1.06-1.50]).

CONCLUSIONS

Vulnerable populations, including infants, racial/ethnic minorities, and publicly insured children, had higher odds of increased resource utilization during hospitalizations for SSTIs. The findings of this study provide potential targets for future preventive and public health interventions.

Acute MRSA sinusitis with intracranial extension and marginal vancomycin susceptibility

Methicillin resistant Staphylococcus aureus (MRSA) is increasingly being described as a cause of acute sinusitis. We present a patient with acute MRSA sinusitis complicated by rapid intracranial extension, marginal vancomycin susceptibility (MIC = 2 mg/L), delayed drainage of intracranial abscess, and subsequent development of rifampin resistance. Given the relatively high risk of intracranial extension of severe acute bacterial sinusitis and high mortality associated with invasive MRSA infections, we suggest early surgical drainage of intracranial abscesses in these circumstances. We believe this is important given the limited intracranial penetration of currently available treatment options for MRSA, especially those with a vancomycin minimal inhibitory concentration (MIC) of ≥2 mg/L.

Ceftaroline fosamil: a brief clinical review

Ceftaroline is a novel cephalosporin with a favorable tolerability profile and broad in vitro activity against many resistant Gram-positive and common Gram-negative organisms. Ceftaroline fosamil is the first cephalosporin to be approved by the United States Food and Drug Administration (FDA) for the treatment of adults with acute bacterial skin and soft tissue infections, including those caused by methicillin-resistant Staphylococcus aureus (MRSA). It is also approved by the FDA for the treatment of adults with community-acquired bacterial pneumonia, including cases caused by Streptococcus pneumoniae (with or without concurrent bacteremia), although there are no data at this time to support the use of ceftaroline fosamil for the treatment of pneumonia caused by MRSA. Ceftaroline fosamil is likewise approved by the European Commission for the treatment of adults with complicated skin and soft tissue infections or community-acquired pneumonia. This review summarizes the pharmacokinetic and microbiologic properties of ceftaroline, as well as the safety and efficacy data that led to its approval by the FDA in 2010 and the European Commission in 2012. Future directions to be addressed are also highlighted.

Antimicrobial activity of ceftaroline tested against staphylococci with reduced susceptibility to linezolid, daptomycin, or vancomycin from U.S. hospitals, 2008 to 2011

Vancomycin, linezolid, and daptomycin are very active against staphylococci, but isolates with decreased susceptibility to these antimicrobial agents are isolated sporadically. A total of 19,350 Staphylococcus aureus isolates (51% methicillin resistant [MRSA]) and 3,270 coagulase-negative staphylococci (CoNS) were collected consecutively from 82 U.S. medical centers from January 2008 to December 2011 and tested for susceptibility against ceftaroline and comparator agents by the reference broth microdilution method. Among S. aureus strains, 14 isolates (0.07%) exhibited decreased susceptibility to linezolid (MIC, ≥ 8 μg/ml), 18 (0.09%) to daptomycin (MIC, ≥ 2 μg/ml), and 369 (1.9%) to vancomycin (MIC, ≥ 2 μg/ml; 368 isolates at 2 μg/ml and 1 at 4 μg/ml). Fifty-one (1.6%) CoNS were linezolid resistant (MIC, ≥ 8 μg/ml), and four (0.12%) were daptomycin nonsusceptible (MIC, ≥ 2 μg/ml). Ceftaroline was very active against S. aureus overall (MIC50/90, 0.5/1 μg/ml; 98.5% susceptible), including MRSA (MIC50/90, 0.5/1 μg/ml; 97.2% susceptible). All daptomycin-nonsusceptible and 85.7% of linezolid-resistant S. aureus isolates were susceptible to ceftaroline. Against S. aureus isolates with a vancomycin MIC of ≥ 2 μg/ml, 91.9, 96.2, and 98.9% were susceptible to ceftaroline, daptomycin, and linezolid, respectively. CoNS strains were susceptible to ceftaroline (MIC50/90, 0.25/0.5 μg/ml; 99.1% inhibited at ≤ 1 μg/ml), including methicillin-resistant (MIC50/90, 0.25/0.5 μg/ml), linezolid-resistant (MIC50/90, 0.5/0.5 μg/ml), and daptomycin-nonsusceptible (4 isolates; MIC range, 0.03 to 0.12 μg/ml) strains. In conclusion, ceftaroline demonstrated potent in vitro activity against staphylococci with reduced susceptibility to linezolid, daptomycin, or vancomycin, and it may represent a valuable treatment option for infections caused by these multidrug-resistant staphylococci.

Incidence, microbiology, and patient characteristics of skin and soft-tissue infections in a U.S. population: a retrospective population-based study

Background

Skin and soft tissue infections (SSTIs) are commonly occurring infections with wide-ranging clinical manifestations, from mild to life-threatening. There are few population-based studies of SSTIs in the period after the rapid increase in community-acquired methicillin-resistant Staphyloccus aureus (MRSA).

Methods

We used electronic databases to describe the incidence, microbiology, and patient characteristics of clinically-diagnosed skin and soft tissue infections (SSTIs) among members of a Northern California integrated health plan. We identified demographic risk factors associated with SSTIs and MRSA infection.

Results

During the three-year study period from 2009 to 2011, 376,262 individuals experienced 471,550 SSTI episodes, of which 23% were cultured. Among cultured episodes, 54% were pathogen-positive. Staphylococcus aureus (S. aureus) was isolated in 81% of pathogen-positive specimens, of which nearly half (46%) were MRSA. The rate of clinically-diagnosed SSTIs in this population was 496 per 10,000 person-years. After adjusting for age group, gender, race/ethnicity and diabetes, Asians and Hispanics were at reduced risk of SSTIs compared to whites, while diabetics were at substantially higher risk compared to non-diabetics. There were strong age group by race/ethnicity interactions, with African Americans aged 18 to <50 years being disproportionately at risk for SSTIs compared to persons in that age group belonging to other race/ethnicity groups. Compared to Whites, S. aureus isolates of African-Americans and Hispanics were more likely to be MRSA (Odds Ratio (OR): 1.79, Confidence Interval (CI): 1.67 to 1.92, and, OR: 1.24, CI: 1.18 to 1.31, respectively), while isolates from Asians were less likely to be MRSA (OR: 0.73, CI: 0.68 to 0.78).

Conclusions

SSTIs represent a significant burden to the health care system. The majority of culture-positive SSTIs were caused by S. aureus, and almost half of the S. aureus SSTIs were methicillin-resistant. The reasons for African-Americans having a higher likelihood, and Asians a lower likelihood, for their S. aureus isolates to be methicillin-resistant, should be further investigated.

[Hyperbaric oxygenation for necrotizing soft tissue infections: pro]

Necrotizing soft tissue infections are a complex pathological spectrum of symptoms and result in a significantly increased risk of mortality depending on the degree of dissemination as well as the underlying bacterial infection. Hyperbaric oxygen therapy (HBOT) can significantly improve the effectiveness of a multidisciplinary treatment concept consisting of surgical debridement, critical care and antibiotic treatment. HBOT itself assists solid wound healing by bactericidal and bacteriostatic effects and by increasing the oxygen supply up to the cellular level resulting in an optimization of oxygen-dependent metabolic processes. The efficacy of treatment in a centre of cooperating specialized departments can therefore be increased by utilizing HBOT as adjunct treatment. Nevertheless, if a HBOT facility is available, excluding HBOT is equivalent to omission of an effective therapy option to the disadvantage of patients.

Skin and soft tissue infections and associated complications among commercially insured patients aged 0-64 years with and without diabetes in the U.S

Introduction

Skin and soft tissue infections (SSTIs) are common infections occurring in ambulatory and inpatient settings. The extent of complications associated with these infections by diabetes status is not well established.

Methods

Using a very large repository database, we examined medical and pharmacy claims of individuals aged 0–64 between 2005 and 2010 enrolled in U.S. health plans. Diabetes, SSTIs, and SSTI-associated complications were identified by ICD-9 codes. SSTIs were stratified by clinical category and setting of initial diagnosis.

Results

We identified 2,227,401 SSTI episodes, 10% of which occurred in diabetic individuals. Most SSTIs were initially diagnosed in ambulatory settings independent from diabetes status. Abscess/cellulitis was the more common SSTI group in diabetic and non-diabetic individuals (66% and 59%, respectively). There were differences in the frequencies of SSTI categories between diabetic and non-diabetic individuals (p<0.01). Among SSTIs diagnosed in ambulatory settings, the SSTI-associated complication rate was over five times higher in people with diabetes than in people without diabetes (4.9% vs. 0.8%, p<0.01) and SSTI-associated hospitalizations were 4.9% and 1.1% in patients with and without diabetes, respectively. Among SSTIs diagnosed in the inpatient setting, bacteremia/endocarditis/septicemia/sepsis was the most common associated complication occurring in 25% and 16% of SSTIs in patients with and without diabetes, respectively (p<0.01).

Conclusions

Among persons with SSTIs, we found SSTI-associated complications were five times higher and SSTI-associated hospitalizations were four times higher, in patients with diabetes compared to those without diabetes. SSTI prevention efforts in individuals with diabetes may have significant impact on morbidity and healthcare resource utilization.

Potential role of tedizolid phosphate in the treatment of acute bacterial skin infections

Tedizolid phosphate (TR-701), a prodrug of tedizolid (TR-700), is a next-generation oxazolidinone that has shown favorable results in the treatment of acute bacterial skin and skin-structure infections in its first Phase III clinical trial. Tedizolid has high bioavailability, penetration, and tissue distribution when administered orally or intravenously. The activity of tedizolid was greater than linezolid against strains of Staphylococcus spp., Streptococcus spp., and Enterococcus spp. in vitro studies, including strains resistant to linezolid and those not susceptible to vancomycin or daptomycin. Its pharmacokinetic characteristics allow for a once-daily administration that leads to a more predictable efficacy and safety profile than those of linezolid. No hematological adverse effects have been reported associated with tedizolid when used at the therapeutic dose of 200 mg in Phase I, II, or III clinical trials of up to 3 weeks of tedizolid administration. Given that the clinical and microbiological efficacy are similar for the 200, 300, and 400 mg doses, the lowest effective dose of 200 mg once daily for 6 days was selected for Phase III studies in acute bacterial skin and skin-structure infections, providing a safe dosing regimen with low potential for development of myelosuppression. Unlike linezolid, tedizolid does not inhibit monoamine oxidase in vivo, therefore interactions with adrenergic, dopaminergic, and serotonergic drugs are not to be expected. In conclusion, tedizolid is a novel antibiotic with potent activity against Gram-positive microorganisms responsible for skin and soft tissue infections, including strains resistant to vancomycin, linezolid, and daptomycin, thus answers a growing therapeutic need.

Microbiology of skin and soft tissue infections in the age of community-acquired methicillin-resistant Staphylococcus aureus

The objectives of this study were to determine the etiology of skin and soft-tissue infections (SSTIs) in a general population, and to describe patient characteristics, SSTI types, frequency of microbiologic testing, and the role of methicillin-resistant Staphylococcus aureus (MRSA) over time. Using electronic databases, we identified SSTI episodes and microbiologic testing among members of a large US health plan. Between 2006 and 2009, 648699 SSTI episodes were identified, of which 23% had a specimen, of which 15% were blood. A pathogen was identified in 58% of SSTI cultures. S. aureus was the most common pathogen (80% of positive cultures). Half of S. aureus isolates were MRSA. Among cellulitis and abscess episodes with a positive blood culture, 21% were methicillin-sensitive S. aureus, 16% were MRSA, 21% were beta-hemolytic streptococci and 28% were Gram negative bacteria. Between 1998 and 2009, the percentage of SSTIs for which a culture was obtained increased from 11% to 24%. In SSTI episodes with a culture-confirmed pathogen, MRSA increased from 5% in 1998 to 9% in 2001 to 42% in 2005, decreasing to 37% in 2009. These data can inform the choice of antibiotics for treatment of SSTIs.

Uncovering common bacterial skin infections

The four most common bacterial skin infections are impetigo, erysipelas, cellulitis, and folliculitis. This article summarizes current information about the etiology, clinical presentation, diagnosis, prevention, treatment, and implications for primary care practice needed to effectively diagnose and treat common bacterial skin infections.

Trends in resource utilization for hospitalized children with skin and soft tissue infections

OBJECTIVE

To describe trends in national resource utilization for pediatric skin and soft tissue infection (SSTI) hospitalizations.

METHODS

This was a cross-sectional analysis of hospital discharges from 1997 to 2009 within the Healthcare Cost and Utilization Project Kids' Inpatient Database for children with isolated SSTIs. Outcomes examined included patient and hospital characteristics, number of hospitalizations, and resource utilization including length of stay (LOS), hospital charges, and performance of incision and drainage (I&D). Trends in resource utilization were assessed by using linear regression in a merged data set with survey year as the primary independent variable. Multivariate logistic regression was conducted for 2009 data to assess factors associated with increased I&D.

RESULTS

The weighted proportion of SSTI hospitalizations among all hospitalizations doubled (0.46% vs 1.01%) from 1997 to 2009. During the same period, patient demographic trends included a shift to increased hospitalizations in infant and preschool-age groups as well as publicly insured children. Mean LOS decreased from 3.11 to 2.71 days. Increased resource utilization included changes in mean charges from $6722 to $11 534 per hospitalization and a twofold increase in I&D (21% to 44%). Factors associated with I&D include young age, African American race, female gender, publicly or uninsured children, and southern region of the United States.

CONCLUSIONS

SSTI is responsible for an emerging increase in health services utilization. Additional study is warranted to identify interventions that may effectively address this public health burden.

A randomized trial of tigecycline versus ampicillin-sulbactam or amoxicillin-clavulanate for the treatment of complicated skin and skin structure infections

BACKGROUND

Complicated skin and skin structure infections (cSSSIs) frequently result in hospitalization with significant morbidity and mortality.

METHODS

In this phase 3b/4 parallel, randomized, open-label, comparative study, 531 subjects with cSSSI received tigecycline (100 mg initial dose, then 50 mg intravenously every 12 hrs) or ampicillin-sulbactam 1.5-3 g IV every 6 hrs or amoxicillin-clavulanate 1.2 g IV every 6-8 hrs. Vancomycin could be added at the discretion of the investigator to the comparator arm if methicillin-resistant Staphylococcus aureus (MRSA) was confirmed or suspected within 72 hrs of enrollment. The primary endpoint was clinical response in the clinically evaluable (CE) population at the test-of-cure (TOC) visit. Microbiologic response and safety were also assessed. The modified intent-to-treat (mITT) population comprised 531 subjects (tigecycline, n = 268; comparator, n = 263) and 405 were clinically evaluable (tigecycline, n = 209; comparator, n = 196).

RESULTS

In the CE population, 162/209 (77.5%) tigecycline-treated subjects and 152/196 (77.6%) comparator-treated subjects were clinically cured (difference 0.0; 95% confidence interval [CI]: -8.7, 8.6). The eradication rates at the subject level for the microbiologically evaluable (ME) population were 79.2% in the tigecycline treatment group and 76.8% in the comparator treatment group (difference 2.4; 95% CI: -9.6, 14.4) at the TOC assessment. Nausea, vomiting, and diarrhea rates were higher in the tigecycline group.

CONCLUSIONS

Tigecycline was generally safe and effective in the treatment of cSSSIs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00368537.

[Clinical symptoms and therapy of necrotizing skin and soft tissue infections]

Skin and soft tissue infections are among the most common diseases requiring surgical treatment. The presentation of patients varies from folliculitis to severe necrotizing infections with a fatal outcome. The diagnosis of a necrotizing infection is often difficult. The correct diagnosis is often made after deterioration of the patient's condition in the rapid course of the disease. The early and correct diagnosis and immediate surgery are decisive for the prognosis. Treatment at a specialized intensive care unit and the administration of a broad spectrum antibiotic are pivotal for the survival of individual patients.

Mode of action, in vitro activity, and in vivo efficacy of AFN-1252, a selective antistaphylococcal FabI inhibitor

The mechanism of action of AFN-1252, a selective inhibitor of Staphylococcus aureus enoyl-acyl carrier protein reductase (FabI), which is involved in fatty acid biosynthesis, was confirmed by using biochemistry, macromolecular synthesis, genetics, and cocrystallization of an AFN-1252-FabI complex. AFN-1252 demonstrated a low propensity for spontaneous resistance development and a time-dependent reduction of the viability of both methicillin-susceptible and methicillin-resistant S. aureus, achieving a ≥2-log(10) reduction in S. aureus counts over 24 h, and was extremely potent against clinical isolates of S. aureus (MIC(90), 0.015 μg/ml) and coagulase-negative staphylococci (MIC(90), 0.12 μg/ml), regardless of their drug resistance, hospital- or community-associated origin, or other clinical subgroup. AFN-1252 was orally available in mouse pharmacokinetic studies, and a single oral dose of 1 mg/kg AFN-1252 was efficacious in a mouse model of septicemia, providing 100% protection from an otherwise lethal peritoneal infection of S. aureus Smith. A median effective dose of 0.15 mg/kg indicated that AFN-1252 was 12 to 24 times more potent than linezolid in the model. These studies, demonstrating a selective mode of action, potent in vitro activity, and in vivo efficacy, support the continued investigation of AFN-1252 as a targeted therapeutic for staphylococcal infections.

Global fluoroquinolone resistance epidemiology and implictions for clinical use

This paper on the fluoroquinolone resistance epidemiology stratifies the data according to the different prescription patterns by either primary or tertiary caregivers and by indication. Global surveillance studies demonstrate that fluoroquinolone resistance rates increased in the past years in almost all bacterial species except S. pneumoniae and H. influenzae, causing community-acquired respiratory tract infections. However, 10 to 30% of these isolates harbored first-step mutations conferring low level fluoroquinolone resistance. Fluoroquinolone resistance increased in Enterobacteriaceae causing community acquired or healthcare associated urinary tract infections and intraabdominal infections, exceeding 50% in some parts of the world, particularly in Asia. One to two-thirds of Enterobacteriaceae producing extended spectrum β-lactamases were fluoroquinolone resistant too. Furthermore, fluoroquinolones select for methicillin resistance in Staphylococci. Neisseria gonorrhoeae acquired fluoroquinolone resistance rapidly; actual resistance rates are highly variable and can be as high as almost 100%, particularly in Asia, whereas resistance rates in Europe and North America range from <10% in rural areas to >30% in established sexual networks. In general, the continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some guidelines, for example, treatment of urinary tract, intra-abdominal, skin and skin structure infections, and traveller's diarrhea, or even precludes the use in indications like sexually transmitted diseases and enteric fever.

Activity analyses of staphylococcal isolates from pediatric, adult, and elderly patients: AWARE Ceftaroline Surveillance Program

Ceftaroline, the active metabolite of the prodrug ceftaroline fosamil, is a broad-spectrum cephalosporin with bactericidal activity against resistant Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA), and common Gram-negative organisms. We evaluated the activity of ceftaroline and various antimicrobial agents against S. aureus isolates according to patient age. A total of 2143 consecutive unique patient strains of clinical significance were collected between January and December 2010 from 65 US medical centers as part of the Assessing Worldwide Antimicrobial Resistance Evaluation (AWARE) Program. Ceftaroline and various comparator agents were tested by reference Clinical and Laboratory Standards Institute broth microdilution methods. Ceftaroline was consistently active against methicillin-susceptible S. aureus (MSSA) (MIC(50), 0.25 μg/mL; MIC(90), 0.25 μg/mL; 100.0% susceptible) and MRSA (MIC(50), 0.50 μg/mL, MIC(90), 1 μg/mL; 98.4% susceptible) from all age groups. In general, resistance rates to erythromycin, clindamycin, and levofloxacin were higher in the population aged ≥ 65 years, whereas resistance rates to clindamycin and levofloxacin were lowest among isolates from patients aged 6-17 years. When tested against MSSA, levofloxacin resistance was higher among isolates from patients aged ≥ 65 years (16.1%) than among isolates from the other age groups (6.1%-10.5%), and ceftaroline was generally 16-fold more active than ceftriaxone (MIC(50), 4 μg/mL; MIC(90), 4 μg/mL; 97.9% susceptible overall). Ceftaroline (MIC(50), 0.50 μg/mL; MIC(/90), 1 μg/mL), daptomycin (MIC(50), 0.25 μg/mL; MIC(90), 0.5 μg/mL), linezolid (MIC(50), 1 μg/mL; MIC(90), 1 μg/mL), and vancomycin (MIC(50), 1 μg/mL(;) MIC(90), 1 μg/mL) were the most active compounds tested against MRSA strains, and the activity of these compounds did not vary significantly among the age groups. In contrast, susceptibility rates to clindamycin and levofloxacin varied from 94.0% and 60.7% (aged 6-17 years), respectively, to only 57.6% and 15.1% (aged ≥ 65 years), respectively, among MRSA strains. The results of this study showed major differences in the susceptibility rates to clindamycin and levofloxacin according to patient age group. The results also indicate that ceftaroline is highly active against MSSA and MRSA isolated from US medical centers, independent of patient age group.

In vitro activity and microbiological efficacy of tedizolid (TR-700) against Gram-positive clinical isolates from a phase 2 study of oral tedizolid phosphate (TR-701) in patients with complicated skin and skin structure infections

Tedizolid (TR-700, formerly torezolid) is the active moiety of the prodrug tedizolid phosphate (TR-701), a next-generation oxazolidinone, with high potency against Gram-positive species, including methicillin-resistant Staphylococcus aureus (MRSA). A recently completed randomized, double-blind phase 2 trial evaluated 200, 300, or 400 mg of oral tedizolid phosphate once daily for 5 to 7 days in patients with complicated skin and skin structure infections. This report examines the in vitro activity of tedizolid and Zyvox (linezolid) against Gram-positive pathogens isolated at baseline and describes the microbiological and clinical efficacy of tedizolid. Of 196 isolates tested, 81.6% were S. aureus, and of these, 76% were MRSA. The MIC(50) and MIC(90) of tedizolid against both methicillin-susceptible S. aureus (MSSA) and MRSA were 0.25 μg/ml, compared with a MIC(50) of 1 μg/ml and MIC(90) of 2 μg/ml for linezolid. For coagulase-negative staphylococci (n = 7), viridans group streptococci (n = 15), and beta-hemolytic streptococci (n = 3), the MICs ranged from 0.03 to 0.25 μg/ml for tedizolid and from 0.12 to 1 μg/ml for linezolid. The microbiological eradication rates at the test-of-cure visit (7 to 14 days posttreatment) in the microbiologically evaluable population (n = 133) were similar in all treatment groups, with overall eradication rates of 97.7% for all pathogens, 97.9% for MRSA, and 95.7% for MSSA. The clinical cure rates for MRSA and MSSA infections were 96.9% and 95.7%, respectively, across all dose groups. This study confirms the potent in vitro activity of tedizolid against pathogenic Gram-positive cocci, including MRSA, and its 4-fold-greater potency in comparison with linezolid. All dosages of tedizolid phosphate showed excellent microbiological and clinical efficacy against MRSA and MSSA.

Antibacterials as adjuncts to incision and drainage for adults with purulent methicillin-resistant Staphylococcus aureus (MRSA) skin infections

The annual incidence of skin and soft tissue infections (SSTIs) has nearly tripled in the US since the early 1990s. Many purulent SSTIs in the community setting are caused by methicillin-resistant Staphylococcus aureus (MRSA). Incision and drainage (I&D) are indicated for most purulent MRSA infections; however, the use of adjunctive antibacterials is controversial. The objective of this study was to systematically evaluate studies that have investigated whether or not antibacterials provide added benefit to I&D alone for purulent MRSA SSTIs. We included articles from MEDLINE and The Cochrane Library that fulfilled the following criteria: (i) original research; (ii) English language; (iii) compared I&D alone versus I&D plus antibacterials for purulent MRSA SSTIs; and (iv) compared patient outcomes. We also reviewed the references of these articles to identify other relevant studies. Studies that solely examined paediatric patients were excluded. To facilitate cross-study comparison, we systematically evaluated the following study characteristics: (i) study design; (ii) patient population; (iii) comparator groups; (iv) sample size; (v) outcome measures; (vi) outcome definitions; (vii) duration of follow-up; and (viii) measurement and adjustment of potential confounding variables. Eleven studies, spanning more than 30 years, met inclusion criteria. Two of these were conducted prior to the emergence of MRSA in the community; another evaluated cephalexin versus placebo for MRSA. None of these found added benefit of adjunctive antibacterials. Four studies compared health outcomes between patients who received 'active' or 'appropriate' therapy and those who received 'inactive' or 'inappropriate' therapy after I&D for purulent MRSA SSTIs. Two of these studies found 'active' or 'appropriate' therapy to be beneficial, while two others did not. Four studies compared health outcomes between patients who received anti-MRSA antibacterials plus I&D with those who received alternative antibacterials plus I&D for purulent MRSA SSTIs. Three of these reported improved outcomes with anti-MRSA antibacterials, while another reported mixed findings. Presently, the bulk of the available evidence suggests anti-MRSA antibacterials provide added benefit to I&D alone for purulent MRSA SSTIs; however, the current evidence is limited to small, case-control, observational studies.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Metal ion acquisition in Staphylococcus aureus: overcoming nutritional immunity

Transition metals are essential nutrients to virtually all forms of life, including bacterial pathogens. In Staphylococcus aureus, metal ions participate in diverse biochemical processes such as metabolism, DNA synthesis, regulation of virulence factors, and defense against oxidative stress. As an innate immune response to bacterial infection, vertebrate hosts sequester transition metals in a process that has been termed "nutritional immunity." To successfully infect vertebrates, S. aureus must overcome host sequestration of these critical nutrients. The objective of this review is to outline the current knowledge of staphylococcal metal ion acquisition systems, as well as to define the host mechanisms of nutritional immunity during staphylococcal infection.

Antistaphylococcal activities of the new fluoroquinolone JNJ-Q2

The new broad-spectrum fluoroquinolone JNJ-Q2 displays in vitro activity against Gram-negative and Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and ciprofloxacin-resistant MRSA isolates. Tested with isogenic methicillin-susceptible S. aureus (MSSA) and MRSA strains bearing quinolone-resistant target mutations, JNJ-Q2 displayed MICs ≤ 0.12 μg/ml, values 16- to 32-fold lower than those determined for moxifloxacin. Overexpression of the NorA efflux pump did not impact JNJ-Q2 MICs. Inhibition of S. aureus DNA gyrase and DNA topoisomerase IV enzymes demonstrated that JNJ-Q2 was more potent than comparators against wild-type enzymes and enzymes carrying quinolone-resistant amino acid substitutions, and JNJ-Q2 displayed equipotent activity against both enzymes. In serial-passage studies comparing resistance selection in parallel MRSA cultures by ciprofloxacin and JNJ-Q2, ciprofloxacin readily selected for mutants displaying MIC values of 128 to 512 μg/ml, which were observed within 18 to 24 days of passage. In contrast, cultures passaged in the presence of JNJ-Q2 displayed MICs ≤ 1 μg/ml for a minimum of 27 days of serial passage. A mutant displaying a JNJ-Q2 MIC of 4 μg/ml was not observed until after 33 days of passage. Mutant characterization revealed that ciprofloxacin-passaged cultures with MICs of 256 to 512 μg/ml carried only 2 or 3 quinolone resistance-determining region (QRDR) mutations. Cultures passaged with JNJ-Q2 selection for up to 51 days displayed MICs of 1 to 64 μg/ml and carried between 4 and 9 target mutations. Established in vitro biofilms of wild-type or ciprofloxacin-resistant MRSA exposed to JNJ-Q2 displayed greater decreases in bacterial counts (7 days of exposure produced 4.5 to >7 log(10) CFU decreases) than biofilms exposed to ciprofloxacin, moxifloxacin, rifampin, or vancomycin.

Epidemiology and outcomes of complicated skin and soft tissue infections in hospitalized patients

Complicated skin and soft tissue infections (cSSTIs) are among the most rapidly increasing reasons for hospitalization. To describe inpatients with regard to patient characteristics, cSSTI origin, appropriateness of initial antibiotics, and outcomes, we performed a retrospective cohort study in patients hospitalized for cSSTI. To identify independent predictors of outcomes, we performed multivariate analyses. Of 1,096 eligible patients, 48.7% had health care-associated (HCA) cSSTI and 51.3% had community-acquired (CA) cSSTI. After adjustment for baseline variables, hospital length of stay (LOS) was longer for HCA than for CA cSSTI (difference, 2.1 days; 95% confidence interval [CI], 0.8 to 3.5; P < 0.05). Other covariates associated with a longer LOS were need for dialysis (regression coefficient ± standard error, 4.5 ± 1.1) and diabetic wound diagnosis (2.6 ± 1.0) (all P < 0.05). In the subset with culture-positive cSSTI within 24 h of admission, the most common pathogen was Staphylococcus aureus (298/449 [66.4%]), of which 74.8% (223/298) were methicillin-resistant S. aureus (MRSA). Eighty-three patients (18.5%) received inappropriate initial antibiotics. After adjustment for other variables, the following were associated with inappropriate initial therapy: direct admission to hospital (not via emergency department), cSSTI caused by MRSA or mixed pathogens, and cSSTI caused by pathogens other than S. aureus or streptococci (all P < 0.05). We did not find an association between inappropriate therapy and outcomes, except in the subset with ulcers (adjusted odds ratio, 11.8; 95% CI, 1.3 to 111.1; P = 0.03). More studies are needed to examine the impact of HCA cSSTI and inappropriate initial therapy on outcomes.

[Molecular characterisation of methicillin resistant Staphylococcus aureus strains ST398 in patients with skin infections and their relatives]

INTRODUCTION

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) of sequence type ST398 is a genetic lineage also described in human infections.

METHODS

Cutaneous infections related with MRSA ST398 are described in 3 patients, two of them pig farmers. The MRSA nasal carriage by patients and their relatives was also studied. MRSA ST398 strains were typed (SCCmec, spa, agr and MLST) and the antimicrobial resistance pattern and virulence genes were determined.

RESULTS

Twenty MRSA ST398 isolates were recovered in lesions of three patients, and in nasal samples of two patients and five relatives. Isolates were typed: spa-type t011 or t108; agr-type I and SCCmec IVa or V. MRSA strains were tetracycline-resistant and 15 of them showed a phenotype and genotype of multi-resistance, but they were free of tested virulence genes.

CONCLUSIONS

LA-MRSA ST398 is an emergent problem in our country, mainly associated with skin and soft tissue infections in people with professional relationships with pig farms. Tetracycline resistance is an important marker for MRSA ST398 detection.

Comparison of Staphylococcus aureus from skin and soft-tissue infections in US emergency department patients, 2004 and 2008

BACKGROUND

In the past decade, new methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged as a predominant cause of community-associated skin and soft-tissue infections (SSTIs). Little information exists regarding trends in MRSA prevalence and molecular characteristics or regarding antimicrobial susceptibility profiles of S. aureus isolates.

METHODS

We enrolled adults with acute, purulent SSTIs presenting to a US network of 12 emergency departments during August 2008. Cultures and clinical information were collected. S. aureus isolates were characterized by antimicrobial susceptibility testing, pulsed-field gel electrophoresis, and toxin genes detection. The prevalence of S. aureus and MRSA and isolate genetic characteristics and susceptibilities were compared with those from a similar study conducted in August 2004.

RESULTS

The prevalence of MRSA was 59% among all SSTIs during both study periods; however, the prevalence by site varied less in 2008 (38%-84%), compared with 2004 (15%-74%). Pulsed-field type USA300 continued to account for almost all MRSA isolates (98%). Susceptibility to trimethoprim-sulfamethoxazole, clindamycin, and tetracycline among MRSA isolates remained greater than 90% in 2008. A higher proportion of MRSA infections were treated with an agent to which the infecting isolate was susceptible in vitro in 2008 (97%), compared with 2004 (57%).

CONCLUSIONS

Similar to 2004, MRSA remained the most common identifiable cause of purulent SSTIs among patients presenting to a network of US emergency departments in 2008. The infecting MRSA isolates continued to be predominantly pulsed-field type USA300 and susceptible to recommended non-β-lactam oral agents. Clinician prescribing practices have shifted from MRSA-inactive to MRSA-active empirical antimicrobial regimens.