Methicillin-resistant S. aureus infections among patients in the emergency department

Staphylococcus aureus, Antibiotic Resistance, and the Interaction with Human Neutrophils

Significance:Staphylococcus aureus is among the leading causes of bacterial infections worldwide. The high burden of S. aureus among human and animal hosts, which includes asymptomatic carriage and infection, is coupled with a notorious ability of the microbe to become resistant to antibiotics. Notably, S. aureus has the ability to produce molecules that promote evasion of host defense, including the ability to avoid killing by neutrophils. Recent Advances: Significant progress has been made to better understand S. aureus-host interactions. These discoveries include elucidation of the role played by numerous S. aureus virulence molecules during infection. Based on putative functions, a number of these virulence molecules, including S. aureus alpha-hemolysin and protein A, have been identified as therapeutic targets. Although it has not been possible to develop a vaccine that can prevent S. aureus infections, monoclonal antibodies specific for S. aureus virulence molecules have the potential to moderate the severity of disease. Critical Issues: Therapeutic options for treatment of methicillin-resistant S. aureus (MRSA) are limited, and the microbe typically develops resistance to new antibiotics. New prophylactics and/or therapeutics are needed. Future Directions: Research that promotes an enhanced understanding of S. aureus-host interaction is an important step toward developing new therapeutic approaches directed to moderate disease severity and facilitate treatment of infection. This research effort includes studies that enhance our view of the interaction of S. aureus with human neutrophils. Antioxid. Redox Signal. 34, 452-470.

A Murine Skin Infection Model Capable of Differentiating the Dermatopathology of Community-Associated MRSA Strain USA300 from Other MRSA Strains

USA300 is a predominant and highly virulent community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain that is a leading cause of skin and soft tissue infections. We established a murine intradermal infection model capable of demonstrating dermatopathological differences between USA300 and other MRSA strains. In this model, USA300 induced dermonecrosis, uniformly presenting as extensive open lesions with a histologically documented profound inflammatory cell infiltrate extending below the subcutis. In contrast, USA400 and a colonizing control strain M92 caused only localized non-ulcerated skin infections associated with a mild focal inflammatory infiltrate. It was also determined that the dermonecrosis induced by USA300 was associated with significantly increased neutrophil recruitment, inhibition of an antibacterial response, and increased production of cytokines/chemokines associated with disease severity. These results suggest that induction of severe skin lesions by USA300 is related to over-activation of neutrophils, inhibition of host antibacterial responses, and selective alteration of host cytokine/chemokine profiles.

Sex differences in hospitalized adult patients with cellulitis: A prospective, multicenter study

OBJECTIVES

Sex differences in adult cellulitis, a frequent cause of hospitalization, have not been analyzed. These differences were investigated in a large cellulitis series.

METHODS

This was a prospective observational study of 606 Spanish hospitalized cellulitis patients. Different comorbidities, clinical, diagnostic, and treatment data were compared between the sexes. Multiple logistic regression modeling was performed to determine the variables independently associated with sex.

RESULTS

Overall 606 adult cellulitis patients were enrolled; 314 (51.8%) were male and 292 (48.2%) were female. Females were older (mean age 68.8 vs 58.9 years, p < 0.0001), less likely to have prior wounds (p = 0.02), and more likely to have venous insufficiency (p = 0.0002) and edema/lymphedema (p = 0.0003) than males. The location of the infection differed between the sexes (p = 0.02). Males were more likely to have positive pus cultures (p = 0.0008), the causing agent identified (p = 0.04), and higher rates of Staphylococcus aureus infection (p = 0.04) and received longer antibiotic treatment (p = 0.03). Factors independently associated with female sex in the multivariate analysis were older age (p < 0.0001), prior cellulitis (p = 0.01), presence of edema/lymphedema as the predisposing factor (p = 0.004), negative versus positive pus culture (p = 0.0002), and location of cellulitis other than in the lower extremities (p = 0.035).

CONCLUSIONS

Differences between male and female patients with cellulitis were age, recurrence, presence of edema/lymphedema, positivity of pus culture, and topography of the infection.

National Trends in Incidence of Purulent Skin and Soft Tissue Infections in Patients Presenting to Ambulatory and Emergency Department Settings, 2000-2015

Nationally representative data from 2000-2015 demonstrated a rise in the incidence of outpatient visits for skin infections, peaking in 2010-2013, followed by a plateau. While cephalexin was the most frequently prescribed antibiotic at the beginning, trimethoprim-sulfamethoxazole was most frequently prescribed by the end of the study period.

Subcutaneous abscess caused by Streptococcus pneumoniae serotype 28F in an infant: a case report

Background

Invasive pneumococcal disease (IPD) is defined by the detection of Streptococcus pneumoniae on culture from samples obtained from a normally sterile site. Pneumococcal conjugate vaccines (PCV) have been developed for the prevention of IPD that is caused by highly virulent serotypes. Despite the effective reduction of IPD caused by vaccine serotypes after the introduction of PCV, there has been a rapid increase in the incidence of IPD caused by non-vaccine serotypes, and serotype replacement has become a global issue.

Case presentation

We report a previously healthy 4-month-old girl presenting with a large subcutaneous abscess caused by S. pneumoniae, identified as non-vaccine serotype 28F. The patient had received routine vaccination, including PCV vaccination. After the incision and drainage of the subcutaneous abscess, the patient was treated with antibiotics. She was discharged on Day 7 of hospitalization without any residual sequelae.

Conclusions

Subcutaneous abscess is a common pediatric skin and soft tissue infection, whereas pneumococcal subcutaneous abscesses are quite rare. As the pneumococcal serotype 28F caused a subcutaneous abscess, this serotype possibly has a high virulence. The incidence of IPD caused by non-vaccine serotypes, such as 28F, is expected to increase in the future. The consolidation of international data on pneumococcal serotypes is important for the development of novel PCV.

Community-genotype methicillin-resistant Staphylococcus aureus skin and soft tissue infections in Latin America: a systematic review

BACKGROUND

Community-genotype methicillin-resistant Staphylococcus aureus (CG-MRSA) emerged in the 1990s as a global community pathogen primarily involved in skin and soft tissue infections (SSTIs) and pneumonia. To date, the CG-MRSA SSTI burden in Latin America (LA) has not been assessed.

OBJECTIVE

The main objective of this study was to report the rate and genotypes of community-genotype methicillin-resistant Staphylococcus aureus (CG-MRSA) causing community-onset skin and soft tissue infections (CO-SSTIs) in LA over the last two decades. In addition, this research determined relevant data related to SSTIs due to CG-MRSA, including risk factors, other invasive diseases, and mortality.

DATA SOURCES

Relevant literature was searched and extracted from five major databases: Embase, PubMed, LILACS, SciELO, and Web of Science.

METHODS

A systematic review was performed, and a narrative review was constructed.

RESULTS

An analysis of 11 studies identified epidemiological data across LA, with Argentina presenting the highest percentage of SSTIs caused by CG-MRSA (88%). Other countries had rates of CG-MRSA infection ranging from 0 to 51%. Brazil had one of the lowest rates of CG-MRSA SSTI (4.5-25%). In Argentina, being younger than 50 years of age and having purulent lesions were predictive factors for CG-MRSA CO-SSTIs. In addition, the predominant genetic lineages in LA belonged to sequence types 8, 30, and 5 (ST8, ST30, and ST5).

CONCLUSION

There are significant regional differences in the rates of CG-MRSA causing CO-SSTIs. It is not possible to conclude whether or not CG-MRSA CO-SSTIs resulted in more severe SSTI presentations or in a higher mortality rate.

Efficient and selective DNA modification on bacterial membranes

With highly precise self-assembly and programmability, DNA has been widely used as a versatile material in nanotechnology and synthetic biology. Recently, DNA-based nanostructures and devices have been engineered onto eukaryotic cell membranes for various exciting applications in the detection and regulation of cell functions. While in contrast, the potential of applying DNA nanotechnology for bacterial membrane studies is still largely underexplored, which is mainly due to the lack of tools to modify DNA on bacterial membranes. Herein, using lipid–DNA conjugates, we have developed a simple, fast, and highly efficient system to engineer bacterial membranes with designer DNA molecules. We have constructed a small library of synthetic lipids, conjugated with DNA oligonucleotides, and characterized their membrane insertion properties on various Gram-negative and Gram-positive bacteria. Simply after incubation, these lipid–DNA conjugates can be rapidly and efficiently inserted onto target bacterial membranes. Based on the membrane selectivity of these conjugates, we have further demonstrated their applications in differentiating bacterial strains and potentially in pathogen detection. These lipid–DNA conjugates are promising tools to facilitate the possibly broad usage of DNA nanotechnology for bacterial membrane analysis, functionalization, and therapy.

A lipid-based approach to effectively modify DNA molecules onto various types of bacterial membranes after simple incubation.

Targeting Skin-Resident Memory T Cells via Vaccination to Combat Staphylococcus aureus Infections

Tissue-resident memory T cells are important in adaptive immunity against many infections, rendering these cells attractive potential targets in vaccine development. Genetic and experimental evidence highlights the importance of cellular immunity in protection from Staphylococcus aureus skin infections, yet skin-resident memory T cells are, thus far, an untested component of immunity during such infections. Novel methods of generating and sampling vaccine-induced skin memory T cells are paralleled by discoveries of global, skin-wide immunosurveillance. We propose skin-resident memory CD4⁺ T cells as a potential missing link in the search for correlates of protection during S. aureus infections. A better appreciation of their phenotypes and functions could accelerate the development of preventive vaccines against this highly virulent and antibiotic-resistant pathogen.

Staphylococcal Skin and Soft Tissue Infections

Staphylococcus aureus is the most common bacteria causing purulent skin and soft tissue infections. Many disease-causing S aureus strains are methicillin resistant; thus, empiric therapy should be given to cover methicillin-resistant S aureus. Bacterial wound cultures are important for characterizing local susceptibility patterns. Definitive antibiotic therapy is warranted, although there are no compelling data demonstrating superiority of any one antibiotic over another. Antibiotic choice is predicated by the infection severity, local susceptibility patterns, and drug-related safety, tolerability, and cost. Response to therapy is expected within the first days; 5 to 7 days of therapy is typically adequate to achieve cure.

Antibiotic resistance and persistence-Implications for human health and treatment perspectives

Antimicrobial resistance (AMR) and persistence are associated with an elevated risk of treatment failure and relapsing infections. They are thus important drivers of increased morbidity and mortality rates resulting in growing healthcare costs. Antibiotic resistance is readily identifiable with standard microbiological assays, and the threat imposed by antibiotic resistance has been well recognized. Measures aiming to reduce resistance development and spreading of resistant bacteria are being enforced. However, the phenomenon of bacteria surviving antibiotic exposure despite being fully susceptible, so-called antibiotic persistence, is still largely underestimated. In contrast to antibiotic resistance, antibiotic persistence is difficult to measure and therefore often missed, potentially leading to treatment failures. In this review, we focus on bacterial mechanisms allowing evasion of antibiotic killing and discuss their implications on human health. We describe the relationship between antibiotic persistence and bacterial heterogeneity and discuss recent studies that link bacterial persistence and tolerance with the evolution of antibiotic resistance. Finally, we review persister detection methods, novel strategies aiming at eradicating bacterial persisters and the latest advances in the development of new antibiotics.

Staphylococcus aureus and Hyper-IgE Syndrome

Hyper-immunoglobulin E syndrome (HIES) is a primary immunodeficiency disease characterized by recurrent Staphylococcus aureus (S. aureus) infections, eczema, skeletal abnormalities and high titers of serum immunoglobulin E. Although the genetic basis of HIES was not known for almost a half century, HIES most frequently exhibits autosomal dominant trait that is transmitted with variable expressivity. Careful genetic studies in recent years identified dominant-negative mutations in human signal transducer and activator of transcription 3 (STAT3) gene as the cause of sporadic and dominant forms of HIES. The STAT3 mutations were localized to DNA-binding, SRC homology 2 (SH2) and transactivating domains and disrupted T helper 17 (T_H17) cell differentiation and downstream expression of T_H17 cytokines IL-17 and IL-22. Deficiency of IL-17 and IL-22 in turn is responsible for suboptimal expression of anti-staphylococcal host factors, such as neutrophil-recruiting chemokines and antimicrobial peptides, by human keratinocytes and bronchial epithelial cells. T_H17 cytokines deficiency thereby explains the recurrent staphylococcal lung and skin infections of HIES patients.

Emerging Viral and Bacterial Infections: Within an Era of Opioid Epidemic

The opioid epidemic is a public health crisis that continues to impact healthcare in the United States of America (USA). While changes in opioid prescribing have curbed the medical use of opioids, the increase in nonmedical use, largely driven by injection drug use (IDU), has contributed to the escalating incidence of opioid use disorder (OUD). Furthermore, IDU is associated with high-risk injection practices that can increase the risk of acquiring viral and bacterial infections. Here in this comprehensive review, we aimed to summarize the epidemiology and management of OUD, along with the screening and antimicrobial treatment of associated infections, specifically focused on human immunodeficiency virus, hepatitis C virus, skin and soft tissue infections, endocarditis, and osteomyelitis. Medication-assisted therapy (MAT) and infection guidelines from the USA will be presented.

The surgical management of cutaneous abscesses: A UK cross-sectional survey

Aim

Cutaneous abscesses are one of the most common acute general surgery presentations. This study aimed to understand the current practice in the management of cutaneous abscesses in the United Kingdom (UK), once the decision has been made that acute surgical incision and drainage (I&D) is required.

Method

General surgeons from across the UK were surveyed on their opinions on the optimum management of cutaneous abscesses. Outcomes measured included anaesthesia, incision technique, antibiotic administration, departmental abscess pathways, and post-drainage management. A combination of Likert scales, multiple-choice questions, and short answer questions were used. Comparisons were made of Likert scales between regions using a two-sample independent t-test. The survey was peer reviewed and distributed through the Association of Coloproctology of Great Britain and Ireland (ACPGBI) network between April and June 2018.

Results

Sixty-one responses were collected from surgeons throughout the UK. Of these respondents, 69% indicated that cutaneous abscesses would always or usually require a General Anaesthetic (GA) for treatment, and 82% indicated that abscesses were at least sometimes not treated until the next day due to a lack of resources. While 79% of surgeons stated that pus swabs are always or are usually taken, 44% of respondents never or rarely chased the results. The main indications for giving antibiotics were sepsis/systemically unwell patients, and cellulitis. 31% of responding centres had an abscess management protocol, and 82% of respondents confirmed that they would always pack the abscess wound post-operatively.

Conclusion

‘Incision and drainage’ is currently the most widely used technique for the surgical management of cutaneous abscess. However, this study demonstrates the significant variability in the use of anaesthesia, antibiotics, packing and the use of protocols to guide and streamline patient management.

•

There are no current NICE guidelines specifically covering cutaneous abscess management.

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There is significant practice variation in the management of cutaneous abscesses across the UK.

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Wound packing is still commonplace, despite guidelines recommending that there is evidence that it should be avoided.

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New recommendations on the use of antibiotics whilst treating cutaneous abscesses are yet to be taken up by most surgeons.

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Surgically managed cutaneous abscesses in the UK are preferably managed under a general anaesthetic.

Clinical characteristics and molecular analysis of USA300 and ST 764 methicillin-resistant Staphylococcus aureus isolates from outpatients in Japan by PCR-Based open reading frame typing

INTRODUCTION

USA300 is the most common community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strain. Sequence type (ST) 764 MRSA is a new local variant of the ST 5 lineage. The objective of this study was to determine the clinical characteristics of USA300 and ST 764 infections among outpatients in Japan.

METHODS

We obtained MRSA isolates from 132 outpatients who visited our hospital from January 2016 to December 2017 and compared USA300 infection group to ST 764 infection group. Molecular analysis, including that of various toxins and other virulence factors, of the MRSA isolates were performed. In particular, we investigated the relationships among PCR-based open reading frame typing (POT) scores, MRSA clones, and virulence factors.

RESULTS

Twenty-seven USA300 isolates (20.5%) and 16 ST 764 isolates (12.1%) were identified. Although USA300 and ST 764 had lower rates of risk factors, their infection rates were higher. USA300-infected patients had higher rates of deep skin and soft tissue infections compared with the non-USA300 CA-MRSA-infected patients. Notably, the USA300 and ST 764 isolates had unique POT scores.

CONCLUSIONS

Our results indicated that USA300 MRSA was spreading in an area 120 km west of Tokyo, Japan. We observed multiple cases of ST 764 MRSA infection, raising concerns about the antimicrobial resistance of ST 764, as it limits the choices of antibiotics to treat infection. The POT score can predict the presence of toxins and virulence factors, as well as the clone identity of MRSA with high accuracy.

A multifaceted intervention improves antibiotic stewardship for skin and soft tissues infections

OBJECTIVE

Assess the effectiveness of a multifaceted stewardship intervention to reduce frequency and duration of inappropriate antibiotic use for emergency department (ED) patients with skin and soft tissue infections (SSTI). We hypothesized the antibiotic stewardship program would reduce antibiotic duration and improve guideline adherence in discharged SSTI patients.

DESIGN

Nonrandomized controlled trial.

SETTING

Academic EDs (intervention site and control site).

PATIENTS OR PARTICIPANTS

Attending physicians and nurse practitioners at participating EDs.

INTERVENTION(S)

Education regarding guideline-based treatment of SSTI, tests of antimicrobial treatment of SSTI, implementation of a clinical treatment algorithm and order set in the electronic health record, and ED clinicians' audit and feedback.

RESULTS

We examined 583 SSTIs. At the intervention site, clinician adherence to guidelines improved from 41% to 51% (aOR = 2.13 [95% CI: 1.20-3.79]). At the control site, there were no changes in adherence during the "intervention" period (aOR = 1.17 [0.65-2.12]). The between-site comparison of these during vs. pre-intervention odds ratios was not different (aOR = 1.82 [0.79-4.21]). Antibiotic duration decreased by 26% at the intervention site during the intervention compared to pre-intervention (Adjusted Geometric Mean Ratio [95% CI] = 0.74 [0.66-0.84]). Adherence was inversely associated with SSTI severity (severe vs mild; adjusted OR 0.42 [0.20-0.89]) and purulence (0.32 [0.21-0.47]). Mean antibiotic prescription duration was 1.95 days shorter (95% CI: 1.54-2.33) in the time period following the intervention than pre-intervention period.

CONCLUSIONS

A multifaceted intervention resulted in modest improvement in adherence to guidelines compared to a control site, driven by treatment duration reductions.

Gene editing in dermatology: Harnessing CRISPR for the treatment of cutaneous disease

The discovery of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) system has revolutionized gene editing research. Through the repurposing of programmable RNA-guided CRISPR-associated (Cas) nucleases, CRISPR-based genome editing systems allow for the precise modification of specific sites in the human genome and inspire novel approaches for the study and treatment of inherited and acquired human diseases. Here, we review how CRISPR technologies have stimulated key advances in dermatologic research.  We discuss the role of CRISPR in genome editing for cutaneous disease and highlight studies on the use of CRISPR-Cas technologies for genodermatoses, cutaneous viruses and bacteria, and melanoma. Additionally, we examine key limitations of current CRISPR technologies, including the challenges these limitations pose for the widespread therapeutic application of CRISPR-based therapeutics.

Vancomycin Hypersensitivity Reactions Documented in Electronic Health Records

BACKGROUND

Vancomycin, the most common antimicrobial used in US hospitals, can cause diverse adverse reactions, including hypersensitivity reactions (HSRs). Yet, little is known about vancomycin reactions documented in electronic health records.

OBJECTIVE

To describe vancomycin HSR epidemiology from electronic health record allergy data.

METHODS

This was a cross-sectional study of patients with 1 or more encounter from 2017 to 2019 and an electronic health record vancomycin drug allergy label (DAL) in 2 US health care systems. We determined prevalence and trends of vancomycin DALs and assessed active DALs by HSR phenotype determined from structured (coded) and unstructured (free-text) data using natural language processing. We investigated demographic associations with documentation of vancomycin red man syndrome (RMS).

RESULTS

Among 4,490,618 patients, 14,426 (0.3%) had a vancomycin DAL with 18,761 documented reactions (2,248 [12.0%] free-text). Quarterly mean vancomycin DALs added were 253 ± 12 and deleted were 12 ± 2. Of 18,761 vancomycin HSRs, 7,903 (42.1%) were immediate phenotypes and 3,881 (20.7%) were delayed phenotypes. Common HSRs were rash (32% of HSRs) and RMS (16% of HSRs). Anaphylaxis was coded in 6% cases of HSRs. Drug reaction eosinophilia and systemic symptoms syndrome was the most common coded vancomycin severe cutaneous adverse reaction. RMS documentation was more likely for males (odds ratio, 1.30; 95% CI, 1.17-1.44) and less likely for blacks (odds ratio, 0.59; 95% CI, 0.47-0.75).

CONCLUSIONS

Vancomycin causes diverse adverse reactions, including common (eg, RMS) and severe (eg, drug reaction eosinophilia and systemic symptoms syndrome) reactions entered as DAL free-text. Anaphylaxis comprised 6% of documented vancomycin HSRs, although true vancomycin IgE-mediated reactions are exceedingly rare. Improving vancomycin DAL documentation requires more coded entry options, including a coded entry for RMS.

Neutrophil Recruitment to Noninvasive MRSA at the Stratum Corneum of Human Skin Mediates Transient Colonization

Staphylococcus aureus is a leading cause of skin and soft issue infection, but paradoxically, it also transiently, and often harmlessly, colonizes human skin. An obstacle to understanding this contradiction has been a shortage of in vivo models reproducing the unique structure and immunology of human skin. In this work, we developed a humanized model to study how healthy adult human skin responds to colonizing methicillin-resistant S. aureus (MRSA). We demonstrate the importance of the outer stratum corneum as the major site of bacterial colonization and how noninvasive MRSA adhesion to corneocytes induces a local inflammatory response in underlying skin layers. This signaling recruits neutrophils to the skin, where they control bacterial numbers, mediating transiency in colonization. This work highlights the spatiotemporal aspects of human skin colonization and demonstrates a subclinical inflammatory response to noninvasive MRSA that allows human skin to regulate the bacterial population at its outer surface.

Superior High-Energy-Density Biocidal Agent Achieved with a 3D Metal-Organic Framework

A significant number of challenges are encountered when developing biocidal agents with high throwing capacity for biosafety applications. Now a three-dimensional metal-organic framework (3D MOF) {MOF (2), [Cu(atrz)(IO₃)₂]_n (atrz = 4,4'-azo-1,2,4-triazole)} was obtained using a postsynthetic method from MOF (1) {[Cu(atrz)₃(NO₃)₂]_n}. Benefitting from the oxygen-rich and small volume of the iodate (IO₃) ligands (2.73 Å) in MOF (2) compared to the atrz ligand (7.70 Å) in MOF (1), the density of MOF (2) is 3.168 g cm^-3, nearly twice that of its precursor. Its detonation velocity of 7271 ms^-1 exceeds that of TNT (trinitrotoluene) and its detonation pressure of 40.6 GPa is superior to that of HMX (cyclotetramethylenetetranitramine) (1,3,5,7-tetranitro-1,3,5,7-tetrazoctane, 39.2 Gpa), which are the highest detonation properties for a biocidal agent. Its superior detonation performance results in its main product, I₂, being distributed over a wide area, markedly reducing the diffusion of harmful microorganisms. This study offers novel insight not only for high-energy-density materials but also for huge potential applications as biocidal agents.

Design and synthesis of novel desfluoroquinolone-aminopyrimidine hybrids as potent anti-MRSA agents with low hERG activity

Despite the fact that the introduction of a fluorine atom at the C-6 position has resulted in the evolution of fluoroquinolones, fluoroquinolone-induced cardiac toxicity has drawn considerable attention. In this context, desfluoroquinolone-based hybrids with involvement of C-7 aminopyrimidine functional group were designed and synthesized. The biological results showed majority of these hybrids still demonstrated potent anti-MRSA activity with MIC values between 0.38 and 1.5 μg/mL, despite the lack of the typical C-6 fluorine atom. Particularly, the most active B14 exhibited activities at submicromolar concentrations against a panel of MRSA strains including vancomycin-intermediate strains, levofloxacin-resistant isolates, and linezolid-resistant isolates, etc. As expected, it also displayed highly selective toxicity toward bacterial cells and low hERG inhibition. Further resistance development study indicated MRSA is unlikely to acquire resistance against B14. The docking study revealed that two hydrogen bonds were formed between the C-7 substituent and the surrounding DNA bases, which might contribute to overcome resistance by reducing the dependence on the magnesium-water bridge interactions with topoisomerase IV. These results indicate a promising strategy for developing new antibiotic quinolones to combat multidrug resistance and cardiotoxicity.

Two Cases of Intrafamilial Transmission of Community-Acquired Methicillin-Resistant Staphylococcus aureus Producing Both PVL and TSST-1 Causing Fatal Necrotizing Pneumonia and Sepsis

Introduction

Staphylococcus aureus produces numerous toxins, such as toxic shock syndrome toxin 1 (TSST-1) and Panton–Valentine leukocidin (PVL). We isolated community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strains producing both TSST-1 and PVL isolated from severe necrotizing pneumonia cases in a Nepali family. Detection of these CA-MRSA strains is rare in the world, and infection with these strains can take a rapidly progressive and lethal course. In this study, we traced the clinical course of this case and conducted a genetic analysis of the isolated strains.

Case Report

We described 2 familial cases (a 20-year-old male and 61-year-old female) of severe necrotizing pneumonia caused by CA-MRSA with the TSST-1 and PVL genes. A 20-year-old Nepalese male was admitted to our hospital after a 3-day history of high fever and coughing. Despite resuscitation efforts, he died of multiple organ failure. A 61-year-old Nepalese female was admitted to our hospital with a complaint of high fever and dyspnea for 1 day. She was the grandmother of the male subject and mostly stayed at his residence in Japan. We administered intravenous antibiotics, including anti-MRSA antibiotics, and she improved in 2 weeks. The sequence type of the isolates was ST22/SCCmec type IVa, and the spa type was t005. The virulence genes detected were as follows: PVL gene (lukSF-pv), TSST-1 gene (tst-1), sec, seg, sei, sel, sem, sen, seo, and seu. ST22 was not the dominant CA-MRSA clone type in Japan. Some of the reports demonstrated that PVL-/TSST-1-positive ST22-MRSA strains are prevalent in Nepal. Therefore, the MRSA strains were thought to be acquired from Nepal.

Conclusion

These cases highlight the emergence of TSST-1- and PVL-positive CA-MRSA infection and its association with life-threatening community-acquired necrotizing pneumonia. Clinicians should note the possibility of introducing MRSA strains from abroad and be aware of this illness to initiate appropriate treatment.

Simple Wound Irrigation in the Postoperative Treatment for Surgically Drained Spontaneous Soft Tissue Abscesses: A Prospective, Randomized Controlled Trial

BACKGROUND

Soft tissue abscesses are among the most frequently encountered medical problems treated by different surgeons. Standard therapy remains incision and drainage with sterile saline irrigation during postoperative wound healing period. Aim of this prospective randomized controlled trial was to compare sterile irrigation versus nonsterile irrigation.

STUDY DESIGN

A single center randomized controlled trial was performed to investigate postoperative wound irrigation. The control group used sterile irrigation, and the intervention group used nonsterile irrigation. Primary endpoints were reinfection and reintervention rates, assessed during follow-up controls for up to 2 years. Secondary endpoints were the duration of wound healing, inability to work, pain and quality of life.

RESULTS

Between 04/2016 and 05/2017, 118 patients were randomized into two groups, with 61 allocated to the control- and 57 to the intervention group. Reinfection occurred in a total of 4 cases (6.6%) in the sterile protocol and 4 (7%) in the nonsterile protocol. Quality of life and pain values were comparable during the wound healing period, and patients treated according to the nonsterile irrigation protocol used significantly fewer wound care service teams. Despite equal wound persistence rates, a substantially shorter amount of time off from work was reported in the nonsterile protocol group (p value 0.086).

CONCLUSION

This prospective, randomized trial indicates that a nonsterile irrigation protocol for patients operated on for soft tissue abscesses is not inferior to the standard sterile protocol. Moreover, a nonsterile irrigation protocol leads to a shorter period of inability to work with comparable pain and quality of life scores during the wound healing period.

Budget Impact Analysis of Dalbavancin in the Treatment of Acute Bacterial Skin and Skin Structure Infections in Three European Countries

BACKGROUND AND OBJECTIVE

Acute bacterial skin and skin structure infections (ABSSSIs) have been defined by the US Food and Drug Administration (FDA) in 2013 to include a subset of complicated skin and skin structure infections commonly treated with parenteral antibiotic therapy. Inpatient treatment of ABSSSIs involves a significant economic burden on the healthcare system. This study aimed to evaluate the economic impact on the National Health System associated with the management of non-severe ABSSSIs treated in hospitals with innovative long-acting dalbavancin compared to standard antibiotic therapy in Italy, Spain, and Austria.

METHODS

A budget impact analysis was developed to evaluate the direct costs associated with the management of ABSSSI from the national public health system perspective. The model considered the possibility of early discharge of patients directly from the Emergency Department (ED), after 1 night in the hospital, or after two or three nights in the hospital. A scenario with Standard of Care was compared with a dalbavancin scenario, where patients had the possibility of being discharged early. The epidemiological and cost parameters were extrapolated from national administrative databases and from a systematic literature review for each country. The analysis was conducted in a 3-year time horizon. A one-way deterministic sensitivity analysis was conducted to examine the robustness of the results.

RESULTS

The model estimated an average annual number of patients with non-severe ABSSSI in Italy, Spain, and Austria equal to 5396, 7884, and 1788, respectively. A total annual expenditure of about €9.9 million, €13.5 million, and €3.4 million was estimated for treating the full set of ABSSSI patients in Italy, Spain, and Austria, respectively. Dalbavancin reduced the in-hospital length of stay in each country. In the first year of its introduction, dalbavancin significantly reduced the total economic burden in Italy and Spain (- €352,252 and - €233,991, respectively), while it increased the total economic burden in Austria (€80,769, 0.7% of the total expenditure for these patients); in the third year of its introduction, dalbavancin reduced the total economic burden in each Country (- €1.1 million, - €810,650, and - €70,269, respectively).

CONCLUSIONS

The introduction of dalbavancin in a new patient pathway to treat non-severe ABSSSI could generate a significant reduction in hospitalized patients and the overall patient length of stay in hospital.

Nusbiarylins Inhibit Transcription and Target Virulence Factors in Bacterial Pathogen Staphylococcus aureus

The emergence of multidrug resistance in the clinically significant pathogen Staphylococcus aureus is a global health burden, compounded by a diminishing drug development pipeline, and a lack of approved novel antimicrobials. Our previously reported first-in-class bacterial transcription inhibitors “nusbiarylins” presented a promising prospect towards the discovery of novel antimicrobial agents with a novel mechanism. Here we investigated and characterised the lead nusbiarylin compound, MC4, and several of its chemical derivatives in both methicillin-resistant S. aureus (MRSA) and the S. aureus type strains, demonstrating their capacity for the arrest of growth and cellular respiration, impairment of RNA and intracellular protein levels at subinhibitory concentrations. In some instances, derivatives of MC4 were also shown to attenuate the production of staphylococcal virulence factors in vitro, such as the exoproteins α-toxin and Panton–Valentine Leukocidin (PVL). Trends observed from quantitative PCR assays suggested that nusbiarylins elicited these effects possibly by acting via but not limited to the modulation of global regulatory pathways, such as the agr regulon, which coordinates the expression of S. aureus genes associated with virulence. Our findings encourage the continued development of more potent compounds within this novel family of bacterial transcription inhibitors.

Skin and Soft-Tissue Infections: It's More Than Just Skin Deep

Skin and soft-tissue infection (SSTI) are one of the most common infections in both the community and hospital settings and account for nearly 4.8 million emergency department visits annually. These infections can vary in presentation, treatment, management, and potential for complication. As emergency medicine providers, early recognition and diagnosis of the disease are key. Point-of-care ultrasound is an invaluable tool that has contributed to the expeditious evaluation of these diseases with ultimate guidance for clinical management for SSTIs. This article reviews 3 SSTIs-cellulitis, abscess, and necrotizing fasciitis-and presents a common case study for consideration.

Incidence of Multidrug Resistant Infections in Emergency Department Patients with Suspected Sepsis

BACKGROUND

Inappropriate antibiotic therapy in sepsis is associated with poor outcomes, clinicians often provide routine coverage for multidrug resistant (MDR) bacteria. However, these regimens may contribute to problems related to antibiotic overuse. To understand the incidence and related factors of multidrug resistant bacterial infections in ED patients with sepsis, we examined how often patients with sepsis in our emergency department had MDR infections. We also explored risk factors for, and outcomes from, MDR bacterial infections.

METHODS

We reviewed records of patients presenting to our emergency department (ED) meeting criteria for severe sepsis or septic shock from March 2012 to July 2013. Patient demographics, comorbidities, preadmission location, and APACHE II scores were analyzed, as were clinical outcomes.

RESULTS

A total of 191 episodes were examined. 108 (57%) cases were culture-positive, and of these, 23 (12.0%) had an MDR pathogen recovered. Among patients with positive cultures, MDR patients used mechanical ventilation more often 29% vs. 52% (P = 0.03) and had longer mean ICU and hospital length of stays: 4.0 vs 9.3 (P < 0.08) and 10.6 vs 20.8 (P = 0.01), respectively. We did not identify statistically significant predictors of MDR infection.

CONCLUSIONS

The overall number of infections due to MDR bacteria was low, and MDR gram-negative infections were uncommon. The use of multiple empiric antibiotics for resistant gram-negative infections in the ED may be beneficial in only a small number of cases. Additionally, empiric coverage for vancomycin-resistant enterococci may need to be considered more often. Larger studies may help further elucidate the rates of MDR infections in ED patients, and identify specific risk factors to rationally guide empiric antibiotic treatment.

Prevalence and association of Panton-Valentine Leukocidin gene with the risk of sepsis in patients infected with Methicillin Resistant Staphylococcus aureus

BACKGROUND

Panton-Valentine Leukocidin (PVL), is one of the virulence gene expressed by Methicillin Resistant Staphylococcus aureus (MRSA) and is known to be associated with severe form of community acquired MRSA infection. The aim of this study is to investigate its prevalence in our setting and patient's clinical outcome.

METHODS

A cross sectional study involve retrospective record review were done involving 90 MRSA positive isolates between November 2016 and October 2017. Multiplex PCR was performed to detect femA, mecA and PVL genes. Clinical presentation and outcomes of patients were reviewed and presented as descriptive analysis.

RESULTS

All of the 90 MRSA isolates included in this study were positive for femA and mecA genes following PCR. PVL gene was detected in 20% (n = 18) of the isolates of which 61.1% (n = 11) were community acquired infections and 38.8% (n = 7) were hospital acquired. Case distribution from community acquired infections include patients with skin and soft tissue infections (33.3%, n = 6), infected diabetic foot ulcers (16.7%, n = 3), and one patient each (5.5%, n = 1) for community acquired pneumonia and meningitis. Half of the PVL positive MRSA cases (50%, n = 9) were having sepsis and four of them succumbed to death due to severe infection.

CONCLUSION

This study shows a high prevalence of PVL positive MRSA infection in our population. Skin and soft tissue infections accounting for the major sources. In addition, the presence of the PVL gene is associated with increased risk for developing sepsis.

Epidemiology of burn-related infections in the largest burn unit in Saudi Arabia

OBJECTIVES

To first describe the epidemiological data of burns, including burn types and burn-related infections, in adult and pediatric patients. Second, to determine the effect of Methicillin-Resistant Staphylococcus aureus (MRSA) on length of hospital stay and, third, to determine if the microbiological profile differs in patients with severe and non-severe burns. Methods: This is a retrospective chart review in which medical records of all burn patients admitted to Al-Noor Specialist Hospital, Makkah, Kingdom of Saudi Arabia between January 2016 and January 2017 were reviewed for demographic, microbiological, and burn data using a data-collection sheet. No randomization was necessary as all patients were included. Descriptive and inferential statistics were performed on the collected data. Results: Of 250 patients, 53.6% were pediatric patients and 68.4% were male patients. The most common organism in blood and wound cultures of minor burns was Staphylococcus aureus. Methicillin-resistant Staphylococcus aureus (MRSA) frequency was 82.5%. Length of stay increased in patients with infected burn injuries. Conclusion: The pediatric population had a high frequency of burn injuries, representing an incentive for more focused educational prevention programs in that group. Additionally, burn infections carry significant morbidity, and are associated with longer hospital stay. These data can help implement various prevention programs.

Comparison between a novel tap water wound irrigation device with sterile saline device in an open traumatic wound animal model

Study objective

Open traumatic wounds present to US emergency departments at a rate of approximately 12 million per year. Tap water wound irrigation usage has not been adopted by providers thus negating a potential cost saving of approximately US$65,600,000 per year when compared to saline irrigation. A novel tap water wound irrigation device can reduce bacterial counts in rats inoculated with MRSA as effectively as a commonly used sterile saline wound irrigation system.

Methods

Two groups of six Sprague–Dawley rats were used for this study. Two 3 cm incisions were made into the dorsum of each Sprague–Dawley rat and each incision was inoculated with 100 µl of MRSA. One wound served as the control, the other wound was either irrigated with the sterile saline wound irrigation system or a novel tap water wound irrigation device. The wounds were homogenized, plated, and bacterial colonies were enumerated to determine the final concentration of bacteria in each wound.

Results

There was no significant statistical difference in the reduction of MRSA in wounds treated with the sterile saline system relative to wounds treated with tap water (one-way ANOVA with post hoc Dunnet's test).

Conclusion

The novel tap water wound irrigation device is as effective as the sterile saline wound irrigation device at reducing bacterial counts in a rat laceration model when compared to non-irrigated controls. Adopting the use of a convenient, effective, and inexpensive wound irrigation system using tap water could help save the health care system millions of dollars in direct costs, shipping cost, and would not be affected by saline shortages.

Epidemiological and Clinical Evidence for the Role of Toxins in S. aureus Human Disease

Staphylococcus aureus asymptomatically colonizes approximately 30–50% of the population and is a leading cause of bacteremia, bone/joint infections, and skin infections in the US. S. aureus has become a major public health threat due to antibiotic resistance and an increasing number of failed vaccine attempts. To develop new anti-staphylococcal preventive therapies, it will take a more thorough understanding of the current role S. aureus virulence factors play in contributing to human disease. This review focuses on the clinical association of individual toxins with S. aureus infection as well as attempted treatment options. Further understanding of these associations will increase understanding of toxins and their importance to S. aureus pathogenesis.

Tedizolid (torezolid) for the treatment of complicated skin and skin structure infections

INTRODUCTION

Acute bacterial skin and skin structure infections (ABSSSI) are among the most frequent infectious diseases. Recently, several new antibiotics with activity against MRSA have been approved. Tedizolid, a second-generation oxazolidinone approved for ABSSSI offers theoretical advantages over first-generation oxazolidinones.

AREAS COVERED

A comprehensive online search of Medline, ClinicalTrials.gov, and conference presentations was made, selecting articles between January 2000 and April 2020. In this review, the authors discuss the chemical and microbiological properties of tedizolid, summarize its efficacy, safety, and potential role in the treatment of ABSSSI as well as the potential for future indications.

EXPERT OPINION

Tedizolid has proven to be non-inferior compared to linezolid for the treatment of ABSSSI in two registrational phase III clinical trials, being well tolerated. Tedizolid exhibits antibacterial activity against the most important ABSSSI pathogens (including multidrug-resistant strains of MRSA), as well as mycobacteria and Nocardia. It appears to have a safe profile, including decreased myelotoxicity and no significant drug interactions. Preliminary studies with longer duration of therapy seem to confirm these potential benefits. Overall, tedizolid expands the newly acquired armamentarium to treat ABSSSI. The role of tedizolid for other indications is under investigation and has yet to be determined.

Pediatric Community-Acquired Bone and Joint Staphylococcus Aureus Infections In Europe: Severe Infections are Associated to Panton-Valentine Leucocidin Presence

To analyze host and pathogen factors related to disease severity of community-acquired bone and joint infections in children, a cohort of pediatric patients was prospectively recruited from 13 centers in 7 European countries. A total of 85 children were included, 11 (13%) had a severe infection. Panton-Valentine leukocidin-positive isolates were 17%, and 6% of the isolates were methicillin-resistant Staphylococcus aureus. Multivariate analysis identified Panton-Valentine leukocidin presence (adjusted odds ratio, 12.6; P = 0.01) as the only factor independently associated with severe outcome, regardless of methicillin resistance.

Staphylococcus aureus Epicutaneous Infection Is Suppressed by Lactococcus lactis Strain Plasma via Interleukin 17A Elicitation

BACKGROUND

Lactococcus lactis strain Plasma (LC-Plasma) was revealed to stimulate plasmacytoid dendritic cells and induce antiviral immunity in vitro and in vivo. In this study, we assessed the effects of LC-Plasma on skin immunity.

METHODS

To evaluate the effect of LC-Plasma on skin immunity and Staphylococcus aureus epicutaneous infection, lymphocyte activities in skin-draining lymph nodes (SLNs) and gene expression in skin were analyzed after 2 weeks of oral administration of LC-Plasma. To evaluate the mechanisms of interleukin 17A production, SLN lymphocytes were cultured with or without LC-Plasma, and the interleukin 17A concentrations in supernatants were measured.

RESULTS

Oral administration of LC-Plasma activated plasma dendritic cells in SLNs, augmented skin homeostasis, and elicited suppression of Staphylococcus aureus, Staphylococcus epidermidis, and Propionibacterium acnes proliferation. In addition, significant suppression of the S. aureus burden and reduced skin inflammation were observed following oral administration of LC-Plasma. Furthermore, a subsequent in vitro study revealed that LC-Plasma could elicit interleukin 17A production from CD8+ T cells and that its induction mechanism depended on the Toll-like receptor 9 signaling pathway, with type I interferon partially involved.

CONCLUSIONS

Our results suggest that LC-Plasma oral administration enhances skin homeostasis via plasma dendritic cell activation in SLNs, resulting in suppression of S. aureus epicutaneous infection and skin inflammation.

The First Report on Pharmacokinetic/Pharmacodynamic Study of Trimethoprim/Sulfamethoxazole against Staphylococcus aureus with a Neutropenic Murine Thigh Infection Model

INTRODUCTION

With an increase in the incidence of Staphylococcus aureus infections in the healthcare settings and in the community, trimethoprim/sulfamethoxazole (TMP/SMX) has been suggested as a convenient treatment option. However, the appropriate dosage regimen of TMP/SMX is unclear.

OBJECTIVE

This study aimed to examine the pharmacokinetics/pharmacodynamics (PK/PD) of TMP/SMX against S. aureus using a neutropenic murine thigh infection model.

METHODS

Five S. aureus isolates with TMP/SMX (1:5 fixed ratio) minimum inhibitory concentrations (MICs) of 0.032-64 μg/mL were tested. The antimicrobial efficacy of TMP/SMX (1-689 mg/kg/day: dose shown as SMX dosage) was calculated as the change in bacterial density after 24 h of treatment. The plasma concentrations of TMP/SMX were detected using high-performance liquid chromatography.

RESULTS

After TMP/SMX single dose (130 mg/kg), the half-life, area under the blood concentration curve (AUC0-∞), and the protein binding ratio of SMX were 1.5 h, 718.2 μg h/mL, and 73.0 ± 8.3%, respectively. The free AUC/MIC and free %time (%T) above the MIC of SMX were better correlated with the in vivo antimicrobial activity than Cmax/MIC (free AUC/MIC, R2 = 0.69; free %T > MIC, R2 = 0.71; free Cmax/MIC, R2 = 0.53). The distributed doses (2-3 times per day) of TMP/SMX (130, 260, and 390 mg/kg/day) showed higher antimicrobial activity than the single dosage. However, TMP/SMX did not show its antimicrobial activity at <100% free %T > MIC.

CONCLUSIONS

The TMP/SMX treatment demonstrated that the free AUC/MIC of SMX was the better predictor of the PK/PD index of TMP/SMX.

Staphylococcus aureus Nasal Colonization among Children with Sickle Cell Disease at the Children's Hospital, Accra: Prevalence, Risk Factors, and Antibiotic Resistance

The aim of this study was to investigate S. aureus carriage among children with sickle cell disease (SCD), including the prevalence, risk factors, and antibiotic resistance. The study was cross-sectional, and involved 120 children with SCD recruited at the Princess Marie Louise Children’s Hospital (PML) in Accra and 100 apparently healthy children from environs of the hospital. Nasal swab samples were collected from the study participants and cultured for bacteria. Confirmation of S. aureus and methicillin-resistant Staphylococcus aureus (MRSA) isolates were done using the tube coagulase test and mecA polymerase chain reaction, respectively. All the S. aureus isolates were tested against standard antimicrobial agents using the Kirby-Bauer method. A structured questionnaire was used to obtain the socio-demographic and clinical data of the study participants. Binary logistic regression was used to identify determinants of S. aureus and MRSA carriage among the study participants. The nasal carriage prevalence of S. aureus was 33.3% (n = 40) and 10% (n = 10) among the participants of the SCD and control groups, respectively. As regards MRSA nasal carriage prevalence, the respective values were 3.33% (n = 4) and 0.00% (n = 0). SCD was significantly associated with S. aureus colonization (p < 0.0001, OR = 4.045), but not MRSA colonization (p = 0.128). In the SCD group, the significant predictors of S. aureus carriage were increasing age (p = 0.003; OR = 1.275) and living in self-contained apartments (p = 0.033; OR = 3.632), whereas male gender (p = 0.018; OR = 0.344) and the practice of self-medication (p = 0.039; OR = 0.233) were protective of S. aureus carriage. In the control group, a history of hospitalization in the past year was a risk factor for the carriage of S. aureus (p = 0.048; OR = 14.333). Among the participants of the SCD and control groups, respectively, the resistance prevalence recorded by S. aureus against the various antibiotics investigated were penicillin (100% each), cotrimoxazole (27.5% vs. 20%), tetracycline (25% vs. 50%), rifampicin (82.5% vs. 50%), erythromycin (30% vs. 20%), clindamycin (32.5% vs. 50%), gentamicin (7.5% vs. 20%), cefoxitin (27.5% vs. 20%), linezolid (30% vs. 40%), and fusidic acid (95% vs. 80%). The proportion of S. aureus isolates that were multidrug resistant (MDR) was 92.5% (37/40) in the SCD group and 100% (10/10) in the control group.

Gene editing in dermatology: Harnessing CRISPR for the treatment of cutaneous disease

The discovery of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) system has revolutionized gene editing research. Through the repurposing of programmable RNA-guided CRISPR-associated (Cas) nucleases, CRISPR-based genome editing systems allow for the precise modification of specific sites in the human genome and inspire novel approaches for the study and treatment of inherited and acquired human diseases. Here, we review how CRISPR technologies have stimulated key advances in dermatologic research.  We discuss the role of CRISPR in genome editing for cutaneous disease and highlight studies on the use of CRISPR-Cas technologies for genodermatoses, cutaneous viruses and bacteria, and melanoma. Additionally, we examine key limitations of current CRISPR technologies, including the challenges these limitations pose for the widespread therapeutic application of CRISPR-based therapeutics.

Obesity Is Not an Independent Predictor of Necrotizing Soft Tissue Infection Outcomes

Background: Necrotizing soft tissue infections (NSTIs) are a group of rapidly progressive infections of the skin and its underlying tissue. These infections result in substantial morbidity and mortality. The focus of this study was to determine if obesity is associated with a worsened clinical outcome or prolonged hospital course for patients with NSTIs. Patients and Methods: We conducted a retrospective chart review of patients with NSTI presenting to a single tertiary hospital. Fat content, measured with body mass index (BMI) and abdominal fat thicknesses, including subcutaneous and visceral fat, were compared against primary and secondary outcomes of NSTIs. Results: We found that women had a higher mortality rate compared with men (27% vs. 15% mortality). Women also had an increased subcutaneous abdominal fat thickness (55.7 vs. 36.9 mm, p = 0.028). However, no measurements of fat, BMI, subcutaneous fat, or visceral fat differed between survivors and mortalities of NSTIs. In fact, with the exception of a higher BMI in those who developed acute kidney injury (AKI, p = 0.034), we found no correlation between increases in fat measurement and secondary outcome, including propensity to develop sepsis during hospitalization, length of hospital stay, length of intensive care stay, or antibiotic usage. Multivariable logistic regression analysis was conducted, and we found no statistically significant differences in primary or secondary outcomes. Conclusion: Women appear to have a higher mortality in NSTI, although the reasons for this are unclear. Obesity, as measured by BMI, subcutaneous, and visceral fat thicknesses, does not appear to be an independent risk factor.

Effects of Tormentic Acid and the Extracts from Callistemon citrinus on the Production of Extracellular Proteases by Staphylococcus aureus

Staphylococcus aureus is among the common nosocomial pathogens. Antibiotics have been used to treat S. aureus infections. However, there has been increased mortality associated with drug-resistant strains of S. aureus. Extracellular proteases have been implicated to be responsible for the transition of S. aureus from an adhesive pathogen to an invasive pathogen. The development of resistant strains has necessitated the search for new sources of drugs. Plants have been traditionally used as sources of therapeutic molecules. The objective of this study was to determine the effect of tormentic acid and the extracts from Callistemon citrinus on the production of extracellular proteases by S. aureus. The broth microdilution antibacterial susceptibility assay was used to determine the antibacterial effects of tormentic acid and the extracts on S. aureus. Both extracts showed a minimum inhibitory concentration (MIC) value of 50 μg/ml. The water : ethanol (50 : 50) and the dichloromethane : methanol (50 : 50) extracts were found to be bactericidal against S. aureus at a concentration of 100 μg/ml and 50 μg/ml, respectively. The effect of tormentic acid and extracts on extracellular protease production was investigated using the protease assay. A zone of proteolytic activity (Pr) was measured as the ratio of the diameter of the colony to the total diameter of colony plus zone of hydrolysis. The extracts reduced the production of extracellular proteases, while tormentic acid completely inhibited the production of extracellular proteases by S. aureus. The Pr value for tormentic acid was found to be 1. The Pr values of the dichloromethane : methanol extract and the water : ethanol extract were 0.92 and 0.84, respectively. In conclusion, tormentic acid was shown to inhibit extracellular protease production; therefore, there is need to explore its use in antivirulence therapy to combat S. aureus infections.

Prevalence, clinical expression, invasiveness and outcome of Staphylococcus aureus containing Panton-Valentine leukocidin in children treated in a university hospital of Lithuania

Background: There is a high prevalence of Staphylococcus aureus virulence factor Panton-Valentine leukocidin (PVL) in North-East parts of Europe. The aim was to evaluate data regarding the PVL occurrences in Lithuania, determine the relationship with Methicillin resistant Staphylococcus aureus (MRSA), association with demographic and clinical conditions, invasiveness and severity of the disease in children treated in hospital Kauno klinikos (KK).Methods: We performed a prospective case-cohort single-center study on paediatric patients hospitalized from 2012 to 2015 to KK. We compared characteristics in PVL positive [SA-PVL(+)] and PVL negative [SA-PVL(-)] groups among non-invasive and invasive infections. Logistic regression was performed to detect PVL predicting factors and Cox regression was presented to define factors associated with admission to intensive care unit (ICU).Results: PVL was detected in 51.5%, MRSA in 7.0% and MRSA-PVL(+) in 4.8% of cases. In general, PVL was associated with older age comparing with SA-PVL(-) (median 8.5 vs. 4.0 years, p < .001). Skin and soft tissue infections were presented in 87.9% of all SA-PVL(+) cases. Invasive infections (44.7% vs. 12.1%, p < .001) and co-morbidities (20.5% vs. 2.9%, p < .001) were associated with SA-PVL(-) infections compared to SA-PVL(+), but ICU admission number was higher in invasive SA-PVL(+) cases comparing to invasive SA-PVL(-) cases (41.2% vs. 10.2%, p = .007).Conclusions: There was a high prevalence of pvl gene in patients treated in KK. SA-PVL(+) infections were associated with SSTI and were not common in invasive infections, but the invasive infections caused by SA-PVL(+) were related to severe disease progression and admission to ICU.

Septic Arthritis of the Hip in Children: A Critical Analysis Review

Septic arthritis of the hip is a common and potentially devastating condition in children. Septic arthritis is most commonly caused by Staphylococcus aureus, but other pathogens should be considered on the basis of patient age and presence of risk factors. Diagnosis of septic arthritis is based on history and physical examination, laboratory tests, radiographs, ultrasound, and arthrocentesis. Treatment comprises empiric antibiotics and joint debridement, and antibiotics are subsequently tailored on the basis of culture data, local resistance patterns, and clinical response. Late sequelae of septic arthritis include osteonecrosis, chondrolysis, growth disturbance, subluxation or dislocation, and progressive ankylosis. Surgical treatments to address these issues have been described.

Rare presentation of sepsis caused by necrotizing scalp infection

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is a rising cause of skin and soft tissue infections over the last decade with potentially serious complications. In this article, we describe a case of a large scalp and post-auricular abscess complicated by bacteremia. This is a case of a 73-year-old female who presented with altered mental status was found to have two fluctuant scalp abscesses, bacteremia with necrosis. The patient was promptly treated with intravenous antibiotics, multiple operative debridements without calvarial periosteum involvement defects requiring split-thickness skin grafts for wound closure. This case highlights the severity of a CA-MRSA skin infection in an atypical location.

Unbiased Identification of Immunogenic Staphylococcus aureus Leukotoxin B-Cell Epitopes

Unbiased identification of individual immunogenic B-cell epitopes in major antigens of a pathogen remains a technology challenge for vaccine discovery. We therefore developed a platform for rapid phage display screening of deep recombinant libraries consisting of as few as one major pathogen antigen. Using the bicomponent pore-forming leukocidin (Luk) exotoxins of the major pathogen Staphylococcus aureus as a prototype, we randomly fragmented and separately ligated the hemolysin gamma A (HlgA) and LukS genes into a custom-built phage display system, termed pComb-Opti8. Deep sequence analysis of barcoded amplimers of the HlgA and LukS gene fragment libraries demonstrated that biopannng against a cross-reactive anti-Luk monoclonal antibody (MAb) recovered convergent molecular clones with short overlapping homologous sequences. We thereby identified an 11-amino-acid sequence that is highly conserved in four Luk toxin subunits and is ubiquitous in representation within S. aureus clinical isolates. The isolated 11-amino-acid peptide probe was predicted to retain the native three-dimensional (3D) conformation seen within the Luk holotoxin. Indeed, this peptide was recognized by the selecting anti-Luk MAb, and, using mutated peptides, we showed that a particular amino acid side chain was essential for these interactions. Furthermore, murine immunization with this peptide elicited IgG responses that were highly reactive with both the autologous synthetic peptide and the full-length Luk toxin homologues. Thus, using a gene fragment- and phage display-based pipeline, we have identified and validated immunogenic B-cell epitopes that are cross-reactive between members of the pore-forming leukocidin family. This approach could be harnessed to identify novel epitopes for a much-needed S. aureus-protective subunit vaccine.

Factors associated with sepsis development in 606 Spanish adult patients with cellulitis

Background

Cellulitis, a frequent cause of admission of adult patients to medical wards, occasionally evolves to sepsis. In this study we analyze the factors related to sepsis development.

Methods

Prospective and observational study of 606 adult patients with cellulitis admitted to several Spanish hospitals. Comorbidities, microbiological, clinical, lab, diagnostic, and treatment data were analyzed. Sepsis was diagnosed according to the criteria of the 2016 International Sepsis Definitions Conference. Multiple logistic regression modelling was performed to determine the variables independently associated with sepsis development.

Results

Mean age was 63.4 years and 51.8% were men. Overall 65 (10.7%) patients developed sepsis, 7 (10.8%) of whom died, but only 4 (6.2%) due to cellulitis. Drawing of blood (P < 0.0001) or any (P < 0.0001) culture, and identification of the agent (P = 0.005) were more likely among patients with sepsis. These patients had also a longer duration of symptoms (P = 0.04), higher temperature (P = 0.03), more extensive cellulitis (P = 0.02), higher leukocyte (P < 0.0001) and neutrophil (P < 0.0001) counts, serum creatinine (P = 0.001), and CRP (P = 0.008) than patients without sepsis. Regarding therapy, patients with sepsis were more likely to undergo changes in the initial antimicrobial regimen (P < 0.0001), received more antimicrobials (P < 0.0001), received longer intravenous treatment (P = 0.03), and underwent surgery more commonly (P = 0.01) than patients without sepsis. Leukocyte counts (P = 0.002), serum creatinine (P = 0.003), drawing of blood cultures (P = 0.004), change of the initial antimicrobial regimen (P = 0.007) and length of cellulitis (P = 0.009) were independently associated with sepsis development in the multivariate analysis.

Conclusions

Increased blood leukocytes and serum creatinine, blood culture drawn, modification of the initial antimicrobial regimen, and maximum length of cellulitis were associated with sepsis in these patients.

A Multiplex Fluidic Chip for Rapid Phenotypic Antibiotic Susceptibility Testing

Prompt and effective antimicrobial therapy is crucial for the management of patients with severe bacterial infections but is becoming increasingly difficult to provide due to emerging antibiotic resistance. The traditional methods for antibiotic susceptibility testing (AST) used in most clinical laboratories are reliable but slow with turnaround times of 2 to 3 days, which necessitates the use of empirical therapy with broad-spectrum antibiotics. There is a great need for fast and reliable AST methods that enable starting targeted treatment within a few hours to improve patient outcome and reduce the overuse of broad-spectrum antibiotics. The multiplex fluidic chip for phenotypic AST described in the present study may enable data on antimicrobial resistance within 2 to 4 h, allowing for an early initiation of appropriate antibiotic therapy.

Many patients with severe infections receive inappropriate empirical treatment, and rapid detection of bacterial antibiotic susceptibility can improve clinical outcome and reduce mortality. To this end, we have developed a multiplex fluidic chip for rapid phenotypic antibiotic susceptibility testing of bacteria. A total of 21 clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus were acquired from the EUCAST Development Laboratory and tested against amikacin, ceftazidime, and meropenem (Gram-negative bacteria) or gentamicin, ofloxacin, and tetracycline (Gram-positive bacteria). The bacterial samples were mixed with agarose and loaded in an array of growth chambers in the chip where bacterial microcolony growth was monitored over time using automated image analysis. MIC values were automatically obtained by tracking the growth rates of individual microcolonies in different regions of antibiotic gradients. Stable MIC values were obtained within 2 to 4 h, and the results showed categorical agreement with reference MIC values as determined by broth microdilution in 86% of the cases.

Decreasing the Duration of Discharge Antibiotic Treatment Following Inpatient Skin and Soft Tissue Abscess Drainage

Supplemental Digital Content is available in the text.

Introduction:

Skin and soft tissue abscesses do not require prolonged systemic antimicrobial treatment following drainage. We aimed to decrease the duration of discharge antibiotic treatment to less than 5 days following inpatient incision and drainage of uncomplicated abscesses.

Methods:

A new treatment protocol that defined uncomplicated abscesses, as well as inclusion and exclusion criteria, was created to monitor the accurate duration of prescribed therapy at discharge. We implemented a treatment algorithm that takes into account the epidemiologic changes in microbial etiologies and the presence of systemic findings for patients after surgical incision and drainage. We used control charts to assess the impact of the interventions.

Results:

Four hundred and eighteen patients were discharged following abscess drainage from our inpatient infectious diseases unit in 2016. The patients were 3 months to 21 years of age. Only 72 (17%) patients had prescribed discharge antibiotic treatment courses that were less than 5 days [range 0–31 days, median 8 days (IQR 6, 9)], and the average prescribed course at discharge was 8.6 days. During the study period, we significantly decreased the average duration of discharge antibiotics to 7.3 days in all patients (P = 0.0016, 95% CI: −2.1036 to −0.4964, difference of means −1.3). The discharge treatment duration of patients with uncomplicated abscess was shorter at 4.7 days [range 0–9 days, median 5 days, (IQR 3, 5)]. Prescription compliance to less than 5 days treatment course at discharge increased from the baseline of 17% to 42% overall.

Conclusions:

Standardizing definitions of uncomplicated skin and soft tissue abscesses was critical to the success of this project. In addition to possible improved treatment adherence and decreased side effects, our protocol led to decreased patient care costs with no documented changes in readmission rates.

Antimicrobial stewardship in patients with acute bacterial skin and skin-structure infections: An international Delphi consensus

OBJECTIVES

The aim of this survey was to identify a set of actions aimed to improve the diagnosis and management of acute bacterial skin and skin-structure infections (ABSSSIs) and the implementation of some principles of antimicrobial stewardship (AMS) in this setting.

METHODS

A list of 76 statements for which there was a lack of clarity were generated by an expert panel and were validated by a group of experts. The questionnaire was administered to 112 experts in infectious diseases or microbiology. Participants were asked to vote on a list of statements. An agreement threshold of 66% was required to reach consensus.

RESULTS

Overall, 57 responders participated in the survey. Positive consensus was reached on the fact that ABSSSIs represent a significant cause of infection in the emergency department, are frequently associated with increased hospital stay and are mainly caused by Staphylococcus aureus. The panellists strongly supported collection of samples from purulent infections by needle aspiration as well as collection of blood cultures in the presence of signs/symptoms of systemic infection. The importance of source control and prompt adequate microbiological documentation, the objective to reduce the length of hospital stay, the choice of a narrow-spectrum antibiotic and the role of new therapeutic options (e.g. long-acting drugs) in improving compliance also reached a positive consensus.

CONCLUSION

This Delphi survey provides useful indicators for the implementation of AMS principles in the clinical management of ABSSSI and offers interesting elements of discussion about the barriers existing in Europe for optimal implementation of AMS programmes.