Current Epidemiology, Etiology, and Burden of Acute Skin Infections in the United States

The epidemiology of repeatedly positive bacterial skin infections in Auckland children, New Zealand

OBJECTIVE

Māori and Pacific New Zealanders are disproportionately affected by Acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Repeated S. pyogenes skin infections in childhood are thought to increase the risk of developing ARF/RHD. This study investigated the epidemiology of repeated bacterial skin infections within Auckland, New Zealand.

METHOD

Microbiology results from wound swabs collected in primary care between 2010 and 2020 were used to estimate the rate of repeatedly positive infections, along with rate ratios and 95% CIs, across demographic groups.

RESULTS

S. aureus infections impacted all groups; but Māori (Rate Ratio: 10.0, 95% CI: 8.5-11.6) and Pacific children (Rate Ratio: 14.6, 95% CI: 12.6-17.0) under 10 years of age were at a greater risk of repeated S. pyogenes infections compared to their non-Māori/non-Pacific counterparts. The relative risk of subsequent S. pyogenes infection was 4.1 times higher (95% CI: 4.0-4.3) following an initial S. pyogenes infection compared to those negative for S. pyogenes.

CONCLUSION

Māori and Pacific children's heightened vulnerability to repeated S. pyogenes skin infections supports the immune priming theory of ARF/RHD. Targeted public health initiatives, primary care interventions and Group A Streptococcal vaccine are crucial to reduce repeated S. pyogenes exposure and potentially lower ARF risks.

Improving Empiric Antibiotic Selection for Patients Hospitalized With Skin and Soft Tissue Infection: The INSPIRE 3 Skin and Soft Tissue Randomized Clinical Trial

Importance

Empiric extended-spectrum antibiotics are routinely prescribed for patients hospitalized with skin and soft tissue infections (SSTIs) despite low likelihoods of infection with multidrug-resistant organisms (MDROs).

Objective

To evaluate whether computerized provider order entry (CPOE) prompts presenting patient-specific and pathogen-specific MDRO infection risk estimates could reduce empiric extended-spectrum antibiotics for noncritically ill patients admitted with SSTI.

Design, Setting, and Participants

This cluster randomized clinical trial included 92 hospitals and assessed the effect of an antibiotic stewardship bundle that included CPOE prompts vs routine stewardship on antibiotic selection during the first 3 hospital days (empiric period) in noncritically ill adults hospitalized with SSTI. The trial population included adults 18 years and older treated with empiric antibiotics for SSTI in non-intensive care unit (ICU) settings. Data were collected from January 2019 to December 2023.

Interventions

CPOE prompts recommending standard-spectrum antibiotics in patients prescribed extended-spectrum antibiotics during the empiric period when absolute risk of MDRO SSTI was estimated to be less than 10%, coupled with feedback and education.

Main Outcomes and Measures

The primary outcome was empiric extended-spectrum antibiotic days of therapy (summed number of different extended-spectrum antibiotics targeting Pseudomonas and/or MDR gram-negative bacteria received per patient each calendar day). The secondary outcome was antipseudomonal days of therapy. Safety outcomes included days to ICU transfer and hospital length of stay. Outcomes compared differences between baseline and intervention periods across strategies.

Results

Among 118 562 patients admitted with SSTI at 92 hospitals, 67 033 (56.7%) were male and the mean (SD) age was 58.0 (17.5) years. A total of 57 837 patients were included in the baseline period and 60 725 in the intervention period. Receipt of any empiric extended-spectrum antibiotic during the baseline and intervention periods was 57.0% (16 855 of 29 595) and 56.0% (17 534 of 31 337), respectively, for the routine stewardship group compared with 55.4% (15 650 of 28 242) and 43.0% (12 647 of 29 388), respectively, for the CPOE group. Empiric extended-spectrum days of therapy per 1000 empiric days targeting Pseudomonas and/or MDR gram-negative pathogens was 511.5 during the baseline period and 488.7 during the intervention period in the routine stewardship group and was 496.2 and 359.1, respectively, in the CPOE bundle group (rate ratio, 0.72; 95% CI, 0.67-0.79; P < .001). There was no evidence of inferiority in the CPOE bundle group for mean (SD) hospital length of stay (routine stewardship, 6.5 [3.8] days; CPOE bundle, 6.4 [3.8] days) and days to ICU transfer (routine stewardship, 6.3 [3.2] days; CPOE bundle, 6.3 [3.1] days).

Conclusions and Relevance

In this randomized clinical trial, CPOE prompts recommending standard-spectrum empiric antibiotics for low-risk patients hospitalized with SSTI coupled with education and feedback significantly reduced use of extended-spectrum antibiotics without increasing admissions to ICUs or hospital length of stay.

Trial Registration

ClinicalTrials.gov Identifier: NCT05423756.

Skin mycobiota-mediated antagonism against Staphylococcus aureus through a modified fatty acid

Microbiota promote host health by inhibiting pathogen colonization, yet how host-resident fungi or mycobiota contribute to this process remains unclear. The human skin mycobiota is uniquely stable compared with other body sites and dominated by skin-adapted yeasts of the genus Malassezia. We observe that colonization of human skin by Malassezia sympodialis significantly reduces subsequent colonization by the prominent bacterial pathogen Staphylococcus aureus. In vitro, M. sympodialis generates a hydroxyl palmitic acid isomer from environmental sources that has potent bactericidal activity against S. aureus in the context of skin-relevant stressors and is sufficient to impair S. aureus skin colonization. Leveraging experimental evolution to pinpoint mechanisms of S. aureus adaptation in response to antagonism by Malassezia, we identified multiple mutations in the stringent response regulator Rel that promote survival against M. sympodialis and provide a competitive advantage on human skin when M. sympodialis is present. Similar Rel alleles have been reported in S. aureus clinical isolates, and natural Rel variants are sufficient for tolerance to M. sympodialis antagonism. Partial stringent response activation underlies tolerance to clinical antibiotics, with both laboratory-evolved and natural Rel variants conferring multidrug tolerance in a manner that is dependent on the alternative sigma factor SigB. These findings demonstrate the ability of the mycobiota to mediate pathogen colonization resistance through generation of a hydroxy palmitic acid isomer, identify new mechanisms of bacterial adaptation in response to microbiota antagonism, and reveal the potential for microbiota-driven evolution to shape pathogen antibiotic susceptibility.

Global changes in Staphylococcus aureus virulence and metabolism during colonization of healthy skin

Staphylococcus aureus and its antibiotic-resistant derivative, methicillin-resistant S. aureus (MRSA), are the leading causative agents of skin and soft tissue infections globally. S. aureus transiently colonizes the skin of healthy adults, and this transient colonization likely precedes an active infection. In recent years, there have been efforts to elucidate specific factors that help MRSA transition to an active infection, but the specific genetic determinants required for this transition following skin colonization are largely unknown. To address this question, we developed a model of asymptomatic colonization of mouse skin by MRSA. From this model, we could determine the MRSA and mouse transcriptional profiles by RNA sequencing (RNAseq) at 5- and 24-hour post-colonization. The fadXDEBA locus, required for fatty acid metabolism, was highly upregulated in our data, as were numerous virulence factors. RNAseq data were confirmed via functional in vitro and in vivo promoter-fusion assays using live bioluminescent imaging of the fadXDEBA locus promoter driving fadB transcription. We analyzed the functional capacity of members of the fadXDEBA locus, which encode crucial enzymatic components of the S. aureus β-oxidation pathway. The genes fadD and fadA modulate MRSA resistance to fosfomycin and other oxidative stressors during growth in the presence of the common skin fatty acid, palmitic acid. Overall, our data demonstrate that there are global changes to the MRSA transcriptome, priming the bacteria for survival by upregulation of known virulence factors and metabolic genes implicated in host skin-nutrient utilization.IMPORTANCEStaphylococcus aureus is a major global agent of skin and soft tissue infections. S. aureus colonizes the skin transiently, an important precursor to infection. However, little is known about how S. aureus adapts to the skin at the transcriptional level. This study provides an overview of the S. aureus transcriptome during mouse skin colonization via RNA sequencing. We identified that the most highly upregulated genes during colonization are related to fatty acid metabolism. The disruption of certain genes in the fatty acid degradation pathway altered resistance of S. aureus to the antibiotic fosfomycin. This study provides an important step in understanding the transcriptional changes that occur during S. aureus skin colonization and may reveal novel targets of therapeutic interest for preventing skin infections.

Clinical and microbiological characteristics of skin and soft tissue infections of the extremities with bacteremia in patients with malignancy

INTRODUCTION

Although skin and soft tissue infections (SSTIs) of the extremities are primarily caused by Gram-positive cocci (GPC), some cases are caused by Gram-negative rod (GNR). In addition, malignancy is a recognized risk factor for GNR infection. Nevertheless, information on the clinical and microbiologic characteristics of SSTIs of the extremities caused by GNR in patients with malignancy is limited.

METHODS

Clinical and microbiological characteristics of patients with malignancy who developed bacteremic SSTIs of the extremities at a single cancer center over eight years were reviewed. In addition, whole-genome sequencing of the GNR isolates causing necrotizing fasciitis was conducted.

RESULTS

Of 42 cases identified, 32 cases (76.2 %) and 10 cases (23.8 %) were caused by GPC and GNR, respectively. Four cases in the GNR group were due to Escherichia coli, and the remaining cases were caused by diverse species. The majority of cases in the GNR group were hospital-onset and the lesions were limited to a single extremity. Chronic liver disease, cellular immunodeficiency, or anatomic abnormalities of the gastrointestinal, biliary, or urinary tract underlay seven GNR cases (70 %). Inappropriate empiric therapy was numerically more common in the GNR group compared to the GPC group (33.3 % vs. 9.4 %, p = 0.107). Whole-genome sequencing analysis revealed that two cases of GNR necrotizing fasciitis were caused by E. coli ST1193-fimH64 and Klebsiella pneumoniae K2-ST86.

CONCLUSIONS

GNR organisms are a significant cause of SSTIs of the extremities in patients with malignancy and may be associated with inappropriate empiric therapy.

Recurrence of skin and soft tissue infections: identifying risk factors and treatment strategies

PURPOSE OF REVIEW

Recurrent skin and soft tissue infections (RSSTIs) are challenging for the clinicians due to morbidity and healthcare-related costs. Here, we review updates on risk factors and management.

RECENT FINDINGS

RSSTIs rates range between 7 and 45%. Local and systemic conditions can favour RSSTIs, with comorbidities such as obesity, diabetes, cancer and immunosuppressive disease becoming increasingly relevant. Streptococcus spp . and Staphylococcus aures (including methicillin resistant, MRSA) are the leading causative pathogens of RSSTIs, but also Gram-negative bacteria and polymicrobial infection should be considered. To prevent recurrences, treatment of underlying predisposing factor, complete source control and appropriate antibiotic therapy are crucial. Antibiotic prophylaxis for recurrent erysipelas and decolonization for MRSA carriers demonstrated some advantages, but also long-term loss of efficacy and possible adverse effects. Clinical score and patients risk stratification could be useful tools to target prophylaxis and decolonization strategies. To reduce hospitalization rates and costs, outpatient oral and parenteral antibiotic therapy (OPAT) and long-acting antibiotics are being implemented.

SUMMARY

Management of RSSTIs requires both preventive interventions on modifiable risk factors and pharmacological strategies, with a patient tailored approach.

The future approach for the management of acute bacterial skin and skin structure infections

PURPOSE OF REVIEW

To discuss the new available options for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) and how to implement in the clinical practice innovative approaches for their management.

RECENT FINDINGS

The availability of long-acting antibiotics, including dalbavancin and oritavancin, changed the approach to patients with ABSSSI. Direct discharge from the emergency department and early discharge from the hospital should be considered in patients with ABSSSI. Despite limited data about different bactericidal properties, the choice between dalbavancin and oritavacin is usually based on patients' characteristics and comorbidities. Delafloxacin and omadacycline are other options and have the advantage to be available for both intravenous and oral formulations, allowing a sequential therapy and switch from intravenous to oral treatment in clinically stable patients. Further studies should elucidate the profile of patients who may beneficiate from these drugs.

SUMMARY

Early discharge from the hospital should be considered in patients with ABSSSI at a high risk of methicillin-resistant Staphylococcus aureus and in vulnerable patients for which hospitalization may have detrimental consequences. In elderly individuals, patients with diabetes mellitus, oncological people who need for continuing their healthcare pathway, this approach may reduce complications and costs related to hospitalization.

Omadacycline for the treatment of skin and soft tissue infections

PURPOSE OF REVIEW

To evaluate the current evidence on the use of omadacycline for the treatment of skin and soft tissue infections (SSTIs).

RECENT FINDINGS

This narrative review examines the available data on the pharmacology, clinical efficacy, safety profile, and comparative effectiveness of omadacycline in treating SSTIs, with a focus on its potential role in everyday clinical practice.

SUMMARY

Omadacycline is a viable option for outpatient therapy and early discharge in patients with SSTIs, particularly in frail populations and those undergoing chronic polypharmacotherapy. Emerging real-world evidence highlights its potential utility beyond approved indications, particularly for infections caused by multidrug-resistant microorganisms where treatment options are limited. However, further studies are needed to confirm its role in contexts beyond its current approvals.

Complicated skin and skin structure infections in alcoholics, a retrospective cohort study

BACKGROUND

Alcoholism increases the risk of skin and skin structure infections (SSSIs). Furthermore, in complicated SSSIs (cSSSIs) alcoholism is associated with delayed treatment response and a higher risk of blood culture positivity, suggesting poor outcomes. In pneumonia and bacteremia alcoholism is linked with higher mortality, longer hospital treatment and more ICU treatment.

METHODS

We conducted a population-based retrospective cohort study including all cases of complicated skin and skin structure infections (n = 460) treated in Gothenburg, Sweden and Helsinki, Finland from 2008 - 2011. Patients were stratified as alcoholics (9%) and non-alcoholics (91%) and patient and disease factors, treatment, and outcomes were compared.

RESULTS

Alcoholics were comparatively younger and more often male, with more liver diseases. We observed higher rates of bacteraemia, intensive care unit admission, surgical intervention, and clinical failure in alcoholics. Alcoholism was associated with longer length of stay and more interdepartmental transfers. We did not observe differences in infection type or time from symptom onset to diagnosis. Mortality was low and equivalent in alcoholics and non-alcoholics.

CONCLUSIONS

Alcoholism is associated with increased cSSSI disease severity and resource utilisation.

Antimicrobial Resistance Surveillance of Skin and Soft Tissue Infections: Hospital-Wide Bacterial Species and Antibiograms to Inform Management at a Zonal Tertiary Hospital in Mwanza, Tanzania

Purpose

The National Action Plan on antimicrobial resistance (NAP-AMR) in Tanzania is focused on blood stream infections and urinary tract infections despite skin and soft tissue infections (SSTIs) being common. This study assessed the proportion of laboratory-confirmed SSTIs, identify bacterial species involved, analyze AMR phenotypes, and investigate the risk factors associated with multidrug-resistant (MDR) SSTIs.

Patients and Methods

Analytical cross-sectional study was conducted between January and June 2023, involving 614 patients with SSTIs. Patients' information was collected using standard AMR surveillance tools, and either pus swabs or pus aspirate or necrotic tissues were collected and analyzed using standard microbiological procedures, WHONET and STATA software programs.

Results

The median age (interquartile range) of patients was 34 (14-54) years with males accounting for 54.4%. Laboratory-confirmed SSTIs was 72.5% (445/614), yielding 586 bacterial isolates. The most frequent SSTIs types were surgical site infections (30.0%), chronic wounds (27.9%), and traumatic wounds (19.7%). The commonest pathogens were Staphylococcus aureus (17.1%), Escherichia coli (17.1%), and K. pneumoniae (16.0%). The AMR phenotypes identified were methicillin resistant Staphylococcus aureus, 29.0%; Extended-spectrum beta lactamase producing Gram-negative bacteria, 47.3%; and carbapenem resistant Gram-negative bacteria, 12.9%. The overall MDR SSTIs was 40.9% (251/614) and was significantly higher among inpatients compared to outpatients [OR (95% CI); p-value: 1.86 (1.33-2.59); p-value<0.001].

Conclusion

Approximately three-quarter of patients have laboratory-confirmed SSTIs caused predominantly by MDR pathogens. Revisiting SSTIs treatment guidelines at BMC and inclusion of SSTIs in the on-going AMR surveillance in Tanzania are recommended.

Evaluation of prescribing practices and treatment failure for purulent skin and soft tissue infections in patients with obesity

Objective

Evaluate prescribing practices and risk factors for treatment failure in obese patients treated for purulent cellulitis with oral antibiotics in the outpatient setting.

Design

Retrospective, multicenter, observational cohort.

Setting

Emergency departments, primary care, and urgent care sites throughout Michigan.

Patients

Adult patients with a body mass index of ≥ 30 kg/m2 who received ≥ 5 days of oral antibiotics for purulent cellulitis were included. Key exclusion criteria were chronic infections, antibiotic treatment within the past 30 days, and suspected polymicrobial infections.

Methods

Obese patients receiving oral antibiotics for purulent cellulitis between February 1, 2020, and August 31, 2023, were assessed. The primary objective was to describe outpatient prescribing trends. Secondary objectives included comparing patient risk factors for treatment failure and safety outcomes between patients experiencing treatment success and those experiencing treatment failure.

Results

Two hundred patients were included (Treatment success, n = 100; Treatment failure, n = 100). Patients received 11 antibiotic regimens with 26 dosing variations; 45.5% were inappropriately dosed. Sixty-seven percent of patients received MRSA-active therapy. Treatment failure was similar between those appropriately dosed (46.4%) versus under-dosed (54.4%) (P = 0.256), those receiving 5-7 days of therapy (47.1%) versus 10-14 days (54.4%) (P = 0.311), and those receiving MRSA-active therapy (52.2%) versus no MRSA therapy (45.5%) (P = 0.367). Patients treated with clindamycin were more likely to experience treatment failure (73.7% vs 47.5%, P = 0.030).

Conclusions

Nearly half of antimicrobial regimens prescribed for outpatient treatment of cellulitis in patients with obesity were suboptimally prescribed. Opportunities exist to optimize agent selection, dosing, and duration of therapy in this population.

Factors Associated With Observation Unit Admission in Emergency Department Patients With Skin and Soft Tissue Infections

Objectives

Skin and soft tissue infections (SSTIs) constitute a significant portion of emergency department (ED) cases, with some requiring admission into the observation unit (OU) for ongoing care. Identifying factors linked to OU admission is essential for optimizing patient disposition decisions.

Methods

A retrospective cohort study identified patients with the International Classification of Diseases 10th Revision (ICD-10) codes indicating SSTI at an urban, tertiary care ED over 3 years (2017-2019) who were ultimately discharged. Patients admitted at index visit were excluded. Medical charts were reviewed for demographic and clinical data. Simple logistic regression models explored bivariate associations with OU admission, while a multiple logistic regression model adjusted for demographics, clinical characteristics, vital signs, and pre-index visit and in-ED management.

Results

Among 1675 patients (42.9% female; mean age, 45.5 ± 15.4 years; 56.4% identifying as Black), 20.7% (n = 346) were admitted to the OU. Unadjusted analysis showed associations between OU admission and factors, including age, history of intravenous drug use (IVDU), lower extremity SSTI, subjective systemic illness, fever at index visit, ED surgical consultation, and pre-index visit antimicrobial choice. After adjustment, age (odds ratio [OR], 1.16; 95% CI, 1.04-1.30), immunocompromised status (OR, 1.83; 95% CI, 1.07-3.13), extremity cellulitis (lower: OR, 2.51; 95% CI, 1.55-4.14; upper: OR, 2.35; 95% CI, 1.36-4.12), surgical consultation (OR, 2.64; 95% CI, 1.79-3.91), and prehospital methicillin-resistant Staphylococcus aureus (MRSA) antibiotic prescription (OR, 2.76; 95% CI, 1.69-4.54; P = .0001) remained statistically significant.

Conclusion

Identifying factors associated with OU admission provides insights into clinician decision making, potentially identifying patients who might benefit from OU admission through future work, which should focus on predictors of hospital admission, OU failure, and antimicrobial selection to reduce OU failure rates.

Global burden of bacterial skin diseases from 1990 to 2045: an analysis based on global burden disease data

Bacterial skin diseases are a category of inflammatory skin conditions caused by bacterial infections, which impose a significant global disease burden. However, they have not been well assessed or predicted on a global scale. It is necessary to update the estimates and forecast future trends of the global burden of bacterial skin diseases to evaluate the impact of past healthcare policies and to provide guidance and information for new national and international healthcare strategies. We aimed to describe the burden and trend of bacterial skin diseases and to predict the burden up to 2045. To achieve this, we employed a cross-sectional analysis based on Global Burden of Disease (GBD) data, utilizing advanced statistical models to quantify trends and forecast future burdens. Data on incidence and disability-adjusted life years (DALYs) of bacterial skin diseases were obtained from Global Burden of Disease 2021. We used average annual percent change (AAPC) by Joinpoint Regression to quantify the temporal trends. We conducted decomposition analysis to understand the contribution of aging, epidemiological changes, and population growth. Bayesian Age-Period-Cohort model was used to predict burden up to 2045. Global incidence rate of bacterial skin diseases increased from 8,988.74 per 100,000 in 1990 to 10,823.88 per 100,000, with AAPC of 0.62% (0.61 ~ 0.63%). The highest incidence rate was in low Socio-demographic Index (SDI) region and population aged < 35. The DALYs rate increased from 20.82 per 100,000 in 1990 to 25.45 per 100,000 in 2021, with AAPC of -0.11% (-0.34 ~ 0.13%). The highest increase of DALYs was in high SDI region and population aged > 85. Among the three evaluated factors of decomposition analysis, the major drivers of incident case rise were population growth, followed by epidemiological changes; the major drivers of DALYs case rise were population growth, followed by aging. The number of incidence cases has increased since 1990, reaching nearly 90 million in 2021 and expected to hit 1.2 billion in 2045. The incidence rate has also risen. Meanwhile, DALYs showed an upward trend from 1990 to 2005, peaking at 32/100,000, then a downward trend. Our findings align with our initial objectives, demonstrating a significant increase in the global incidence of bacterial skin diseases and highlighting the need for targeted prevention and treatment strategies. The variation in burden across different regions and age groups underscores the importance of tailored public health interventions. Predictive models suggest a continued rise in incidence rates and incident cases through 2045, emphasizing the urgency for action. This study provides a foundation for future research and policy development aimed at reducing the burden of bacterial skin diseases worldwide.

Use of lipoglycopeptides for moderate to severe ABSSSI in the emergency department

The burden of acute bacterial skin and skin structure infections (ABSSSI) continue to plague the healthcare system. One approach to managing moderate-to-severe ABSSSI in low-risk patients involves use of a single dose lipoglycopeptide (LGP), dalbavancin or oritavancin, in the emergency department (ED) and discharge to home with follow-up care. Limited ED studies indicate decreased hospital stays, ED revisits, readmissions, and healthcare costs, as well as improved patient satisfaction with use of these antibiotics. However, existing literature has limitations and gaps, such as insufficient quantifiable data on patient selection criteria, outcome predictors, and risk factors leading to treatment failure. Moreover, there is lack of research on the impact of LGPs on organizational productivity, patient quality of life, and utility in indications beyond ABSSSI. This review focuses on the role of long-acting LGPs in the ED setting for select patients presenting with ABSSSI, aiming to avoid hospitalizations, expedite patient discharge, and prevent readmissions while acknowledging potential limitations of therapy. Additionally, it provides insights into strategies and considerations specifically relevant to implementing this therapeutic approach in the ED.

Early-Stage IM Treatment with the Host-Derived Immunostimulant CPDI-02 Increases Curative Protection of Healthy Outbred Mice Against Subcutaneous Infection with Community-Acquired Methicillin-Resistant Staphylococcus aureus USA300

Background/Objectives: Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) greatly complicates the treatment of skin and soft tissue infections (SSTI). It was previously found that subcutaneous (SQ) treatment with the mononuclear phagocyte (MP)-selective activator complements peptide-derived immunostimulant-02 (CPDI-02; formerly EP67) and increases prophylaxis of outbred CD-1 mice against SQ infection with CA-MRSA. Here, we determined if treatment with CPDI-02 also increases curative protection. Methods: Female CD-1 mice were challenged SQ with CA-MRSA USA300 LAC, then CPDI-02 or inactive scCPDI-02 was administered by a topical, SQ, IM, or IV route at 6 or 24 h post-challenge. Abscess sizes were compared over 10 days and CA-MRSA burden, neutrophils, MP, and pro-inflammatory cytokines were compared in subcutaneous abscesses. CPDI-02 PK and distribution in female CD-1 mice were compared after IM or IV dosing and CPDI-02 toxicity in male and female CD-1 mice was determined by IM dose escalation and repeat IM dosing. Results: Repeat IM treatment starting at 6 h post-challenge decreased maximum abscess surface area, CA-MRSA burden, and time to resolution, whereas repeat treatment by a topical, SQ, or IV route had no effect. Repeat treatment starting at 24 h post-challenge was ineffective by the current routes. Single IM treatment starting at 6 h post-challenge was as effective as repeat IM treatment, increased systemic exposure to CPDI-02, and, in subcutaneous abscesses, initially decreased IL-1β and increased MP. CPDI-02 was tolerated between 130 and 170 mg/kg after IM dose escalation and between 65 and 130 mg/kg after repeat IM dosing with males being more tolerant. Conclusions: Single early-stage IM treatment with CPDI-02 may increase curative protection against SSTI caused by CA-MRSA and/or other pathogens controlled by activated MP.

A novel methionyl-tRNA synthetase inhibitor targeting gram-positive bacterial pathogens

New antibiotics are needed to treat gram-positive bacterial pathogens. MRS-2541 is a novel inhibitor of methionyl-tRNA synthetase with selective activity against gram-positive bacteria. The minimum inhibitory concentrations (MICs) against Staphylococcus aureus, Streptococcus pyogenes, and Enterococcus species range from 0.063 to 0.5 µg/mL. Given orally to mice at 50 mg/kg every 8 hours, MRS-2541 shows sustained plasma levels well above these MICs. In the mouse thigh infection model, MRS-2541 decreased methicillin-resistant Staphylococcus aureus and Streptococcus pyogenes bacterial loads to the same degree as linezolid. MRS-2541 is a promising new antibiotic for development against skin and soft tissue infections.

Collagen binding adhesin restricts Staphylococcus aureus skin infection

Staphylococcus aureus causes approximately 80% of skin and soft tissue infections (SSTIs). Collagen is the most abundant human extracellular matrix protein with critical roles in wound healing, and S. aureus encodes a collagen binding adhesin (Cna). The role of this protein during skin infections is unknown. Here we report that inability to bind collagen results in worsened pathology of intradermal Δcna S. aureus infection. WT/Cna+ S. aureus showed reduced infection severity, aggregate formation, and significantly improved clearance of bacteria. Cna binds to the collagen-like domain of serum C1q protein to reduce its opsonophagocytic functions. We demonstrate that infection of C1qKO mice with WT bacteria show results similar to the Δcna group. Conversely, inability to bind collagen resulted in an amplified inflammatory response caused in part by macrophage and neutrophil small molecule mediators released at the infection site (MMP-9, MMP-12, LTB4), resulting in increased immune cell infiltration and death.

Antibiotic stewardship in the emergency department setting: Focus on oral antibiotic selection for adults with skin and soft tissue infections

PURPOSE

An advisory panel of experts was convened by the ASHP Foundation as a part of its Medication-Use Evaluation Resources initiative to provide commentary on an approach to antibiotic stewardship in the treatment of skin and soft tissue infections (SSTIs), with a focus on oral antibiotics in the emergency department (ED) setting for patients who will be treated as outpatients. Considerations include a need to update existing guidelines to reflect new antibiotics and susceptibility patterns, patient-specific criteria impacting antibiotic selection, and logistics unique to the ED setting.

SUMMARY

While national guidelines serve as the gold standard on which to base SSTI treatment decisions, our advisory panel stressed that institutional guidelines must be regularly updated and grounded in local antimicrobial resistance patterns, patient-specific factors, and logistical considerations. Convening a team of experts locally to establish institution-specific guidelines as part of a comprehensive antibiotic stewardship program can ensure patients receive the most appropriate oral therapy for the outpatient treatment of SSTIs in patients visiting the ED.

CONCLUSION

SSTI treatment considerations for antibiotic selection in the ED supported by current, evidence-based guidelines, including guidance on optimal oral antibiotic selection for patients discharged for outpatient treatment, are a useful tool to improve the quality and efficiency of care, enhance patient-centric outcomes and satisfaction, decrease healthcare costs, and reduce overuse of antibiotics.

Global Trends and Scientific Impact of Topical Probiotics in Dermatological Treatment and Skincare

The skin plays a crucial role in maintaining homeostasis and protecting against external aggressors. Recent research has highlighted the potential of probiotics and postbiotics in dermatological treatments and skincare. These beneficial microorganisms interact with the skin microbiota, modulate the immune response, and enhance the skin barrier, offering a promising therapeutic avenue for various skin conditions, such as acne, dermatitis, eczema, and psoriasis. This bibliometric study aims to analyze the global trends and scientific impact of topical probiotics in dermatology. By reviewing 106 articles published between 2013 and 2023, the study categorizes the applications of probiotics in wound healing, inflammatory skin diseases, and general skincare. The findings indicate a significant increase in publications from 2021 onwards, attributed to the heightened focus on medical research during the COVID-19 pandemic. This study also identifies the most productive countries, institutions, and authors in this field, highlighting the importance of international collaborations. The results underscore the efficacy of probiotic-based topical formulations in improving skin health, reducing inflammation, and enhancing wound healing. This comprehensive analysis supports the development of new therapeutic strategies based on topical probiotics and encourages high-quality research in this promising area.

Lower extremity infections: Essential anatomy and multimodality imaging findings

In modern practice, imaging plays an integral role in the diagnosis, evaluation of extent, and treatment planning for lower extremity infections. This review will illustrate the relevant compartment anatomy of the lower extremities and highlight the role of plain radiographs, CT, US, MRI, and nuclear medicine in the diagnostic workup. The imaging features of cellulitis, abscess and phlegmon, necrotizing soft tissue infection, pyomyositis, infectious tenosynovitis, septic arthritis, and osteomyelitis are reviewed. Differentiating features from noninfectious causes of swelling and edema are discussed.

The ever-changing microenvironment of Staphylococcus aureus in cutaneous infections

BACKGROUND

Staphylococcus aureus is responsible for the majority of skin and soft tissue infections, which are often diagnosed at a late stage, thereby impacting treatment efficacy. Our study was designed to reveal the physiological changes at different stages of infection by S. aureus through the combined analysis of variations in the skin microenvironment, providing insights for the diagnosis and treatment of S. aureus infections.

METHODS

We established a murine model of skin and soft tissue infection with S. aureus as the infectious agent to investigate the differences in the microenvironment at different stages of infection. By combining analysis of the host immune status and histological observations, we elucidate the progression of S. aureus infection in mice.

RESULTS

The results indicate that the infection process in mice can be divided into at least two stages: early infection (1-3 days post-infection) and late infection (5-7 days post-infection). During the early stage of infection, notable symptoms such as erythema and abundant exudate at the infection site were observed. Histological examination revealed infiltration of numerous neutrophils and bacterial clusters, accompanied by elevated levels of cytokines (IL-6, IL-10). There was a decrease in microbial alpha diversity within the microenvironment (Shannon, Faith's PD, Chao1, Observed species, Simpson, Pielou's E). In contrast, during the late stage of infection, a reduction or even absence of exudate was observed at the infected site, accompanied by the formation of scabs. Additionally, there was evidence of fibroblast proliferation and neovascularization. The levels of cytokines and microbial composition gradually returned to a healthy state.

CONCLUSION

This study reveals synchrony between microbial composition and histological/immunological changes during S. aureus-induced SSTIs.

Prevalence, resistance profiles and factors associated with skin and soft-tissue infections at Jinja regional referral hospital: A retrospective study

Skin and soft-tissue infections (SSTI) are common cases of hospital-acquired infections with aetiological agents exhibiting antimicrobial resistance (AMR). This is a global public health predicament responsible for a high burden of infectious diseases and threatens the achievement of Sustainable Development Goals (SDGs), especially in Low- and Middle-Income countries (LMICs). This study determined the prevalence of SSTI, proportion of laboratory-investigated cases, AMR-profiles, and factors associated with SSTI and multi-drug resistance (MDR). This was based on records of patients suspected of SSTI for the period of 2019-2021 at Jinja Regional Referral Hospital. The analysis involved 268 randomly selected patient reports using WHONET 2022 and Stata 17 at the 95% confidence level. The prevalence of SSTI was 66.4%. Cases that involved laboratory testing were 14.1%. Staphylococcus aureus (n = 51) was the most isolated organism. MDR pathogens explained 47% of infections. Methicillin-resistant Staphylococcus aureus (MRSA) was up to 44%. In addition, 61% of Gram-negatives had the potential to produce extended-spectrum beta-lactamases (ESBL), while 27% were non-susceptible to carbapenems. Ward of admission was significantly associated with infection (aPR = 1.78, 95% CI: 1.00-3.18, p-value = 0.04). Age category (19-35) was an independent predictor for MDR infections (aPR = 2.30, 95%CI:1.02-5.23, p-value = 0.04). The prevalence of SSTI is high with MDR pathogens responsible for almost half of the infections. Gentamicin and ciprofloxacin can be considered for empirical management of strictly emergency SSTI cases suspected of Staphylococcus aureus. Given the high resistance observed, laboratory-based diagnosis should be increased to use the most appropriate treatment. Infection Prevention and Control (IPC) strategies should be heightened to reduce the prevalence of SSTI. Recognizing SSTI under the Global Antimicrobial resistance Surveillance System (GLASS) would lead to improved preparedness and response to AMR.

Infectious Aspects of Chronic Wounds

The treatment, maintenance, and suppression of infection in chronic wounds remain a challenge to all practitioners. From an infectious disease standpoint, knowing when a chronic wound has progressed from colonized to infected, when to use systemic antimicrobial therapy and when and how to culture such wounds can be daunting. With few standardized clinical guidelines for infections in chronic wounds, caring for them is an art form. However, there have been notable advances in the diagnosis, treatment, and management of infected wounds. This article will discuss the pathophysiology of infection in older adults, including specific infections such as cutaneous candidiasis, necrotizing soft tissue infection, osteomyelitis, and infections involving hardware.

Design of Ultrasound-Driven Charge Interference Therapy for Wound Infection

Wound infections, especially those caused by pathogenic bacteria, present a considerable public health concern due to associated complications and poor therapeutic outcomes. Herein, we developed antibacterial nanoparticles, namely, PGTP, by coordinating guanidine derivatives with a porphyrin-based sonosensitizer. The synthesized PGTP nanoparticles, characterized by their strong positive charge, effectively disrupted the bacterial biosynthesis process through charge interference, demonstrating efficacy against both Gram-negative and Gram-positive bacteria. Additionally, PGTP nanoparticles generated reactive oxygen species under ultrasound stimulation, resulting in the disruption of biofilm integrity and efficient elimination of pathogens. RNA-seq analysis unveiled the detailed mechanism of wound healing, revealing that PGTP nanoparticles, when coupled with ultrasound, impair bacterial metabolism by interfering with the synthesis and transcription of amino acids. This study presents a novel approach to combatting wound infections through ultrasound-driven charge-interfering therapy, facilitated by advanced antibacterial nanomaterials.

ER-mitochondria association negatively affects wound healing by regulating NLRP3 activation

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common causative agent of acute bacterial skin and skin-structure infections (ABSSSI), one of the major challenges to the health system worldwide. Although the use of antibiotics as the first line of intervention for MRSA-infected wounds is recommended, important side effects could occur, including cytotoxicity or immune dysregulation, thus affecting the repair process. Here, we show that the oxazolidinone antibiotic linezolid (LZD) impairs wound healing by aberrantly increasing interleukin 1 β (IL-1β) production in keratinocytes. Mechanistically, LZD triggers a reactive oxygen species (ROS)-independent mitochondrial damage that culminates in increased tethering between the endoplasmic reticulum (ER) and mitochondria, which in turn activates the NLR family pyrin domain-containing 3 (NLRP3) inflammasome complex by promoting its assembly to the mitochondrial surface. Downregulation of ER-mitochondria contact formation is sufficient to inhibit the LZD-driven NLRP3 inflammasome activation and IL-1β production, restoring wound closure. These results identify the ER-mitochondria association as a key factor for NLRP3 activation and reveal a new mechanism in the regulation of the wound healing process that might be clinically relevant.

Integrative model-based comparison of target site-specific antimicrobial effects: A case study with ceftaroline and lefamulin

OBJECTIVE

Predictions of antimicrobial effects typically rely on plasma-based pharmacokinetic-pharmacodynamic (PK-PD) targets, ignoring target-site concentrations and potential differences in tissue penetration between antibiotics. In this study, we applied PK-PD modelling to compare target site-specific effects of antibiotics by integrating clinical microdialysis data, in vitro time-kill curves, and antimicrobial susceptibility distributions. As a case study, we compared the effect of lefamulin and ceftaroline against methicillin-resistant Staphylococcus aureus (MRSA) at soft-tissue concentrations.

METHODS

A population PK model describing lefamulin concentrations in plasma, subcutaneous adipose and muscle tissue was developed. For ceftaroline, a similar previously reported PK model was adopted. In vitro time-kill experiments were performed with six MRSA isolates and a PD model was developed to describe bacterial growth and antimicrobial effects. The clinical PK and in vitro PD models were linked to compare antimicrobial effects of ceftaroline and lefamulin at the different target sites.

RESULTS

Considering minimum inhibitory concentration (MIC) distributions and standard dosages, ceftaroline showed superior anti-MRSA effects compared to lefamulin both at plasma and soft-tissue concentrations. Looking at the individual antibiotics, lefamulin effects were highest at soft-tissue concentrations, while ceftaroline effects were highest at plasma concentrations, emphasising the importance of considering target-site PK-PD in antibiotic treatment optimisation.

CONCLUSION

Given standard dosing regimens, ceftaroline appeared more effective than lefamulin against MRSA at soft-tissue concentrations. The PK-PD model-based approach applied in this study could be used to compare or explore the potential of antibiotics for specific indications or in populations with unique target-site PK.

Current challenges in acute bacterial skin infection management

PURPOSE OF REVIEW

There are aspects of skin and soft tissue infections (SSTIs) that remain unresolved, such as current numbers, classification criteria, how best to define severity and predict the outcome, what diagnostic tests to perform, what new treatment options are available, or what the duration of antibiotic treatment should be. We have reviewed the literature over the last 18 months to clarify these issues and provide our opinion.

RECENT FINDINGS

SSTIs are common and among the top 10 most frequent infections worldwide. They represent a burden on the healthcare system and have a major impact on the quality of life of patients. Regarding classification, the Infectious Diseases Society of America (IDSA) provides a practical guide that distinguishes between uncomplicated and complicated infections, acute and chronic wound infections, and necrotising and nonnecrotizing infections based on skin extension and tissue necrosis. With new microbiological and imaging diagnostic techniques, SSTIs can now be better diagnosed. New PCR techniques are available, and mass spectrometry can be applied to samples collected in liquid transport media. Moreover, new treatment methods such as photodynamic therapy, reactive oxygen, and phages are emerging. SSTI patients can be treated with shorter antibiotic courses if they receive an active drug with good tissue penetration. Antibiotic treatment in necrotizing infections can be shortened to 48 h after the last debridement.

SUMMARY

SSTIs remain a challenge regarding rapid and accurate diagnosis and clinical management.

Current Development of Thiazole-Containing Compounds as Potential Antibacterials against Methicillin-Resistant Staphylococcus aureus

The emergence of multi-drug-resistant bacteria is threatening to human health and life around the world. In particular, methicillin-resistant Staphylococcus aureus (MRSA) causes fatal injuries to human beings and serious economic losses to animal husbandry due to its easy transmission and difficult treatment. Currently, the development of novel, highly effective, and low-toxicity antimicrobials is important to combat MRSA infections. Thiazole-containing compounds with good biological activity are widely used in clinical practice, and appropriate structural modifications make it possible to develop new antimicrobials. Here, we review thiazole-containing compounds and their antibacterial effects against MRSA reported in the past two decades and discuss their structure-activity relationships as well as the corresponding antimicrobial mechanisms. Some thiazole-containing compounds exhibit potent antibacterial efficacy in vitro and in vivo after appropriate structural modifications and could be used as antibacterial candidates. This Review provides insights into the development of thiazole-containing compounds as antimicrobials to combat MRSA infections.

Green synthesis of epigallocatechin gallate-ferric complex nanoparticles for photothermal enhanced antibacterial and wound healing

Bacterial infections are a significant global health concern, particularly in the context of skin infections and chronic wounds, which was further exacerbated by the emerging of antibiotic resistance. Therefore, there are urgent needs to develop alternative antibacterial strategies without inducing significant resistance. Photothermal therapy (PTT) is a promising alternative approach but usually faces limitations such as the need for stable and environmental-friendly PTT agents and ensuring biocompatibility with living tissues, necessitating ongoing research for its clinical advancement. Herein, in this study, with the aim to develop a green synthesized PTT agent for photothermal enhanced antibacterial and wound healing, we proposed a facile one-pot method to prepare epigallocatechin gallate-ferric (EGCG-Fe) complex nanoparticles. The obtained nanoparticles showed improved good size distribution and stability with high reproducibility. More importantly, EGCG-Fe complex nanoparticles have additional photothermal conversion ability which can give photothermal enhanced antibacterial effect on various pathogens, including Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) strains. EGCG-Fe complex nanoparticles also showed powerful biofilm prevention and destruction effects with promoted antibacterial and wound healing on mice model. In conclusion, EGCG-Fe complex nanoparticles can be a robust green material with effective and novel light controllable antibacterial properties for photothermal enhanced antibacterial and wound healing applications.

Real-World Use of Dalbavancin for Treatment of Soft Tissue and Bone Infection in Children: Safe, Effective and Hospital-Time Sparing

Acute bacterial skin and skin structure infections (ABSSSI) and osteoarticular infections compound the burden of morbidity, mortality and prolonged hospitalizations among gram-positive infections. Dalbavancin, a second-generation, intravenous lipoglycopeptide, due to its prolonged half-life, can be a valuable alternative in their treatment when administered as inpatient treatment at the price of an extended hospital stay. Between October 2019 and September 2023, 31 children and adolescents were treated with dalbavancin because of bone and joint infections (n = 12 patients, 39%), ABSSSI (n = 13 patients, 42%), mainly for the limbs, facial cellulitis or complicated ABSSSI (n = 6 patients, 19%), at five Italian pediatric centers. Microbiological study provided gram-positive bacterial isolate in 16 cases, in 11 cases from a positive blood culture; 9 of them were MRSA. Twenty-five patients were initially treated with a different antibiotic therapy: beta-lactam-based in 18 patients (58%), glycopeptide-based in 15 patients (48%) and daptomycin in 6 (19%). The median time that elapsed between admission and start of dalbavancin was 18 days. A total of 61 doses of dalbavancin were administered to the 31 patients: 16 received a single dose while the remaining 15 patients received between two (n = 9) and nine doses. The frequency of administration was weekly in five cases or fortnightly in nine patients. Median length of stay in hospital was 16 days. Median time to discharge after the first dose of dalbavancin was 1 day. Treatment was very well-tolerated: of the 61 administered doses, only four doses, administered to four patients, were associated with an adverse event: drug extravasation during intravenous administration occurred in two patients, with no sequelae; however, in two patients the first administration was stopped soon after infusion start: in one (ID #11), due to headache and vomiting; in another (ID #12) due to a systemic reaction. In both patients, drug infusion was not repeated. None of the remaining 29 patients reported treatment failure (resistant or recurrent disease) or an adverse effect during a median follow-up time of two months. The use of dalbavancin was safe, feasible and also effective in shortening the hospital stay in children and adolescents.

Isolation, identification, and biological characterization of bacterial endophytes isolated from Gunnera perpensa L

In the present study, eleven endophytic bacterial strains, Herbaspirillum sp. (GP-SGM1, GP-SGM2, GP-SGM3, and GP-SGM11), Pseudomonas sp. (GP-SGM4, GP-SGM5), Novosphingobium sp. GP-SGM6, Chryseobacterium sp. GP-SGM7, Labedella sp. GP-SGM8, Brevibacterium sp. GP-SGM9, and Pseudomonas sp. GP-SGM10, were isolated from the rhizomes of Gunnera perpensa L. The growth kinetics, assessed through maximum growth rates (μmax) and optical density (OD) values, revealed that GP-SGM7 exhibited highest μmax values of 0.33 ± 0.01 hours (h)-1 with an OD of 4.20 ± 0.04. In contrast, GP-SGM11 exhibited the lowest μmax of 0.12 ± 0.05 h-1 and the smallest OD of 1.50 ± 0.00. In addition, the endophyte crude extracts were tested for antibacterial activity against five pathogenic strains using the disk diffusion method, with GP-SGM7 crude extracts exhibiting promising antibacterial activity against Klebsiella pneumoniae and Staphylococcus aureus. Antioxidant activity was determined by DPPH (2, 2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays. The crude extracts of GP-SGM1, GP-SGM7, GP-SGM9, and GP-SGM10 were the most effective at scavenging DPPH radicals, with GP-SGM7 also exhibiting a high FRAP value of 0.54 ± 0.01. These findings emphasize the therapeutic potential of endophytic bacteria from G. perpensa L. in addressing skin-related issues, including bacterial infections and free radicals.

Assessment of antibiotic release and antibacterial efficacy from pendant glutathione hydrogels using ex vivo porcine skin

Acute bacterial skin and skin structure infections (ABSSSIs) confer a substantial burden on the healthcare system. Local antibiotic delivery systems can provide controlled drug release directly to the site of infection to maximize efficacy and minimize systemic toxicity. The purpose of this study was to examine the antibacterial activity of antibiotic-loaded glutathione-conjugated poly(ethylene glycol) hydrogels (GSH-PEG) against ABSSSIs utilizing an ex vivo porcine dermal explant model. Vancomycin- or meropenem-loaded GSH-PEG hydrogels at 3 different dose levels were loaded over 1 h. Drug release was monitored in vitro under submerged conditions, by the Franz cell diffusion method, and ex vivo utilizing a porcine dermis model. Antibacterial activity was assessed ex vivo on porcine dermis explants inoculated with Staphylococcus aureus or Pseudomonas aeruginosa isolates treated with vancomycin- or meropenem-loaded GSH-PEG hydrogels, respectively. Histological assessment of the explants was conducted to evaluate tissue integrity and viability in the context of the experimental conditions. A dose-dependent release was observed from vancomycin and meropenem hydrogels, with in vitro Franz cell diffusion data closely representing ex vivo vancomycin release, but not high dose meropenem release. High dose vancomycin-loaded hydrogels resulted in a >3 log10 clearance against all S. aureus isolates at 48 h. High dose meropenem-loaded hydrogels achieved 6.5, 4, and 2 log10 reductions in CFU/ml against susceptible, intermediate, and resistant P. aeruginosa isolates, respectively. Our findings demonstrate the potential application of GSH-PEG hydrogels for flexible, local antibiotic delivery against bacterial skin infections.

The Etiology, Antibiotic Therapy and Outcomes of Bacteremic Skin and Soft-Tissue Infections in Onco-Hematological Patients

OBJECTIVES

to assess the current epidemiology, antibiotic therapy and outcomes of onco- hematological patients with bacteremic skin and soft-tissue infections (SSTIs), and to identify the risk factors for Gram-negative bacilli (GNB) infection and for early and overall mortality.

METHODS

episodes of bacteremic SSTIs occurring in cancer patients at two hospitals were prospectively recorded and retrospectively analyzed.

RESULTS

Of 164 episodes of bacteremic SSTIs, 53% occurred in patients with solid tumors and 47% with hematological malignancies. GNB represented 45.5% of all episodes, led by Pseudomonas aeruginosa (37.8%). Multidrug resistance rate was 16%. Inadequate empirical antibiotic therapy (IEAT) occurred in 17.7% of episodes, rising to 34.6% in those due to resistant bacteria. Independent risk factors for GNB infection were corticosteroid therapy and skin necrosis. Early and overall case-fatality rates were 12% and 21%, respectively. Risk factors for early mortality were older age, septic shock, and IEAT, and for overall mortality were older age, septic shock and resistant bacteria.

CONCLUSIONS

GNB bacteremic SSTI was common, particularly if corticosteroid therapy or skin necrosis. IEAT was frequent in resistant bacteria infections. Mortality occurred mainly in older patients with septic shock, resistant bacteria and IEAT. These results might guide empirical antibiotic therapy in this high-risk population.

Hyperglycemia potentiates increased Staphylococcus aureus virulence and resistance to growth inhibition by Pseudomonas aeruginosa

IMPORTANCE

Individuals with diabetes are prone to more frequent and severe infections, with many of these infections being polymicrobial. Polymicrobial infections are frequently observed in skin infections and in individuals with cystic fibrosis, as well as in indwelling device infections. Two bacteria frequently co-isolated from infections are Staphylococcus aureus and Pseudomonas aeruginosa. Several studies have examined the interactions between these microorganisms. The majority of these studies use in vitro model systems that cannot accurately replicate the microenvironment of diabetic infections. We employed a novel murine indwelling device model to examine interactions between S. aureus and P. aeruginosa. Our data show that competition between these bacteria results in reduced growth in a normal infection. In a diabetic infection, we observe increased growth of both microbes and more severe infection as both bacteria invade surrounding tissues. Our results demonstrate that diabetes changes the interaction between bacteria resulting in poor infection outcomes.

Skin and soft tissue infection incidence before and during the COVID-19 pandemic

Skin and Soft Tissue Infections (SSTIs) are common bacterial infections. We hypothesized that due to the COVID-19 pandemic, SSTI rates would significantly decrease due to directives to avoid unneeded care and attenuated SSTIs risk behaviours. We retrospectively examined all patients with an ICD-10 diagnosis code in the Los Angeles County Department of Health Services, the second largest U.S. safety net healthcare system between 16 March 2017 and 15 March 2022. We then compared pre-pandemic with intra-pandemic SSTI rates using an interrupted time series analysis. We found 72,118 SSTIs, 46,206 during the pre-pandemic period and 25,912 during the intra-pandemic period. Pre-pandemic SSTI rate was significantly higher than the intra-pandemic rate (3.27 vs. 2.31 cases per 1,000 empanelled patient-months, P < 0.0001). The monthly SSTI cases decreased by 1.19 SSTIs/1,000 empanelled patient-months between the pre- and intra-pandemic periods (P = 0.0003). SSTI subgroups (inpatient, observation unit, emergency department, and outpatient clinics), all had significant SSTI decreases between the two time periods (P < 0.05) except for observation unit (P = 0.50). Compared to the pre-COVID-19 pandemic period, medically attended SSTI rates in our large U.S. safety net healthcare system significantly decreased by nearly 30%. Whether findings reflect true SSTI decreases or decreased health system utilization for SSTIs requires further examination.

Liposome-loaded polymeric microneedles for enhanced skin deposition of rifampicin

Methicillin-resistant Staphylococcus aureus (MRSA) is a prevailing bacterial pathogen linked to superficial skin and soft tissue infections (SSTIs). Rifampicin (RIF), a potent antibiotic against systemic and localised staphylococcal infections, faces limitations due to its low solubility. This constraint hampers its therapeutic potential for MRSA-induced SSTIs. To address this, an advanced liposomal system was designed for efficient dermal RIF delivery. Rifampicin-loaded liposomes (LipoRIF) were embedded within polymeric dissolving microneedles (DMNs) to enable targeted intradermal drug delivery. A robust Design of Experiment (DoE) methodology guided the systematic preparation and optimisation of LipoRIF formulations. The optimal LipoRIF formulation integrated within polymeric DMNs. These LipoRIF-DMNs exhibited favourable mechanical properties and effective skin insertion characteristics. Notably, in vitro assays on skin deposition unveiled a transformative result - the DMN platform significantly enhanced LipoRIF deposition within the skin, surpassing LipoRIF dispersion alone. Moreover, LipoRIF-DMNs displayed minimal cytotoxicity toward cells. Encouragingly, rigorous in vitro antimicrobial evaluations demonstrated LipoRIF-DMNs' capacity to inhibit MRSA growth compared to the control group. LipoRIF-DMNs propose a potentially enhanced, minimally invasive approach to effectively manage SSTIs and superficial skin ailments stemming from MRSA infections.

Current approach to skin and soft tissue infections. Thinking about continuity of care

Skin and soft tissue infections are a common reason for patients seeking inpatient and outpatient medical care. Surgery is an essential part of managing in many episodes. Careful evaluation of antibiotic therapy could help clinicians in early identification to patients with treatment failure and to consider an alternative approach or a new surgical revision in "focus control". With the arrival of new drugs, there is a need to refine the appropriate drug's decision-making. Drugs with a long half-life (long-acting lipoglycopeptides such as dalbavancin or oritavancin), which allows weekly administration (or even greater), can reduce hospital admission and length of stay with fewer healthcare resources through outpatient management (home hospitalization or day hospitals). New anionic fluoroquinolones (e.g. delafloxacin), highly active in an acidic medium and with the possibility of switch from the intravenous to the oral route, will also make it possible to achieve these new healthcare goals and promote continuity of care. Therefore, management should rely on a collaborative multidisciplinary group with experience in this infectious syndrome.

Taxifolin as a Metallo-β-Lactamase Inhibitor in Combination with Augmentin against Verona Imipenemase 2 Expressing Pseudomonas aeruginosa

Among the various mechanisms that bacteria use to develop antibiotic resistance, the multiple expression of β-lactamases is particularly problematic, threatening public health and increasing patient mortality rates. Even if a combination therapy-in which a β-lactamase inhibitor is administered together with a β-lactam antibiotic-has proven effective against serine-β-lactamases, there are no currently approved metallo-β-lactamase inhibitors. Herein, we demonstrate that quercetin and its analogs are promising starting points for the further development of safe and effective metallo-β-lactamase inhibitors. Through a combined computational and in vitro approach, taxifolin was found to inhibit VIM-2 expressing P. aeruginosa cell proliferation at <4 μg/mL as part of a triple combination with amoxicillin and clavulanate. Furthermore, we tested this combination in mice with abrasive skin infections. Together, these results demonstrate that flavonol compounds, such as taxifolin, may be developed into effective metallo-β-lactamase inhibitors.

Ultrasonography for Skin and Soft Tissue Infections, Noninfectious Cysts, Foreign Bodies, and Burns in the Critical Care Setting

There are multiple opportunities for the use of ultrasonography in the diagnosis of skin and soft tissue differentials. Ultrasonography is inexpensive, easily reproducible, and able to provide real-time data in situations where condition changes and progression are common. Not only does bedside ultrasonography provide the clinician an in-depth look beyond epidermal structures into body cavities, it remains a safe, nonionizing radiating, effective, cost-efficient, reliable, and accessible tool for the emergency management of life- and limb-threatening integumentary infections. Unnecessary invasive procedures are minimized, providing improved patient outcomes. Integumentary abnormalities secondary to trauma, surgery, and hospitalization are common among critical care patients. This article provides a brief overview and evidence-based recommendations for the use of ultrasonography in the critical care setting for integumentary system conditions, including common skin and soft tissue differentials, foreign bodies, and burn depth assessment.

Oxiconazole Potentiates Gentamicin against Gentamicin-Resistant Staphylococcus aureus In Vitro and In Vivo

Amid the mounting burden of multidrug-resistant (MDR) bacterial infections on health care worldwide, drug repurposing, a time and cost-effective strategy to identify new applications for drugs approved for other indications, can effectively fill the void in the current antibiotic pipeline. In this study, we have repurposed a topical antifungal agent, oxiconazole, in combination with gentamicin against skin infections caused by multidrug-resistant Staphylococcus aureus. Oxiconazole was identified as having antibacterial activity against S. aureus via whole-cell screening assays against clinically relevant bacterial pathogens. It exhibited a potent in vitro profile, including equipotent activity against clinical drug-susceptible and -resistant S. aureus and Enterococcus spp. Checkerboard assays and time-kill kinetics studies demonstrated its concentration-dependent killing and ability to synergize with the approved antibiotics daptomycin and gentamicin against susceptible and MDR S. aureus strains. Oxiconazole also significantly eradicated preformed S. aureus biofilms in vitro. Eventually, in an assessment of its ability to generate resistant S. aureus mutants via serial passaging, oxiconazole displayed an extremely low propensity for developing stable resistance in S. aureus. Its in vivo efficacy alone and in combination with synergistic antibiotics was assessed in a murine superficial skin infection model of S. aureus, where it strongly synergized with gentamicin, exhibiting superior activity to the untreated control and drug-alone treatment groups. Thus, oxiconazole can be repurposed as an antibacterial alone and in combination with gentamicin against susceptible and gentamicin-resistant S. aureus infections. IMPORTANCE Staphylococcus aureus, which causes the majority of nosocomial and community-acquired infections globally, is a WHO high-priority pathogen for antibiotic research and development. In addition to invasive infections, it is the causative agent of moderate to severe skin infections, with an increasing prevalence of infections caused by MDR strains such as methicillin-resistant S. aureus (MRSA). Our study highlights the repurposing of oxiconazole, a topical antifungal agent, as an ideal candidate for combination therapy with gentamicin against susceptible and drug-resistant S. aureus skin infections due to its extremely low propensity for resistance generation in S. aureus, activity against MDR strains, bactericidal killing kinetics alone and in combination, broad antifungal efficacy, and excellent safety and tolerability profile.

Increasing serum iron levels and their role in the risk of infectious diseases: a Mendelian randomization approach

OBJECTIVES

Increased iron stores have been associated with elevated risks of different infectious diseases, suggesting that iron supplementation may increase the risk of infections. However, these associations may be biased by confounding or reverse causation. This is important, since up to 19% of the population takes iron supplementation. We used Mendelian randomization (MR) to bypass these biases and estimate the causal effect of iron on infections.

METHODS

As instrumental variables, we used genetic variants associated with iron biomarkers in two genome-wide association studies (GWASs) of European ancestry participants. For outcomes, we used GWAS results from the UK Biobank, FinnGen, the COVID-19 Host Genetics Initiative or 23andMe, for seven infection phenotypes: 'any infections', combined, COVID-19 hospitalization, candidiasis, pneumonia, sepsis, skin and soft tissue infection (SSTI) and urinary tract infection (UTI).

RESULTS

Most of our analyses showed increasing iron (measured by its biomarkers) was associated with only modest changes in the odds of infectious outcomes, with all 95% odds ratios confidence intervals within the 0.88 to 1.26 range. However, for the three predominantly bacterial infections (sepsis, SSTI, UTI), at least one analysis showed a nominally elevated risk with increased iron stores (P <0.05).

CONCLUSION

Using MR, we did not observe an increase in risk of most infectious diseases with increases in iron stores. However for bacterial infections, higher iron stores may increase odds of infections. Hence, using genetic variation in iron pathways as a proxy for iron supplementation, iron supplements are likely safe on a population level, but we should continue the current practice of conservative iron supplementation during bacterial infections or in those at high risk of developing them.

Neutrophil-intrinsic TNF receptor signaling orchestrates host defense against Staphylococcus aureus

Staphylococcus aureus is the leading cause of skin and soft tissue infections and is a major health burden due to the emergence of antibiotic-resistant strains. To address the unmet need of alternative treatments to antibiotics, a better understanding of the protective immune mechanisms against S. aureus skin infection is warranted. Here, we report that tumor necrosis factor (TNF) promoted protection against S. aureus in the skin, which was mediated by bone marrow-derived immune cells. Furthermore, neutrophil-intrinsic TNF receptor (TNFR) signaling directed immunity against S. aureus skin infections. Mechanistically, TNFR1 promoted neutrophil recruitment to the skin, whereas TNFR2 prevented systemic bacterial dissemination and directed neutrophil antimicrobial functions. Treatment with a TNFR2 agonist showed therapeutic efficacy against S. aureus and Pseudomonas aeruginosa skin infections, which involved increased neutrophil extracellular trap formation. Our findings revealed nonredundant roles for TNFR1 and TNFR2 in neutrophils for immunity against S. aureus and can be therapeutically targeted for protection against bacterial skin infections.

Risk Factors and the Impact of Multidrug-Resistant Bacteria on Community-Acquired Urinary Sepsis

Risk factors for multidrug-resistant bacteria (MDRB) in nosocomial urinary tract infection (UTI) have been widely studied. However, these risk factors have not been analyzed in community-acquired urinary sepsis (US), nor have its outcomes been studied. The aim of our study is to determine risk factors for MDRB in community-acquired US and its influence on outcomes. Prospective observational study of patients with community-acquired US admitted to a university hospital. We compared epidemiological and clinical variables and outcomes of US due to MDRB and non-MDRB. Independent risk factors for MDRB were analyzed using logistic regression. A total of 193 patients were included, 33.7% of them with US due to MDRB. The median age of patients was 82 years. Hospital mortality was 17.6%, with no difference between the MDRB and non-MDRB groups. The length of hospital stay was 5 (4-8) days, with a non-significant tendency to longer hospital stays in the MDRB group (6 (4-10) vs. 5 (4-8) days, p = 0.051). Healthcare-associated US was found to be an independent risk factor for MDR bacteria by multivariate analysis. In conclusion, the impact of MDR bacteria on the outcomes of community-acquired urinary sepsis was mild. Healthcare-associated US was an independent risk factor for MDR bacteria.

Assessing Empiric Antimicrobial Therapy With the Modified Dundee Classification for Nonpurulent Skin and Soft Tissue Infections in a Community Hospital System

Background

The modified Dundee classification has recently been validated in various studies for nonpurulent skin and soft tissue infections. This has yet to be applied in the United States and within community hospital settings to optimize antimicrobial stewardship and ultimately patient care.

Methods

A retrospective, descriptive analysis was performed of 120 adult patients admitted to St. Joseph's/Candler Health System for nonpurulent skin and soft tissue infections between January 2020 and September 2021. Patients were classified into their modified Dundee classes, and frequencies of concordance of their empiric antimicrobial regimens with this classification scheme in the emergency department and inpatient settings were compared, along with possible effect modifiers and possible exploratory measures associated with concordance.

Results

Concordance with the modified Dundee classification for the emergency department and inpatient regimens was 10% and 15%, respectively, with broad-spectrum antibiotic use and concordance positively associated with illness severity. Due to substantial broad-spectrum antibiotic use, possible effect modifiers associated with concordance were unable to be validated, and overall no statistically significant differences among exploratory analyses across classification status were observed.

Conclusions

The modified Dundee classification can help identify gaps in antimicrobial stewardship and excessive broad-spectrum antimicrobial usage toward optimizing patient care.

Rothia from the Human Nose Inhibit Moraxella catarrhalis Colonization with a Secreted Peptidoglycan Endopeptidase

Moraxella catarrhalis is found almost exclusively within the human respiratory tract. This pathobiont is associated with ear infections and the development of respiratory illnesses, including allergies and asthma. Given the limited ecological distribution of M. catarrhalis, we hypothesized that we could leverage the nasal microbiomes of healthy children without M. catarrhalis to identify bacteria that may represent potential sources of therapeutics. Rothia was more abundant in the noses of healthy children compared to children with cold symptoms and M. catarrhalis. We cultured Rothia from nasal samples and determined that most isolates of Rothia dentocariosa and "Rothia similmucilaginosa" were able to fully inhibit the growth of M. catarrhalis in vitro, whereas isolates of Rothia aeria varied in their ability to inhibit M. catarrhalis. Using comparative genomics and proteomics, we identified a putative peptidoglycan hydrolase called secreted antigen A (SagA). This protein was present at higher relative abundance in the secreted proteomes of R. dentocariosa and R. similmucilaginosa than in those from non-inhibitory R. aeria, suggesting that it may be involved in M. catarrhalis inhibition. We produced SagA from R. similmucilaginosa in Escherichia coli and confirmed its ability to degrade M. catarrhalis peptidoglycan and inhibit its growth. We then demonstrated that R. aeria and R. similmucilaginosa reduced M. catarrhalis levels in an air-liquid interface culture model of the respiratory epithelium. Together, our results suggest that Rothia restricts M. catarrhalis colonization of the human respiratory tract in vivo. IMPORTANCE Moraxella catarrhalis is a pathobiont of the respiratory tract, responsible for ear infections in children and wheezing illnesses in children and adults with chronic respiratory diseases. Detection of M. catarrhalis during wheezing episodes in early life is associated with the development of persistent asthma. There are currently no effective vaccines for M. catarrhalis, and most clinical isolates are resistant to the commonly prescribed antibiotics amoxicillin and penicillin. Given the limited niche of M. catarrhalis, we hypothesized that other nasal bacteria have evolved mechanisms to compete against M. catarrhalis. We found that Rothia are associated with the nasal microbiomes of healthy children without Moraxella. Next, we demonstrated that Rothia inhibit M. catarrhalis in vitro and on airway cells. We identified an enzyme produced by Rothia called SagA that degrades M. catarrhalis peptidoglycan and inhibits its growth. We suggest that Rothia or SagA could be developed as highly specific therapeutics against M. catarrhalis.

Bacterial isolates and their antimicrobial susceptibility profile of superficial and deep-seated skin and soft tissue infections

Background

Skin and soft tissue infections (SSTIs) are caused by microbial invasion of healthy or damaged skin. SSTIs are difficult to manage and contribute to chronicity and emergence of antimicrobial resistance.

Objectives

To ascertain the prevalence of bacteria causing SSTIs and their antimicrobial susceptibility patterns.

Methods

A prospective study between November 2020 and May 2021. A total of 447 samples from SSTIs were analyzed.

Results

A total of 347 samples revealed mono-bacterial growth, of which 67% were male. SSTIs are common among patients aged 21-50 years with the dominance (78%) of gram-negative rods (GNRs). Escherichia coli (36%), Klebsiella spp. (22%), Staphylococcus aureus (16%), and Pseudomonas aeruginosa (11%) were predominant organisms. GNRs were highly resistant (>65%) to ciprofloxacin and trimethoprim-sulfamethoxazole. For injectable antibiotics, the highest resistance was determined against ceftriaxone, and the least resistance was determined against amikacin. Resistance against carbapenem was the highest among P. aeruginosa (53%) and Klebsiella spp. (32%). S. aureus showed the highest resistance against ciprofloxacin, and the least resistance was determined against clindamycin. Of 57 S. aureus isolates, 86% isolates were methicillin-resistant Staphylococcus aureus (MRSA). All isolates of P. aeruginosa and S. aureus were sensitive to polymyxin B and vancomycin, respectively. The prevalence of multidrug-resistant E. coli and Klebsiella spp. was higher among deep-seated SSTIs (dSSTIs).

Conclusions

The predominant etiology of SSTIs is GNR. Currently, there is very high resistance against oral antibiotics. Antimicrobial resistance against carbapenem has also increased. Moreover, there is a high frequency of MRSA. MDR E. coli and Klebsiella spp. isolates are frequently involved in dSSTIs.

Skin and soft tissue infections in the elderly

PURPOSE OF REVIEW

To highlight the peculiarity of skin and soft tissue infections (SSTIs) in elderly patients and to provide useful elements for their optimal management.

RECENT FINDINGS

In the COVID-19 era, early discharge from the hospital and implementation of outpatient management is of key importance.

SUMMARY

Elderly patients are at high risk of SSTIs due to several factors, including presence of multiple comorbidities and skin factors predisposing to infections. Clinical presentation may be atypical and some signs of severity, such as fever and increase in C-reactive protein, may be absent or aspecific in this patients population. An appropriate diagnosis of SSTIs in the elderly is crucial to avoid antibiotic overtreatment. Further studies should explore factors associated with bacterial superinfections in patients with pressure ulcers or lower limb erythema. Since several risk factors for methicillin-resistant Staphylococcus aureus (MRSA) may coexist in elderly patients, these subjects should be carefully screened for MRSA risk factors and those with high risk of resistant etiology should receive early antibiotic therapy active against MRSA. Physicians should aim to several objectives, including clinical cure, patient safety, early discharge and return to community. SSTIs in the elderly may be managed using long-acting antibiotics, but clinical follow-up is needed.

Rapid diagnostics for skin and soft tissue infections: the current landscape and future potential

PURPOSE OF REVIEW

Managing antimicrobial therapy in patients with complicated skin and soft tissue infections (SSTI) constitutes a growing challenge due to the wide spectrum of potential pathogens and resistance phenotypes. Today, microbiological documentation relies on cultural methods. This review summarizes the available evidence regarding the clinical input of rapid microbiological diagnostic tools (RMDT) and their impact on the management of antimicrobial therapy in SSTI.

RECENT FINDINGS

Accurate tools are already available for the early detection of methicillin-resistant Staphylococcus aureus (MRSA) in SSTI samples and may help avoiding or shortening empirical anti-MRSA coverage. Further research is necessary to develop and evaluate RMDT detecting group A streptococci (e.g., antigenic test) and Gram-negative pathogens (e.g., multiplex PCR assays), including through point-of-care utilization. Next-generation sequencing (NGS) methods could provide pivotal information for the stewardship of antimicrobial therapy, especially in case of polymicrobial or fungal SSTI and in the immunocompromised host; however, a shortening in the turnaround time and prospective data regarding their therapeutic input are needed to better appraise the clinical positioning of these promising approaches.

SUMMARY

The clinical input of RMDT in SSTI is currently limited due to the scarcity of available dedicated assays and the polymicrobial feature of certain cases. NGS appears as a relevant tool but requires further developments before its implementation in routine clinical practice.

Cost analysis of dalbavancin versus standard of care for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) in two Italian hospitals

Objectives

Thanks to its long half-life, dalbavancin qualifies as an optimal drug for saving costs. We aimed to assess the cost and effectiveness of dalbavancin versus the standard of care (SoC).

Patients and methods

We conducted a multicentre retrospective study, including all hospitalized or outpatients diagnosed with ABSSSIs at Padua University Hospital, Padua and San Paolo Hospital, Milan (1 January 2016 to 31 July 2020). We compared patients according to antibiotic treatment (dalbavancin versus SoC), the number of lines of dalbavancin treatment, and monotherapy or combination (dalbavancin in association with other antibiotics). Primary endpoints were direct medical costs and length of hospital stay (LOS) associated with ABSSSI management; Student's t-test, chi-squared test and one-way ANOVA were used.

Results

One hundred and twenty-six of 228 (55.3%) patients received SoC, while 102/228 (44.7%) received dalbavancin. Twenty-seven of the 102 (26.5%) patients received dalbavancin as first-line treatment, 46 (45.1%) as second-line, and 29 (28.4%) as third- or higher-line treatment. Most patients received dalbavancin as monotherapy (62/102; 60.8%). Compared with SoC, dalbavancin was associated with a significant reduction of LOS (5 ± 7.47 days for dalbavancin, 9.2 ± 5.59 days for SoC; P < 0.00001) and with lower mean direct medical costs (3470 ± 2768€ for dalbavancin; 3493 ± 1901€ for SoC; P = 0.9401). LOS was also reduced for first-line dalbavancin, in comparison with second-, third- or higher-line groups, and for dalbavancin monotherapy versus combination therapy. Mean direct medical costs were significantly lower in first-line dalbavancin compared with higher lines, but no cost difference was observed between monotherapy and combination therapy.

Conclusions

Monotherapy with first-line dalbavancin was confirmed as a promising strategy for ABSSSIs in real-life settings, thanks to its property in reducing LOS and saving direct medical costs.