Prevalence and risk factors associated with vancomycin-resistant Staphylococcus aureus precursor organism colonization among patients with chronic lower-extremity wounds in Southeastern Michigan

Escalation of antimicrobial resistance among MRSA part 1: focus on global spread

INTRODUCTION

Staphylococcus aureus produce numerous virulence factors that influence tissue invasion, cytotoxicity, membrane damage, and intracellular persistence allowing them to be very common human pathogens. S. aureus isolates exhibit considerable diversity though specific genotypes have been associated with antimicrobial resistance (AMR) and toxin gene profiles. MRSA is an important pathogen causing both community-acquired (CA) and healthcare-acquired (HCA) infections. Importantly, over the past several decades, both HCA-MRSA and CA-MRSA have spread all over the globe. Even more concerning is that CA-MRSA clones have disseminated into hospitals and HCA-MRSA have entered the community. Factors that enhance spread of MRSA include: poor antimicrobial stewardship and inadequate infection control. The emergence and spread of multidrug resistant (MDR) MRSA has limited therapeutic options.

AREAS COVERED

The authors discuss the escalation of MRSA, both HCA-MRSA and CA-MRSA across the globe. A literature search of MRSA was performed via PubMed (up to September 2022), using the key words: antimicrobial resistance; β-lactams; community-associated MRSA; epidemiology; infection; multidrug resistance; Staphylococcus aureus.

EXPERT OPINION

Over the past several decades, MRSA has spread all over the globe. We encourage the judicious use of antimicrobials in accordance with antimicrobial stewardship programs along with infection control measures to minimize the spread of MRSA.

Bacterial evolution during human infection: Adapt and live or adapt and die

Microbes are constantly evolving. Laboratory studies of bacterial evolution increase our understanding of evolutionary dynamics, identify adaptive changes, and answer important questions that impact human health. During bacterial infections in humans, however, the evolutionary parameters acting on infecting populations are likely to be much more complex than those that can be tested in the laboratory. Nonetheless, human infections can be thought of as naturally occurring in vivo bacterial evolution experiments, which can teach us about antibiotic resistance, pathogenesis, and transmission. Here, we review recent advances in the study of within-host bacterial evolution during human infection and discuss practical considerations for conducting such studies. We focus on 2 possible outcomes for de novo adaptive mutations, which we have termed "adapt-and-live" and "adapt-and-die." In the adapt-and-live scenario, a mutation is long lived, enabling its transmission on to other individuals, or the establishment of chronic infection. In the adapt-and-die scenario, a mutation is rapidly extinguished, either because it carries a substantial fitness cost, it arises within tissues that block transmission to new hosts, it is outcompeted by more fit clones, or the infection resolves. Adapt-and-die mutations can provide rich information about selection pressures in vivo, yet they can easily elude detection because they are short lived, may be more difficult to sample, or could be maladaptive in the long term. Understanding how bacteria adapt under each of these scenarios can reveal new insights about the basic biology of pathogenic microbes and could aid in the design of new translational approaches to combat bacterial infections.

Validation of predictive factors for infection in adults with chronic leg ulcers: A prospective longitudinal study

AIMS AND OBJECTIVES

To validate the ability of factors to predict infection in adults with chronic leg ulcers over a 12-week period.

BACKGROUND

Leg ulcers affect ~3% of older adults and are often hard to heal. Infection is a leading contributor for delayed healing, causing delayed wound healing, increased hospitalisation, increased healthcare costs and reduced patient quality of life. The importance of early identification of infection has been highlighted for decades, yet little is known about factors that are associated with increased risk of infection in this specific population.

DESIGN

A longitudinal, prospective observational study in a single centre.

METHODS

Between August 2017 and May 2018, a total of 65 adults with chronic leg ulcers were prospectively observed for a 12-week period. Patients were recruited from an outpatient wound clinic at a tertiary hospital in Australia. Data were collected from recruitment (baseline) and each visit (weekly or fortnightly) up until 12 weeks. Descriptive statistics were calculated for all variables. A Cox proportional hazards regression model was used to identify predictive factors for infection. The TRIPOD guidelines for reporting were followed (See Data S1).

RESULTS

The sample consisted of 65 adults with chronic leg ulcers, and 9.2% of these had their ulcer infected at baseline. Two predictive factors, using walking aids and gout, were found to be significantly related to increased likelihood of developing infection within 12 weeks.

CONCLUSION

The present study showed that patients who either used walking aids or were diagnosed with gout were at greater risk of infection compared to those without these factors.

RELEVANCE TO CLINICAL PRACTICE

These findings provide new information for clinicians in early identification of patients at risk of infection, and for patients in enhancing their awareness of their own risk.

Treating drug-resistant wound pathogens with non-medicated dressings: an in vitro study

Objective:

To assess the in vitro antimicrobial performance of a non-medicated hydro-responsive wound dressing (HRWD) on the sequestration and killing of wound relevant microorganisms found on the World Health Organization (WHO) priority pathogens list.

Methods:

Suspensions of Pseudomonas aeruginosa, Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA) were placed on petri dishes. Dressings were each placed on top, incubated for 30 minutes and then removed from the inoculated petri dish. The surface of the dressings previously in contact with the bacterial suspensions were placed directly onto a tryptone soy agar (TSA) plate and incubated for 24 hours. Dressings were then removed from the TSA plate and the level of bacterial growth on the plates was assessed. Sequestered microorganism viability was assessed using LIVE/DEAD viability kits and visualisation by epifluorescence.

Results:

Our results indicated that HRWDs sequester and retain Pseudomonas aeruginosa, Acinetobacter baumannii and MRSA within the dressing. Non-medicated HRWDs containing bound PHMB (polyhexamethylene biguanide, HRWD+PHMB) killed the microorganisms sequestered within the dressing matrix.

Conclusion:

These data suggest that non-medicated HRWD+PHMB is an effective against WHO priority pathogens and promoting goal of antimicrobial stewardship in wound care.

Risk factors for infection in patients with chronic leg ulcers: A survival analysis

AIM

This study aimed to validate the relationships between possible predictive factors and clinically diagnosed infection in adult patients with chronic leg ulcers.

METHODS

This study used a sample of 636 adult participants whose ulcers were diagnosed as either venous, arterial or mixed aetiology leg ulcers and had no clinical signs of infection at recruitment. Data were extracted from recruitment to 12 weeks from six longitudinal prospective studies from 2004 to 2015. Survival analysis was used to investigate mean time-to-infection, including the Kaplan-Meier method and the Cox proportional-hazards regression model.

RESULTS

The sample included 74.7% venous, 19.6% mixed and 5.7% arterial leg ulcers. There were 101 (15.9%) participants diagnosed with infection at least once within 12 weeks of follow-up. Mean time-to-infection was 10.89 weeks (95% CI = 10.66-11.12). After adjustment for potential confounders, a Cox proportional hazards regression model found that depression, using walking aids, calf ankle ratio <1.3, wound area ≥10 cm² and ulcers with slough tissue at recruitment were significant risk factors for wound infection.

CONCLUSION

This study has validated the predictive ability of factors which have been found in a cross-sectional study to be significantly associated with infection in patients with leg ulcers, including venous leg ulcers, arterial leg ulcers and mixed aetiology leg ulcers. Results showed that patients with chronic leg ulcers, who either presented with depression, used walking aids, had a calf ankle ratio <1.3, a wound area ≥10 cm² or an ulcer with slough tissue, had greater likelihood of developing infection compared to those without these factors.

Identifying risk factors associated with infection in patients with chronic leg ulcers

Leg ulcers are hard to heal. Infection causes delayed healing, negatively impacting patients' quality of life, the healthcare system, and society. Early recognition of patients at high risk of infection is essential to prevent complications and reduce negative impacts. However, at present, factors associated with infection in this population are not yet clearly understood. The study aimed to identify factors that were significantly associated with infection in chronic leg ulcers. A sample of 561 patients with chronic leg ulcers, who were previously recruited at outpatient clinics and community settings within Australia between 2008 and 2015, were selected for the current analysis. The prevalence of infection in the sample at study recruitment was 7.8%. A multivariate logistic regression model was used to identify factors associated with infection. The study identified 7 factors that were significantly independently associated with infection, including depression, chronic pulmonary disease, anti-coagulant use, calf ankle circumference ratio < 1.3, ulcer area ≥ 10 cm² , slough in the wound bed tissue, and ulcers with heavy exudate. These findings could assist clinicians in the early recognition of patients at risk of infection and individualise treatment for these patients, thereby promoting wound healing.

Incorporating Cutaneous and Wound Bacterial Bioburden Biomarkers into Clinical Research: A Review of Best Practices

PURPOSE

To provide information about initiating interdisciplinary research related to microbiomes and their role in human immunity, disease, and metabolic processes.

TARGET AUDIENCE

This continuing education activity is intended for physicians and nurses with an interest in skin and wound care.

OBJECTIVES

After participating in this educational activity, the participant should be better able to:1. Describe techniques to identify and characterize bacterial bioburden.2. Identify optimal collection, transport, and storage of samples.

ABSTRACT

OBJECTIVE

The purpose of this review is to provide a roadmap for clinical scientists interested in integrating bacterial bioburden (BB) biomarkers into the next generation of cutaneous or wound disease research studies.

DISCUSSION

Complex relationships exist between humans and their microbiome. Until now, clinical scientists have been limited in fully characterizing relationships between humans and their microbiome. Recent technological innovations, such as next-generation DNA sequencing, also known as deep sequencing or pyrosequencing, have enhanced clinicians' capacity to identify, characterize, and elucidate the role of BB (ie, bacterial load, diversity, pathogenicity) in human immunity, disease, and metabolic processes. The understanding of common terminology, intervening variables that influence BB, limitations of next-generation DNA sequencing, and specimen selection, collection, transport, and storage practices are needed to support interdisciplinary communication, research design, and integrity of the specimen.

CONCLUSION

This review serves as a primer for building foundational knowledge in microbiome research, which will aid clinical scientists with initiating interdisciplinary communication necessary for scientific team building.

Prevalence of and Risk Factors for Vancomycin-Resistant Staphylococcus aureus Precursor Organisms in Southeastern Michigan

We assessed for vancomycin-resistantStaphylococcus aureus(VRSA) precursor organisms in southeastern Michigan, an area known to have VRSA. The prevalence was 2.5% (pSK41-positive methicillin-resistantS. aureus, 2009–2011) and 1.5% (Inc18-positive vancomycin-resistantEnterococcus, 2006–2013); Inc18 prevalence significantly decreased after 2009 (3.7% to 0.82%). Risk factors for pSK41 included intravenous vancomycin exposure.

Infect Control Hosp Epidemiol2014;35(12):1531–1534

Prevalence of and risk factors for vancomycin-resistant Staphylococcus aureus precursor organisms in Southeastern Michigan

We assessed for vancomycin-resistant Staphylococcus aureus (VRSA) precursor organisms in southeastern Michigan, an area known to have VRSA. The prevalence was 2.5% (pSK41-positive methicillin-resistant S. aureus, 2009-2011) and 1.5% (Inc18-positive vancomycin-resistant Enterococcus, 2006-2013); Inc18 prevalence significantly decreased after 2009 (3.7% to 0.82%). Risk factors for pSK41 included intravenous vancomycin exposure.

Prevalence and factors associated with wound colonization by Staphylococcus spp. and Staphylococcus aureus in hospitalized patients in inland northeastern Brazil: a cross-sectional study

Background

Infections by Staphylococcus spp. are often associated with wounds, especially in hospitalized patients. Wounds may be the source of bacteria causing cross-contamination, and are a risk factor for methicillin-resistant Staphylococcus aureus (MRSA) infection. The aim of this study was to investigate the prevalence of wound colonization by Staphylococcus spp., especially S. aureus and MRSA, in hospitalized patients, and to identify the factors associated with such colonization.

Methods

This cross-sectional study enrolled patients with wounds who were hospitalized in a remote and underdeveloped inland region of northeastern Brazil with extreme poverty. Samples were collected using sterile swabs with 0.85% saline solution, and coagulase-negative Staphylococcus spp., S. aureus, and MRSA were identified using standard laboratory procedures. Data regarding the sociodemographic characteristics, antibiotic use, and comorbidities of the patients were collected using the medical records and a questionnaire.

Results

A total of 125 wounds were analyzed. The patients had a mean age of 63.88 years and a mean 3.84 years of school education. Eighty-one wounds (64.80%) were colonized by Staphylococcus spp. Twenty-five wounds (20%) were colonized by S. aureus, 32% of which were colonized by MRSA. Wound colonization by Staphylococcus spp. was associated with pneumonia or other respiratory disease (p = 0.03). Wound colonization by S. aureus was associated with nasal colonization by S. aureus (p < 0.001), fewer days of prior antibiotic use (p = 0.04), admission to a medical ward (p = 0.02), and age >65 years (p = 0.05). Among patients with wound colonization by MRSA, 37.50% had a history of prior antibiotic use, 75% had two or more comorbidities, 25% had cancer or diabetes, 50% had cardiovascular disease, and 50% died.

Conclusions

Wounds can be the source of Staphylococcus spp. infection, and high proportions of wounds are colonized by S. aureus and MRSA. Nasal colonization by S. aureus may be a source for wound colonization by S. aureus, illustrating the importance of preventing cross-contamination in hospital environments, especially among elderly patients. Wounds should be carefully managed to prevent microbial spread, thereby assisting patient recovery and reducing healthcare costs.

Report of the 13th vancomycin-resistant Staphylococcus aureus isolate from the United States

Vancomycin-resistant Staphylococcus aureus (VRSA), an important multidrug-resistant organism of public health concern, has been infrequently identified in the United States since 2002. All previous VRSA isolates belonged to clonal complex 5, a lineage associated primarily with health care. This report describes the most recent (13th) U.S. VRSA isolate, the first to be community associated.