Trends in US hospital admissions for skin and soft tissue infections

Elderly patients are at increased risk for treatment failure in outpatient management of purulent skin infections

OBJECTIVE

Current Infectious Disease Society of America (IDSA) guidelines for the management of purulent skin or soft tissue infections do not account for patient age in treatment recommendations. The study objective was to determine if age was associated with outpatient treatment failure for purulent skin infection after adjusting for IDSA treatment guidelines.

METHODS

We conducted a multicenter retrospective study of adult patients treated for a purulent skin infection and discharged home from four emergency departments between April and September 2014. Patients were followed for one month to assess for treatment failure (defined as need for a change in antibiotics, surgical intervention, or hospitalization). We used multivariable logistic regression to examine the role of patient age on treatment failure adjusting for demographic variables (gender, race), comorbidities and severity of infection.

RESULTS

A total of 467 patients met inclusion criteria (mean age 37.9years [SD 14.0], 48.2% of whom were women). Overall, 12.4% failed initial therapy. Patients 65years and older (n=35) were almost 4 times more likely to fail initial ED therapy in follow-up compared with younger patients (adjusted Odds Ratio (OR) 3.87, 95% Confidence Interval (CI) 1.24-12.10). After adjustment, for every 10years of advancing age there was a 43% increased odds of failing initial treatment (OR 1.43 95% CI 1.09-1.88).

CONCLUSION

Elderly patients with purulent skin infections, whose providers followed the 2014 IDSA guidelines, were more likely to fail initial treatment than younger patients. This study suggests that there is a need to re-evaluate treatment guidelines in elderly patients.

Bacterial Etiology and Risk Factors Associated with Cellulitis and Purulent Skin Abscesses in Military Trainees

Military trainees are at high risk for skin and soft-tissue infections (SSTIs). Although Staphylococcus aureus is associated with purulent SSTI, it is unclear to what degree this pathogen causes nonpurulent cellulitis. To inform effective prevention strategies and to provide novel insights into SSTI pathogenesis, we aimed to determine the etiology of SSTI in this population. We conducted a prospective observational study in US Army Infantry trainees with SSTI (cutaneous abscesses and cellulitis) from July 2012 through December 2014. We used standard microbiology, serology, and high-throughput sequencing to determine the etiology of SSTI. Furthermore, we compared purported risk factors as well as anatomic site colonization for S. aureus. Among 201 SSTI cases evaluated for SSTI risk factors, cellulitis was associated with lower extremity blisters (P = 0.01) and abscess was associated with methicillin-resistant S. aureus (MRSA) colonization (P<0.001). Among the 22 tested cellulitis cases that were part of the microbiome analysis, only 1 leading edge aspirate was culturable (Coagulase-negative Staphylococcus). Microbiome evaluation of aspirate specimens demonstrated that Rhodanobacter terrae was the most abundant species (66.8% average abundance), while abscesses were dominated by S. aureus (92.9% average abundance). Although abscesses and cellulitis share the spectrum of clinical SSTI, the bacterial etiologies as determined by current technology appear distinct. Furthermore, the presence of atypical bacteria within cellulitis aspirates may indicate novel mechanisms of cellulitis pathogenesis.

CLINICAL TRIALS REGISTRATION

NCT01105767.

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.

Thoracoabdominal necrotising soft tissue infection secondary to enterocutaneous fistulae: a case report

OBJECTIVE

Necrotising soft tissue infection is a rare surgical emergency, which requires immediate and aggressive surgical debridement. Following control of the infection, patients are often left with large defects, with wound reconstruction and closure creating significant challenges. Here we describe a case of extensive thoracoabdominal necrotising soft tissue infection and provide a discussion on the standard of care and treatment based on a current literature review.

METHOD

A 53-year-old female presented with bilious and feculent discharge from her surgical incision two weeks after a total abdominal hysterectomy. She was found to have two enterocutaneous fistulae and an extensive abdominal wall necrotising soft tissue infection extending to the lower thorax. Wide excision and debridement were performed, leaving a large triangular defect. Following serial washouts and debridements, a biologic mesh with openings for the enterocutaneous fistulae was used to cover the fascial defect Results: Postoperatively, the patient was discharged to a nursing facility where she remained on total parenteral nutrition due to high fistula output. She subsequently underwent fistulectomy nine months later followed by skin grafting. To date, she has not had any recurrent fistulae or infection.

CONCLUSION

Necrotising soft tissue infection resulting in a large abdominal wall defect secondary to enterocutaneous fistulae poses a significant challenge for source control and abdominal wall reconstruction. After serial debridements, use of biologic mesh for temporary closure followed by staged resection of the bowel with abdominal wall reconstruction can be performed.

DECLARATION OF INTEREST

The authors have no personal financial or institutional interest in any of the drugs, materials, or devices used.

Toward an Objective Diagnostic Test for Bacterial Cellulitis

Background

Prior studies repeatedly showed that cultures of skin lesions diagnosed as "cellulitis" are usually negative. However, lack of a gold standard for diagnosis (against which culture might be judged) and failure to assess the human immune response are important limitations of prior work. In this pilot study, we aimed to develop a criterion standard for research on bacterial cellulitis, to evaluate the sensitivity of procalcitonin for bacterial cellulitis, and to use gene expression analysis to find other candidate diagnostic markers.

Methods

We classified lesions via biopsies, 16s rRNA gene detection, culture, and histopathology. We quantified procalcitonin expression in blood. We also used Nanostring technology to quantify transcription of immunomodulators that may distinguish cases from inflamed controls.

Results

Of 28 participants, 15 had a clinical diagnosis of cellulitis, six had a diagnosis of non-infectious dermatitis, and seven were normal volunteers. Of the “cellulitis” patients, three (20%) had pathogens isolated, and were designated confirmed cases. Procalcitonin was undetectable in all three. HLA-DQA1 was expressed 34-fold more in confirmed cases vs. controls (fold change of geometric mean). Heat maps depicting multiplex gene expression analysis revealed a distinct profile of gene expression in confirmed cases relative to comparators.

Conclusions

Most “cellulitis” patients had microbiologically-negative biopsies. Procalcitonin was undetectable, and HLA-DQA1 elevated, in confirmed bacterial cases. Multivariable transcriptomic profiling results supported our algorithm’s ability to identify patients with true bacterial cellulitis. A larger sample may allow discovery of an immunological signature capable of distinguishing bacterial cellulitis from its mimics in clinical practice.

Sonographic Evaluation of a Pilonidal Cyst

Pilonidal cysts are collections of hair or skin debris located most commonly on or near the natal cleft of the buttocks. These cysts can become infected and cause swelling and bleeding at the site. Once infected, the condition is then termed a pilonidal abscess, and treatment should be followed. Several options are available for treating a pilonidal abscess, depending on the extent of the condition and the patient’s response to antibiotic therapy. This case study of a pilonidal abscess demonstrates the important information that sonography adds to the diagnosis and treatment of this condition.

Decreasing Incidence of Skin and Soft Tissue Infections With a Seasonal Pattern at an Academic Medical Center, 2006-2014

The incidence of SSTIs at University of Chicago Medicine decreased significantly in children and adults with seasonal variation, peaking during the summer months. This suggests a reversal of the massive increase in SSTI incidence after 2000 in the U.S.

Background. The incidence of skin and soft tissue infections (SSTIs) in the United States increased sharply after 2000 with the emergence of USA300 methicillin-resistant Staphylococcus aureus. We examined trends in SSTI incidence in 2006–2014 at the University of Chicago Medicine (UCM).

Methods. Data were obtained for patient encounters at UCM with an International Classification of Diseases, Ninth Revision-coded SSTI diagnosis between January 1, 2006 and March 31, 2014. Incidence density was calculated per 1000 encounters by quarter and year. Encounters were stratified by inpatient, outpatient clinic and emergency department (ED) encounters and by age group, gender, and race. Poisson regression was used to assess change over time.

Results. In 2006–2014, data were collected for 38 201 SSTI-associated encounters among 31 869 subjects. Among all patients treated at UCM, there was a decrease of 1% per year in the incidence of SSTIs during 2006–2013, with an overall decrease of 16%. There was a significant decrease in SSTI-related encounters among inpatients (rate ratio [RR] = 0.97; 95% confidence interval [CI], .96–.98), ED patients (RR = 0.98; 95% CI, .97–.98), adults (RR = 0.98; 95% CI, .97–.98), children (RR = 0.96; 95% CI, .95–.97), and African Americans (RR = 0.99; 95% CI, .98–.99). There was an annual seasonal trend, with the peak incidence occurring during the late summer.

Conclusions. The incidence of SSTIs at UCM decreased in children and adults with seasonal variation, peaking during the summer months. This suggests a reversal of the massive increase in SSTI incidence in the United States after 2000.

Acute bacterial skin and skin structure infections in internal medicine wards: old and new drugs

Skin and soft tissue infections (SSTIs) are a common cause of hospital admission among elderly patients, and traditionally have been divided into complicated and uncomplicated SSTIs. In 2010, the FDA provided a new classification of these infections, and a new category of disease, named acute bacterial skin and skin structure infections (ABSSSIs), has been proposed as an independent clinical entity. ABSSSIs include three entities: cellulitis and erysipelas, wound infections, and major cutaneous abscesses This paper revises the epidemiology of SSTIs and ABSSSIs with regard to etiologies, diagnostic techniques, and clinical presentation in the hospital settings. Particular attention is owed to frail patients with multiple comorbidities and underlying significant disease states, hospitalized on internal medicine wards or residing in nursing homes, who appear to be at increased risk of infection due to multi-drug resistant pathogens and treatment failures. Management of ABSSSIs and SSTIs, including evaluation of the hemodynamic state, surgical intervention and treatment with appropriate antibiotic therapy are extensively discussed.

Deep tissue biopsy vs. superficial swab culture, including microbial loading determination, in the microbiological assessment of Skin and Soft Tissue Infections (SSTIs)

Thirty-two patients affected by SSTIs including DFIs were enrolled between 2013 and 2014. Superficial swab was obtained before and after cleansing with sterile saline, and after ultrasonic debridement; deep tissue biopsy was obtained from ulcer base. Samples were diluted with 1 mL of saline, serial 10-fold dilutions to 10^-6 were made and 50 μL of each dilution was plated onto appropriate media. Bacteria were identified by Vitek II system. Microbial load was expressed as CFU/mL. Statistical analysis was performed by χ2. Incidence of Gram positives was higher than Gram negatives (S. aureus and P. aeruginosa being the most frequent); concordance (same bacteria isolated before and after debridement) never exceeded 60%. Ultrasonic debridement significantly reduced bacterial load or even suppressed bacterial growth. While reliability of superficial swab is poor for microbiological diagnosis of SSTIs, swabbing after ultrasonic debridement and biopsy of the ulcer base may be equally reliable.

Oritavancin: a long-acting antibacterial lipoglycopeptide

Oritavancin is a new lipoglycopeptide antibacterial agent with an exceptionally long terminal half-life and a rapid bactericidal effect. Multiple mechanisms of action lead to a broad activity against Gram-positive bacteria, such as staphylococci, streptococci and enterococci, including methicillin-resistant Staphylococcus aureus. Its long terminal half-life allows for single-dose treatment of acute bacterial skin and skin structure infections. Oritavancin was found to be safe and effective in treating acute bacterial skin and skin structure infections in adults and it is currently approved in the USA and in Europe for this indication. Unfortunately, data for other indications are lacking. Here, we review chemistry, microbiology, pharmacology, efficacy and tolerability of oritavancin.

Skin and soft-tissue infections: a critical review and the role of telavancin in their treatment

Skin and soft-tissue infections (SSTIs) are an important cause of morbidity and mortality among hospitalized patients and a major therapeutic challenge for clinicians. Although uncomplicated SSTIs are managed successfully on an outpatient basis, more serious infections extending to the subcutaneous tissue, fascia, or muscle require complex management. Early diagnosis, selection of appropriate antimicrobials, and timely surgical intervention are key to successful treatment. Surgical-site infections, an important category of SSTI, occur in approximately half a million patients in North America annually. SSTIs are also a potential source for life-threatening bacteremia and metastatic abscesses. Gram-positive organisms, such as Staphylococcus aureus and Streptococcus pyogenes, are the dominant organisms isolated early in the infectious process, whereas gram-negative organisms are found in chronic wounds. Methicillin-resistant S. aureus (MRSA) is a potential bloodstream invader that requires aggressive antimicrobial treatment and surgery. Recent concerns regarding vancomycin activity include heteroresistance in MRSA and increase in the minimum inhibitory concentrations (>1 or 2 µg/mL); however, alternative agents, such as telavancin, daptomycin, linezolid, ceftaroline, dalbavancin, oritavancin, and tedizolid, are now available for the treatment of severe MRSA infections. Here, we present a review of the epidemiology, etiology, and available treatment options for the management of SSTIs.

Focus on JNJ-Q2, a novel fluoroquinolone, for the management of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections

JNJ-Q2 is a novel, fifth-generation fluoroquinolone that has excellent in vitro and in vivo activity against a variety of Gram-positive and Gram-negative organisms. In vitro studies indicate that JNJ-Q2 has potent activity against pathogens responsible for acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP), such as Staphylococcus aureus and Streptococcus pneumoniae. JNJ-Q2 also has been shown to have a higher barrier to resistance compared to other agents in the class and it remains highly active against drug-resistant organisms, including methicillin-resistant S. aureus, ciprofloxacin-resistant methicillin-resistant S. aureus, and drug-resistant S. pneumoniae. In two Phase II studies, the efficacy of JNJ-Q2 was comparable to linezolid for ABSSSI and moxifloxacin for CABP. Furthermore, JNJ-Q2 was well tolerated, with adverse event rates similar to or less than other fluoroquinolones. With an expanded spectrum of activity and low potential for resistance, JNJ-Q2 shows promise as an effective treatment option for ABSSSI and CABP. Considering its early stage of development, the definitive role of JNJ-Q2 against these infections and its safety profile will be determined in future Phase III studies.

Trends in Infectious Disease Hospitalizations in US Children, 2000 to 2012

BACKGROUND

Although infectious diseases (IDs) remain a major public health problem in US children, there have been no recent efforts to examine comprehensively the change in epidemiology of ID hospitalizations.

METHODS

A serial cross-sectional analysis using the Kids' Inpatient Database 2000, 2003, 2006, 2009, and 2012. We identified children ≤19 years of age with a primary diagnosis of IDs. Outcomes were national rate of ID hospitalizations, in-hospital mortality, length-of-stay and hospitalization-related direct costs. Negative binomial and multivariable logistic models were constructed to test the change in hospitalization rate and in-hospital mortality, respectively.

RESULTS

We identified 3,691,672 weighted hospitalizations for IDs, accounting for 24.5% of all pediatric hospitalizations. From 2000 to 2012, the rate of overall ID hospitalizations decreased from 91.0 to 75.8 per 10,000 US children (P < 0.001). The most frequently listed ID subgroup was lower respiratory infections (42.8% of all ID hospitalizations in 2012). Although the hospitalization rate for most ID subgroups decreased, the hospitalization rate for skin infections significantly increased (67.6% increase; P < 0.001). The multivariable model demonstrated a significant decline in in-hospital mortality (odds ratio for comparison of 2012 with 2000, 0.63; 95% confidence interval, 0.51-0.79). From 2000 to 2012, there was no significant change in the median length-of-stay (2 days in 2000 to 2 days in 2012; Ptrend = 0.33). The median direct cost for ID hospitalization increased from $3452 in 2003 to $3784 in 2012 (P = 0.007), with the nationwide direct cost of $4.4 billion in 2012.

CONCLUSIONS

We found a statistically significant decline in overall ID hospitalization rate among US children from 2000 to 2012, whereas skin infections statistically significantly increased. In addition, the median direct cost per ID hospitalization increased by 10% during the study period.

Hot topics in the diagnosis and management of skin and soft-tissue infections

Eighteen hot topics regarding the diagnosis and management of skin and soft-tissue infections (SSTIs) were selected and reviewed by members of the SSTI Working Group of the International Society of Chemotherapy (ISC). Despite the large amount of literature available on the issue selected, there are still many unknowns with regard to many of them and further studies are required to answer these challenging issues that face clinicians on a daily basis.

Molecular characteristics of community-acquired methicillin-resistant Staphylococcus aureus strains isolated from outpatients with skin and soft tissue infections in Wuhan, China

This study aims to investigate the antimicrobial susceptibility, molecular characteristics and virulence genes of community-acquired methicillin-resistant ITALIC! Staphylococcus aureus(CA-MRSA) isolates with skin and soft tissue infections (SSTIs). Outpatients with SSTIs visiting five medical and health institutions were enrolled from 2011 to 2013. Available ITALIC! S. aureus isolates were characterized by antimicrobial susceptibility testing, and detection of PVL genes. For CA-MRSA isolates, we performed typing of staphylococcal cassette chromosome ITALIC! mec(SCC ITALIC! mec), multi locus sequence typing (MLST) and carriage of 27 virulence genes. A total of 203 ITALIC! S. aureusstrains were isolated from 1400 outpatients with SSTIs, and 21 (10.3%) were CA-MRSA isolates. The positive rate of PVL genes among ITALIC! S. aureus, CA-MRSA and methicillin-susceptible ITALIC! S. aureus(MSSA) isolates were 39.4%, 71.4% and 35.7%, respectively. CA-MRSA strains had greater sensitivity to non-β-lactam antimicrobial agents. All CA-MRSA isolates belonged to SCC ITALIC! mecIV and V, accounting for 47.6% and 52.4%, respectively. ST59 was the most common lineage accounting for 76.2%; ST59-SCC ITALIC! mecIVa-PVL-positive clone was found to be the predominant clone, accounting for 38.1%. All CA-MRSA isolates were found to be positive for one or more virulence genes, 28.6% of isolates carried PVL, ITALIC! seb, ITALIC! sek, ITALIC! seq, ITALIC! hla, ITALIC! hlb, ITALIC! hldand ITALIC! hlg-2. CA-MRSA infections were relatively uncommon in outpatients with SSTIs, but they carried many virulence genes, ST59-SCC ITALIC! mecIV a-PVL-positive clone was the predominant clone in Wuhan, China.

Skin and soft-tissue infections: Factors associated with mortality and re-admissions

INTRODUCTION

Skin and soft-tissue infections (SSTIs) are common and are linked to a wide variety of clinical conditions. Few studies have analysed the factors associated with mortality and re-admissions in medical patients with SSTIs. Accordingly, this study sought to describe the clinical and microbiological characteristics of patients diagnosed with SSTIs, and identify mortality and re-admission related factors.

PATIENTS AND METHODS

A total of 308 patients were included in the study. Clinical, socio-demographic and microbiological characteristics were collected. Univariate and logistic regression multivariate analyses were performed in order to identify factors associated with mortality and re-admission.

RESULTS

The bacteria responsible were identified in 95 (30.8%) patients, with gram-positive bacteria being isolated in 67.4% and gram-negative in 55.8% of cases. Multi-resistant bacteria were frequent (39%), and the initial empirical treatment proved inadequate in 25.3% of all cases. In-hospital mortality was 14.9%; the related variables were heart failure (OR=5.96; 95%CI: 1.93-18.47), chronic renal disease (OR=6.04; 95%CI: 1.80-20.22), necrotic infection (OR=4.33; 95%CI: 1.26-14.95), and inadequate empirical treatment (OR=44.74; 95%CI: 5.40-370.73). Six-month mortality was 8%, with the main related factors being chronic renal disease (OR: 3.03; 95%CI: 1.06-8.66), and a Barthel Index score of under 20 (OR: 3.62; 95%CI: 1.17-11.21). Re-admission was necessary in 26.3% of cases, with the readmission-related variables being male gender (OR: 2.12; 95%CI: 1.14-3.94), peripheral vascular disease (OR: 3.05; 95%CI: 1.25-7.41), and an age-adjusted Charlson Comorbidity Index score of over 3 (OR: 3.27; 95%CI: 1.40-7.63).

CONCLUSIONS

Clinical variables such as heart failure, chronic renal disease, peripheral vascular disease, and necrotic infection could help identify high-risk patients. The main factor associated with higher mortality was inadequate initial empirical treatment. Physicians should consider gram-negative, and even extended-spectrum beta-lactamase-producing bacteria when assigning initial empirical treatment for SSTIs, especially in healthcare-associated cases.

Examination of hospital length of stay in Canada among patients with acute bacterial skin and skin structure infection caused by methicillin-resistant Staphylococcus aureus

PURPOSE

Skin infections, particularly those caused by resistant pathogens, represent a clinical burden. Hospitalization associated with acute bacterial skin and skin structure infections (ABSSSI) caused by methicillin-resistant Staphylococcus aureus (MRSA) is a major contributor to the economic burden of the disease. This study was conducted to provide current, real-world data on hospitalization patterns for patients with ABSSSI caused by MRSA across multiple geographic regions in Canada.

PATIENTS AND METHODS

This retrospective cohort study evaluated length of stay (LOS) for hospitalized patients with ABSSSI due to MRSA diagnosis across four Canadian geographic regions using the Discharge Abstract Database. Patients with ICD-10-CA diagnosis consistent with ABSSSI caused by MRSA between January 2008 and December 2014 were selected and assigned a primary or secondary diagnosis based on a prespecified ICD-10-CA code algorithm.

RESULTS

Among 6,719 patients, 3,273 (48.7%) and 3,446 (51.3%) had a primary and secondary diagnosis, respectively. Among patients with a primary or secondary diagnosis, the cellulitis/erysipelas subtype was most common. The majority of patients presented with 0 or 1 comorbid condition; the most common comorbidity was diabetes. The mean LOS over the study period varied by geographic region and year; in 2014 (the most recent year analyzed), LOS ranged from 7.7 days in Ontario to 13.4 days in the Canadian Prairie for a primary diagnosis and from 18.2 days in Ontario to 25.2 days in Atlantic Canada for a secondary diagnosis. A secondary diagnosis was associated with higher rates of continuing care compared with a primary diagnosis (10.6%-24.2% vs 4.6%-12.1%).

CONCLUSION

This study demonstrated that the mean LOS associated with ABSSSI due to MRSA in Canada was minimally 7 days. Clinical management strategies, including medication management, which might facilitate hospital discharge, have the potential to reduce hospital LOS and related economic burden associated with ABSSSI caused by MRSA.

Failure of outpatient antibiotics among patients hospitalized for acute bacterial skin infections: What is the clinical relevance?

BACKGROUND

Infectious Diseases Society of America guidelines recommend that patients hospitalized for acute bacterial skin infections after failure of outpatient antibiotic therapy be managed as "severe" infections; however, the clinical relevance of apparent failure of outpatient therapy is not clear.

METHODS

This was a secondary analysis of a multicenter, retrospective cohort of adults and children hospitalized for cellulitis, abscess, or wound infection. We compared clinical features, laboratory and microbiology findings, antibiotic treatment, and outcomes among patients who received outpatient antibiotics prior to admission and those who did not.

RESULTS

Of 533 patients, 179 (34%) received outpatient antibiotics prior to admission. Compared with those who did not, patients who received antibiotics prior to admission less frequently had fever (18% vs 26%, P=.04) and leukocytosis (33% vs 51%, P<.001). In the 202 cases where a microorganism was identified, Staphylococcus aureus was more common among those who received antibiotics prior to admission (75% vs 58%, P=.02), particularly methicillin-resistant S aureus (41% vs 27%, P=.049), whereas aerobic gram-negative bacilli were less common (3% vs 13%, P=.03). After hospitalization, clinical failure occurred with similar frequency between the 2 groups (12% vs 11%, P=.73).

CONCLUSIONS

Patients hospitalized with skin infections after apparently failing outpatient therapy had clinical features suggestive of less severe infection and similar outcomes compared with patients who did not receive antibiotics prior to admission. Our results suggest that inpatient treatment for patients not responding to outpatient therapy should focus on methicillin-resistant S aureus, not gram-negative pathogens.

Identification of Patient Characteristics Influencing Setting of Care Decisions for Patients With Acute Bacterial Skin and Skin Structure Infections: Results of a Discrete Choice Experiment

PURPOSE

Rates of acute bacterial skin and skin structure infections (ABSSSI) have sharply increased since 2000. Treatment may be administered in the inpatient or outpatient setting; clinical decision-making regarding hospitalization is inconsistent, often leading to hospitalization of some patients with ABSSSI who qualify for outpatient parenteral antimicrobial therapy, which leads to increased overall care costs. New antibiotics such as oritavancin are hypothesized to be a cost-effective option improving accessibility to ambulatory treatment of ABSSSI. The goal of this study was to understand the patient attributes that affect clinical decision-making regarding the setting of care for ABSSSI treatment.

METHODS

An observational, cross-sectional study was conducted that surveyed clinicians of various specialties from the United States and the United Kingdom. The survey collected quantitative responses and used a series of choice-based experimental designs to evaluate patient attributes influencing clinical treatment decisions.

FINDINGS

Infection severity, severe comorbidities, and age ≥ 75 years were observed to have the greatest impact on treatment location decisions (odds ratio [OR], 0.000-0.004 [95% CI, 0.000-0.011], vs mild ABSSSI; OR, 0.246-0.484 [95% CI, 0.154-0.788], vs no active comorbidities; OR, 0.136-0.523 [95% CI, 0.070-0.888], vs ≤ 18 years, respectively). The majority of respondents indicated they would consider oritavancin to avoid postdischarge outpatient parenteral antimicrobial therapy or oral therapy, regardless of the pathogen (63.5%-83.5%).

IMPLICATIONS

Key factors influencing ABSSSI treatment setting were severity of infection, severity of comorbidities, and age. Clinicians surveyed identified patient profiles in which single-dose oritavancin might enable wholly outpatient or shortened inpatient management. Additional studies to elucidate the ABSSSI care pathways that include oritavancin and other novel antibiotics are needed.

Treatment of complicated skin and skin structure infections in areas with low incidence of antibiotic resistance-a retrospective population based study from Finland and Sweden

Complicated skin and skin-structure infections (cSSSI) are a common reason for hospitalization and practically all new antimicrobial agents against Gram-positive bacteria are studied in cSSSI. The aim of this population-based observational study was to assess the treatment of patients with cSSSI in areas with a low incidence of antibiotic resistance. The study population consisted of adult residents who were treated because of cSSSI during 2008-2011 from two Nordic cities, Helsinki and Gothenburg. In the final analysis population (460 patients; mean age 60.8 years; 60.9% male) 13.3% of patients had bacteraemia, 15.9% were admitted to an Intensive Care Unit and 51.5% underwent at least one surgical intervention. Treatment failure occurred in 28.2%, initial antibiotic treatment modification to another intravenous drug in 38.5% and streamlining in 5.0% of the cases. Gram-positive bacteria were predominantly isolated, with staphylococci (24.5%) and streptococci (16.0%) being the most common aetiologies. Median overall durations of hospital stay and antimicrobial treatment were 13 and 17 days, respectively, and on average 3.5 (SD 2.1) different antibiotics were used per patient. Oral antimicrobial treatment was continued in 64.3% of patients after discharge. The overall mortality rates in 30 days and in 12 months were 4.1% and 11.8%, respectively, and 16.4% of patients had a recurrence of SSSI within 12 months. In conclusion, in this population-based study antimicrobial treatment modifications were frequent and the treatment time was longer than recommended. However, bacteraemia, clinical failure and recurrences were more common than in previous non-population-based studies.

Infection-related hospitalizations over 30 years of follow-up in patients starting renal replacement therapy at pediatric age

BACKGROUND

Pediatric renal replacement therapy (RRT) patients surviving long-term are at a much higher risk of mortality compared with the age-matched general population. Recently, we demonstrated a transition from cardiovascular disease to infection as the main cause of death in a long-term follow-up study of pediatric RRT. Here, we explore the burden of infections requiring hospitalization over 30 years of follow-up on RRT.

METHODS

The cohort comprised all 234 Dutch patients on RRT under 15 years of age between 1972 and 1992. We analyzed infection-related hospitalizations during the period 1980–2010. We evaluated the Hospital Admission Rate (HAR) per patient-years (py) and infectious over noninfectious HAR ratio (HARR).

RESULTS

The HAR decreased significantly over time for all patients. The rate of hemodialysis-related infections decreased between 1980 and 1999, but stabilized during 2000–2010, whereas peritoneal dialysis-related infections decreased progressively. Transplantation-related infections did not change, except for urinary tract infections (UTIs), which increased significantly from 3.3/100 py [95%CI 3.2–3.4] in 1980–1989 to 4.4/100 py [4.2–4.5] in 2000–2010 (p <0.001). The contribution of infection to HAR increased significantly in transplanted patients (HARR: 1980–1989: 0.25 [0.2–0.3]; 2000–2010: 1.0 [0.79–1.27], p <0.001).

CONCLUSIONS

Our findings indicate a relative increase in infections requiring hospitalization over time in patients starting RRT during the pediatric age, especially severe UTIs in transplantation. More attention paid to urological abnormalities in cases of recurrent UTI and tailored adjustment of immunosuppression may reduce risk in these patients.

Infectious Disease-Related Emergency Department Visits of Elderly Adults in the United States, 2011-2012

OBJECTIVES

To investigate the frequency of infectious disease (ID)-related emergency department (ED) visits of elderly adults in the United States.

DESIGN

Cross-sectional analysis.

SETTING

Nationwide emergency department sample in 2011-12.

PARTICIPANTS

Individuals in the ED aged 65 and older with a primary diagnosis of an ID.

MEASUREMENTS

ID-related ED visits, hospitalizations, hospital-based mortality.

RESULTS

During 2012, a weighted estimate of 3,123,909 ED visits for IDs was calculated in elderly U.S. adults. This accounted for 13.5% (3.1 million visits) of all ED visits of elderly adults; this burden was higher than that for myocardial infarction and congestive heart failure combined. The rate of ID-related ED visits was 7,231 per 100,000 elderly adults. The most-common diagnoses were lower respiratory infections (26.2%; 95% confidence interval (CI)=25.7-26.6%), urinary tract infections (25.3%, 95% CI=25.0-25.7%), and septicemia (18.9%, 95% CI=18.3-19.6%). Of all ID-related ED visits, 1,786,657 (57.2%, 95% CI=56.6-57.7%) resulted in hospitalization. The leading cause of hospitalization was septicemia, accounting for 32.2% (95% CI=31.1-33.3%) of all ID-related hospitalizations through EDs, followed by lower respiratory infections (27.8%, 95% CI=27.2-28.4%). Overall, 123,894 individuals (4.0%, 95% CI=3.8-4.1%) died during their ED visit or hospitalization. Of these, septicemia was the leading cause of mortality (74.7%, 95% CI=73.8-75.6%), followed by lower respiratory infections (15.2%, 95% CI=14.6-15.9%). Analysis of the 2011 data gave similar results for the burden of ID-related ED visits, hospitalizations, and mortality.

CONCLUSION

Using a nationally representative sample, it was found that the public health burden of IDs in elderly U.S. adults was substantial, as measured by ED visits, subsequent hospitalizations, and hospital-based mortality.

An open-label, non-randomised, phase 1, single-dose study to assess the pharmacokinetics of ceftaroline in patients with end-stage renal disease requiring intermittent haemodialysis

For patients with normal renal function, the recommended ceftaroline fosamil dose is a 600 mg 1-h intravenous (i.v.) infusion every 12 h (q12h). In patients with a creatinine clearance of ≤30 mL/min, including those with end-stage renal disease (ESRD), the recommended dose is a 200 mg 1-h i.v. infusion q12h. This phase 1 study (NCT01664065) evaluated the pharmacokinetics, safety and tolerability of ceftaroline fosamil 200 mg 1-h i.v. infusion in patients with ESRD. Patients with ESRD (n=8) participated in two treatment periods (ceftaroline fosamil 200 mg administered pre- and post-haemodialysis) separated by >1 week. Healthy volunteers (n=7) received a single 600 mg dose of ceftaroline fosamil. Blood (pre- and post-haemodialysis) and dialysate samples were obtained for pharmacokinetic analysis. In patients with ESRD, the geometric mean [coefficient of variation (%CV)] plasma ceftaroline area under the plasma concentration-time curve from zero to infinity (AUC0-∞) following post-haemodialysis ceftaroline fosamil 200 mg infusion was 64.8 (38.9)μg·h/mL, similar to that in volunteers following a 600 mg infusion [62.7 (9.4)μg·h/mL]. Ceftaroline AUC0-∞ decreased by ca. 50% when infusion was initiated pre-haemodialysis. In the pre-haemodialysis treatment period, 80% of the ceftaroline fosamil dose was recovered in dialysate as ceftaroline (73%) and ceftaroline M-1 (7%). The frequency of adverse events was similar across patients with ESRD (pre- and post-haemodialysis) and volunteers (43%, 50% and 43% of subjects, respectively). Ceftaroline fosamil 200 mg 1-h i.v. infusion q12h, administered post-haemodialysis on dialysis days, is an appropriate dosage regimen for ESRD patients.

In Vitro Pharmacodynamics of Vancomycin against Methicillin-Susceptible and -Resistant Staphylococcus aureus: Considering the Variability in Observed Tissue Exposure

Vancomycin is considered a first-line antibiotic for complicated skin and skin structure infections (cSSSI) because of the risk of methicillin-resistant Staphylococcus aureus (MRSA). The vancomycin exposure of tissue can vary widely in patients with cSSSI, yet most models test only the average exposure. The in vitro pharmacodynamic model was used to simulate three tissue exposure levels attained by administering vancomycin at 1 g every 12 h (q12h), based on the median (50th), 25th, and 10th percentile tissue area under the concentration-time curve (AUC) values observed during an in vivo microdialysis study of diabetic patients. Four clinical isolates (two of MRSA [vancomycin MIC, 1 and 2 μg/ml] and two of methicillin-susceptible S. aureus [MSSA] [MIC, 1 and 2 μg/ml]) were evaluated. Experiments were performed over 72 h in duplicate. Time-kill curves were constructed, and the area under the bacterial killing and regrowth curve (AUBC) during the final 24-h dosing interval (48 to 72 h) (AUBC48-72) was calculated. Reductions in the 72-h number of CFU/ml and AUBC48-72 at the different exposure levels were compared. Target tissue vancomycin exposure levels for the 50th (AUC0-12, 102.0 ± 9.1 μg · h/ml), 25th (AUC0-12, 44.3 ± 1.8 μg · h/ml), and 10th (AUC0-12, 25.3 ± 3.1 μg · h/ml) percentiles were obtained in all studies. No differences in the 72-h number of CFU or AUBC were observed between exposure levels when all of the isolates were analyzed together. However, for the two MRSA isolates, the 10th percentile exposure level achieved a lower 72-h number of CFU/ml (-1.4 ± 0.4 log10 CFU/ml, P = 0.007) and a greater AUBC48-72 (97.1 ± 20.0 log10 CFU · h/ml, P = 0.011) than the higher exposure levels. The majority of the tissue exposure levels achieved with a vancomycin dosing regimen of 1 g q12h resulted in substantial killing of MSSA and MRSA; however, the lowest exposure levels observed in a minority of the population may explain the poor vancomycin response.

Rising United States Hospital Admissions for Acute Bacterial Skin and Skin Structure Infections: Recent Trends and Economic Impact

BACKGROUND

The number of ambulatory patients seeking treatment for skin and skin structure infections (SSSI) are increasing. The objective of this study is to determine recent trends in hospital admissions and healthcare resource utilization and identify covariates associated with hospital costs and mortality for hospitalized adult patients with a primary SSSI diagnosis in the United States.

METHODS

We performed a retrospective cross-sectional analysis (years 2005-2011) of data from the US Healthcare Cost and Utilization Project National Inpatient Sample. Recent trends, patient characteristics, and healthcare resource utilization for patients hospitalized with a primary SSSI diagnosis were evaluated. Descriptive and bivariate analyses were conducted to assess patient and hospital characteristics.

RESULTS

A total of 1.8% of hospital admissions for the years 2005 through 2011 were for adult patients with a SSSI primary diagnosis. SSSI-related hospital admissions significantly changed during the study period (P < .001 for trend) ranging from 1.6% (in 2005) to 2.0% (in 2011). Mean hospital length of stay (LOS) decreased from 5.4 days in the year 2005 to 5.0 days in the year 2011 (overall change, P < .001) with no change in hospital costs. Patients with postoperative wound infections had the longest hospital stays (adjusted mean, 5.81 days; 95% confidence interval (CI), 5.80-5.83) and highest total costs (adjusted mean, $9388; 95% CI, $9366-$9410). Year of hospital admission was strongly associated with mortality; infection type, all patient refined diagnosis related group severity of illness level, and LOS were strongly associated with hospital costs.

CONCLUSIONS

Hospital admissions for adult patients in the United States with a SSSI primary diagnosis continue to increase. Decreasing hospital inpatient LOS and mortality rate may be due to improved early treatment. Future research should focus on identifying alternative treatment processes for patients with SSSI that could shift management from inpatient to outpatient treatment settings.

Indications for Plain Radiographs in Uncomplicated Lower Extremity Cellulitis

RATIONALE AND OBJECTIVES

Cellulitis is a common cause for emergency department (ED) presentation and subsequent hospital admission. Underlying fracture, osteomyelitis, or foreign body is often considered in the clinical evaluation of these patients. Accordingly, plain radiographs (XRs) of the affected extremity are often ordered during the initial work-up. The utility of these imaging studies in the treatment of uncomplicated lower-extremity cellulitis, however, remains unclear. In an effort to treat this common problem more efficiently, we evaluated our imaging practices and results in a cohort of consecutive patients admitted to a large public city hospital for treatment of uncomplicated lower-extremity cellulitis.

MATERIALS AND METHODS

Retrospective cohort study of 288 consecutive ED admissions for treatment of uncomplicated cellulitis, of which 214 met the inclusion criteria for this study. Patient demographics, history, vitals, laboratory values, and test results were evaluated with univariate and multivariate statistical analyses.

RESULTS

XRs of the affected lower extremity were obtained in 158 patients (73.8%). Positive XR findings were present in 19 patients (12.0%) and positively correlated with a history of acute trauma to the extremity (P < .001) or the presence of a chronic wound (P < .01). Multivariable logistic regression analysis revealed a history of trauma (P < .001) or the presence of a chronic wound (P < .05) to be independent predictors of positive XR findings with relative risks of 6.24 and 2.98, respectively.

CONCLUSIONS

The establishment of evidence-based guidelines for the treatment of lower-extremity cellulitis has potential to significantly improve clinical efficiency and reduce cost by eliminating unnecessary testing. Based on our results, patients without a recent history of trauma to the affected extremity or the presence of a chronic wound do not appear to warrant XRs. When applied to our cohort, only 48 of 158 patients had a history of trauma or chronic wound. This means that 110 patients unnecessarily had plain films taken as part of their initial work-up. In a largely uninsured inner city patient population such as this cohort, that extra cost falls on the public hospital system.

Incidence of skin and soft tissue infections in ambulatory and inpatient settings, 2005-2010

BACKGROUND

The emergence of community-associated methicillin-resistant S. aureus was associated with dramatically increased skin and soft tissue infection (SSTI) incidence in the first few years of the 21(st) century in the U.S. However, subsequent trends are poorly understood.

METHODS

We examined ambulatory and inpatient data of over 48 million persons years aged 0-64 years from the HealthCore Integrated Research Database (HIRD) between 2005 and 2010. Data were extracted from medical, pharmacy, and eligibility databases. We quantified SSTI incidence, type, and complications and comparative incidence trends for urinary tract infections (UTIs) and pneumonia.

RESULTS

A total of 2,301,803 SSTIs were identified. Most SSTIs (95 %) were treated in the ambulatory setting and most (60 %) were categorized as abscesses or cellulitis. During the study period, SSTI incidence remained relatively stable from 47.9 (95 % CI: 47.8-48.1) cases/1,000 PY in 2005 to 48.5 cases/1,000 PY (95 % CI: 48.3-48.6) in 2010). Persons aged 45-64 years had the highest incidence of both ambulatory-treated and inpatient-treated SSTIs (51.2 (95 % CI: 51.1-51.3) and 3.87 (95 % CI: 3.84-3.90) cases/1,000 PY, respectively). SSTI complications such as myositis, gangrene, and sepsis occurred in 0.93 % (95 % CI: 0.92-0.94 %) and 16.92 % (95 % CI: 16.87-16.97 %) of ambulatory-treated and inpatient-treated patients, respectively. SSTI incidence was approximately twice that of UTIs and tenfold of that of pneumonia.

CONCLUSIONS

Among our large, diverse population of persons less than 65 years, SSTI incidence 2005 through 2010 has remained relatively constant at approximately 4.8 SSTIs per 100 person years, suggesting that previously observed increases in SSTI incidence remain sustained.

Dalbavancin for the treatment of acute bacterial skin and skin structure infections

INTRODUCTION

Acute bacterial skin and skin structure infections (ABSSSI) have increased in incidence and severity. The involvement of resistant organisms, particularly methicillin-resistant Staphylococcus aureus, presents additional challenges. The lipoglycopeptide dalbavancin has a prolonged half-life, high protein binding, and excellent tissue levels which led to its development as a once-weekly treatment for ABSSSI. In the pivotal DISCOVER 1 and DISCOVER 2 trials, dalbavancin proved non-inferior to vancomycin followed by linezolid when used sequentially for ABSSSI, forming the basis for its recent approval in the US and Europe for ABSSSI.

AREAS COVERED

A literature search of published pharmacologic and clinical data was conducted to review the chemistry, pharmacodynamics, and pharmacokinetics of dalbavancin. We also discuss its development process, highlighting efficacy and safety data from pertinent clinical trials and the role it could play in the current clinical landscape.

EXPERT OPINION

DISCOVER 1 and DISCOVER 2 demonstrated dalbavancin's non-inferiority to vancomycin followed by linezolid for ABSSSI and confirmed its safety and tolerability. They were among the first trials to use new, early primary efficacy endpoints, and dalbavancin was among the first agents designated a Qualified Infectious Disease Product for expedited review. Dalbavancin may prove to be a valuable option for ABSSSI patients in whom conventional therapy is limited.

Methicillin-resistant S. aureus (MRSA), extended-spectrum (ESBL)- and plasmid-mediated AmpC ß-lactamase -producing Gram-negative bacteria associated with skin and soft tissue infections in hospital and community settings

AIM

To investigate the characteristics of meticillin-resistant S. aureus (MRSA), extended-spectrum (ESBL), and plasmid-mediated AmpC beta-lactamase producing Gram-negative bacteria causing skin and soft tissue infections (SSTIs) in hospital and outpatient settings of Zenica-Doboj Canton, Bosnia and Herzegovina.

METHODS

Antibiotic susceptibility was determined by disc-diffusion and broth microdillution methods according to CLSI guidelines. MecA gene was detected by PCR, and genetic characterization of MRSA was performed using spa-typing and the algorithm based upon repeat patterns (BURP). Double-disk-synergy test was used to screen for ESBLs. PCR was used to detect blaESBL alleles. Genetic relatedness of the strains was tested by PFGE.

RESULTS

Seventeen in-patients with MRSA, 13 with ESBL-producing Gram-negative bacteria and three patients co-infected with both, were detected. Five MRSA and 16 ESBL-producing Gram-negative bacteria were found in outpatient samples. Klebsiella spp. was isolated in 11 in- and seven outpatients. MLST CC152 was the most prevalent MRSA. Seven (38.9%) Klebsiella spp. yielded amplicons with primers specific for SHV, TEM-1 and CTX-M group 1 β-lactamases. Eight K. pneumonia (44.4%) and 16 (64%) MRSA (including the in- and outpatient) strains were clonally related.

CONCLUSION

The presence of MRSA and ESBL-producing organisms causing SSTIs in the community poses a substantial concern, due to the high morbidity and mortality associated with possible consequent hospital infections.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

Administration of first dose antibiotic in the ED in patients with minor skin and soft tissue infections

BACKGROUND

Patients who present to the emergency department (ED) with mild skin and soft tissue infections (SSTIs) are often given a single dose of an antibiotic before being discharged home on oral antibiotics. The objective of this study was to determine if administration of antibiotics in the ED increases length of stay.

METHODS

This was cross-sectional study using data from the National Hospital Ambulatory Medical Care Survey. Patients with SSTIs who were discharged home with antibiotics were included. Patients were categorized into 2 groups based on whether any antibiotics were administered in the ED. The ED length of stay was compared between the groups. A multivariate analysis was conducted to adjust for pertinent confounders.

RESULTS

There were 3000895 cases of patients with SSTIs who presented to the ED and directly discharged home on antibiotic therapy from 2008 to 2010. Of these, 46.8% (n = 1403710) involved the administration of an antibiotic in the ED, whereas the others only received antibiotic prescriptions upon discharge. The mean ED length of stay was 83.8 ± 160.6 minutes with no antibiotics vs 112.2 ± 193.6 minutes for antibiotic use in the ED (P < .05). After adjusting for confounders, there was a 43% increase in ED length of stay associated with administration of first dose of antibiotics in the ED (exp[b] = 1.43; 95% confidence interval, 1.19-1.70; P < .001).

CONCLUSION

The administration of an antibiotic in the ED before discharge is associated with an increased ED length of stay in patients with SSTIs.

Acute Bacterial Skin and Skin Structure Infections Treated with Intravenous Antibiotics in the Emergency Department or Observational Unit: Experience at the Detroit Medical Center

Introduction

Acute bacterial skin and skin structure infections (ABSSSIs) are frequently treated in emergency departments (EDs) or observation units (OUs) initially with intravenous (IV) antibiotics before discharge on oral therapy. This study aims to describe ABSSSI patients discharged directly from EDs/OUs.

Methods

This is a retrospective cohort study of patients with ABSSSIs treated in EDs/OUs of the Detroit Medical Center from 2012 to 2014. Adults with less than 24 h of IV antibiotics without hospital admission were included. Demographics, clinical characteristics, and severity were compared between ED and OU patients. Resource utilization, including tissue and blood cultures, and use of radiographic analysis was also collected. The primary outcome was 96-h ED revisit/hospitalization.

Results

Analysis included 308 patients; 219 ED and 89 OU. OU patients were significantly more likely to be obese, have COPD/asthma, be diagnosed with cellulitis, and meet at least one systemic inflammatory response syndrome (SIRS) criterion. Tissue cultures were obtained in 21.7% of abscesses in the ED; 67.9% were in uncomplicated abscesses. In the OU tissue cultures were obtained in 48.8% of abscesses and 37.5% were uncomplicated cases. Blood cultures were drawn in 18.3% of ED patients and 56.2% of OU patients, not significantly associated with the presence of SIRS criteria. Radiology was used in the diagnosis of ABSSSIs in 33.5% of ED versus 69.5% OU patients (p < 0.001), Plain film radiograph being the most common. Thirty patients revisited the ED or required hospitalization within 96 h, 23 from the ED (p = 0.479). Prior history of ABSSSI (adjusted odds ratio [aOR] = 2.382, 95% confidence interval [CI] 1.264–6.346) and location on torso/buttocks (aOR = 2.355, 95% CI 1.067–5.197) were independent predictors.

Conclusions

The low rate of ED revisit/hospitalization supports the use of OUs for low acuity ABSSSIs requiring initial IV therapy. Resource utilization within EDs/OUs for the management of ABSSSIs needs to be evaluated for unnecessary testing/procures.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-015-0069-7) contains supplementary material, which is available to authorized users.

The times they are a-changin': new antibacterials for skin and skin structure infections

Twenty-one agents are approved by the US Food and Drug Administration (FDA) for the therapy of skin and soft tissue infections. Of these, the five newest agents, tedizolid, telavancin, oritavancin, dalbavancin, and ceftaroline, are active against and "non-inferior" to vancomycin against methicillin-resistant Staphylococcus aureus (MRSA). Oritavancin is indicated as a single-dose intravenous regimen, while dalbavancin is a two-dose intravenous regimen given 1 week apart. Telavancin has multiple mechanisms of action. A 6-day regimen of once-daily intravenous or oral dose of tedizolid was compared with 10 days of linezolid and found to be "non-inferior" and have fewer side effects. Ceftaroline has not only MRSA activity but also activity against Escherichia coli and Klebsiella spp. We review the spectra of activity of these new agents, their clinical trials and their therapeutic efficacy, noting differences in their dosing schedules, in vitro activities and costs as potential determinants for appropriate utilization.

New developments in the management of severe skin and deep skin structure infections - focus on tedizolid

Tedizolid, a novel oxazolidinone, is approved for treatment of acute bacterial skin and skin structure infections (ABSSSIs). Tedizolid offers several potential advantages over current ABSSSI treatment options. First, tedizolid has a prolonged half-life, which allows for once-daily dosing. Second, tedizolid has broad spectrum activity against Gram-positive organisms including methicillin-resistant Staphylococcus aureus, coagulase-negative staphylococci, and enterococci. Third, tedizolid, available in both intravenous and oral formulations, has high oral bioavailability, allowing for easy oral step-down therapy. Fourth, in patients who have been prescribed selective serotonin reuptake inhibitors or monoamine oxidase inhibitors, tedizolid may have fewer drug interactions than linezolid. Finally, tedizolid may have fewer or comparatively delayed onset side effects than linezolid, including thrombocytopenia and nausea. This review covers the microbiology, pharmacology, mode of action, and pharmacokinetics of tedizolid as well as patient-focused perspectives such as quality of life, patient satisfaction/acceptability, adherence, and uptake and provides expert opinion on the current use of tedizolid for ABSSSIs and potential future therapeutic applications.

Profile of tedizolid phosphate and its potential in the treatment of acute bacterial skin and skin structure infections

Tedizolid phosphate is the first once-daily oxazolidinone approved by the United States Food and Drug Administration for the treatment of acute bacterial skin and skin structure infections (ABSSSI). It is more potent in vitro than linezolid against methicillin-resistant Staphylococcus aureus (MRSA) and other gram-positive pathogens causing ABSSSI, even retaining activity against some linezolid-resistant strains. Tedizolid is approximately 90% protein bound, leading to lower free-drug concentrations than linezolid. The impact of the effect of food, renal or hepatic insufficiency, or hemodialysis on tedizolid's pharmacokinetic have been evaluated, and no dosage adjustment is needed in these populations. In animal and clinical studies, tedizolid's effect on bacterial killing is optimized by the free-drug area under the curve to minimum inhibitory concentration ratio (fAUC/MIC). The 200 mg once-daily dose is able to achieve the target fAUC/MIC ratio in 98% of simulated patients. Two Phase III clinical trials have demonstrated the noninferiority of tedizolid 200 mg once daily for 6 days to linezolid 600 mg twice daily for 10 days. In vitro, animal, and clinical studies have failed to demonstrate that tedizolid inhibits monoamine oxidase to a clinically relevant extent. Tedizolid has several key advantages over linezolid including once daily dosing, decreased treatment duration, minimal interaction with serotonergic agents, possibly associated with less adverse events associated with the impairment of mitochondrial protein synthesis (eg, myelosuppression, lactic acidosis, and peripheral/optic neuropathies), and retains in vitro activity against linezolid-resistant gram-positive bacteria. Economic analyses with tedizolid are needed to describe the cost-effectiveness of this agent compared with other options used for ABSSSI, particularly treatment options active against MRSA.

Treatment outcome measures for randomized controlled trials of antibiotic treatment for acute bacterial skin and skin structure infections in the emergency department setting

Acute bacterial skin and skin structure infections (ABSSSIs), which include cellulitis, abscesses, and wound infections, are among the most commonly encountered conditions in emergency departments (EDs) internationally. Primarily, as a result of the recent epidemic of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) in North America, ED attendances and hospital admissions secondary to ABSSSIs have increased significantly. First-line antibiotic drug therapies for ABSSSIs have therefore changed to take account of CA-MRSA and the threat of evolving antibiotic resistance. Prior to 2010, randomized controlled trials (RCTs) of antibiotic therapy for ABSSSI used broad trial inclusion criteria and utilized investigator-determined clinical resolution, 7 to 14 days after the end of therapy, as the primary outcome measure. In order to produce more objective, reproducible, and quantifiable primary outcome measures, the US Food and Drug Administration (FDA) Center for Drug Evaluation and Research and a multidisciplinary consortium convened by the Foundation for the National Institutes of Health (FNIH) issued significantly changed trial guidance criteria. The currently recommended primary outcome measure is an assessment of greater than 20% reduction in the area of erythema, edema, or induration from baseline, measured at 48 to 72 h after randomization and initiation of drug treatment. In contrast, the European Medicines Agency (EMA) still recommends measurement of clinical resolution at a later time period. We discuss the evolution of changes to trial guidance criteria issued by the FDA since 1998 and the potential difficulties of implementing the recommended primary outcome measured at an earlier time point in RCTs of outpatient antibiotic treatment performed in the ED setting.

Clindamycin versus trimethoprim-sulfamethoxazole for uncomplicated skin infections

BACKGROUND

Skin and skin-structure infections are common in ambulatory settings. However, the efficacy of various antibiotic regimens in the era of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) is unclear.

METHODS

We enrolled outpatients with uncomplicated skin infections who had cellulitis, abscesses larger than 5 cm in diameter (smaller for younger children), or both. Patients were enrolled at four study sites. All abscesses underwent incision and drainage. Patients were randomly assigned in a 1:1 ratio to receive either clindamycin or trimethoprim-sulfamethoxazole (TMP-SMX) for 10 days. Patients and investigators were unaware of the treatment assignments and microbiologic test results. The primary outcome was clinical cure 7 to 10 days after the end of treatment.

RESULTS

A total of 524 patients were enrolled (264 in the clindamycin group and 260 in the TMP-SMX group), including 155 children (29.6%). One hundred sixty patients (30.5%) had an abscess, 280 (53.4%) had cellulitis, and 82 (15.6%) had mixed infection, defined as at least one abscess lesion and one cellulitis lesion. S. aureus was isolated from the lesions of 217 patients (41.4%); the isolates in 167 (77.0%) of these patients were MRSA. The proportion of patients cured was similar in the two treatment groups in the intention-to-treat population (80.3% in the clindamycin group and 77.7% in the TMP-SMX group; difference, -2.6 percentage points; 95% confidence interval [CI], -10.2 to 4.9; P=0.52) and in the populations of patients who could be evaluated (466 patients; 89.5% in the clindamycin group and 88.2% in the TMP-SMX group; difference, -1.2 percentage points; 95% CI, -7.6 to 5.1; P=0.77). Cure rates did not differ significantly between the two treatments in the subgroups of children, adults, and patients with abscess versus cellulitis. The proportion of patients with adverse events was similar in the two groups.

CONCLUSIONS

We found no significant difference between clindamycin and TMP-SMX, with respect to either efficacy or side-effect profile, for the treatment of uncomplicated skin infections, including both cellulitis and abscesses. (Funded by the National Institute of Allergy and Infectious Diseases and the National Center for Advancing Translational Sciences, National Institutes of Health; ClinicalTrials.gov number, NCT00730028.).

Photothermal killing of Staphylococcus aureus using antibody-targeted gold nanoparticles

Purpose

The continued emergence of multidrug resistant bacterial infections and the decline in discovery of new antibiotics are major challenges for health care throughout the world. This situation has heightened the need for novel antimicrobial therapies as alternatives to traditional antibiotics. The combination of metallic nanoparticles and laser exposure has been proposed as a strategy to induce physical damage to bacteria, regardless of antibiotic sensitivity. The purpose of this study was to test the antibacterial effect of antibody-targeted gold nanoparticles combined with pulsed laser irradiation.

Methods

Gold nanoparticles conjugated to antibodies specific to Staphylococcus aureus peptidoglycan were incubated with suspensions of methicillin-resistant and methicillin-sensitive S. aureus (MRSA and MSSA). Bacterial suspensions were then exposed to 8 ns pulsed laser irradiation at a wavelength of 532 nm and fluences ranging from 1 to 5 J/cm². Viability of the bacteria following laser exposure was determined using colony forming unit assays. Scanning electron microscopy was used to confirm the binding of nanoparticles to bacteria and the presence of cellular damage.

Results

The laser-activated nanoparticle treatment reduced the surviving population to 31% of control in the MSSA population, while the survival in the MRSA population was reduced to 58% of control. Significant decreases in bacterial viability occurred when the laser fluence exceeded 1 J/cm², and this effect was linear from 0 to 5 J/cm² (r²=0.97). Significantly less bactericidal effect was observed for nonfunctionalized nanoparticles or functionalized nanoparticles without laser activation.

Conclusion

Laser-activated nanoparticles targeted to S. aureus surface antigens significantly reduced the percentage of viable organisms and represents a promising new treatment modality that could be used either alone or as an adjunct to existing, conventional antibiotic therapy.

Early response to antibiotic treatment in European patients hospitalized with complicated skin and soft tissue infections: analysis of the REACH study

Background

The treatment of complicated skin and soft tissue infections (cSSTI) is challenging and many patients do not receive adequate first-line therapy. REACH (REtrospective Study to Assess the Clinical Management of Patients With Moderate-to-Severe cSSTI or Community-Acquired Pneumonia in the Hospital Setting) was a retrospective observational study of cSSTI patients in real-life settings in European hospitals. In this analysis, we review characteristics and outcomes of patients with an early response (≤72 hours) compared with those without an early response to treatment. We also compare the results according to two differing definitions of early response, one of which (Definition 1) requires resolution of fever within 72 hours, in line with previous US FDA guidelines.

Methods

Patients were adults hospitalized with cSSTIs 2010–2011 and requiring treatment with intravenous antibiotics. Clinical management, clinical outcomes and healthcare resource use were assessed using a descriptive analysis approach.

Results

The analysis set included 600 patients, of which 363 showed early response with Definition 1 and 417 with Definition 2. Initial treatment modification was frequent, and highest in patients without early response (48.1% with Definition 1). Patients without early response were more likely to have diabetes than those with early response (31.6% vs. 22.9%, respectively) and to suffer from more severe disease (e.g. skin necrosis: 14.8% and 7.7%, respectively), to be infected with difficult-to-treat microorganisms and to have recurrent infections. Furthermore, patients without early response had a higher rate of adverse clinical outcomes (e.g. septic shock) and higher use of healthcare resources. The results obtained with the two definitions for early response were largely similar.

Conclusions

This study highlights the significance of early evaluation of patients in hospitals, in potentially preventing prolonged use of inappropriate or ineffective antibacterial therapy.

Trial registration

NCT01293435.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-0822-2) contains supplementary material, which is available to authorized users.

Oritavancin, a single-dose, complete regimen, for the treatment of acute bacterial skin and skin structure infections

Oritavancin, a lipoglycopeptide antibiotic, recently received US FDA approval for the treatment of adult patients with acute bacterial skin and skin structure infections (ABSSSI). Oritavancin, unlike other intravenous antibiotics that are currently available for the treatment of ABSSSI (e.g., vancomycin, daptomycin, telavancin, dalbavancin), offers the option of a single-dose complete regimen. The dosing schedule of oritavancin eliminates the need for an indwelling catheter and introduces the possibility of avoidance of a hospital admission; although, treatment in non-hospital settings has not been adequately evaluated in clinical trials. The availability of oritavancin adds another agent to our antibiotic armamentarium providing dosing flexibility and an alternative treatment option for treatment of ABSSSI caused by susceptible bacteria, including methicillin-resistant Staphylococcus aureus.

Staphylococcus lugdunensis gluteal abscess in a patient with end stage renal disease on hemodialysis

A 57-year-old end stage renal disease patient on hemodialysis (HD) presented with sepsis secondary to right buttock abscess and overlying cellulitis. She was started on broad-spectrum antibiotic therapy and underwent incision and drainage with marked improvement. Her cultures grew methicillin-resistant Staphylococcus lugdunensis. This bacterium is more virulent than other coagulase negative staphylococci and has been implicated in causing a variety of serious infections but it has been underreported as a cause of skin infections in HD patients and possible other patient populations.

Acute bacterial skin and skin structure infections (ABSSSI): practice guidelines for management and care transitions in the emergency department and hospital

BACKGROUND

Acute bacterial skin and skin structure infections (ABSSSI), formally referred to as complicated skin and soft tissue infections, include infections with resistance to previously effective antimicrobials. Increasing dramatically in incidence, they have become a challenging medical problem associated with high direct and indirect costs to both the medical system and society.

OBJECTIVES

To describe the burden of ABSSSI and to explore multidisciplinary approaches to its management and new treatments that can be initiated in the emergency department.

DISCUSSION

We offer a best practice model aimed at providing risk-stratified and convenient care for ABSSSI at the lowest possible cost, while minimizing complications, readmissions, and inappropriate antibiotic use. In doing so, we focus on the care provided by emergency physicians and hospitalists and the transition of management between them for inpatient care, as well as the facilitation of observation or direct-to-outpatient care for suitable patients.

CONCLUSIONS

A standard, consistent, and multidisciplinary approach to ABSSSI can streamline care, reduce admissions, support antimicrobial stewardship, and improve clinical and resource consumption outcomes.

Assessing the economic value of avoiding hospital admissions by shifting the management of gram+ acute bacterial skin and skin-structure infections to an outpatient care setting

OBJECTIVE

To estimate, from a US payer perspective, the cost offsets of treating gram positive acute bacterial skin and skin-structure infections (ABSSSI) with varied hospital length of stay (LOS) followed by outpatient care, as well as the cost implications of avoiding hospital admission.

METHODS

Economic drivers of care were estimated using a literature-based economic model incorporating inpatient and outpatient components. The model incorporated equal efficacy, adverse events (AE), resource use, and costs from literature. Costs of once- and twice-daily outpatient infusions to achieve a 14-day treatment were analyzed. Sensitivity analyses were performed. Costs were adjusted to 2015 US$.

RESULTS

Total non-drug medical cost for treatment of ABSSSI entirely in the outpatient setting to avoid hospital admission was the lowest among all scenarios and ranged from $4039-$4924. Total non-drug cost for ABSSSI treated in the inpatient setting ranged from $9813 (3 days LOS) to $18,014 (7 days LOS). Inpatient vs outpatient cost breakdown was: 3 days inpatient ($6657)/11 days outpatient ($3156-$3877); 7 days inpatient ($15,017)/7 days outpatient ($2495-$2997). Sensitivity analyses revealed a key outpatient cost driver to be peripherally inserted central catheter (PICC) costs (average per patient cost of $873 for placement and $205 for complications).

LIMITATIONS

Drug and indirect costs were excluded and resource use was not differentiated by ABSSSI type. It was assumed that successful ABSSSI treatment takes up to 14 days per the product labels, and that once-daily and twice-daily antibiotics have equal efficacy.

CONCLUSION

Shifting ABSSSI care to outpatient settings may result in medical cost savings greater than 53%. Typical outpatient scenarios represent 14-37% of total medical cost, with PICC accounting for 28-43% of the outpatient burden. The value of new ABSSSI therapies will be driven by eliminating the need for PICC line, reducing length of stay and the ability to completely avoid a hospital stay.

Ceftaroline fosamil for treating skin and skin structure infections or community-acquired pneumonia in patients with renal insufficiency

The Clinical Assessment Program and Teflaro(®) Utilization Registry (CAPTURE) is a multicenter retrospective study, conducted in the USA, describing the contemporary use of ceftaroline fosamil. Ceftaroline is primarily excreted by the kidneys and the dose should be reduced in patients with moderate to severe renal insufficiency. This article describes the clinical effectiveness of ceftaroline fosamil in the treatment of acute bacterial skin and skin structure infection (ABSSSI) or community-acquired bacterial pneumonia (CABP) patients with renal insufficiency. There were 985 ABSSSI patients and 344 CABP patients, of which 22 and 31%, respectively, had renal insufficiency. Ceftaroline fosamil was mostly administered to patients as second-line therapy. Overall clinical success was 78-91% among ABSSSI or CABP patients with renal insufficiency and, overall, >50% of patients were discharged to home. Ceftaroline fosamil is an effective treatment option for ABSSSI or CABP patients with renal insufficiency.

The potential role of nemonoxacin for treatment of common infections

INTRODUCTION

Nemonoxacin , a novel non-fluorinated quinolone, exhibits potent activity against Gram-positive bacteria, including MRSA and fluoroquinolone-resistant MRSA, Gram-negative and atypical pathogens. This agent also has a reduced propensity for resistance development in many kinds of pathogens.

AREAS COVERED

This article reviews currently available clinical and in vitro data that support the potential role of nemonoxacin for the treatment of common infectious diseases, including community-acquired pneumonia (CAP), Clostridium difficile infections (CDIs), acute bacterial skin and skin structure infections (ABSSSIs) and sexually transmitted diseases (STDs). One recent Phase II trial comparing either 500 mg or 750 mg oral nemonoxacin with 500 mg oral levofloxacin for mild to moderate CAP demonstrated that nemonoxacin had comparable clinical success with levofloxacin. Nemonoxacin showed lower MICs against clinical C. difficile isolates than commercially available fluoroquinolones, making it a potential therapeutic agent if novel formulations are developed to maintain a higher concentration in the human gut. For STDs, nemonoxacin also showed good activity against some common pathogens, such as Chlamydia trachomatis and Neisseria gonorrhoeae.

EXPERT OPINION

Although in vitro studies have shown promising results regarding the susceptibility to nemonoxacin of common pathogens causing CDIs, ABSSSIs and STDs, further clinical trials are needed to prove its efficacy.