Antimicrobial Management of Complicated Skin and Skin Structure Infections in the Era of Emerging Resistance

Efficacy and Safety of Antibiotics in the Treatment of Methicillin-Resistant Staphylococcus aureus (MRSA) Infections: A Systematic Review and Network Meta-Analysis

BACKGROUND

Vancomycin is a first-line drug for the treatment of MRSA infection. However, overuse of vancomycin can cause bacteria to become resistant, forming resistant strains and making infections more difficult to treat. This study aimed to evaluate the efficacy and safety of different antibiotics in the treatment of MRSA infections and to compare them, mainly with vancomycin, to find better vancomycin alternatives.

METHODS

All studies were obtained from the PubMed and Embase databases from inception to 13 April 2023. The three comprehensive indicators of clinical cure success rate, clinical microbiological success rate, and adverse reactions were evaluated, and the clinical cure success rates of three disease types, complex skin and skin structure infections (cSSSIs), complex skin and soft tissue infections (cSSTIs), and pneumonia, were analyzed in subgroups. All statistical analyses were performed using R and STATA 14.0 software for network meta-analysis.

RESULTS

A total of 38 trials with 6281 patients were included, and 13 drug treatments were evaluated. For MRSA infections, the results of network meta-analysis showed that the clinical success rates of linezolid, the combination of vancomycin and rifampin, and the combination of minocycline and rifampin were better than that of vancomycin (RR 1.71; 95%-CI 1.45-2.02), (RR 2.46; 95%-CI 1.10-5.49) (RR, 2.77; 95%-CI 1.06-7.21). The success rate of clinical microbiological treatment with vancomycin was inferior to that with telavancin (RR 0.74; 95%-CI 0.55-0.99). Linezolid had a higher rate of adverse reactions than teicoplanin (RR 5.35; 95%-CI 1.10-25.98). Subgroup analysis showed that vancomycin had a lower clinical success rate than linezolid in the treatment of MRSA-induced cSSSIs, cSSTIs, and pneumonia (RR 0.59; 95%-CI 0.44-0.80) (RR 0.55; 95%-CI 0.35-0.89) (RR 0.55; 95%-CI 0.32-0.93).

CONCLUSIONS

This systematic review and NMA provide a new comparison framework for the clinical treatment of MRSA infection. The NMA suggests that linezolid may be the antibiotic of choice for the treatment of MRSA infections, with the ability to improve clinical and microbiological success rates despite its disadvantage in terms of adverse effects. At the same time, the combination of minocycline and rifampicin may be the most effective drug to treat MRSA-induced cSSSIs, tedizolid may be the best drug to treat MRSA-induced cSSTIs, and the combination of vancomycin and rifampicin may be the most effective treatment for MRSA-induced pneumonia. More high-quality studies are still needed in the future to further identify alternatives to vancomycin.

TRIAL REGISTRATION

PROSPERO registration number CRD42023416788.

In Vitro Activities of Ceftobiprole, Dalbavancin, Tedizolid and Comparators against Clinical Isolates of Methicillin-Resistant Staphylococcus aureus Associated with Skin and Soft Tissue Infections

Skin and soft tissue infections (SSTIs) are associated with significant morbidity and healthcare costs, especially when caused by methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin is a preferred antimicrobial therapy for the management of complicated SSTIs (cSSTIs) caused by MRSA, with linezolid and daptomycin regarded as alternative therapeutic options. Due to the increased rates of antimicrobial resistance in MRSA, several new antibiotics with activity against MRSA have been recently introduced in clinical practice, including ceftobiprole, dalbavancin, and tedizolid. We evaluated the in vitro activities of the aforementioned antibiotics against 124 clinical isolates of MRSA obtained from consecutive patients with SSTIs during the study period (2020-2022). Minimum inhibitory concentrations (MICs) for vancomycin, daptomycin, ceftobiprole, dalbavancin, linezolid and tedizolid were evaluated by the MIC Test Strip using Liofilchem strips. We found that when compared to the in vitro activity of vancomycin (MIC₉₀ = 2 μg/mL), dalbavancin possessed the lowest MIC₉₀ (MIC₉₀ = 0.094 μg/mL), followed by tedizolid (MIC₉₀ = 0.38 μg/mL), linezolid, ceftobiprole, and daptomycin (MIC₉₀ = 1 μg/mL). Dalbavancin demonstrated significantly lower MIC₅₀ and MIC₉₀ values compared to vancomycin (0.064 vs. 1 and 0.094 vs. 2, respectively). Tedizolid exhibited an almost threefold greater level of in vitro activity than linezolid, and also had superior in vitro activity compared to ceftobiprole, daptomycin and vancomycin. Multidrug-resistant (MDR) phenotypes were detected among 71.8% of the isolates. In conclusion, ceftobiprole, dalbavancin and tedizolid exhibited potent activity against MRSA and are promising antimicrobials in the management of SSTIs caused by MRSA.

The clinical and economic burden of community-onset complicated skin and skin structure infections in Korea

BACKGROUND/AIMS

To investigate epidemiologic characteristics, clinical and economic burdens, and factors associated with mortality in complicated skin and skin structure infection (cSSSI) patients in Korea.

METHODS

A retrospective, observational, nationwide study was conducted between April to July 2012 at 14 tertiary-hospitals in Korea. Eligible patients were hospitalized adults with community acquired cSSSI, who underwent surgical intervention and completed treatment between November 2009 and October 2011. Data on demography, clinical characteristics, outcomes and medical resource utilization were collected through medical record review. Direct medical costs were calculated by multiplying quantities of resources utilized by each unit price in Korea.

RESULTS

Of 473 patients enrolled, 449 patients (except 24 patients with no record on surgical intervention) were eligible for analysis. Microbiological testing was performed on 66.1% of patients and 8.2% had multiple pathogens. Among culture confirmed pathogens (n = 297 patients, 340 episodes), 76.2% were gram-positive (Staphylococcus aureus; 41.2%) and 23.8% were gram-negative. The median duration of hospital stay was 16 days. Among treated patients, 3.3% experienced recurrence and 4.2% died in-hospital. The mean direct medical costs amounted to $4,195/ person, with the greatest expenses for hospitalization and antibiotics. The in-hospital mortality and total medical costs were higher in combined antibiotics therapy than monotherapy (p < 0.05). Charlson's comorbidity index ≥ 3, standardized early warning scoring ≥ 4, sub-fascia infections and combined initial therapy, were all found to be associated with higher mortality.

CONCLUSION

Korean patients with community-onset cSSSI suffer from considerable clinical and economic burden. Efforts should be made to reduce this burden through appropriate initial treatment.

Synergy between conventional antibiotics and anti-biofilm peptides in a murine, sub-cutaneous abscess model caused by recalcitrant ESKAPE pathogens

With the antibiotic development pipeline running dry, many fear that we might soon run out of treatment options. High-density infections are particularly difficult to treat due to their adaptive multidrug-resistance and currently there are no therapies that adequately address this important issue. Here, a large-scale in vivo study was performed to enhance the activity of antibiotics to treat high-density infections caused by multidrug-resistant Gram-positive and Gram-negative bacteria. It was shown that synthetic peptides can be used in conjunction with the antibiotics ciprofloxacin, meropenem, erythromycin, gentamicin, and vancomycin to improve the treatment outcome of murine cutaneous abscesses caused by clinical hard-to-treat pathogens including all ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter cloacae) pathogens and Escherichia coli. Promisingly, combination treatment often showed synergistic effects that significantly reduced abscess sizes and/or improved clearance of bacterial isolates from the infection site, regardless of the antibiotic mode of action. In vitro data suggest that the mechanisms of peptide action in vivo include enhancement of antibiotic penetration and potential disruption of the stringent stress response.

Antimicrobial Peptides and Their Therapeutic Potential for Bacterial Skin Infections and Wounds

Alarming data about increasing resistance to conventional antibiotics are reported, while at the same time the development of new antibiotics is stagnating. Skin and soft tissue infections (SSTIs) are mainly caused by the so called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) which belong to the most recalcitrant bacteria and are resistant to almost all common antibiotics. S. aureus and P. aeruginosa are the most frequent pathogens isolated from chronic wounds and increasing resistance to topical antibiotics has become a major issue. Therefore, new treatment options are urgently needed. In recent years, research focused on the development of synthetic antimicrobial peptides (AMPs) with lower toxicity and improved activity compared to their endogenous counterparts. AMPs appear to be promising therapeutic options for the treatment of SSTIs and wounds as they show a broad spectrum of antimicrobial activity, low resistance rates and display pivotal immunomodulatory as well as wound healing promoting activities such as induction of cell migration and proliferation and angiogenesis. In this review, we evaluate the potential of AMPs for the treatment of bacterial SSTIs and wounds and provide an overview of the mechanisms of actions of AMPs that contribute to combat skin infections and to improve wound healing. Bacteria growing in biofilms are more resistant to conventional antibiotics than their planktonic counterparts due to limited biofilm penetration and distinct metabolic and physiological functions, and often result in chronification of infections and wounds. Thus, we further discuss the feasibility of AMPs as anti-biofilm agents. Finally, we highlight perspectives for future therapies and which issues remain to bring AMPs successfully to the market.

Ceftaroline fosamil treatment outcomes compared with standard of care among hospitalized patients with complicated skin and soft tissue infections

AIM

Compare clinical and cost outcomes associated with ceftaroline fosamil with other commonly used antibiotics in complicated skin and soft tissue infections.

METHODS

Retrospective analysis of hospital records from 2010 to 2013 in Premier's Perspective comparative database for adults with complicated skin and soft tissue infection treated with intravenous ceftaroline fosamil, vancomycin, daptomycin, linezolid or tigecycline. Length of stay, inpatient costs and mortality were compared between propensity score-matched treatment groups.

RESULTS & CONCLUSION

Compared with the other commonly used antibiotics, matched patients in the ceftaroline fosamil treatment group had an equivalent (1%) or lower (compared with linezolid, 2%) in-hospital mortality rate, and significantly lower (p < 0.001) average unadjusted and regression-adjusted length of stay and inpatient costs (savings of $3398.80 compared with daptomycin).

Epidemiology and Outcomes of Complicated Skin and Soft Tissue Infections among Inpatients in Southern China from 2008 to 2013

Complicated skin and soft tissue infections (cSSTI) are some of the most commonly treated infections in hospitals, and place heavy economic burdens on patients and society. Here we report the findings from an analysis of cSSTI based on a retrospective study which was conducted within the Chinese inpatient population. We focused our research on the analysis of the patient population, antibiotic treatment, clinical outcome and economic burden. The study population comprised 527 selected patients hospitalized between 2008 and 2013. Among the hospitalizations with microbiological diagnoses, 61.41% (n = 113) were diagnosed as infected with Gram-positive bacteria, while 46.20% (n = 85) were infected with Gram-negative bacteria. The most commonly found Gram-positive bacteria was Staphylococcus aureus (40.76%, n = 75), and the most common Gram-negative bacteria was Escherichia coli (14.13%, n = 26). About 20% of the Staphylococcus aureus were methicillin-resistant. The resistance rate of isolated Staphylococcus aureus or Escherichia coli to penicillin was around 90%; in contrast, the resistance rate to vancomycin, linezolid or imipenem was low (<20%). A large percentage of patients were treated with cephalosporins and fluoroquinolones, while vancomycin and imipenem were also included to treat drug-resistant pathogens. Over half of the hospitalizations (58.43%, n = 336) experienced treatment modifications. The cost to patients with antibiotic modifications was relatively higher than to those without. In conclusion, our study offers an analysis of the disease characteristics, microbiological diagnoses, treatment patterns and clinical outcomes of cSSTI in four hospitals in Guangdong Province, and sheds lights on the current clinical management of cSSTI in China.

The large scale antibacterial, antifungal and anti-phage efficiency of Petamcin-A: new multicomponent preparation for skin diseases treatment

BACKGROUND

Human and animal skin diseases of bacterial, fungal and viral nature and their complications are widespread and globally cause a serious trouble. Their prevalence is increasing mainly due to drug resistance. Consequently, demand has increased for new effective antimicrobial drugs, which also should be less toxic, possess a wider spectrum of action and be economically more beneficial. The goal was to investigate antibacterial, antifungal and anti-phage activity of Petamcin-A-a new multicomponent preparation. It contains acetic acid and hexamethylenetetramine as main active antimicrobial components, as well as phosphatidylcholine, tocopheryl acetate and glycerol as excipients.

METHODS

Bacteriostatic activity and minimal inhibitory concentrations of the preparation against various test-organisms were determined by agar well diffusion assay. Antifungal activity was tested by agar dilution assay. To explore anti-phage activity double agar overlay plaque assay was used. Nystatin, chlorhexidine and acetic acid were used as control agents for comparative analysis. Statistical analysis was done with GraphPad Prism 5.03 or R 3.1.0 software.

RESULTS

The results showed a higher activity of Petamcin-A against all bacterial and fungal test strains compared with its components or control agents. The preparation was more effective against tested gram-positive bacteria than gram-negative ones. Petamcin-A expressed bactericidal activity against almost all test strains. In addition, the preparation demonstrated high activity against T4 phage of Escherichia coli C-T4 completely inhibiting its growth. 5-fold diluted Petamcin-A also exhibited considerable activity reducing phage concentration by 2.6 Log10.

CONCLUSIONS

Petamcin-A has a high antimicrobial activity against all tested strains of bacteria, yeasts and moulds. The preparation also exhibited high anti-phage activity. Moreover, taking into account that Petamcin-A has no observable toxicity on skin and its components are not expensive, it can be advantageous for management of various skin medical conditions.

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.

Clinical and bacteriological efficacy of twice daily topical retapamulin ointment 1% in the management of impetigo and other uncomplicated superficial skin infections

BACKGROUND

Cutaneous bacterial infections are common in children and adults and frequently are caused by Staphylococcus aureus (S. aureus). Treatment failures with topical agents are not uncommon and have been shown to be secondary to bacterial resistance.

OBJECTIVE

To determine clinical and bacteriological efficacy of retapamulin ointment 1% in treatment of patients with cutaneous bacterial infections caused by methicillin-resistant S. aureus (MRSA) and other bacteria.

METHODS

Prospective, nonrandomized, uncontrolled, open label, single center trial conducted between April 2008 and November 2012 that evaluated efficacy of retapamulin ointment 1% in the treatment of impetigo, folliculitis, and other minor soft tissue infections in children and adults. Fifty patients, who presented to a dermatology outpatient clinic and were clinically diagnosed with impetigo, folliculitis, or minor soft tissue infection suitable for treatment with a topical antibiotic, were screened. Thirty-eight patients were enrolled and received treatment: topical retapamulin ointment 1% twice daily for 5 days. Seven patients were MRSA positive and qualified for the primary efficacy population. One patient withdrew due to an adverse event. Clinical and microbiological exams were performed at baseline and follow-up 5 to 7 days later to assess clinical, microbiological, and therapeutic responses. Primary outcome was clinical response at follow-up in primary efficacy population with MRSA isolated as the baseline pathogen. Secondary outcomes included clinical, microbiologic, and therapeutic responses in patients who were culture positive for any species of bacteria.

RESULTS

Clinical response at follow-up in the primary efficacy population (MRSA-positive patients) was not sufficiently powered to demonstrate significance; however, outcomes were excellent, with 7 of 7 patients demonstrating clinical success (5 of 7) or clinical improvement (2 of 7) at follow-up. Barring lack of significance due to small total sample size for patients who were culture positive for any species of bacteria (n = 35), overall success rates were favorable for clinical, microbiologic, and therapeutic responses with values of 66%, 97%, and 69%, respectively. Adverse events (AEs) were mild or moderate in severity. No serious AEs were reported.

CONCLUSION

Safety profile appears favorable given the low number of AEs. Study design limits conclusions that can be drawn. Nevertheless, this study supports use of topical retapamulin 1% ointment in treatment of cutaneous bacterial infections, particularly those caused by S. aureus, including MRSA.

Clinical and Economic Consequences of Failure of Initial Antibiotic Therapy for Hospitalized Patients With Complicated Skin and Skin-Structure Infections

Objective.

To estimate the consequences of failure of initial antibiotic therapy for patients with complicated skin and skin-structure infections.

Design.

Retrospective cohort study.

Setting.

Large US multihospital database.

Patients.

We identified a total of 47,219 patients (age 18 years or older) who were admitted to the hospital for complicated skin and skin-structure infections from April 1, 2003, through March 31, 2004, and who received intravenous antibiotics during the first 2 hospital-days (ie, initial antibiotic therapy). Failure of therapy was defined as drainage, debridement, or receipt of other intravenous antibiotics at any subsequent time (except for changes to narrower-spectrum agents or any therapy change immediately before discharge). Predictors of failure of antibiotic therapy and mortality were examined using multivariate logistic regression. Analysis of covariance was used to estimate the impact of treatment failure on duration of intravenous antibiotic therapy, length of stay, and total inpatient charges.

Results.

For 10,782 admitted patients (22.8%), there was evidence of failure of initial antibiotic therapy. In multivariate analyses, treatment failure was associated with receipt of vasoactive medications during the first 2 hospital-days (odds ratio [OR], 1.66 [95% confidence interval {CI}, 1.19-2.31]), initiation of antibiotic therapy in the intensive care unit (OR, 1.53 [95% CI, 1.28-1.84]), and the patient's Charlson comorbidity index (OR per 1-point increase, 1.06 [95% CI, 1.04-1.08]); treatment failure was also was associated with a 3-fold increase in mortality (OR, 2.91 [95% CI, 2.34-3.62]). Compared with patients for whom initial treatment was successful, patients who experienced treatment failure received intravenous antibiotic therapy for a mean of 5.7 additional days, were hospitalized for a mean of 5.4 additional days, and incurred a mean of $5,285 (in 2003 dollars) in additional inpatient charges (all P <.01).

Conclusion.

Failure of initial antibiotic therapy in the treatment of complicated skin and skin-structure infections is associated with significantly worse clinical and economic outcomes.

Modeling economic implications of alternative treatment strategies for acute bacterial skin and skin structure infections

OBJECTIVE

The economic implications from the US Medicare perspective of adopting alternative treatment strategies for acute bacterial skin and skin structure infections (ABSSSIs) are substantial. The objective of this study is to describe a modeling framework that explores the impact of decisions related to both the location of care and switching to different antibiotics at discharge.

METHODS

A discrete event simulation (DES) was developed to model the treatment pathway of each patient through various locations (emergency department [ED], inpatient, and outpatient) and the treatments prescribed (empiric antibiotic, switching to a different antibiotic at discharge, or a second antibiotic). Costs are reported in 2012 USD.

RESULTS

The mean number of days on antibiotic in a cohort assigned to a full course of vancomycin was 11.2 days, with 64% of the treatment course being administered in the outpatient setting. Mean total costs per patient were $8671, with inpatient care accounting for 58% of the costs accrued. The majority of outpatient costs were associated with parenteral administration rather than drug acquisition or monitoring. Scenarios modifying the treatment pathway to increase the proportion of patients receiving the first dose in the ED, and then managing them in the outpatient setting or prescribing an oral antibiotic at discharge to avoid the cost associated with administering parenteral therapy, therefore have a major impact and lower the typical cost per patient by 11-20%. Since vancomycin is commonly used as empiric therapy in clinical practice, based on these analyses, a shift in treatment practice could result in substantial savings from the Medicare perspective.

CONCLUSIONS

The choice of antibiotic and location of care influence the costs and resource use associated with the management of ABSSSIs. The DES framework presented here can provide insight into the potential economic implications of decisions that modify the treatment pathway.

Anti-cooperative ligand binding and dimerisation in the glycopeptide antibiotic dalbavancin

Dalbavancin, a semi-synthetic glycopeptide with enhanced antibiotic activity compared to vancomycin and teicoplanin, binds to the C-terminal lysyl-d-alanyl-d-alanine subunit of Lipid II, inhibiting peptidoglycan biosynthesis. In this study, micro-calorimetry and electrospray ionization (ESI)-MS have been used to investigate the relationship between oligomerisation of dalbavancin and binding of a Lipid II peptide mimic, diacetyl-Lys-d-Ala-d-Ala (Ac2-Kaa). Dalbavancin dimerised strongly in an anti-cooperative manner with ligand-binding, as was the case for ristocetin A, but not for vancomycin and teicoplanin. Dalbavancin and ristocetin A both adopt an 'closed' conformation upon ligand binding, suggesting anti-cooperative dimerisation with ligand-binding may be a general feature of dalbavancin/ristocetin A-like glycopeptides. Understanding these effects may provide insight into design of novel dalbavancin derivatives with cooperative ligand-binding and dimerisation characteristics that could enhance antibiotic activity.

Sequential intravenous/oral moxifloxacin monotherapy for complicated skin and skin structure infections: a meta-analysis of randomised controlled trials

OBJECTIVES

The presumed superiority of moxifloxacin for the treatment of complicated skin and skin structure infections (cSSSIs) is based on laboratory data, but has not yet been established on clinical grounds. The aim of this meta-analysis was to evaluate the efficacy and safety of sequential intravenous (i.v.)/oral (p.o.) moxifloxacin monotherapy for the treatment of cSSSIs.

METHODS

Randomised controlled trials (RCTs) published prior to November 2012 were systematically retrieved from PubMed, MEDLINE, EMBASE, ScienceDirect, ClinicalTrials.gov and the Cochrane Central Register of Controlled Trials. Finally, a meta-analysis of all RCTs eligible for inclusion criteria was performed.

RESULTS

Three studies that enrolled 2255 patients were included in the meta-analysis. There were no statistically significant differences between patients given moxifloxacin and those given other antibiotics with regard to clinical success rate [1667 patients, odds ratio (OR) = 0.83, 95% confidence interval (CI) 0.63 to 1.09, p = 0.18], bacteriological success rate (bacteriological success rates: 1502 patients, OR = 0.90, 95% CI 0.68-1.18, p = 0.45) or mortality (2207 patients, OR = 1.96, 95% CI 0.79-4.88, p = 0.15). Significantly, more overall adverse events (AEs) were associated with the use of moxifloxacin than with other antibiotics (2207 patients, OR = 1.21, 95%CI 1.00-1.45, p = 0.04). However, there was no statistically significant difference in the occurrence of drug-related AEs, serious AEs or serious drug-related AEs between patients given moxifloxacin and those given other antibiotics.

CONCLUSION

Sequential i.v./p.o. moxifloxacin monotherapy is an effective and relatively safe option for the treatment of cSSSIs. Other benefits of moxifloxacin may make it a more viable option compared with the currently used regimens.

Ceftaroline fosamil use in hospitalized patients with acute bacterial skin and skin structure infections: Budget impact analysis from a hospital perspective

PURPOSE

The budgetary impact of adding ceftaroline fosamil to a hospital formulary for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) was evaluated.

METHODS

A three-year hospital budget impact model was constructed with three initial treatment options for ABSSSIs: ceftaroline fosamil, vancomycin plus aztreonam, and other vancomycin-containing regimens. The target population was hospitalized adult patients with an ABSSSI. Clinical cure rates with initial treatment were assumed to be similar to those from ceftaroline fosamil clinical trials. Patients who did not respond to initial treatment were assumed to be treated successfully with second-line antimicrobial therapy. Length of stay and cost per hospital day (by success or failure with initial treatment) were estimated based on a large database from more than 100 U.S. hospitals. Other model inputs included the annual number of ABSSSI admissions, projected annual case growth rate, proportion of ABSSSI target population receiving vancomycin-containing regimen, expected proportion of ABSSSI target population to be treated with ceftaroline fosamil, drug acquisition cost, cost of antibiotic administration, and cost of vancomycin monitoring. Sensitivity analysis using 95% confidence limits of clinical cure rates was also performed.

RESULTS

The estimated total cost of care for treating a patient with an ABSSSI was $395 lower with ceftaroline fosamil ($15,087 versus $15,482) compared with vancomycin plus aztreonam and $72 lower ($15,087 versus $15,159) compared with other vancomycin-containing regimens.

CONCLUSION

Model estimates indicated that adding ceftaroline fosamil to the hospital formulary would not have a negative effect on a hospital's budget for ABSSSI treatment.

Acute bacterial skin and skin structure infections: current perspective

A skin and skin structure infection is a bacterial infection of skin and associated tissues. It may be complicated skin and skin structure infection or uncomplicated skin and skin structure infection. Recently, the Food and Drug Administration has called them acute bacterial skin and skin structure infections (ABSSSI). ABSSSI are common and encompass a variety of disease presentations and severity. Increased antimicrobial resistance among both Gram-positive and Gram-negative bacteria with methicillin-resistant Staphylococcus aureus is the main problem in treatment. So, development of newer agents to fight against resistant microbes is the need of the hour. Ceftaroline, a newer cephalosporin, is one promising agent.

Nonviral human beta defensin-3 expression in a bioengineered human skin tissue: a therapeutic alternative for infected wounds

The innate immune system differentially regulates the expression of host defense peptides to combat infection during wound healing. We enhanced the expression of a host defense peptide, human beta defensin-3 (hBD-3), in keratinocytes to generate a three-dimensional biologic dressing to improve healing of infected wounds. The NIKS human keratinocyte cell line was stably transfected ex vivo with a construct containing an epidermis-specific promoter driving hBD-3 (NIKS(hBD) (-3) ) using nonviral methods. Levels of hBD-3 mRNA and protein in three-dimensional skin tissue produced from NIKS(hBD) (-3) were determined using quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Tissue architecture was characterized by hematoxylin and eosin staining and by indirect immunofluorescence using proliferation and keratinocyte differentiation markers. Antimicrobial activity was assessed using an in vitro bacterial growth assay and in vivo using a murine burn infection model. Three-dimensional full thickness skin tissues containing epidermal NIKS(hBD) (-3) or control NIKS possessed histologic features of interfollicular epidermis and exhibited normal tissue growth and differentiation. NIKS(hBD) (-3) tissue contained approximately fivefold more hBD-3 protein than tissue containing unmodified control NIKS. In vitro studies showed that NIKS(hBD) (-3) tissue produced a significant reduction in the growth of Staphylococcus aureus multiple peptide resistance factor (mprF) compared with control tissue. In an in vivo infected murine burn model, NIKS(hBD) (-3) tissue resulted in a 90% reduction in bacterial growth. These results demonstrate that sustained delivery of hBD-3 by a bioengineered skin tissue results in a therapeutically relevant reduction in growth of a S. aureus strain in an animal model of infected third-degree burn wounds.

Bacterial resistance and impetigo treatment trends: a review

Impetigo is a common cutaneous infection that is especially prevalent in children. The prevalence of colonization and infection with resistant strains is continually increasing, forcing clinicians to reevaluate treatment strategies. Newer topical agents are effective in treating infections with resistant strains and may help minimize resistance and adverse effects from systemic agents. Use of topical disinfectants to decrease colonization is an important adjunctive measure. Physicians should be aware of local resistance patterns in impetigo to help guide therapy.

Ceftaroline in complicated skin and skin-structure infections

Ceftaroline is an advanced-generation cephalosporin antibiotic recently approved by the US Food and Drug Administration for the treatment of complicated skin and skin-structure infections (cSSSIs). This intravenous broad-spectrum antibiotic exerts potent bactericidal activity by inhibiting bacterial cell wall synthesis. A high affinity for the penicillin-binding protein 2a (PBP2a) of methicillin-resistant Staphylococcus aureus (MRSA) makes the drug especially beneficial to patients with MRSA cSSSIs. Ceftaroline has proved in multiple well-conducted clinical trials to have an excellent safety and efficacy profile. In adjusted doses it is also recommended for patients with renal or hepatic impairment. Furthermore, the clinical effectiveness and high cure rate demonstrated by ceftaroline in cSSSIs, including those caused by MRSA and other multidrug-resistant strains, warrants its consideration as a first-line treatment option for cSSSIs. This article reviews ceftaroline and its pharmacology, efficacy, and safety data to further elucidate its role in the treatment of cSSSIs.

Resistance and the management of complicated skin and skin structure infections: the role of ceftobiprole

Antimicrobial resistant bacteria are an increasing concern due to the resulting increase in morbidity, mortality, and health-care costs associated with the administration of inadequate or delayed antimicrobial therapy. The implications of inadequate antimicrobial therapy in complicated skin and skin structure infections (cSSSIs) have gained more attention recently, most likely due to the recent emergence of community-acquired methicillin resistant Staphylococcus aureus (MRSA) and the already high prevalence of MRSA in the nosocomial setting. Due to the continuous threat of resistance arising and the limitations of currently available agents for the treatment of cSSSIs, it is necessary to develop new antimicrobials for this indication. Ceftobiprole medocaril, the prodrug of ceftobiprole, is a parental investigational cephalosporin for the treatment of cSSSIs displaying a wide-spectrum of activity against both Gram-positive and Gram-negative species, including MRSA. Ceftobiprole displays noncomplex linear pharmacokinetics, is eliminated primarily by glomerular filtration, and distributes to extracellular fluid. Additionally, it has been shown that the extent of distribution to the site of action with regard to cSSSIs, ie, the extracellular space fluid of subcutaneous adipose tissue and skeletal muscle, is expected to be efficacious, as free concentrations meet efficacy targets for most pathogens. Similar to other beta-lactams, it displays an excellent safety and tolerability profile with the primary adverse events being dysgeusia in healthy volunteers, resulting from the conversion of the prodrug to the active, and nausea in patients. Ceftobiprole has demonstrated noninferiority in two large-scale pivotal studies comparing it to vancomycin, clinical cure rates 93.3% vs 93.5%, respectively, or vancomycin plus ceftazidime, clinical cure rates 90.5% vs 90.2%, respectively. Given the pharmacokinetic and pharmacodynamic properties, ceftobiprole is a promising new agent for the treatment of cSSSIs and has the potential to be used as a single agent for empiric treatment.

A retrospective review of clinical experience with daptomycin for a variety of wound types in a burn and wound care facility

OBJECTIVE

Daptomycin is a novel antibiotic with activity against many Gram-positive organisms that has demonstrated efficacy in the management of skin and soft tissue infections (SSTIs). However, data regarding the use of daptomycin for the management of burn wound infections are lacking. We assessed the efficacy and safety of daptomycin in the treatment of complicated skin and soft tissue infections (cSSTIs), including burn wound infections.

METHODS

We performed a retrospective review of patients receiving daptomycin for burn wound infections and other cSSTIs in a referral burn and wound treatment center.

RESULTS

Our review revealed an overall success rate (microbiological cure + clinically improved) of 99.5%, with an overall success rate of 98.5% among burn patients, specifically. The overall success rate was 100% among patients in the three other diagnosis groups (cSSTIs, chronic wounds, and other infections). A success rate of 98% was noted among the subset of patients with wounds associated with bacteremia.

CONCLUSIONS

Our study suggests that daptomycin is a safe and effective agent for the management of burn wound infections, although further study is warranted to confirm these results.

Antimicrobial agents for complicated skin and skin-structure infections: justification of noninferiority margins in the absence of placebo-controlled trials

BACKGROUND

The United States Food and Drug Administration requires clinical trial noninferiority margins to preserve a fraction (eg, 50%) of the established comparator drug's efficacy versus placebo. Lack of placebo-controlled trials for many infections complicates noninferiority margin justification for and, hence, regulatory review of new antimicrobial agents. Noninferiority margin clarification is critical to enable new antimicrobial development. In the absence of placebo-controlled trials, we sought to define the magnitude of efficacy of antimicrobial agents and resulting noninferiority margins for studies of complicated skin and skin-structure infection (SSSI).

METHODS

We systematically reviewed literature on complicated SSSI published during 1900-1950 (before widespread penicillin resistance) to define treatment outcomes and confidence intervals (CIs). Antimicrobial efficacy was calculated as the lower limit CI of the cure rate with antimicrobials minus the upper limit CI of the cure rate without antimicrobials.

RESULTS

We identified 90 articles describing >28,000 patients with complicated SSSI. For cellulitis/erysipelas, cure rates were 66% (95% CI, 64%-68%) without antibiotics and 98% (95% CI, 96%-99%) for penicillin-treated patients, and penicillin reduced mortality by 10%. Cure rates for wound/ulcer infections were 36% (95% CI, 32%-39%) without antibiotics and 83% (95% CI, 81%-85%) for penicillin-treated patients. For major abscesses, cure rates were 76% (95% CI, 71%-80%) without antibiotics and 96% (95% CI, 94%-98%) for penicillin-treated patients; penicillin reduced mortality by 6%.

CONCLUSION

Systematic review of historical literature enables rational noninferiority margin justification in the absence of placebo-controlled trials and may facilitate regulatory review of noninferiority trials. Noninferiority margins of 14% for cellulitis/erysipelas, 21% for wound/ulcer infections, and 7% for major abscesses would preserve >or= 50% of antibiotic efficacy versus placebo for these complicated SSSI subsets.

Cost-effectiveness of linezolid versus vancomycin for hospitalized patients with complicated skin and soft-tissue infections in France

Studies have shown similar clinical cure rates and shorter length of hospitalization when using linezolid compared to vancomycin in patients with complicated skin and soft-tissue infections due to suspected or proven methicillin-resistant Staphylococcus aureus (MRSA).

OBJECTIVE

This study had for aim to compare the cost-effectiveness of linezolid versus vancomycin in French healthcare settings.

METHOD

A decision-analytic model followed an average patient from the initiation of an empiric treatment until cure, death or second-line treatment failure. A clinical data probability was obtained from clinical trials, resource utilization data (including treatment duration and length of hospitalization) and prevalence of MRSA was obtained from a Delphi panel, and costs from published sources.

RESULTS

First-line cure rate for linezolid-treated patients was 90.7% versus 85.5% for vancomycin; the total cure rates after two lines of treatment were 98.5% and 98.0%, respectively. The average total cost was 7,778euro for linezolid versus 8,777euro for vancomycin. The mean estimated length of hospitalization after two lines of treatment was 10.7 days for linezolid versus 13.3 days for vancomycin. The increased effectiveness and reduced cost lead to more frequent prescription. This did not change after one-way sensitivity analyses.

CONCLUSION

Linezolid may be considered as a cost-effective treatment for patients with complicated skin and soft-tissue infections suspected to be MRSA related in France.

Inflammation and the host response to injury, a large-scale collaborative project: patient-oriented research core--standard operating procedures for clinical care VII--Guidelines for antibiotic administration in severely injured patients

When the clinical decision to treat a critically ill patient with antibiotics has been made, one must attempt to identify the site of infection based on clinical signs and symptoms, laboratory or diagnostic radiology studies. Identification of site requires, examination of patient, inspection of all wounds, chest radiograph, and calculation of clinical pulmonary infection score if ventilated, obtaining blood cultures, urinalysis, and line change if clinical suspicion of central venous catheter (CVC) source. If it is impossible to identify site, obtain cultures from all accessible suspected sites and initiate empiric, broad spectrum antibiotics. If likely site can be identified answer these questions: Is intra-abdominal site suspected? Is pulmonary source of infection suspected? Is skin, skin structure or soft tissue site suspected? If yes, does the patient have clinical signs suspicion for necrotizing soft tissue infection (NSTI)? Is a CVC infection suspected? Risk factors for more complicated infections are discussed and specific antibiotic recommendations are provided for each type and severity of clinical infection. Decision to continue, discontinue and/or alter antibiotic/antimicrobial treatment should be based on the clinical response to treatment, diagnostic or interventional findings, and culture and sensitivity data, bearing in mind that not all patients with infections will have positive cultures because of limitations of specimen handling, microbiology laboratory variations, time between specimen acquisition and culture, or presence of effective antibiotics at the time that specimens were obtained. It should also be noted that not all patients with increased temperature/WBC have an infection. Discontinuation of antibiotics is appropriate if cultures and other diagnostic studies are negative.

Outcomes associated with initial versus later vancomycin use in patients with complicated skin and skin-structure infections

BACKGROUND

Delayed coverage of pathogens including meticillin-resistant Staphylococcus aureus (MRSA) in pneumonia and bacteraemia has been associated with increased mortality and length of hospital stay (LOS). However, less is known about the impact of delayed appropriate coverage in complicated skin and skin-structure infections (cSSSIs).

OBJECTIVE

To evaluate the clinical and economic outcomes associated with early versus late use of vancomycin in the management of patients hospitalized for cSSSIs.

METHODS

Retrospective analysis was performed using an inpatient claims database of >500 US hospitals in 2005. Using prescription claims, patients with primary or secondary cSSSI admissions were classified into three groups: 1 = early vancomycin monotherapy; 2 = early vancomycin combination therapy; 3 = late vancomycin therapy. Outcomes studied included LOS and inpatient hospital costs. One-way analysis of variance was used for unadjusted analysis and multivariate regression methods were used to control for co-variates.

RESULTS

A total of 34,942 patients (27.78% of all patients with cSSSIs) were treated with vancomycin. Mean age was 54.7 years and 54.3% of the patients were males. Mean unadjusted total LOS was 8.46, 9.44 and 13.2 days, and hospital costs in 2005 values were USD10 211.94, USD12 361.94 and USD18 344.00 for groups 1, 2 and 3, respectively. In-hospital mortality rate was highest in group 3 (4.18%) and lowest in group 1 (1.75%). Generalized linear models used to control for potential confounding variables between early versus late vancomycin use suggest that among cSSSI patients late vancomycin use is an independent predictor of higher LOS and costs.

CONCLUSION

In this large inpatient database, later vancomycin use in patients with cSSSIs appears to be significantly associated with higher LOS and total costs.

Efficacy and safety of tigecycline compared with vancomycin or linezolid for treatment of serious infections with methicillin-resistant Staphylococcus aureus or vancomycin-resistant enterococci: a Phase 3, multicentre, double-blind, randomized study

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are causing serious nosocomial infections. Tigecycline was evaluated in hospitalized patients with MRSA or VRE infection.

PATIENTS AND METHODS

A randomized (3:1), double-blind, multicentre, Phase 3 study compared the safety and efficacy of tigecycline with vancomycin or linezolid in hospitalized patients with MRSA or VRE infection, respectively. Patients were treated for 7-28 days and the test-of-cure (TOC) assessment was made 12-37 days after the last dose. The primary efficacy endpoint was the clinical response (cure, failure and indeterminate) in the co-primary, microbiologically evaluable (ME) and microbiologically modified intent-to-treat (m-mITT) populations at the TOC assessment.

RESULTS

For MRSA infection, clinical cure rates in the ME population (n = 117) were 81.4% (70 of 86 patients) with tigecycline and 83.9% (26 of 31 patients) with vancomycin. In the m-mITT population (n = 133), clinical cure occurred in 75 of 100 tigecycline-treated patients (75.0%) and in 27 of 33 vancomycin-treated patients (81.8%). In patients with complicated skin and skin structure infections caused by MRSA, cure rates were similar with tigecycline or vancomycin (86.4% versus 86.9% in ME population; and 78.6% versus 87.0% in m-mITT population). In patients with MRSA infection, nausea or vomiting occurred more frequently with tigecycline than with vancomycin (41.0% versus 17.9%); most cases were mild, with only three patients discontinuing treatment. In patients with VRE (total enrollment, 15), 3 of 3 and 3 of 8 patients in the ME and m-mITT populations, respectively, were cured by tigecycline, compared with 2 of 3 patients in the ME and m-mITT populations treated with linezolid.

CONCLUSIONS

Tigecycline is safe and effective in hospitalized patients with serious infection caused by MRSA. There were too few cases of VRE to draw any conclusions.

In vitro activity of ceftobiprole against pathogens from two phase 3 clinical trials of complicated skin and skin structure infections

In phase 3 clinical trials for ceftobiprole treatment of complicated skin and skin structure infections, 1,219 gram-positive and 276 gram-negative aerobic baseline pathogens were identified. Ceftobiprole inhibited all staphylococcal isolates, including methicillin-resistant strains, at MICs of </=4 mug/ml. Against Enterobacteriaceae and Pseudomonas aeruginosa isolates, the potency of ceftobiprole was similar to that of cefepime.

Novel antibiotics for the management of diabetic foot infections

Foot infections are a major cause of morbidity in diabetic patients. Staphylococcus aureus is the most important pathogen in mild infections; moderate to severe infections are frequently polymicrobial. Multidrug resistance is an increasing problem in isolates from diabetic feet. Worldwide, up to 30% of patients with diabetic foot infection (DFI) are colonised with methicillin-resistant S. aureus (MRSA), whilst extended-spectrum beta-lactamase-producing Gram-negative bacteria are also common in some countries. This emergence of drug resistance has coincided with the launch or imminent availability of many new antibiotics. Most of these were developed to target multidrug-resistant Gram-positive bacteria, although some have a spectrum of activity that includes Gram-negative bacteria and anaerobes. There is a variable amount of experience with these agents in treating skin and skin-structure infections (SSSIs), especially for DFI. However, at least some have a spectrum of activity and/or pharmacological properties that suggest that they may be of value in managing DFIs. The aim of this paper is to review evidence for the efficacy of new antibiotics in the management of SSSIs, including any data relating specifically to the diabetic foot, and to consider where they might fit into the therapeutic armory against DFI.

Update on daptomycin: the first approved lipopeptide antibiotic

Daptomycin, the first approved member of the lipopeptide antibiotic class, exhibits potent bactericidal in vitro activity against most Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus species and penicillin-resistant Streptococcus species. Since its approval in 2003 for the treatment of complicated skin and skin structure infections, several review articles have summarised daptomycin's mechanism of action, pharmacokinetics, pharmacodynamics, clinical trials and safety profiles. The objective of this paper is to summarise past information with a focus on the latest susceptibility data of isolates collected worldwide, new pharmacodynamic studies, clinical data regarding bacteraemia/endocarditis and postmarketing surveillance in the treatment of skin and skin-structure infections.

Postmarketing clinical experience in patients with skin and skin-structure infections treated with daptomycin

A registry describing daptomycin's clinical use was analyzed to describe treatment of skin and skin-structure infections (SSSIs). The Cubicin Outcomes Registry and Experience (CORE) 2004 retrospectively collected demographic, microbiologic, and clinical outcome information of patients treated with daptomycin (Cubicin; Cubist Pharmaceuticals, Inc., Lexington, MA). The database was accessed to identify patients with a diagnosis of an SSSI with an outcome determined. Of 577 patients identified with a SSSI, 522 (90%) were evaluable. Diabetes mellitus and peripheral vascular disease were present in 27% and 10% of the population, respectively. Pathogens were identified for 65% of all patients-Staphylococcus aureus (75%; 85% methicillin-resistant) and Enterococcus species (19%; 44% vancomycin-resistant) most commonly. Concomitant use of other antibiotics was common (42%). Of 522 patients studied, 334 (64%) had complicated infections (cSSSIs), and 188 (36%) had uncomplicated infections (uSSSIs). Overall cure, improved, and failure rates were 53%, 43%, and 4%, respectively, for cSSSI and 66%, 32%, and 2%, respectively, for uSSSI. The median dose administered was 4.0 mg/kg for cSSSI (mean, 4.5+/-1.0 mg/kg; range, 2.3 to 12 mg/kg) and 4.0 mg/kg for uSSSI (mean, 4.2+/-0.8 mg/kg; range, 2.1 to 9 mg/kg); the dose was significantly higher in cSSSI (P <0.001, median test). Median daptomycin treatment duration was 12 days (range, 1 to 148 days) and was longer for cSSSI than for uSSSI (14 vs. 10 days, P = 0.002). The results of this study support previously published reports and suggest that daptomycin is effective for the treatment of skin infections due to gram-positive pathogens.

Efficacy of gaseous nitric oxide in the treatment of skin and soft tissue infections

Bacterial burden significantly interferes with the healing process in chronic ulcers. Nitric oxide (NO) plays a key role in regulating skin's response to infection and wound healing. In previous studies, we demonstrated that exogenous NO gas (gNO) at 200 parts per million (ppm) exhibits potent antimicrobial effects against a representative range of pathogens. The aim of the present study is to explore the antimicrobial properties of gNO in vivo and to determine skin cells' sensitivity to the cytotoxic effects of gNO. To test gNO's antimicrobial effects, full-thickness wounds were infected with Staphylococcus aureus on the dorsal skin surface of New Zealand White rabbit and treated with 200 ppm gNO for 8 hours/day for 3 consecutive days. Significant reduction in wound bacterial content was observed in the presence of gNO. In a separate experiment, primary cultures of human fibroblasts, keratinocytes, and endothelial cells were established to test gNO's cytotoxicity in the skin. Methyl thiazolyl tetrazolium proliferation assays demonstrated that human skin cells, unlike bacterial cells, exhibited significant resistance toward gNO cytotoxicity. In vitro migration studies on keratinocytes and endothelial cells revealed that gNO treatment does not seem to interfere with reepithelialization and angiogenesis during the process of wound healing. Following 24 hours of gNO treatment, fibroblasts expressed significantly higher levels of procollagen and, to a lesser degree, a decrease in matrix metalloproteinase -1 mRNA. In conclusion, the present study provides evidence for the potential application of high doses of gNO as an antimicrobial agent for the treatment of infection in chronic nonhealing ulcers or burn patients, without compromising the viability, and function of skin cells.

Skin and skin structure infections: treatment with newer generation fluoroquinolones

Skin and skin structure infections (SSSI) are an emerging issue in healthcare. They are responsible for increasing heathcare utilization, both in hospitalizations and intravenous antibiotic use. SSSI are caused by an evolving variety of pathogens, including Gram-positive, Gram-negative, and anaerobic bacteria. In combination with mounting resistance patterns, this diverse range of bacteria mandate empiric broad-spectrum antibiotic coverage. Historically, cephalosporins and penicillins have been the mainstay of treatment, but recent data suggest newer generation fluoroquinolones are being used with increasing frequency. In 2005, moxifloxacin joined gatifloxacin and levofloxacin as newer generation fluoroquionolones with Food and Drug Administration indications for SSSIs. Even within this group there exist subtle differences that impact optimal management. This paper offers the clinician a comparative review of the antimicrobial spectrum, pharmacodynamics, pharmacokinetics, and clinical efficacy data to support the appropriate use of fluoroquinolones in SSSIs.

Potency and spectrum of garenoxacin tested against an international collection of skin and soft tissue infection pathogens: report from the SENTRY antimicrobial surveillance program (1999-2004)

The spectrum and potency of garenoxacin, a novel des-F(6)-quinolone, against a large international collection (11723 strains) of Gram-positive and Gram-negative bacterial pathogens that cause skin and soft tissue infections (SSTIs) were evaluated for the years 1999 to 2004. Consecutive nonduplicate bacterial isolates were collected from patients with documented community-acquired or nosocomial SSTI in >70 medical centers participating in the SENTRY Antimicrobial Surveillance Program in North America (37.4%), Europe (26.7%), Latin America (16.7%), and the Asia-Pacific region (19.2%). All isolates were tested using the reference broth microdilution methods against garenoxacin, ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin, and representative comparator agents used for the empiric or directed therapy for SSTI. Ranking pathogens producing SSTI during these years included Staphylococcus aureus (42.8%), Pseudomonas aeruginosa (11.1%), Escherichia coli (9.0%), Enterococcus spp. (7.3%), Klebsiella spp. (4.8%), Enterobacter spp. (4.7%), beta-hemolytic streptococci (4.3%), coagulase-negative staphylococci (4.0%), Proteus mirabilis (2.5%), and Acinetobacter spp. (2.1%). Garenoxacin was the most potent agent tested against S. aureus and was at least 2-fold more active than gatifloxacin (MIC(50), 0.06 mg/L) and 8-fold more active than levofloxacin (MIC(50), 0.25 mg/L). Furthermore, garenoxacin was 2- to 8-fold more potent than the fluoroquinolones against beta-hemolytic and viridans group streptococci, as well as up to 4-fold more active against enterococci. Garenoxacin was largely comparable with the comparator fluoroquinolones against E. coli, Klebsiella spp., and Acinetobacter spp., but it is less active than these agents against P. aeruginosa. In summary, garenoxacin was documented to be the most potent quinolone when tested against key Gram-positive pathogens (S. aureus, beta-hemolytic streptococci, viridans group streptococci, and enterococci) and was similar in activity to these agents against other species (Enterobacteriaceae and Acinetobacter spp.). These in vitro data suggest that garenoxacin warrants further clinical studies in SSTI, especially against staphylococci and streptococcal pathogens.

Investigational treatments for postoperative surgical site infections

Surgical site infections rank third among nosocomial infections, representing a global threat, associated with the emergence of multi-drug-resistant bacteria. The pharmaceutical industry has recently curtailed developmental programmes; however, the need for new compounds is extremely important. This article reviews new antimicrobials and immunointerventional targets for their potential to treat surgical site infections in comparison with recently licensed compounds. Daptomycin, dalbavancin, oritavancin, telavancin, iclaprim and ranbezolid seem to be promising agents against infections caused by Gram-positive pathogens and effectively address the present problems of multi-resistance in Gram-positive infections. Peptide deformylase inhibitors and immunostimulating agents open new perspectives in this field; however, very few compounds targeting Gram-negative problematic pathogens are in the pipeline of the future. Tigecycline (recently marketed) ceftobiprole, ceftaroline and doripenem seem to possess an extended anti-Gram-positive and -negative spectrum. Among these compounds, only doripenem demonstrates activity against Pseudomonas aeruginosa, for which there is a clear unmet need for new compounds, focusing on new targets.

Use of Pharmacodynamic Principles to Optimise Dosage Regimens for Antibacterial Agents in the Elderly

Throughout most of the world we are witnessing an ever increasing number of aged people as a percentage of the general population. In the coming years, the unique spectrum of infections presented by an elderly population, particularly those in long-term care facilities, will challenge our ability to maintain an effective battery of antibacterials. The pharmacokinetic parameters of most antibacterial agents are altered when assessed in the elderly due in part to non-pathological physiological changes. The inability to clear a drug from the body due to declining lung, kidney/bladder, gastrointestinal and circulatory efficiency can cause accumulation in the body of drugs given in standard dosages. While this may have the potential benefit of achieving therapeutic concentrations at a lower dose, there is also a heightened risk of attaining toxic drug concentrations and an increased chance of unfavourable interactions with other medications. Pharmacodynamic issues in the elderly are related to problems that arise from treating elderly patients who may have a history of previous antibacterial treatment and exposure to resistant organisms from multiple hospitalisations. Furthermore, the elderly often acquire infections in tandem with other common disease states such as diabetes mellitus and heart disease. Thus, it is essential that optimised dosage strategies be designed specifically for this population using pharmacodynamic principles that take into account the unique circumstances of the elderly. Rational and effective dosage and administration strategies based on pharmacodynamic breakpoints and detailed understanding of the pharmacokinetics of antibacterials in the elderly increase the chances of achieving complete eradication of an infection in a timely manner. In addition, this strategy helps prevent selection of drug-resistant bacteria and minimises the toxic effects of antibacterial therapy in the elderly patient.