Epidemiology of necrotizing infection caused by Staphylococcus aureus and Streptococcus pyogenes at an Iowa hospital

A genome-scale metabolic model of a globally disseminated hyperinvasive M1 strain of Streptococcus pyogenes

Streptococcus pyogenes is responsible for a range of diseases in humans contributing significantly to morbidity and mortality. Among more than 200 serotypes of S. pyogenes, serotype M1 strains hold the greatest clinical relevance due to their high prevalence in severe human infections. To enhance our understanding of pathogenesis and discovery of potential therapeutic approaches, we have developed the first genome-scale metabolic model (GEM) for a serotype M1 S. pyogenes strain, which we name iYH543. The curation of iYH543 involved cross-referencing a draft GEM of S. pyogenes serotype M1 from the AGORA2 database with gene essentiality and autotrophy data obtained from transposon mutagenesis-based and growth screens. We achieved a 92.6% (503/543 genes) accuracy in predicting gene essentiality and a 95% (19/20 amino acids) accuracy in predicting amino acid auxotrophy. Additionally, Biolog Phenotype microarrays were employed to examine the growth phenotypes of S. pyogenes, which further contributed to the refinement of iYH543. Notably, iYH543 demonstrated 88% accuracy (168/190 carbon sources) in predicting growth on various sole carbon sources. Discrepancies observed between iYH543 and the actual behavior of living S. pyogenes highlighted areas of uncertainty in the current understanding of S. pyogenes metabolism. iYH543 offers novel insights and hypotheses that can guide future research efforts and ultimately inform novel therapeutic strategies.IMPORTANCEGenome-scale models (GEMs) play a crucial role in investigating bacterial metabolism, predicting the effects of inhibiting specific metabolic genes and pathways, and aiding in the identification of potential drug targets. Here, we have developed the first GEM for the S. pyogenes highly virulent serotype, M1, which we name iYH543. The iYH543 achieved high accuracy in predicting gene essentiality. We also show that the knowledge obtained by substituting actual measurement values for iYH543 helps us gain insights that connect metabolism and virulence. iYH543 will serve as a useful tool for rational drug design targeting S. pyogenes metabolism and computational screening to investigate the interplay between inhibiting virulence factor synthesis and growth.

Global Streptococcus pyogenes strain diversity, disease associations, and implications for vaccine development: a systematic review

The high strain diversity of Streptococcus pyogenes serves as a major obstacle to vaccine development against this leading global pathogen. We did a systematic review of studies in PubMed, MEDLINE, and Embase that reported the global distribution of S pyogenes emm-types and emm-clusters from Jan 1, 1990, to Feb 23, 2023. 212 datasets were included from 55 countries, encompassing 74 468 bacterial isolates belonging to 211 emm-types. Globally, an inverse correlation was observed between strain diversity and the UNDP Human Development Index (HDI; r=-0·72; p<0·0001), which remained consistent upon subanalysis by global region and site of infection. Greater strain diversity was associated with a lower HDI, suggesting the role of social determinants in diseases caused by S pyogenes. We used a population-weighted analysis to adjust for the disproportionate number of epidemiological studies from high-income countries and identified 15 key representative isolates as vaccine targets. Strong strain type associations were observed between the site of infection (invasive, skin, and throat) and several streptococcal lineages. In conclusion, the development of a truly global vaccine to reduce the immense burden of diseases caused by S pyogenes should consider the multidimensional diversity of the pathogen, including its social and environmental context, and not merely its geographical distribution.

Clinical Impact of Staphylococcus aureus Skin and Soft Tissue Infections

The pathogenic bacterium Staphylococcus aureus is the most common pathogen isolated in skin-and-soft-tissue infections (SSTIs) in the United States. Most S. aureus SSTIs are caused by the epidemic clone USA300 in the USA. These infections can be serious; in 2019, SSTIs with S. aureus were associated with an all-cause, age-standardized mortality rate of 0.5 globally. Clinical presentations of S. aureus SSTIs vary from superficial infections with local symptoms to monomicrobial necrotizing fasciitis, which can cause systemic manifestations and may lead to serious complications or death. In order to cause skin infections, S. aureus employs a host of virulence factors including cytolytic proteins, superantigenic factors, cell wall-anchored proteins, and molecules used for immune evasion. The immune response to S. aureus SSTIs involves initial responders such as keratinocytes and neutrophils, which are supported by dendritic cells and T-lymphocytes later during infection. Treatment for S. aureus SSTIs is usually oral therapy, with parenteral therapy reserved for severe presentations; it ranges from cephalosporins and penicillin agents such as oxacillin, which is generally used for methicillin-sensitive S. aureus (MSSA), to vancomycin for methicillin-resistant S. aureus (MRSA). Treatment challenges include adverse effects, risk for Clostridioides difficile infection, and potential for antibiotic resistance.

Sodium hyaluronates applied in the face affects the diversity of skin microbiota in healthy people

OBJECTIVE

A healthy and stable microbiome has many beneficial effects on the host, while an unbalanced or disordered microbiome can lead to various skin diseases. Hyaluronic acid is widely used in the cosmetics and pharmaceutical industries; however, specific reports on its effect on the skin microflora of healthy people have not been published. This study aimed to determine the effect of sodium hyaluronate on the facial microflora of healthy individuals.

METHODS

Face of 20 healthy female volunteers between 18 and 24 years was smeared with sodium hyaluronate solution once per day. Cotton swabs were used to retrieve samples on days 0, 14, and 28, and high-throughput sequencing of 16 S rRNA was used to determine the changes in bacterial community composition.

RESULTS

Facial application of HA can reduce the abundance of pathogenic bacteria, such as Cutibacterium and S. aureus, and increase the colonization of beneficial bacteria.

CONCLUSION

This is the first intuitive report to demonstrate the effect of hyaluronic acid on facial microflora in healthy people. Accordingly, sodium hyaluronate was found to have a positive effect on facial skin health.

Case Report: Necrotizing fasciitis caused by Staphylococcus aureus positive for a new sequence variant of exfoliative toxin E

Objectives: Necrotizing fasciitis (NF) caused by S. aureus is a rare, aggressive and rapidly progressing superficial fascia infection with a high mortality rate. The aim of this study was to identify virulence-related genes from a complete genome sequence of a methicillin-susceptible S. aureus (MSSA) isolate recovered from a monomicrobial case of NF.

Materials and methods: The MSSA isolate UMCG579 was cultured from a pus collection from the subcutis of a patient with NF. The genome of isolate UMCG579 was sequenced using MinION (Oxford Nanopore) and MiSeq (illumina) platforms.

Results: The genome of the UMCG579 isolate was composed of a 2,741,379 bp chromosome and did not harbor any plasmids. Virulence factor profiling identified multiple pore-forming toxin genes in the UMCG579 chromosome, including the Panton-Valentine leukocidin (PVL) genes, and none of the superantigen genes. The UMCG579 isolate harbored a new sequence variant of the recently described ete gene encoding exfoliative toxin (type E). A search in the GenBank database revealed that the new sequence variant (ete2) was exclusively found among isolates (n = 115) belonging to MLST CC152. While the majority of S. aureus ete-positive isolates were recovered from animal sources, S. aureus ete2-positive isolates originated from human carriers and human infections. Comparative genome analysis revealed that the ete2 gene was located on a 8777 bp genomic island.

Conclusion: The combination of two heterogeneously distributed potent toxins, ETE2 and PVL, is likely to enhance the pathogenic ability of S. aureus isolates. Since anti-virulence therapies for the treatment of S. aureus infections continue to be explored, the understanding of specific pathogenetic mechanisms may have an important prophylactic and therapeutic value. Nevertheless, the exact contribution of ETE sequence variants to S. aureus virulence in NF infections must be determined.

Distinctions between Fournier's gangrene and lower extremity necrotising fasciitis: microbiology and factors affecting mortality

OBJECTIVES

In this study, we aimed to illustrate distinctions between Fournier's gangrene (FG) and lower extremity necrotising fasciitis (NF) and screen out possible risk factors of poor prognosis for each cohort.

METHODS

The medical records of qualified patients with NF admitted to the Second People's Hospital of Yibin from January 2016 to June 2021 were retrospectively reviewed. All participants were anatomically categorised into FG and lower extremity NF groups, and their baseline data and microbiological results were compared. Further comparisons of critical parameters were conducted between survivors and nonsurvivors within each group.

RESULTS

A total of 49 patients were included in the study with a median age of 58 years, and overall mortality was 20.4%. There were 18 patients with FG and 31 patients with lower extremity NF. A microbiology distinction was found-the predominance of gram-negative infection in FG and gram-positive infection in lower extremity NF. High Fournier's gangrene severity index scores (greater than 7), advanced age, procalcitonin and D-dimer value were identified as risk factors for FG, and the presentation of sepsis was an alarming indicator for lower extremity NF.

CONCLUSIONS

The distinction of microbiology might provide advice for appropriate antibacterial administrations. In addition, with practical prognostic predicting tools, clinicians might be able to identify patients at increased risk and intervene promptly to avoid unfavourable outcomes.

Necrotizing Soft Tissue Infection: A Single-Center Retrospective Study of Treatment and Outcomes

Introduction

Necrotizing fasciitis is a severe inflammatory disease of the body's soft tissue characterized by spreading rapidly and high mortality. Rapid surgical intervention along with other supportive measures of treatment have a great impact on the outcome of treatment.

Material and methods

This study was conducted by a retrospective medical record review of all patients with a microbiologically and clinically confirmed diagnosis of necrotizing fasciitis who were admitted to the general surgery department at the General Hospital Novi Pazar, Serbia, during the period between 2017 and 2020. Demographic, clinical, laboratory, and microbiology data were analyzed.

Results

A total of 13 cases were identified, which represents 0.21% of the total number of patients treated at the surgical department during the period January 2017 to November 2020. The mean age of patients was 55 years, with a male/female ratio of 1:1.6. All of them had at least one comorbidity and more than half had three or more. Diabetes, cardiovascular diseases, and obesity were the most common comorbidities. The most common causes of infection were Klebsiella spp, Pseudomonas aeruginosa, S. pyogenes, and S. aureus. All patients received multiple surgical interventions (mean 2.3).

Conclusion

Treating necrotizing fasciitis requires a multidisciplinary approach. Early diagnosis and rapid clinical response allow for better disease outcomes. Getting to know more about necrotizing fasciitis will help doctors make better decisions when treating it.

A case of streptococcus necrotizing fasciitis secondary to acute tonsillitis and review of literatures

Necrotizing fasciitis, officially named by Wilson in 1952, was a rare potentially life-threatening necrotizing soft tissue infections disease. The main lesions showed subcutaneous fat and fascia layer in progressive necrosis, generally not involving muscles. It was characterized by acute onset, rapid progress, and dangerous condition, often accompanied by systemic toxin shock, which was a relatively rare clinical acute critical disease with high mortality rate. Necrotizing fasciitis is a rare but clinical critical disease. The overall incidence of necrotizing fasciitis is approximately 0.04 cases per 1000 persons in the United States, the 30-day mortality is 27%, and necrotizing fasciitis–related mortality in Asian region is about 28%. Streptococcus pyogenes (group A streptococcus) are human-specific pathogens that can cause upper respiratory tract infection such as tonsillitis, associated with post-infection diseases such as rheumatic fever, and also can induce severe invasive diseases such as necrotizing fasciitis and streptococcus toxin shock syndrome. This article reports a case of streptococcus necrotizing fasciitis secondary to suppurative tonsillitis, which was seldom reported before and our successful management with delayed debridement. This study was anonymous and was approved by the local Research Ethics Committee. Informed consent was obtained from the patient.

Etiology, characteristics, and outcomes of community-onset necrotizing fasciitis in Korea: A multicenter study

Background

Necrotizing fasciitis (NF) is a serious skin and soft tissue infection causing high mortality. Investigating region specific epidemiologic factors associated with NF is important for establishing appropriate treatment strategies. This multicenter study was done to provide an update of the microbial etiology, clinical characteristics, and outcomes of NF in Korea.

Materials and methods

A retrospective cohort of adult patients with NF was established using patient data from 13 general hospitals between January 2012 and December 2015 in Korea. We evaluated microbial etiology and clinical characteristics to identify risk factors associated with in-hospital mortality; analyses were performed using binary logistic regression models.

Results

A total of 161 patients with NF were included. The most common underlying disease was diabetes mellitus (66 cases, 41.0%). A total of 148 organisms were isolated from 119 (73.9%) patients. Enteric Gram-negative organisms (36 patients) were the most common pathogen, followed by Staphylococcus aureus (30 patients) and streptococci (28 patients). Methicillin-resistant Staphylococcus aureus (MRSA) was identified in 6.2% (10/161) of patients. Of 37 enteric Gram-negative isolates tested, 26 (70.3%) isolates were susceptible to ceftriaxone. The in-hospital mortality rate was 22.4%. Intensive care unit admission, septic shock, and Gram-negative organism infections were significantly associated with in-hospital mortality, and surgery was not a favorable prognostic factor.

Conclusions

As initial empirical antibiotics, glycopeptides against MRSA and broad-spectrum antibiotics against third-generation cephalosporin-resistant organisms should be considered for patients with community-onset NF in Korea.

[Infective Endocarditis Causing Native and Prosthetic Heart Valve Dysfunction]

Infective endocarditis (IE) is the disease that has high inhospital mortality. Heart valves dysfunction - both native and prosthetic - is the primary IE complication requiring a surgical intervention. The IE causes and its course have been discussed in this review. In particular, the role of concomitant infectious foci in the formation and development of IE have been considered, the mechanisms of mutual transition of subacute and acute clinical forms have been described. Modern diagnostic principles and methods based on the Duke criteria system have been mentioned, as well as the difficulties that follow the patient's clinical status evaluation. The normobiotic microbiota participation, as well as the possibilities for their identification using blood culture and PCR technique, have been closely reviewed. According to modern researches and publications, there have been made the conclusion about the contribution of obligate anaerobic bacteria, fungi and viruses to the development of endocarditis. There have been described the hypothesis about the presumptive strategy for the cardiac dysfunction formation as a result of the IE causative agents cells metabolic activity based on a literature data analysis in the article: vegetation formed by Staphylococcus aureus can lead to the heart valve stenosis, and the influence of hyaluronidases, collagenases on a heart valve structure can lead to regurgitation. The pathogens cells ability to avoid the human immune system response is caused by the biofilms, fibrin vegetations formation and the enzymes production - cytotoxins (streptolysins, leukocidin, etc.). It has been suggested that the mediators of inflammation and leukocyte cells participate in the destruction of native and prosthetic tissues due to an IE pathogens inaccessibility for immunocompetent cells.

Cervicofacial necrotising fasciitis by clindamycin-resistant and methicillin-resistant Staphylococcus aureus (MRSA) in a young healthy man

An otherwise healthy 24-year-old man presented with 1 week of fever, facial pain and swelling. He initially sought care at an outside hospital, where he was diagnosed with folliculitis and sent home with oral antibiotics. On arrival at our institution, CT neck was ordered, which demonstrated diffuse submental phlegmon, prompting incision and drainage. After initial improvement, the patient experienced high fevers and increased swelling just 12 hours later. The decision was made to take the patient for operative exploration, and wide debridement was performed due to suspicion for necrotising fasciitis intraoperatively that was ultimately confirmed on final pathology. Final speciation of intraoperative culture demonstrated a clindamycin-resistant and methicillin-resistant strain of Staphylococcus aureus The patient was managed with intravenous antibiotics, additional debridement and careful wound care. Delayed partial closure of wound was eventually performed once patient showed marked and persistent clinical improvement. The patient was discharged on hospital day 12 with close follow-up.

Recent advances on topical antimicrobials for skin and soft tissue infections and their safety concerns

Antimicrobial resistance of disease-related microorganisms is considered a worldwide prevalent and serious issue which increases the failure of treatment outcomes and leads to high mortality. Considering that the increased resistance to systemic antimicrobial therapy often needs of the use of more toxic agents, topical antimicrobial therapy emerges as an attractive route for the treatment of infectious diseases. The topical antimicrobial therapy is based on the absorption of high drug doses in a readily accessible skin surface, resulting in a reduction of microbial proliferation at infected skin sites. Topical antimicrobials retain the following features: (a) they are able to escape the enzymatic degradation and rapid clearance in the gastrointestinal tract or the first-pass metabolism during oral administration; (b) alleviate the physical discomfort related to intravenous injection; (c) reduce possible adverse effects and drug interactions of systemic administrations; (d) increase patient compliance and convenience; and (e) reduce the treatment costs. Novel antimicrobials for topical application have been widely exploited to control the emergence of drug-resistant microorganisms. This review provides a description of antimicrobial resistance, common microorganisms causing skin and soft tissue infections, topical delivery route of antimicrobials, safety concerns of topical antimicrobials, recent advances, challenges and future prospective in topical antimicrobial development.

Necrotizing soft tissue infection: clinical characteristics and outcomes at a reconstructive center in Jilin Province

BACKGROUND

To investigate the clinical characteristics and treatment outcomes in necrotizing fasciitis (NF) patients in a reconstructive unit in northeastern China.

METHODS

Medical records of patients diagnosed with and treated for NF in the extremities from November 2013 to December 2016 were retrospectively reviewed. Demographic data, clinical presentation, duration of signs and symptoms, location of infection, predisposing factors, causative microbiological organisms, laboratory risk indicator for necrotizing fasciitis (LRINEC) score, number of surgical debridements, length of hospital stay, treatments, and outcomes were recorded.

RESULTS

A total of 39 consecutive patients were treated for severe NF (32 male and 7 female). Diabetes mellitus and blunt trauma were the most common risk factors (13 and 9 cases, respectively). The positive predictive value of the LRINEC score in NF diagnosis was 46.2%. Mean duration of signs and symptoms was 4.6 days. Staphylococcus aureus was the most commonly isolated bacteria (20 cases). All patients underwent their first debridement within 12 h of presentation (mean, 4.6 h). Mean number of surgical treatments was 2.8 (range, 2-5) per patient, including debridements. All patients survived, and mean length of hospital stay was 30.81 (range, 21-43) days. Three patients underwent limb amputation.

CONCLUSIONS

In our clinical experience, early detection and aggressive debridement are the cornerstones of NF treatment. Antibiotic therapy and intensive care support is essential in severe cases of NF. Anaerobic tissue culture and frozen section biopsy could be adopted as routine tests for diagnosis and decision-making in NF. These findings should inform clinical decisions about the treatment of individual patients with NF.

Treatment of Staphylococcus aureus Infections

Staphylococcus aureus, although generally identified as a commensal, is also a common cause of human bacterial infections, including of the skin and other soft tissues, bones, bloodstream, and respiratory tract. The history of S. aureus treatment is marked by the development of resistance to each new class of antistaphylococcal antimicrobial drugs, including the penicillins, sulfonamides, tetracyclines, glycopeptides, and others, complicating therapy. S. aureus isolates identified in the 1960s were sometimes resistant to methicillin, a ß-lactam antimicrobial active initially against a majority S. aureus strains. These MRSA isolates, resistant to nearly all ß-lactam antimicrobials, were first largely confined to the health care environment and the patients who attended it. However, in the mid-1990s, new strains, known as community-associated (CA-) MRSA strains, emerged. CA-MRSA organisms, compared with health care-associated (HA-) MRSA strain types, are more often susceptible to multiple classes of non ß-lactam antimicrobials. While infections caused by methicillin-susceptible S. aureus (MSSA) strains are usually treated with drugs in the ß-lactam class, such as cephalosporins, oxacillin or nafcillin, MRSA infections are treated with drugs in other antimicrobial classes. The glycopeptide drug vancomycin, and in some countries teicoplanin, is the most common drug used to treat severe MRSA infections. There are now other classes of antimicrobials available to treat staphylococcal infections, including several that have been approved after 2009. The antimicrobial management of invasive and noninvasive S. aureus infections in the ambulatory and in-patient settings is the topic of this review. Also discussed are common adverse effects of antistaphylococcal antimicrobial agents, advantages of one agent over another for specific clinical syndromes, and the use of adjunctive therapies such as surgery and intravenous immunoglobulin. We have detailed considerations in the therapy of noninvasive and invasive S. aureus infections. This is followed by sections on specific clinical infectious syndromes including skin and soft tissue infections, bacteremia, endocarditis and intravascular infections, pneumonia, osteomyelitis and vertebral discitis, epidural abscess, septic arthritis, pyomyositis, mastitis, necrotizing fasciitis, orbital infections, endophthalmitis, parotitis, staphylococcal toxinoses, urogenital infections, and central nervous system infections.