Impetigo: A need for new therapies in a world of increasing antimicrobial resistance

International comparison of guidelines for management of impetigo: a systematic review

BACKGROUND

Impetigo is a common superficial skin infection that affects people worldwide and is usually treated with antibiotics; therefore, its management has implications for global antibiotic stewardship.

OBJECTIVE

This systematic review and narrative synthesis compares and contrasts international impetigo management guidelines.

METHODS

Guidelines for treatment of impetigo that were produced by a national authority; available to primary care physicians; and published since 2008 were included. Following a comprehensive search strategy, data extraction from eligible studies was performed independently in duplicate. Details of antiseptic and antibiotic treatment; methicillin-resistant Staphylococcus aureus treatment; and conservative management and preventative measures were tabulated and analysed descriptively.

RESULTS

Fifty-one guidelines were included from 42 different countries. All guidelines recommended systemic antibiotics, 78% of these only for widespread lesions or failure of topical antibiotic treatment. The first-line systemic antibiotic treatment was restricted to narrow-spectrum options in 21 (41%) whilst 7 (14%) recommended only broad-spectrum antibiotics first-line. Thirty-four (67%) guidelines included recommendations for topical antibiotic use. Twenty guidelines (39%) did not mention antiseptic treatment for impetigo. Guidelines did not always provide clear indications for different treatment options.

CONCLUSIONS

Despite potentially equal efficacy to systemic antibiotics, only two-thirds of guidelines include topical antibiotic options. Many fail to include recommendations for non-antibiotic treatments such as antiseptics, preventative measures and conservative management, despite potential for antibiotic-sparing. Provision of clear definitions of disease severity and indications for treatment would enhance the ability of clinicians to adhere to recommendations.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018117770.

Emerging Treatment Strategies for Impetigo in Endemic and Nonendemic Settings: A Systematic Review

PURPOSE

Impetigo affects approximately 162 million children worldwide at any given time. Lack of consensus on the most effective treatment strategy for impetigo and increasing antibiotic resistance continue to drive research into newer and alternative treatment options. We conducted a systematic review to assess the effectiveness of new treatments for impetigo in endemic and nonendemic settings.

METHODS

We searched PubMed, MEDLINE, CINAHL, Web of Science, and Embase via Scopus for studies that explored treatments for bullous, nonbullous, primary, and secondary impetigo published between August 1, 2011, and February 29, 2020. We also searched online trial registries and hand-searched the reference lists of the included studies. We used the revised Cochrane risk of bias (version 2.0) tool for randomized trials and the National Heart, Lung, and Blood Institute for nonrandomized uncontrolled studies to assess the risk of bias.

FINDINGS

We included 10 studies that involved 6651 participants and reported on 9 treatments in the final analysis. Most clinical trials targeted nonbullous impetigo or did not specify this. The risk of bias varied among the studies. In nonendemic settings, ozenoxacin 1% cream appeared to have the strongest evidence base compared with retapamulin and a new minocycline formulation. In endemic settings, oral co-trimoxazole and benzathine benzylpenicillin G injection were equally effective in the treatment of severe impetigo. Mass drug administration intervention emerged as a promising public health strategy to reduce the prevalence of impetigo in endemic settings.

IMPLICATIONS

This review highlights the limited research into new drugs used for the treatment of impetigo in endemic and nonendemic settings. Limited recent evidence supports the use of topical ozenoxacin or retapamulin for impetigo treatment in nonendemic settings, whereas systemic antibiotics and the mass drug administration strategy have evidence for use in endemic settings. Given the troubling increase in resistance to existing treatments, there is a clear need to ensure the judicious use of antibiotics and to develop new treatments and alternative strategies; this is particularly important in endemic settings. PROSPERO identifier: CRD42020173042.

A comparative review of current topical antibiotics for impetigo

INTRODUCTION

Impetigo is a superficial bacterial skin infection largely affecting the pediatric population. The objective of this review is to provide a comparison of mechanism of action, efficacy and safety of the available topical antibiotics for impetigo.

AREAS COVERED

Randomized clinical trials that evaluated the use of topical antibiotics for treatment of impetigo were included. Two thousand eighty-nine studies were initially identified, and five randomized clinical trials met the criteria for further analysis.

EXPERT OPINION

Topical antibiotics had greater resolution of impetigo in comparison to vehicle in these pivotal clinical trials. Adverse events were minimal, with the most common being pruritus at the application site. Cost or insurance coverage may be a limiting factor in choosing the best therapeutic agent, with mupirocin ointment having the lowest cost. Mupirocin has shown clinical efficacy against MRSA but a bacterial culture is recommended to rule out resistance. Ozenoxacin and retapamulin are effective alternatives but may entail higher cost. Retapamulin is indicated for lesions of impetigo that are colonized by MSSA and streptococcus S. pyogenes but not MRSA based on clinical efficacy of phase III trials. Fusidic acid, available in other countries, is a non-FDA approved medication although rising resistance rates represent a growing concern.

Intolerable Burden of Impetigo in Endemic Settings: A Review of the Current State of Play and Future Directions for Alternative Treatments

Impetigo (school sores) is a common superficial bacterial skin infection affecting around 162 million children worldwide, with the highest burden in Australian Aboriginal children. While impetigo itself is treatable, if left untreated, it can lead to life-threatening conditions, such as chronic heart and kidney diseases. Topical antibiotics are often considered the treatment of choice for impetigo, but the clinical efficacy of these treatments is declining at an alarming rate due to the rapid emergence and spread of resistant bacteria. In remote settings in Australia, topical antibiotics are no longer used for impetigo due to the troubling rise of antimicrobial resistance, demanding the use of oral and injectable antibiotic therapies. However, widespread use of these agents not only contributes to existing resistance, but also associated with adverse consequences for individuals and communities. These underscore the urgent need to reinvigorate the antibiotic discovery and alternative impetigo therapies in these settings. This review discusses the current impetigo treatment challenges in endemic settings in Australia and explores potential alternative antimicrobial therapies. The goals are to promote intensified research programs to facilitate effective use of currently available treatments, as well as developing new alternatives for impetigo.

New Antibiotics for the Treatment of Acute Bacterial Skin and Soft Tissue Infections in Pediatrics

Acute bacterial skin and soft tissue infections (aSSTIs) are a large group of diseases that can involve exclusively the skin or also the underlying subcutaneous tissues, fascia, or muscles. Despite differences in the localization and severity, all these diseases are due mainly to Gram-positive bacteria, especially Staphylococcus aureus and Streptococcus pyogenes. aSSTI incidence increased considerably in the early years of this century due to the emergence and diffusion of community-acquired methicillin-resistant S. aureus (CA-MRSA). Despite the availability of antibiotics effective against CA-MRSA, problems of resistance to these drugs and risks of significant adverse events have emerged. In this paper, the present knowledge on the potential role new antibiotics for the treatment of pediatric aSSTIs is discussed. The most recent molecules that have been licensed for the treatment of aSSTIs include ozenoxacin (OZ), ceftaroline fosamil (CF), dalbavancin (DA), oritavancin (OR), tedizolid (TD), delafloxacin (DL), and omadacycline (OM). However, only OZ and CF have been licensed for use in children with aSSTIs, although the superiority of these antibiotics to those routinely used for the treatment of aSSTIs should be further demonstrated. Waiting for additional studies, OZ and CF should be prescribed for aSSTI treatment in the presence of the potential failure of old molecules.

Impetigo Animal Models: A Review of Their Feasibility and Clinical Utility for Therapeutic Appraisal of Investigational Drug Candidates

Impetigo (school sores), a superficial skin infection commonly seen in children, is caused by the gram-positive bacteria Staphylococcus aureus and/or Streptococcus pyogenes. Antibiotic treatments, often topical, are used as the first-line therapy for impetigo. The efficacy of potential new antimicrobial compounds is first tested in in vitro studies and, if effective, followed by in vivo studies using animal models and/or humans. Animal models are critical means for investigating potential therapeutics and characterizing their safety profile prior to human trials. Although several reviews of animal models for skin infections have been published, there is a lack of a comprehensive review of animal models simulating impetigo for the selection of therapeutic drug candidates. This review critically examines the existing animal models for impetigo and their feasibility for testing the in vivo efficacy of topical treatments for impetigo and other superficial bacterial skin infections.

Antibiotic stewardship in skin infections: a cross-sectional analysis of early-career GP's management of impetigo

OBJECTIVE

To establish the prevalence and associations of systemic antibiotic prescription for impetigo by early-career general practitioners (GPs) (GP registrars in their first 18 months in general practice).

DESIGN

A cross-sectional analysis of data from the Registrar Clinical Encounters in Training (ReCEnT) study.

SETTING

ReCEnT is an ongoing multisite cohort study of Australian registrars' in-consultation clinical practice across five Australian states.

PARTICIPANTS

Registrars participating in ReCEnT from 2010 to 2017.

OUTCOME MEASURES

Management of impetigo with systemic antibiotics.

RESULTS

1741 registrars (response rate 96%) provided data from 384 731 problems identified in 246 434 consultations. Impetigo, on first presentation or follow-up, was managed in 930 (0.38%, 95% CI 0.35 to 0.40) consultations and comprised 0.24% (95% CI 0.23 to 0.26) of problems. 683 patients presented with a new diagnosis of impetigo of which 38/683 (5.6%) were not prescribed antibiotics; 239/683 (35.0%) were prescribed solely topical antibiotics; 306/683 (44.8%) solely systemic antibiotics and 100/683 (14.6%) both systemic and topical antibiotics. The most common systemic antibiotic prescribed was cephalexin (53.5%). Variables independently associated with prescription of systemic antibiotics were an inner regional (compared with major city) location (OR 1.82, 95% CI 1.06 to 3.13; p=0.028), seeking in-consultation information or advice (OR 2.17, 95% CI 1.47 to 3.23; p<0.001) and ordering pathology (OR 2.13, 95% CI 1.37 to 3.33; p=0.01).

CONCLUSIONS

Australian early-career GPs prescribe systemic antibiotics (the majority broad-spectrum) for a high proportion of initial impetigo presentations. Impetigo guidelines should clearly specify criteria for systemic antibiotic prescription and individual antibiotic choice. The role of non-antibiotic management and topical antiseptics needs to be explored further.

Infectious dermatoses that can manifest as vesicles

In dermatology, diseases that manifest as blisters or blister-like lesions are common, and some of these features are caused by infectious diseases. Here, we summarize and describe these diseases to increase their clinical awareness and diagnosis.

Therapeutic Potential of an Endolysin Derived from Kayvirus S25-3 for Staphylococcal Impetigo

Impetigo is a contagious skin infection predominantly caused by Staphylococcus aureus. Decontamination of S. aureus from the skin is becoming more difficult because of the emergence of antibiotic-resistant strains. Bacteriophage endolysins are less likely to invoke resistance and can eliminate the target bacteria without disturbance of the normal microflora. In this study, we investigated the therapeutic potential of a recombinant endolysin derived from kayvirus S25-3 against staphylococcal impetigo in an experimental setting. First, the recombinant S25-3 endolysin required an incubation period of over 15 minutes to exhibit efficient bactericidal effects against S. aureus. Second, topical application of the recombinant S25-3 endolysin decreased the number of intraepidermal staphylococci and the size of pustules in an experimental mouse model of impetigo. Third, treatment with the recombinant S25-3 endolysin increased the diversity of the skin microbiota in the same mice. Finally, we revealed the genus-specific bacteriolytic effect of recombinant S25-3 endolysin against staphylococci, particularly S. aureus, among human skin commensal bacteria. Therefore, topical treatment with recombinant S25-3 endolysin can be a promising disease management procedure for staphylococcal impetigo by efficient bacteriolysis of S. aureus while improving the cutaneous bacterial microflora.

Ozenoxacin: A Novel Topical Quinolone for Impetigo

Objective: To review the data supporting Food and Drug Administration (FDA) labeling of ozenoxacin and evaluate its place in therapy for impetigo. Data Sources: A literature search was conducted using PubMed (1966 to May 2018) and Google Scholar (2000 to May 2018) with the search terms ozenoxacin, T-3912, and GF-001001-00. Other resources included clinicaltrials.gov , the manufacturing product label, and the FDA website. Study Selection and Data Extraction: All relevant English-language data from abstracts, phase 1 to 4 studies, and review articles were included. Data Synthesis: FDA labeling of ozenoxacin was based on 2 phase 3 studies conducted in patients 2 months of age and older. Ozenoxacin demonstrated efficacy and safety for use in bullous or nonbullous impetigo from Staphylococcus aureus or Streptococcus pyogenes as compared with placebo. The lack of systemic absorption results in minimal adverse drug reactions. Studies did not detect possible adverse events commonly associated with other quinolone antibiotics. Relevance to Patient Care and Clinical Practice: This topical quinolone has bactericidal activity against Gram-positive organisms, including methicillin-resistant Staphylococcus aureus. Ozenoxacin may have an expanded clinical role for the treatment of localized impetigo if resistance to current therapies increases significantly. However, ozenoxacin is unlikely to play a significant role in the treatment of impetigo in the foreseeable future, because of lack of direct comparative clinical efficacy data with currently recommended therapies and likely high cost. Conclusions: Ozenoxacin, the first nonfluorinated quinolone, is a safe, topical treatment for impetigo in patients 2 months of age and older. Although clinical trials demonstrate efficacy compared with placebo, comparative trials to current treatment options are needed to identify its therapeutic use.

More Than Skin Deep: Autophagy Is Vital for Skin Barrier Function

The skin is a highly organized first line of defense that stretches up to 1.8 m² and is home to more than a million commensal bacteria. The microenvironment of skin is driven by factors such as pH, temperature, moisture, sebum level, oxidative stress, diet, resident immune cells, and infectious exposure. The skin has a high turnover of cells as it continually bares itself to environmental stresses. Notwithstanding these limitations, it has devised strategies to adapt as a nutrient-scarce site. To perform its protective function efficiently, it relies on mechanisms to continuously remove dead cells without alarming the immune system, actively purging the dying/senescent cells by immunotolerant efferocytosis. Both canonical (starvation-induced, reactive oxygen species, stress, and environmental insults) and non-canonical (selective) autophagy in the skin have evolved to perform astute due-diligence and housekeeping in a quiescent fashion for survival, cellular functioning, homeostasis, and immune tolerance. The autophagic “homeostatic rheostat” works tirelessly to uphold the delicate balance in immunoregulation and tolerance. If this equilibrium is upset, the immune system can wreak havoc and initiate pathogenesis. Out of all the organs, the skin remains under-studied in the context of autophagy. Here, we touch upon some of the salient features of autophagy active in the skin.