Tensor modeling of MRSA bacteremia cytokine and transcriptional patterns reveals coordinated, outcome-associated immunological programs

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is a common and life-threatening infection that imposes up to 30% mortality even when appropriate therapy is used. Despite in vitro efficacy determined by minimum inhibitory concentration breakpoints, antibiotics often fail to resolve these infections in vivo, resulting in persistent MRSA bacteremia. Recently, several genetic, epigenetic, and proteomic correlates of persistent outcomes have been identified. However, the extent to which single variables or their composite patterns operate as independent predictors of outcome or reflect shared underlying mechanisms of persistence is unknown. To explore this question, we employed a tensor-based integration of host transcriptional and cytokine datasets across a well-characterized cohort of patients with persistent or resolving MRSA bacteremia outcomes. This method yielded high correlative accuracy with outcomes and immunologic signatures united by transcriptomic and cytokine datasets. Results reveal that patients with persistent MRSA bacteremia (PB) exhibit signals of granulocyte dysfunction, suppressed antigen presentation, and deviated lymphocyte polarization. In contrast, patients with resolving bacteremia (RB) heterogeneously exhibit correlates of robust antigen-presenting cell trafficking and enhanced neutrophil maturation corresponding to appropriate T lymphocyte polarization and B lymphocyte response. These results suggest that transcriptional and cytokine correlates of PB vs. RB outcomes are complex and may not be disclosed by conventional modeling. In this respect, a tensor-based integration approach may help to reveal consensus molecular and cellular mechanisms and their biological interpretation.

Antibiotic prescribing and outcomes for patients with uncomplicated purulent skin and soft tissue infections in the emergency department

INTRODUCTION

Current guidelines suggest adjuvant antibiotics after incision and drainage (I&D) of small, uncomplicated abscesses may improve patient outcomes, minimize pain, and prevent recurrence. The objective was to explore antibiotic prescribing at ED discharge and describe patient outcomes.

METHODS

This was a health records review of adult patients (≥ 18 years) discharged from an academic hospital ED (annual census 65,000) over a 2-year period with diagnosis of an uncomplicated skin abscess. Outcomes included any unplanned return ED visits within 30 days, repeat I&D, and escalation to intravenous (IV) antibiotics.

RESULTS

Of 389 ED visits, 85.6% patients underwent I&D, of which 62.2% were prescribed antibiotics at discharge. Of these patients, 36.7% received guideline recommended antibiotics (TMP-SMX or clindamycin). Of all patients who underwent I&D, 13.2% had an unplanned return ED visit within 30 days, 6.9% required repeat I&D, and 0.6% patients were escalated to IV antibiotics. Patients treated with cefalexin were more likely to have an unplanned return ED visit within 30 days (20.0 vs 5.3%; Δ14.7, 95% CI 4.6-24.4), and were more likely to have a repeat I&D within 30 days (13.7 vs 0%; Δ13.7, 95% CI 6.4-22.0), compared to patients prescribed guideline recommended antibiotics. Treatment with guideline recommended antibiotics reduced treatment failure significantly in MRSA positive patients (0.0 vs 44.4%; Δ44.4, 95% CI 13.4-73.3).

CONCLUSIONS

Antibiotics were prescribed for most abscesses that underwent I&D. Less than half of the patients received antibiotics that were guideline recommended. Compared to those who received cefalexin, patients prescribed TMP-SMX or clindamycin had fewer return ED visits and were less likely to have a repeat I&D within 30 days. However, adjuvant antibiotic use did not significantly improve outcomes overall, with most patients not requiring a change in management irrespective of antibiotic use.

Bacteriological profile of paediatric skin and soft tissue infections and their antibiogram at a tertiary care teaching hospital in north India

The increasing complexity of wound care in pediatric patients along with delay in the initiation of treatment predisposes these patients to many complications such as pressure ulcers, non-healing surgical wounds and skin damage. A retrospective study was conducted over a period of five years to gain insight into the etiology of pediatric wound infection. A total of 2819 wound culture positive cases were included. Most samples were from the burn ward (30.15%) followed by the general surgery ward (20.46%). Overall, the most common isolate was Staphylococcus aureus (39.73%) followed by Pseudomonas spp (19.12%). The prevalence of MRSA (Methicillin resistant S. aureus), CRE (Carbapenem-resistant Enterobacteriaceae), CRP (Carbapenem resistant Pseudomonas), CRAB (Carbapenem resistant Acinetobacter baumannii) was 47.3%, 62.5%, 70.5%, 96.4%, respectively. The high degree of resistance in children highlights the importance of regular surveillance for identification of common pathogens and optimization of antimicrobial treatment for multidrug resistant organisms.

Just the Facts: Methicillin-resistant Staphylococcus aureus and soft tissue abscess in the emergency department

Soft tissue abscess used to be an easy emergency department (ED) presentation: perform an incision and drainage (I + D) and discharge your patient. Times have changed. Methicillin-resistant Staphylococcus aureus (MRSA) is now a major cause of soft tissue abscess in ED patients. MRSA is, by definition, resistant to cloxacillin and cephalosporins. Almost all Canadian strains are susceptible to vancomycin and linezolid. MRSA strains are variably susceptible to trimethoprim-sulfamethoxazole (TMP-SMX), tetra/doxycycline, and clindamycin, with pooled Canadian clindamycin resistance just over 40%.

Utility of Soft Tissue Lateral Neck Radiographs in the Emergency Department: The 5-Year Experience of a Large Tertiary Care Pediatric Hospital

INTRODUCTION

Although retropharyngeal infection (RPI) may present with voice change, drooling, fever, and a toxic appearance, diagnosis based on symptoms alone is unreliable. As incidence is increasing in children and drug-resistant bacterial strains such as methicillin-resistant Staphylococcus aureus are becoming more common, we decided to assess the clinical utility of lateral neck radiography.

OBJECTIVE

The aim of this study was to review the experience of a large tertiary care pediatric emergency department (ED) in using lateral soft tissue neck radiographs in the diagnosis of suspected RPI.

METHODS

A retrospective analysis of all lateral soft tissue neck radiograph reports from 2011 to 2015 in conjunction with a review of patients' charts to describe clinical and laboratory findings, disposition, and final diagnosis was performed. Patients aged 31 days to 18 years who presented to the ED with suspicion of RPI were included.

RESULTS

Review of 366 radiographic reports revealed that 46 were positive for RPI, 286 were negative, and 34 indeterminate. A final discharge diagnosis of RPI was made in 38 patients. Lateral neck radiographs had a sensitivity of 84.3% and a specificity of 93.7% for diagnosing RPI. In triage, most patients had no fever (264, 72.1%), stridor (356, 97%), drooling (348, 95%), or voice change (342, 93%). Surgical intervention occurred in 15 patients (39.5%) with a final diagnosis of RPI.

CONCLUSIONS

Lateral neck radiography is useful for diagnosis of RPI in the ED with good sensitivity and specificity. Additional imaging is to be considered at the behest of physician's clinical judgment.

Comparison of Effectiveness of Germania Honey Compared to Manuka Honey in Methicillin-Resistant Staphylococcus aureus (MRSA) Killing

Purpose:

Manuka honey is currently used in medical-grade sterile wound treatment products and has been shown to be effective in methicillin-resistant Staphylococcus aureus (MRSA) killing in vitro and in wound healing in a number of case studies and series. Locally produced honey in Pakistan and Chile have been proposed to be as effective as Manuka honey in bacterial killing in vitro, presenting potentially more accessible and affordable alternatives. In this study, we compared the effectiveness of a local Germania honey from Saudi Arabia to Manuka honey MGO 550 for in vitro killing of MRSA.

Methodology:

Overnight Muller Hinton broth cultures of 50 wound culture isolates of MRSA from 50 patients were incubated with a series of dilutions of Manuka honey MGO 550 and corresponding Germania honey dilutions for 24 h. Turbidity was assessed to determine whether bacterial growth had occurred, and no growth was confirmed by a further 24 h sub-culture on blood agar.

Results/Key findings:

Manuka honey MGO 550 was significantly more effective than Germania honey at MRSA killing at 100% v/v, 50% v/v and 25% v/v (p=0.025, 0.000265, and 0.000112 respectively)

Conclusion:

Manuka honey MGO 550 is significantly more effective in killing MRSA in vitro than Germania honey. Germania honey does not appear to be a promising locally produced alternative to Manuka honey for the development of honey-based wound dressings. Further experiments could determine if Germania honey is effective against other bacterial species.

In Vitro Antimicrobial Activities of Commercially Available Tea Tree (Melaleuca alternifolia) Essential Oils

Melaleuca alternifolia tea tree oil (TTO) is largely used in cutaneous infections. Clinical observations reported antibacterial, antifungal, and antiviral activities, whereas in vitro experiments ascribed most of biological properties to terpinen-4-ol. Since different plant chemotypes and storage conditions result in variations of chemical composition of commercially available TTO, in this study we investigated the antimicrobial activity and the chemical profile of ten commercially available TTO products. The antimicrobial activity was assessed against Candida glabrata, Herpes simplex virus type 1 (HSV-1), methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa grown in planktonic mode or biofilms. Only five out of ten TTO batches reported significant antimicrobial activity. The identified TTO products reduced bacterial survival in biofilms, generated oxidative damage in C. glabrata, and diminished HSV-1 infectivity. GC-MS analysis revealed that all the analyzed TTO batches fitted into the terpinen-4-ol chemotype even if we reported great variability in composition of nine major ISO-specified TTO components. Overall, we were not able to ascribe the antimicrobial activity to the content in terpinen-4-ol. We therefore conclude that the antimicrobial activity of TTO results from complex interaction among different components.

Protective immunity in recurrent Staphylococcus aureus infection reflects localized immune signatures and macrophage-conferred memory

Staphylococcus aureus is the leading cause of skin and skin structure infection (SSSI), a primary portal of entry for invasive infection. Our prior studies discovered a role for protective innate memory against recurrent methicillin-resistant S. aureus (MRSA) SSSI. In the present study, the dynamics and mechanisms of this response were explored in recurrent SSSI in WT mice. Priming by prior infection reduced skin lesion severity and MRSA burden, and protected against dissemination at day 7 but not day 2. Cytokine and cellular signatures in SSSI differed at day 2 versus 7, and were distinct in skin versus blood or spleen. Cytokines associated with protection in skin included increased IL-17, IL-6, monokine inducible by IFN-γ (MIG), and RANTES, while increased IP-10 correlated with protection from dissemination. Cellular signatures of protection included increased Th17, M1 macrophage, and dendritic cell populations in abscesses, and total macrophages in lymph nodes. Priming potentiated S. aureus-specific phagocytic killing by bone marrow-derived macrophages in vitro, and their adoptive transfer into naïve skin afforded protective efficacy in vivo. Present findings indicate that protective immunity in recurrent S. aureus infection is locally targeted, and involves specific memory conferred by macrophages. These insights provide targets for vaccine and immunotherapeutic development against MRSA.

Antibiotic therapy for skin and soft tissue infections: a protocol for a systematic review and network meta-analysis

BACKGROUND

Skin and soft tissue infections (SSTIs) in hospital and community settings impose a substantial socio-economic burden. Therapeutic uncertainty due to the availability of a wide range of antibiotics and the need for empirical treatment decisions complicate SSTI clinical management. Completion of numerous pairwise meta-analyses to account for this variability in antibiotics is impractical, and many head-to-head comparisons of potential interest are likely not available. In comparing multiple antibiotics simultaneously, this network meta-analysis aims to identify the antibiotic(s) with the greatest value in the treatment of SSTIs, in terms of patient-important outcomes such as efficacy and safety.

METHODS

We will conduct a systematic review to identify randomized controlled trials of persons with suspected or confirmed SSTI assigned to orally or parenterally administered antibiotic therapy that report results on at least one outcome of interest. We will search MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL), along with trial registries. Our primary outcome of interest is clinical success at the test-of-cure visit. Secondary outcomes may include (1) early clinical success (2-3 days after the therapy starts), (2) mortality, (3) adverse events, (4) treatment duration, and (5) length of hospital stay. Independent reviewers will complete screening of titles, abstracts, and full texts, data extraction, risk of bias assessment (using the Cochrane Risk of Bias tool), and evaluation of the certainty of evidence (using the GRADE approach) in duplicate. We will complete pairwise and network meta-analyses within the Bayesian framework when possible using a random effects model. We will stratify SSTIs by severity into uncomplicated and complicated SSTIs when possible. Subgroup analyses by age, infection type, comorbidity, and suspected or confirmed methicillin-resistant Staphylococcus aureus (MRSA)-associated infection are planned.

DISCUSSION

This study has several strengths compared to previous reviews: inclusion of a wider range of infection types, antibiotics, and outcomes; a comprehensive search strategy; a priori subgroup analyses; application of GRADE; and improved interpretability of findings through visual presentation of results. We hope our findings will inform future research, health care professionals, and policy makers resulting in improved evidence-based clinical management of SSTIs.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018085607.

Molecular Epidemiology of Staphylococcus aureus among Patients with Skin and Soft Tissue Infections in Two Chinese Hospitals

Background:

Staphylococcus aureus is one of the predominant causes of skin and soft tissue infections (SSTIs), but limited data were available regarding the characterization of S. aureus from SSTIs patients in Jiangsu Province in China. We aimed to investigate the molecular epidemiology of S. aureus among SSTIs patients in two hospitals of Jiangsu Province.

Methods:

Sixty-two patients with SSTIs from two Chinese hospitals in Jiangsu Province were enrolled in this study, and 62 S. aureus isolates were collected from February 2014 to January 2015. S. aureus isolates were characterized by antimicrobial susceptibility testing, toxin gene detection, and molecular typing with sequence type, Staphylococcus protein A gene type, accessory gene regulator (agr) group, and Staphylococcal cassette chromosome mec type.

Results:

Sixteen (25.8%) methicillin-resistant S. aureus (MRSA) isolates were detected, and there was no isolate found resistant to vancomycin, teicoplanin, sulfamethoxazole-trimethoprim, and linezolid. The sei was the toxin gene most frequently found, and no lukS/F-PV-positive isolates were detected among the SSTIs’ patients. Molecular analysis revealed that ST398 (10/62, 16.1%; 2 MRSA and 8 methicillin-susceptible S. aureus) to be the dominant clone, followed by ST5 (8/62, 12.9%) and ST7 (8/62, 12.9%).

Conclusions:

The livestock ST398 was the most common clone among patients with S. aureus SSTIs in Jiangsu Province, China. Surveillance and further studies on the important livestock ST398 clone in human infections are necessarily requested.

Community- and Healthcare-Associated Methicillin-Resistant Staphylococcus aureus Strains: An Investigation Into Household Transmission, Risk Factors, and Environmental Contamination

OBJECTIVE To measure transmission frequencies and risk factors for household acquisition of community-associated and healthcare-associated (HA-) methicillin-resistant Staphylococcus aureus (MRSA). DESIGN Prospective cohort study from October 4, 2008, through December 3, 2012. SETTING Seven acute care hospitals in or near Toronto, Canada. PARTICIPANTS Total of 99 MRSA-colonized or MRSA-infected case patients and 183 household contacts. METHODS Baseline interviews were conducted, and surveillance cultures were collected monthly for 3 months from household members, pets, and 8 prespecified high-use environmental locations. Isolates underwent pulsed-field gel electrophoresis and staphylococcal cassette chromosome mec typing. RESULTS Overall, of 183 household contacts 89 (49%) were MRSA colonized, with 56 (31%) detected at baseline. MRSA transmission from index case to contacts negative at baseline occurred in 27 (40%) of 68 followed-up households. Strains were identical within households. The transmission risk for HA-MRSA was 39% compared with 40% (P=.95) for community-associated MRSA. HA-MRSA index cases were more likely to be older and not practice infection control measures (P=.002-.03). Household acquisition risk factors included requiring assistance and sharing bath towels (P=.001-.03). Environmental contamination was identified in 78 (79%) of 99 households and was more common in HA-MRSA households. CONCLUSION Household transmission of community-associated and HA-MRSA strains was common and the difference in transmission risk was not statistically significant. Infect Control Hosp Epidemiol 2016;1-7.

Factors influencing drainage setting and cost for cutaneous abscesses among pediatric patients

OBJECTIVE

To evaluate the clinical and microbiological factors associated with skin and soft tissue infections drained in the emergency department (ED) vs operative drainage (OD) in a tertiary care children's hospital.

METHODS

This was a cross-sectional study among children aged 2 months to 17 years who required incision and drainage (I&D). Demographic information, signs and symptoms, abscess size and location, and wound culture/susceptibility were recorded. Patient-specific charges were collected from the billing database. Multivariate regression analysis was used to determine factors determining setting for I&D and the effect of abscess drainage location on cost.

RESULTS

Of 335 abscesses, 241 (71.9%) were drained in the ED. OD for abscesses was favored in children with prior history of abscess (odds ratio [OR], 3.18; 95% confidence interval [CI], 1.36-7.44; P = .01) and labial location (OR, 37.81; 95% CI, 8.12-176.03; P < .001). For every 1-cm increase in size, there was approximately a 26% increase in the odds of having OD (OR, 1.26; 95% CI, 1.11-1.44, P < .001). Methicillin-resistant Staphylococcus aureus was identified in 72% of the 300 abscesses cultured and 12.3% were clindamycin resistant. OD was more expensive than I&D in the ED. Per abscess that underwent I&D, OD is $3804.29 more expensive than I&D in the ED while controlling for length of stay.

DISCUSSION

Clinical factors associated with OD rather than I&D in the ED included history of abscess, increased abscess length, and labial location. Microbiological factors did not differ based on I&D setting. For smaller, nonlabial abscesses, ED drainage may result in significant cost savings.

Characterization of Staphylococcus aureus Isolated from Non-Native Patients with Skin and Soft Tissue Infections in Shanghai

BACKGROUND

Staphylococcus aureus is one predominant cause of skin and soft-tissue infections (SSTIs), but little information exists regarding the characterization of S. aureus from non-native patients with SSTIs in China.

METHODS

In this study, we enrolled 52 non-native patients with S. aureus SSTIs, and 65 native control patients with S. aureus SSTIs in Shanghai. 52 and 65 S. aureus isolates were collected from both groups, respectively. S. aureus isolates were characterized by antimicrobial susceptibility testing, toxin gene detection, and molecular typing with sequence type, spa type, agr group and SCCmec type.

RESULTS

Methicillin-resistant S. aureus (MRSA) was detected in 8 non-native patients and 14 native patients with SSTIs. Overall, antimicrobial susceptibilities of S. aureus isolated from non-native patients were found higher than those from native patients. CC59 (ST338 and ST59) was found in a total of 14 isolates (4 from non-native patients; 10 from native patients), 9 of which were carrying lukS/F-PV (3 from non-native patients; 6 from native patients). ST7 was found in 12 isolates and all 12 isolates were found in native patients. The livestock-associated clone ST398 was found in 11 isolates (6 from non-native patients; 5 from native patients), and 5 ST398 lukS/F-PV-positive methicillin-susceptible S. aureus (MSSA) were all discovered among non-native patients. The molecular epidemiology of S. aureus isolated from non-native patients was quite different from those from native patients. lukS/F-PV was more frequent in isolates originating from non-native patients with SSTIs compared to native patients (31 vs. 7, P <0.0001).

CONCLUSIONS

CC59 was the most common clonal complex among patients with SSTIs in Shanghai. The other most common sequence types were ST7 and Livestock ST398. The molecular epidemiology of S. aureus isolated from non-native patients was quite different from those from native patients. S. aureus isolated from non-native patients was more likely to carry lukS/F-PV.

Update on management of skin and soft tissue infections in the emergency department

Skin and soft tissue infections (SSTIs) are frequently treated in the emergency department (ED) setting. Recent studies provide critical new information that can guide new approaches to the diagnosis and treatment of SSTIs in the ED. Rapid polymerase chain reaction assays capable of detecting MRSA in approximately 1 h hold significant potential to improving antibiotic stewardship in SSTI care. Emergency ultrasound continues to demonstrate value in guiding appropriate management of SSTIs, including the early diagnosis of necrotizing infections. Since emerging in the 1990s, community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) continues to increase in prevalence, and it represents a significant challenge to optimizing ED antibiotic use for SSTI management. Growing literature reinforces the current recommendation of incision and drainage without antibiotics for uncomplicated abscesses. Selecting antibiotics with CA-MRSA coverage is recommended when treating purulent SSTIs; however, it is generally not necessary in cases of nonpurulent cellulitis. Future advances in ED SSTI care may involve expansion of outpatient parenteral antimicrobial therapy protocols and the recent development of a novel, once weekly antibiotic with activity against MRSA.

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.