Molecular and Clinical Characteristics of Invasive Group A Streptococcal Infection in Sweden

A Cross-Sectional Analysis of Pediatric Necrotizing Soft Tissue Infection Cases and Racial Disparities From the 2016 to 2020 National Inpatient Sample

INTRODUCTION

The incidence, treatment, and outcomes of necrotizing soft tissue infections (NSTIs) and associated racial disparities have been described in adults, but research in the pediatric population is limited. The purpose of this study is to provide a nationally representative characterization of pediatric NSTI and determine the presence of any racial disparities.

METHODS

The National Inpatient Sample was analyzed from 2016 through 2020. Patients aged less than 20 y with a diagnosis of necrotizing fasciitis, Fournier's gangrene, or gas gangrene (based on International Classification of Diseases, Tenth Revision, Clinical Modification codes) were included for analysis.

RESULTS

A total of 355 patients were identified. Black and Hispanic patients accounted for the most admissions in 2016 and 2018, respectively (P = 0.024). Compared to White patients, more Black patients were insured by Medicaid (P = 0.037) and were in the first zip code-based income quartile (P = 0.005). The leading infection overall was necrotizing fasciitis and most patients (81.7%) underwent a surgical procedure by the first calendar day after admission. Although the proportion of Black patients undergoing subcutaneous tissue and fascia excisions was more than that of White patients (P = 0.005), there were no significant differences by race in the time to first procedure, the total number of procedures, or number of postoperative complications. Our amputation and mortality rates were low and unreportable, but there were no differences by race.

CONCLUSIONS

NSTI is rare in the pediatric population and mortality is low. Black patients are disproportionately diagnosed, but these disparities do not extend to disease treatment or outcomes.

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.

Immunomodulating Enzymes from Streptococcus pyogenes-In Pathogenesis, as Biotechnological Tools, and as Biological Drugs

Streptococcus pyogenes, or Group A Streptococcus, is an exclusively human pathogen that causes a wide variety of diseases ranging from mild throat and skin infections to severe invasive disease. The pathogenesis of S. pyogenes infection has been extensively studied, but the pathophysiology, especially of the more severe infections, is still somewhat elusive. One key feature of S. pyogenes is the expression of secreted, surface-associated, and intracellular enzymes that directly or indirectly affect both the innate and adaptive host immune systems. Undoubtedly, S. pyogenes is one of the major bacterial sources for immunomodulating enzymes. Major targets for these enzymes are immunoglobulins that are destroyed or modified through proteolysis or glycan hydrolysis. Furthermore, several enzymes degrade components of the complement system and a group of DNAses degrade host DNA in neutrophil extracellular traps. Additional types of enzymes interfere with cellular inflammatory and innate immunity responses. In this review, we attempt to give a broad overview of the functions of these enzymes and their roles in pathogenesis. For those enzymes where experimentally determined structures exist, the structural aspects of the enzymatic activity are further discussed. Lastly, we also discuss the emerging use of some of the enzymes as biotechnological tools as well as biological drugs and vaccines.

A Case of Severe Mpox Complicated with Streptococcus pyogenes Sepsis in a Patient with HIV Infection

Since May 2022, a global outbreak of human Mpox has rapidly spread in non-endemic countries. We report a case of a 34-year-old man admitted to hospital for a six-day history of fever associated with vesiculo-pustular rash involving the face, limbs, trunk and perianal region, lymphadenopathy and severe proctitis and pharyngitis. He was HIV-positive and virologically suppressed by stable antiretroviral therapy. On admission, Mpox virus-specific RT-PCR was positive from multiple samples. Additionally, blood cultures yielded Streptococcus pyogenes, prompting a 14-day-course of penicillin G and clindamycin. Due to the worsening of proctitis along with right ocular mucosa involvement, tecovirimat treatment was started with a rapid improvement in both skin and mucosal involvement. The patient was discharged after 21 days of hospitalization and the complete clinical resolution occurred 38 days after symptom onset. This is a case of Mpox with extensive multi-mucosal (ocular, pharyngeal and rectal) and cutaneous extension and S. pyogenes bacteraemia probably related to bacterial translocation from the skin or oral cavity that was eased by Mpox lesions/inflammation. The HIVinfection, although well controlled by antiretroviral therapy, could have played a role in the severe course of Mpox, suggesting the importance of a prompt antiviral treatment in HIV-positive patients.

Factors associated with mortality in patients with extremity necrotizing soft-tissue infections: a single academic center experience

PURPOSE

Necrotizing soft-tissue infection (NSTI) is a surgical emergency associated with high mortality. This study primarily aimed to identify the factors associated with in-hospital mortality due to NSTI in the extremities at a single institution. Secondarily, we aimed to clarify the effectiveness of the optimal combination of hyperbaric oxygen therapy (HBOT) and surgery for NSTI treatment.

STUDY DESIGN

Retrospective observational study.

METHODS

This study included all patients newly diagnosed with NSTI in the extremity from 2003 to 2021 in our hospital. Factors associated with mortality, including patient's characteristics, duration from onset to hospitalization, NSTI type, and clinical data at the initial visit; acute disseminated intravascular coagulation (DIC), laboratory risk indicator for necrotizing fasciitis score, and sequential organ failure assessment score; treatment, initial surgery, surgery times, amputation, HBOT, combined surgery with HBOT, and clinical outcomes; amputation rate, mortality rate, and hospitalization duration were examined.

RESULTS

A total of 37 cases were treated for NSTIs. The median age was 64 years (range: 22-86). Five cases (13.5%) died during hospitalization. Ten patients were diagnosed with DIC at the initial visit, of whom four died. HBOT combined with surgery was performed in 23 cases, and 16 cases underwent multiple surgeries. Factors associated with mortality included DIC (p = 0.015, 95% confidence interval [CI]: 0.015-0.633) and multiple surgeries combined with HBOT (p = 0.028, 95% CI: 1.302-95.418).

CONCLUSION

This study demonstrates that DIC at the initial visit is associated with mortality in extremity NSTI. Additionally, HBOT might improve prognosis when combined with multiple surgeries.

Antiphospholipid syndrome after streptococcal toxic shock syndrome later diagnosed as Behcet's disease

Streptococcal toxic shock syndrome is a severe complication of group A streptococci. The production of antiphospholipid antibodies has been associated with streptococcal infections and with autoimmune diseases. Furthermore, streptococcal infections could be a trigger of Behcet's disease. We report a case of a boy who presented antiphospholipid syndrome after streptococcal toxic shock syndrome later he was diagnosed with Behcet's disease.

Necrotising soft-tissue infections

The incidence of necrotising soft-tissue infections has increased during recent decades such that most physicians might see at least one case of these potentially life-threatening infections in their career. Despite advances in care, necrotising soft-tissue infections are still associated with high morbidity and mortality, underlining a need for continued education of the medical community. In particular, failure to suspect necrotising soft-tissue infections, fuelled by poor awareness of the disease, promotes delays to first surgical debridement, amplifying disease severity and adverse outcomes. This Review will focus on practical approaches to management of necrotising soft-tissue infections including prompt recognition, initiation of specific management, exploratory surgery, and aftercare. Increased alertness and awareness for these infections should improve time to diagnosis and early referral to specialised centres, with improvement in the prognosis of necrotising soft-tissue infections.

Streptococcus pyogenes infection of a mediastinal cyst after endoscopic ultrasound-guided fine-needle aspiration

Mediastinal masses are uncommon and difficult to diagnose. Endoscopic ultrasound with fine-needle aspiration (EUS-FNA) is a minimally invasive technique for diagnosis of mediastinal lesions with few complications. Our report described a mediastinal bronchogenic cyst with soft tissue density infected by Streptococcus pyogenes (S. pyogenes) after EUS-FNA, accompanied by respiratory cardiac arrest and superior vena cava syndrome. The patient underwent cardiopulmonary resuscitation to gain the chance for emergency surgery and recovered. Clinicians should be aware that mediastinal mass with soft tissue density shown on imaging may be mediastinal cyst containing high density mucin, FNA should be avoided if cystic masses cannot be ruled out.

Invasive group A streptococcal disease in pregnant women and young children: a systematic review and meta-analysis

BACKGROUND

The incidence of invasive disease caused by group A streptococcus (GAS) has increased in multiple countries in the past 15 years. However, despite these reports, to the best of our knowledge, no systematic reviews and combined estimates of the incidence of invasive GAS have been done in key high-risk groups. To address this, we estimated the incidence of invasive GAS disease, including death and disability outcomes, among two high-risk groups-namely, pregnant women and children younger than 5 years.

METHODS

We did a systematic review and meta-analyses on invasive GAS outcomes, including incidence, case fatality risks, and neurodevelopmental impairment risk, among pregnant women, neonates (younger than 28 days), infants (younger than 1 year), and children (younger than 5 years) worldwide and by income region. We searched several databases for articles published from Jan 1, 2000, to June 3, 2020, for publications that reported invasive GAS outcomes, and we sought unpublished data from an investigator group of collaborators. We included studies with data on invasive GAS cases, defined as laboratory isolation of Streptococcus pyogenes from any normally sterile site, or isolation of S pyogenes from a non-sterile site in a patient with necrotising fasciitis or streptococcal toxic shock syndrome. For inclusion in pooled incidence estimates, studies had to report a population denominator, and for inclusion in pooled estimates of case fatality risk, studies had to report aggregate data on the outcome of interest and the total number of cases included as a denominator. We excluded studies focusing on groups at very high risk (eg, only preterm infants). We assessed heterogeneity with I2.

FINDINGS

Of the 950 published articles and 29 unpublished datasets identified, 20 studies (seven unpublished; 3829 cases of invasive GAS) from 12 countries provided sufficient data to be included in pooled estimates of outcomes. We did not identify studies reporting invasive GAS incidence among pregnant women in low-income and middle-income countries (LMICs) nor any reporting neurodevelopmental impairment after invasive GAS in LMICs. In nine studies from high-income countries (HICs) that reported invasive GAS in pregnancy and the post-partum period, invasive GAS incidence was 0·12 per 1000 livebirths (95% CI 0·11 to 0·14; I2=100%). Invasive GAS incidence was 0·04 per 1000 livebirths (0·03 to 0·05; I2=100%; 11 studies) for neonates, 0·13 per 1000 livebirths (0·10 to 0·16; I2=100%; ten studies) for infants, and 0·09 per 1000 person-years (95% CI 0·07 to 0·10; I2=100%; nine studies) for children worldwide; 0·12 per 1000 livebirths (95% CI 0·00 to 0·24; I2=100%; three studies) in neonates, 0·33 per 1000 livebirths (-0·22 to 0·88; I2=100%; two studies) in infants, and 0·22 per 1000 person-years (0·13 to 0·31; I2=100%; two studies) in children in LMICs; and 0·02 per 1000 livebirths (0·00 to 0·03; I2=100%; eight studies) in neonates, 0·08 per 1000 livebirths (0·05 to 0·11; I2=100%; eight studies) in infants, and 0·05 per 1000 person-years (0·03 to 0·06; I2=100%; seven studies) in children for HICs. Case fatality risks were high, particularly among neonates in LMICs (61% [95% CI 33 to 89]; I2=54%; two studies).

INTERPRETATION

We found a substantial burden of invasive GAS among young children. In LMICs, little data were available for neonates and children and no data were available for pregnant women. Incidences of invasive GAS are likely to be underestimates, particularly in LMICs, due to low GAS surveillance. It is essential to improve available data to inform development of prevention and management strategies for invasive GAS.

FUNDING

Wellcome Trust.

Patient Characteristics and Outcomes in Necrotizing Soft-tissue Infections: Results from a Prospective Cohort Study in a Tertiary Care Center Intensive Care Unit in South India

Background

Materials and methods

Results

Conclusion

How to cite this article

Consistent Biofilm Formation by Streptococcus pyogenes emm 1 Isolated From Patients With Necrotizing Soft Tissue Infections

Objectives

Biofilm formation has been demonstrated in muscle and soft tissue samples from patients with necrotizing soft tissue infection (NSTI) caused by Streptococcus pyogenes, but the clinical importance of this observation is not clear. Although M-protein has been shown to be important for in vitro biofilm formation in S. pyogenes, the evidence for an association between emm type and biofilm forming capacity is conflicting. Here we characterize the biofilm forming capacity in a collection of S. pyogenes isolates causing NSTI, and relate this to emm type of the isolates and clinical characteristics of the patients.

Methods

Bacterial isolates and clinical data were obtained from NSTI patients enrolled in a multicenter prospective observational study. Biofilm forming capacity was determined using a microtiter plate assay.

Results

Among 57 cases, the three most frequently encountered emm types were emm1 (n = 22), emm3 (n = 13), and emm28 (n = 7). The distribution of biofilm forming capacity in emm1 was qualitatively (narrow-ranged normal distribution) and quantitatively (21/22 isolates in the intermediate range) different from other emm types (wide ranged, multimodal distribution with 5/35 isolates in the same range as emm1). There were no significant associations between biofilm forming capacity and clinical characteristics of the patients.

Conclusions

The biofilm forming capacity of emm1 isolates was uniform and differed significantly from other emm types. The impact of biofilm formation in NSTI caused by S. pyogenes on clinical outcomes remains uncertain.

Necrotizing Soft Tissue Infections: More than What Meets the Eye

How to cite this article: Kundu R, Srinivasan S. Necrotizing Soft Tissue Infections: More than What Meets the Eye. Indian J Crit Care Med 2022;26(4):411-413.

Severe acute otitis media and mastoiditis caused by group A beta-hemolytic streptococcus

OBJECTIVE

To describe the characteristics, diagnostics, treatment, and outcome of severe acute otitis media (AOM) and acute mastoiditis (AM) caused by group A beta-hemolytic streptococcus (GAS).

STUDY DESIGN

A retrospective cohort study.

METHODS

The yearly incidence of inpatient care-needing GAS AOM/AM patients in our hospital catchment area between 2002 and 2018 was investigated. A detailed analysis was performed for cases treated during the last GAS epidemic in 2017-2018. Anamnesis, signs and symptoms, pure-tone audiometry results, treatment, complications, and outcome were collected from medical charts. Patients responded to an otology-specific health-related quality of life survey (EOS-16) 1.5 to 3 years after their treatment.

RESULTS

The number of GAS infections peaks at approximately 7-year intervals. During 2017 and 2018, altogether 37 patients (29 adults and 8 children) were hospitalized due to GAS AOM/AM. AM was diagnosed in 14 (38%) patients. The disease progression was typically very rapid. At presentation, all patients had severe ear pain, 68% tympanic membrane perforation and discharge, 43% fever, and 43% vertigo. In pure-tone audiometry, there was usually a marked mixed hearing loss at presentation. There was a significant recovery in both air and bone conduction thresholds; the pure tone average improvement from presentation was 32.3 ± 14.8 dB. Rapid strep tests (RST) proved to be more sensitive than bacterial culture in identifying GAS as a cause of AOM/AM.

CONCLUSION

GAS AOM/AM has a rapid onset. Hearing loss usually includes a sensorineural component, which is usually reversible with adequate treatment. RST seems to be useful in detecting GAS from middle ear discharge.

LEVEL OF EVIDENCE

4.

New Insights on Streptococcus dysgalactiae subsp. dysgalactiae Isolates

Streptococcus dysgalactiae subsp. dysgalactiae (SDSD) has been considered a strict animal pathogen. Nevertheless, the recent reports of human infections suggest a niche expansion for this subspecies, which may be a consequence of the virulence gene acquisition that increases its pathogenicity. Previous studies reported the presence of virulence genes of Streptococcus pyogenes phages among bovine SDSD (collected in 2002-2003); however, the identity of these mobile genetic elements remains to be clarified. Thus, this study aimed to characterize the SDSD isolates collected in 2011-2013 and compare them with SDSD isolates collected in 2002-2003 and pyogenic streptococcus genomes available at the National Center for Biotechnology Information (NCBI) database, including human SDSD and S. dysgalactiae subsp. equisimilis (SDSE) strains to track temporal shifts on bovine SDSD genotypes. The very close genetic relationships between humans SDSD and SDSE were evident from the analysis of housekeeping genes, while bovine SDSD isolates seem more divergent. The results showed that all bovine SDSD harbor Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas IIA system. The widespread presence of this system among bovine SDSD isolates, high conservation of repeat sequences, and the polymorphism observed in spacer can be considered indicators of the system activity. Overall, comparative analysis shows that bovine SDSD isolates carry speK, speC, speL, speM, spd1, and sdn virulence genes of S. pyogenes prophages. Our data suggest that these genes are maintained over time and seem to be exclusively a property of bovine SDSD strains. Although the bovine SDSD genomes characterized in the present study were not sequenced, the data set, including the high homology of superantigens (SAgs) genes between bovine SDSD and S. pyogenes strains, may indicate that events of horizontal genetic transfer occurred before habitat separation. All bovine SDSD isolates were negative for genes of operon encoding streptolysin S, except for sagA gene, while the presence of this operon was detected in all SDSE and human SDSD strains. The data set of this study suggests that the separation between the subspecies "dysgalactiae" and "equisimilis" should be reconsidered. However, a study including the most comprehensive collection of strains from different environments would be required for definitive conclusions regarding the two taxa.

Discriminatory plasma biomarkers predict specific clinical phenotypes of necrotizing soft-tissue infections

BACKGROUNDNecrotizing soft-tissue infections (NSTIs) are rapidly progressing infections frequently complicated by septic shock and associated with high mortality. Early diagnosis is critical for patient outcome, but challenging due to vague initial symptoms. Here, we identified predictive biomarkers for NSTI clinical phenotypes and outcomes using a prospective multicenter NSTI patient cohort.METHODSLuminex multiplex assays were used to assess 36 soluble factors in plasma from NSTI patients with positive microbiological cultures (n = 251 and n = 60 in the discovery and validation cohorts, respectively). Control groups for comparative analyses included surgical controls (n = 20), non-NSTI controls (i.e., suspected NSTI with no necrosis detected upon exploratory surgery, n = 20), and sepsis patients (n = 24).RESULTSThrombomodulin was identified as a unique biomarker for detection of NSTI (AUC, 0.95). A distinct profile discriminating mono- (type II) versus polymicrobial (type I) NSTI types was identified based on differential expression of IL-2, IL-10, IL-22, CXCL10, Fas-ligand, and MMP9 (AUC >0.7). While each NSTI type displayed a distinct array of biomarkers predicting septic shock, granulocyte CSF (G-CSF), S100A8, and IL-6 were shared by both types (AUC >0.78). Finally, differential connectivity analysis revealed distinctive networks associated with specific clinical phenotypes.CONCLUSIONSThis study identifies predictive biomarkers for NSTI clinical phenotypes of potential value for diagnostic, prognostic, and therapeutic approaches in NSTIs.TRIAL REGISTRATIONClinicalTrials.gov NCT01790698.FUNDINGCenter for Innovative Medicine (CIMED); Region Stockholm; Swedish Research Council; European Union; Vinnova; Innovation Fund Denmark; Research Council of Norway; Netherlands Organisation for Health Research and Development; DLR Federal Ministry of Education and Research; and Swedish Children's Cancer Foundation.

Surgical Infection Society 2020 Updated Guidelines on the Management of Complicated Skin and Soft Tissue Infections

Background: The Surgical Infection Society (SIS) Guidelines for the treatment of complicated skin and soft tissue infections (SSTIs) were published in October 2009 in Surgical Infections. The purpose of this project was to provide a succinct update on the earlier guidelines based on an additional decade of data. Methods: We reviewed the previous guidelines eliminating bite wounds and diabetic foot infections including their associated references. Relevant articles on the topic of complicated SSTIs from 2008-2020 were reviewed and graded individually. Comparisons were then made between the old and the new graded recommendations with review of the older references by two authors when there was disparity between the grades. Results: The majority of new studies addressed antimicrobial options and duration of therapy particularly in complicated abscesses. There were fewer updated studies on diagnosis and specific operative interventions. Many of the topics addressed in the original guidelines had no new literature to evaluate. Conclusions: Most recommendations remain unchanged from the original guidelines with the exception of increased support for adjuvant antimicrobial therapy after drainage of complex abscess and increased data for the use of alternative antimicrobial agents.

Pathogenic Mechanisms of Streptococcal Necrotizing Soft Tissue Infections

Necrotizing skin and soft tissue infections (NSTIs) are severe life-threatening and rapidly progressing infections. Beta-hemolytic streptococci, particularly S. pyogenes (group A streptococci (GAS)) but also S. dysgalactiae subsp. equisimilis (SDSE, most group G and C streptococcus), are the main causative agents of monomicrobial NSTIs and certain types, such as emm1 and emm3, are over-represented in NSTI cases. An arsenal of bacterial virulence factors contribute to disease pathogenesis, which is a complex and multifactorial process. In this chapter, we summarize data that have provided mechanistic and immuno-pathologic insight into host-pathogens interactions that contribute to tissue pathology in streptococcal NSTIs. The role of streptococcal surface associated and secreted factors contributing to the hyper-inflammatory state and immune evasion, bacterial load in the tissue and persistence strategies, including intracellular survival and biofilm formation, as well as strategies to mimic NSTIs in vitro are discussed.

Beta-Haemolytic Group A, C and G Streptococcal Infections in Southern Hungary: A 10-Year Population-Based Retrospective Survey (2008-2017) and a Review of the Literature

Introduction

Pyogenic β-hemolytic streptococci (including Group A, C and G Streptococcus) are some of the most important Gram-positive bacterial pathogens in human medicine. Although effective therapy is available, invasive streptococcal infections are associated with a significant disease burden.

Methods

In this retrospective study, the epidemiological characteristics of invasive Group A (iGAS) and Group C and G (iGCGS) streptococci, along with tonsillo-pharyngitis-causing pGAS and pGCGS infections, were assessed in Southern Hungary. A total of 1554 cases of streptococcal tonsillo-pharyngitis infections (26.5–44.1/100,000 persons, pGAS: 95.5%; n=1484) and 1104 cases of invasive streptococcal infections were detected (12.5–31.4/100,000 persons, iGAS: 77.9%; n=861).

Results

The average age of the affected patients in the various groups were the following: pGAS: 13.2±13.1 years, pGCGS: 21.0±15.0 years (p=0.039), iGAS: 49.1±12.8 years, iGCGS: 58.7±18.5 years (p>0.05). iGAS isolates originated from abscesses (47.1%), blood culture samples (24.1%), surgical samples (16.7%), biopsies (4.6%), pleural fluid (3.5%), pus (2.0%), synovial fluid (1.3%) and cerebrospinal fluid samples (0.7%). In contrast, iGCGS isolates mainly originated from blood culture samples (53.8%), abscesses (22.9%), surgical samples (12.3%), synovial fluid (5.1%), pleural fluid (3.7%), pus (1.8%) and cerebrospinal fluid samples (0.4%). All respective isolates were susceptible to benzyl-penicillin; overall resistance levels for erythromycin (10.5% for GAS, 21.4% for GCGS) and clindamycin (9.2% for GAS, 17.2% for GCGS) were significantly higher in GCGS isolates, while resistance levels for norfloxacin were higher in GAS isolates (13.5% for GAS, 6.9% for GCGS).

Conclusion

The rates of resistance to macrolides and clindamycin are a cause for concern (especially among GCGS isolates); however, resistance levels are still relatively low, compared to Southern European countries.

A prospective survey of Streptococcus pyogenes infections in French Brittany from 2009 to 2017: Comprehensive dynamic of new emergent emm genotypes

Streptococcus pyogenes or group A Streptococcus (GAS) causes diseases ranging from uncomplicated pharyngitis to life-threatening infections. It has complex epidemiology driven by the diversity, the temporal and geographical fluctuations of the circulating strains. Despite the global burden of GAS diseases, there is currently no available vaccination strategy against GAS infections. This study, based on a longitudinal population survey, aimed to understand the dynamic of GAS emm types and to give leads to better recognition of underlying mechanisms for the emergence of successful clones. From 2009 to 2017, we conducted a systematic culture-based diagnosis of GAS infections in a French Brittany population with a prospective recovery of clinical data. The epidemiological analysis was performed using emm typing combined with the structural and functional cluster-typing system for all the recovered strains. Risk factors for the invasiveness, identified by univariate analysis, were computed in a multiple logistic regression analysis, and the only independent risk factor remaining in the model was the age (OR for the entire range [CI_95%] = 6.35 [3.63, 11.10]; p<0.0001). Among the 61 different emm types identified, the most prevalent were emm28 (16%), emm89 (15%), emm1 (14%), and emm4 (8%), which accounted for more than 50% of circulating strains. During the study period, five genotypes identified as emm44, 66, 75, 83, 87 emerged successively and belonged to clusters D4, E2, E3, and E6 that were different from those gathering “Prevalent” emm types (clusters A-C3 to 5, E1 and E4). We previously reported significant genetic modifications for emm44, 66, 83 and 75 types resulting possibly from a short adaptive evolution. Herein we additionally observed that the emergence of a new genotype could occur in a susceptible population having specific risk factors or probably lacking a naturally-acquired cluster-specific immune cross-protection. Among emergent emm types, emm75 and emm87 tend to become prevalent with a stable annual incidence and the risk of a clonal expansion have to be considered.

Epidemiological Situation of Necrotizing Fasciitis and Factors in Thailand and Factors Associated with Its Morbidity and Mortality, 2014-2018

INTRODUCTION

Necrotizing fasciitis (NF) is a rare skin and soft-tissue bacterial infection with high morbidity and mortality. Knowledge about the prevalence and incidence of NF in Thailand is quite sparse. The objective of this study was to determine the prevalence of NF in Thailand and factors that may be potentially associated with NF morbidity and mortality.

METHODS

A cross-sectional study using secondary data from Thailand's national health databases between 2014 and 2018 was conducted. Descriptive statistics using median and percentage formats were used. This was complemented by multivariable logistic regression to determine the association between various factors (such as age and underlying diseases) with NF morbidity and mortality. Univariate spatial data analysis was exercised to identify the geographical hot spots in which the disease appeared.

RESULTS

During 2014-2018, we found 90,683 NF cases. About 4.86% of the cases died. The median age for all cases was 59.39 years old. The annual incidence of NF demonstrated an upward trend (from 26.08 per 100,000 population in 2014 to 32.64 per 100,000 population in 2018). The monthly incidence was highest between May and August. A high incidence cluster (as indicated by local Moran's I) was found in the north-eastern region of Thailand. The most infected sites were on the ankles and feet (43.18%) with an amputation rate of 7.99% in all cases. Multivariable logistic regression indicated that the significant risk factor for amputation was a presence of underlying diseases, namely diabetes (OR 7.94, 95% CI 7.34-8.61). Risk factors for mortality included being elderly (OR 1.82, 95% CI 1.68-1.98) and a presence of underlying hypertension (OR 1.16, 95% CI 1.07-1.27), cirrhosis (OR 4.67, 95% CI 4.17-5.21), and malignancy (OR 1.88, 95% CI 1.55-2.26).

DISCUSSION AND CONCLUSION

As the elderly and those with chronic underlying diseases are likely to face non-preferable health outcomes from NF, healthcare providers should pay great attention to these groups of patients. Early and intensive treatment might be considered in these groups of patients. Further studies that aim to validate the volume of actual NF cases and reported NF cases are recommended.

What Demographic and Clinical Factors Are Associated with In-hospital Mortality in Patients with Necrotizing Fasciitis?

BACKGROUND

Necrotizing fasciitis is a rare infection with rapid deterioration and a high mortality rate. Factors associated with in-hospital mortality have not been thoroughly evaluated. Although predictive models identifying the diagnosis of necrotizing fasciitis have been described (such as the Laboratory Risk Indicator for Necrotizing Fasciitis [LRINEC]), their use in predicting mortality is limited.

QUESTIONS/PURPOSES

(1) What demographic factors are associated with in-hospital mortality in patients with necrotizing fasciitis? (2) What clinical factors are associated with in-hospital mortality? (3) What laboratory values are associated with in-hospital mortality? (4) Is the LRINEC score useful in predicting mortality?

METHODS

We retrospectively studied all patients with necrotizing fasciitis at our tertiary care institution during a 10-year period. In all, 134 patients were identified; after filtering out patients with missing data (seven) and those without histologically confirmed necrotizing fasciitis (12), 115 patients remained. These patients were treated with early-initiation antibiotic therapy and aggressive surgical intervention once the diagnosis was suspected. Demographic data, clinical features, laboratory results, and treatment variables were identified. The median age was 56 years and 42% of patients were female. Of the 115 patients analyzed, 15% (17) died in the hospital. Univariate and receiver operating characteristic analyses were performed due to the low number of mortality events seen in this cohort.

RESULTS

The demographic factors associated with in-hospital mortality were older age (median: 64 years for nonsurvivors [interquartile range (IQR) 57-79] versus 55 years for survivors [IQR 45-63]; p = 0.002), coronary artery disease (odds ratio 4.56 [95% confidence interval (CI) 1.51 to 14]; p = 0.008), chronic kidney disease (OR 4.92 [95% CI 1.62 to 15]; p = 0.006), and transfer from an outside hospital (OR 3.47 [95% CI 1.19 to 10]; p = 0.02). The presenting clinical characteristics associated with in-hospital mortality were positive initial blood culture results (OR 4.76 [95% CI 1.59 to 15]; p = 0.01), lactic acidosis (OR 4.33 [95% CI 1.42 to 16]; p = 0.02), and multiple organ dysfunction syndrome (OR 6.37 [95% CI 2.05 to 20]; p = 0.002). Laboratory values at initial presentation that were associated with in-hospital mortality were platelet count (difference of medians -136 [95% CI -203 to -70]; p < 0.001), serum pH (difference of medians -0.13 [95% CI -0.21 to -0.03]; p = 0.02), serum lactate (difference of medians 0.90 [95% CI 0.40 to 4.80]; p < 0.001), serum creatinine (difference of medians 1.93 [95% CI 0.65 to 3.44]; p < 0.001), partial thromboplastin time (difference of medians 8.30 [95% CI 1.85 to 13]; p = 0.03), and international normalized ratio (difference of medians 0.1 [95% CI 0.0 to 0.5]; p = 0.004). The LRINEC score was a poor predictor of mortality with an area under the receiver operating characteristics curve of 0.56 [95% CI 0.45-0.67].

CONCLUSIONS

Factors aiding clinical recognition of necrotizing fasciitis are not consistently helpful in predicting mortality of this infection. Identifying patients with potentially compromised organ function should lead to aggressive and expedited measures for diagnosis and treatment. Future multicenter studies with larger populations and a standardized algorithm of treatment triggered by high clinical suspicion can be used to validate these findings to better help prognosticate this potentially fatal diagnosis.Level of Evidence Level III, therapeutic study.

Morbidity and mortality in critically ill patients with invasive group A streptococcus infection: an observational study

Background

Group A streptococci (GAS) are known to cause serious invasive infections, but little is known about outcomes when patients with these infections are admitted to intensive care. We wanted to describe critically ill patients with severe sepsis or septic shock due to invasive GAS (iGAS) and compare them with other patients with severe sepsis or septic shock.

Methods

Adult patients admitted to a general intensive care unit (ICU) in Sweden (2007–2019) were screened for severe sepsis or septic shock according to Sepsis 2 definition. Individuals with iGAS infection were identified. The outcome variables were mortality, days alive and free of vasopressors and invasive mechanical ventilation, maximum acute kidney injury score for creatinine, use of continuous renal replacement therapy and maximum Sequential Organ Failure Assessment score during the ICU stay. Age, Simplified Acute Physiology Score (SAPS 3) and iGAS were used as independent, explanatory variables in regression analysis. Cox regression was used for survival analyses.

Results

iGAS was identified in 53 of 1021 (5.2%) patients. Patients with iGAS presented a lower median SAPS 3 score (62 [56–72]) vs 71 [61–81]), p <  0.001), had a higher frequency of cardiovascular cause of admission to the ICU (38 [72%] vs 145 [15%], p <  0.001) and had a higher median creatinine score (173 [100–311] vs 133 [86–208] μmol/L, p <  0.019). Of the GAS isolates, 50% were serotyped emm1/T1 and this group showed signs of more pronounced circulatory and renal failure than patients with non-emm1/T1 (p = 0.036 and p = 0.007, respectively). After correction for severity of illness (SAPS 3) and age, iGAS infection was associated with lower mortality risk (95% confidence interval (CI) of hazard ratio (HR) 0.204–0.746, p <  0.001). Morbidity analyses demonstrated that iGAS patients were more likely to develop renal failure.

Conclusion

Critically ill patients with iGAS infection had a lower mortality risk but a higher degree of renal failure compared to similarly ill sepsis patients. emm1/T1 was found to be the most dominant serotype, and patients with emm1/T1 demonstrated more circulatory and renal failure than patients with other serotypes of iGAS.

A Mobile Genetic Element Promotes the Association Between Serotype M28 Group A Streptococcus Isolates and Cases of Puerperal Sepsis

BACKGROUND

Bacterial infections following childbirth-so-called puerperal infections-cause morbidity in 5%-10% of all new mothers. At low frequency, the infection can spread to the blood, resulting in life-threatening sepsis known as puerperal sepsis. Pathogens causing puerperal sepsis include group A Streptococcus (GAS), and epidemiological analyses have identified isolates of a single serotype, M28, as being nonrandomly associated with cases of puerperal sepsis. The genomes of serotype M28 GAS isolates harbor a 36.3-kb mobile genetic element of apparent group B Streptococcus origin, termed region of difference 2 (RD2).

METHODS

The phenotypic (determined via tissue culture and a vaginal colonization model) and regulatory (determined via RNA sequencing analysis) contributions of RD2 were assessed by comparing parental, RD2 deletion mutant, and complemented mutant serotype M28 GAS strains.

RESULTS

RD2 affords serotype M28 isolates an enhanced ability to adhere to human vaginal epithelial cells and to colonize the female reproductive tract in a mouse model of infection. In addition, RD2 influences the abundance of messenger RNAs from >100 core chromosomal GAS genes.

CONCLUSIONS

The data are consistent with RD2 directly, via encoded virulence factors, and indirectly, via encoded regulatory proteins, modifying the virulence potential of GAS and contributing to the decades-old association of serotype M28 isolates with cases of puerperal sepsis.

Acquisition of genetic mutations in Group A Streptococci at infection site and subsequent systemic dissemination of the mutants with lethal mutations in a streptococcal toxic shock syndrome mouse model

Streptococcal toxic shock syndrome (STSS) is caused mainly by Streptococcus pyogenes (Group A Streptococci, GAS), and it has a fatality rate of 25%. Mutations in CsrRS and RopB, which suppress the transcription of many virulence factors, were recently found in clinical isolates from STSS patients, but it is not fully understood when and where GAS acquires the mutations in the host. To resolve this question, we used our mouse model of human STSS to recover GAS strains from injections sites, spleens and blood of moribund mice with STSS-like symptoms, and analyzed the sequence of the covR/covS genes and ropB gene that encode CsrRS and RopB. Fifteen out of twenty mice that were inoculated transdermally into muscles with GAS organisms became moribund with STSS-like symptoms after more than 20 days after inoculation. We found that all the disseminated GAS strains recovered from the blood and spleens of the moribund mice had mutations in either the covR genes or the covS genes. The mutation sites in the GAS strains recovered from the blood and spleen were identical in each mouse, whereas the strains recovered from the muscles included a mix of disseminated strains, other mutant strains, and the parent strain. The mutant strains killed mice significantly earlier than the parent strain. Our data indicated that GAS organisms remained at the injection site, and various mutants appeared there, among which the strain that acquires the mutation in the covR/S gene is expected to overexpress various virulence factors simultaneously and cause systemic infection such as STSS.

Beta-Hemolytic Streptococci and Necrotizing Soft Tissue Infections

β-hemolytic streptococci are major causes of necrotizing soft tissue infections (NSTIs), Streptococcus pyogenes (group A streptococcus; GAS) in particular. NSTIs caused by Streptococcus dysgalactiae (SD) have also been reported. In the INFECT cohort of 409 NSTIs patients, more than a third of the cases were caused by GAS (31%) or SD (7%). Risk factors of streptococcal NSTIs compared to streptococcal cellulitis have previously been largely unknown. The INFECT study confirmed blunt trauma as an important risk factor. In addition, absence of pre-existing skin lesions and a lower BMI were associated with NSTIs. The study also confirmed that septic shock is more frequent in GAS cases than in other types of NSTIs. Septic shock was also among several predictors of mortality. The role of intravenous immunoglobulin (IVIG) in streptococcal NSTIs has been unclear. In the INFECT cohort, IVIG treatment was associated with increased survival. As in other studies, a significant microbial diversity was observed, but with predominance of a few emm types. Overall, the INFECT study gives a comprehensive and contemporary picture of the clinical characteristics and the microbes involved in streptococcal NSTIs. The reported severity of disease underscores the need for new efforts aimed at identifying novel diagnostic measures and improved treatment.

Predictors of Death in Necrotizing Skin and Soft Tissue Infection

BACKGROUND

Necrotizing skin and soft tissue infection (NSTI) is a surgical emergency that is associated with high morbidity and mortality. This study aims to identify predictors of in-hospital death following a NSTI.

MATERIAL AND METHODS

We queried the Healthcare Cost and Utilization Project (HCUP) State Inpatient Database (SID) for California between 2006 and 2011. We used conventional and advanced statistical methods to identify predictors of in-hospital mortality, which included: logistic regression, stepwise logistic regression, decision trees, and K-nearest neighbor (KNN) algorithms.

RESULTS

A total of 10,158 patients had a NSTI. The full and stepwise logistic regression models had a ROC AUC in the validation dataset of 0.83 (95% CI [0.80, 0.86]) and 0.81 (95% CI [0.78, 0.83]), respectively. The KNN and decision tree model had a ROC AUC of 0.84 (95% CI [0.81, 0.85]) and 0.69 (95% CI [0.65, 0.72]), respectively. The top predictors of in-hospital mortality in the KNN and stepwise logistic model included: (1) the presence of in-hospital coagulopathy, (2) having an infectious or parasitic diagnoses, (3) electrolyte disturbances, (4) advanced age, and (5) the total number of beds in a hospital.

CONCLUSION

Patients with a NSTI have high rates of in-hospital mortality. This study highlights the important factors in managing patients with a NSTI which include: correcting coagulopathy and electrolyte imbalances, treating underlying infectious processes, providing adequate resources to the elderly population, and managing patients in high-volume centers.

Antibodies to the conserved region of the M protein and a streptococcal superantigen cooperatively resolve toxic shock-like syndrome in HLA-humanized mice

Invasive streptococcal disease (ISD) and toxic shock syndrome (STSS) result in over 160,000 deaths each year. We modelled these in HLA-transgenic mice infected with a clinically lethal isolate expressing Streptococcal pyrogenic exotoxin (Spe) C and demonstrate that both SpeC and streptococcal M protein, acting cooperatively, are required for disease. Vaccination with a conserved M protein peptide, J8, protects against STSS by causing a dramatic reduction in bacterial burden associated with the absence of SpeC and inflammatory cytokines in the blood. Furthermore, passive immunotherapy with antibodies to J8 quickly resolves established disease by clearing the infection and ablating the inflammatory activity of the M protein, which is further enhanced by addition of SpeC antibodies. Analysis of 77 recent isolates of Streptococcus pyogenes causing ISD, demonstrated that anti-J8 antibodies theoretically recognize at least 73, providing strong support for using antibodies to J8, with or without antibodies to SpeC, as a therapeutic approach.

Necrotizing skin and soft-tissue infections in the intensive care unit

BACKGROUND

Necrotizing skin and soft-tissue infections (NSTI) are rare but potentially life-threatening and disabling infections that often require intensive care unit admission.

OBJECTIVES

To review all aspects of care for a critically ill individual with NSTI.

SOURCES

Literature search using Medline and Cochrane library, multidisciplinary panel of experts.

CONTENT

The initial presentation of a patient with NSTI can be misleading, as features of severe systemic toxicity can obscure sometimes less impressive skin findings. The infection can spread rapidly, and delayed surgery worsens prognosis, hence there is a limited role for additional imaging in the critically ill patient. Also, the utility of clinical scores is contested. Prompt surgery with aggressive debridement of necrotic tissue is required for source control and allows for microbiological sampling. Also, prompt administration of broad-spectrum antimicrobial therapy is warranted, with the addition of clindamycin for its effect on toxin production, both in empirical therapy, and in targeted therapy for monomicrobial group A streptococcal and clostridial NSTI. The role of immunoglobulins and hyperbaric oxygen therapy remains controversial.

IMPLICATIONS

Close collaboration between intensive care, surgery, microbiology and infectious diseases, and centralization of care is fundamental in the approach to the severely ill patient with NSTI. As many aspects of management of these rare infections are supported by low-quality data only, multicentre trials are urgently needed.

Decoding the molecular epidemiology of group A streptococcus - an Indian perspective

PURPOSE

Unlike western countries the knowledge of group A streptococcus (GAS) epidemiology in India remains patchy and incomplete. Typing is crucial for surveillance as well as in predicting the efficacy of multivalent M protein vaccine. The present study aimed to explore the emm types of 206 invasive and non-invasive GAS isolates from South India as well as reviewing all the published literature on GAS molecular epidemiology from India thereby generating a pan-Indian data to predict the conjectural coverage of the 30-valent M-protein vaccine in this population.

METHODOLOGY

emm typing and superantigen (SAg) profiling of GAS along with reviewing literatures on GAS molecular epidemiology from India.

RESULTS

This study revealed a high diversity of emm types with emm 63, 82, 183, 85, 92, 169, 42, 44, 106, 74, 12 being frequently encountered, belonging to twenty emm clusters. The pan-Indian data on prevalent emm types further supports our study findings with 135 emm different types. Six clusters dominated accounting for 80 % of the GAS isolates: E3(26 %), E6(20 %), E2(11 %), E4(10 %), D4(7 %), E1(6 %). No significant association was noted between emm types and the nature of infection (P≥0.05) while a few SAg profiles were significantly associated with certain emm types. Pan Indian data revealed that only 16 % of the emm types encountered were included in proposed 30-valent M protein based vaccine.

CONCLUSION

The coverage among the South Indian GAS isolates was 28.2 % which increased to only 46.6 % with the cross-opsonic effect, thus highlighting the importance of developing a specific multivalent vaccine including the prevalent emm types in India or considering the use of conserved C-repeat vaccines and non-M protein based vaccines.

The Role of Streptococcal and Staphylococcal Exotoxins and Proteases in Human Necrotizing Soft Tissue Infections

Necrotizing soft tissue infections (NSTIs) are critical clinical conditions characterized by extensive necrosis of any layer of the soft tissue and systemic toxicity. Group A streptococci (GAS) and Staphylococcus aureus are two major pathogens associated with monomicrobial NSTIs. In the tissue environment, both Gram-positive bacteria secrete a variety of molecules, including pore-forming exotoxins, superantigens, and proteases with cytolytic and immunomodulatory functions. The present review summarizes the current knowledge about streptococcal and staphylococcal toxins in NSTIs with a special focus on their contribution to disease progression, tissue pathology, and immune evasion strategies.

Necrotizing Fasciitis by Two Anaerobic Bacteria in an Immunocompetent Patient after Minor Trauma: A Case Report

Necrotizing fasciitis (NF) is a soft tissue infection affecting subcutaneous tissue and the muscular fascia without involvement of the muscle and can be either monomicrobial or polymicrobial. Monomicrobial infections are usually caused by group A streptococci, while infections caused by anaerobic germs usually affect immunodepressed patients. We report a rare case of NF caused by two anaerobic bacteria in an immunocompetent patient.

Evaluation and Management of Necrotizing Soft Tissue Infections

Despite advances in antibiotic and surgical management and supportive care for necrotizing soft tissue infections, morbidity and mortality remain substantial. Although there are clinical practice guidelines in place, there still remains much variability in choice and duration of antibiotic therapy, time to initial surgical debridement, and use of adjuvant medical therapies. This article offers an overview of necrotizing soft tissue infections with a focus on current diagnostic and treatment modalities.

Prevalent emm Types among Invasive GAS in Europe and North America since Year 2000

BACKGROUND

Streptococcus pyogenes or group A streptococcus (GAS) is an important human pathogen responsible for a broad range of infections, from uncomplicated to more severe and invasive diseases with high mortality and morbidity. Epidemiological surveillance has been crucial to detect changes in the geographical and temporal variation of the disease pattern; for this purpose the M protein gene (emm) gene typing is the most widely used genotyping method, with more than 200 emm types recognized. Molecular epidemiological data have been also used for the development of GAS M protein-based vaccines.

METHODS

The aim of this paper was to provide an updated scenario of the most prevalent GAS emm types responsible for invasive infections in developed countries as Europe and North America (US and Canada), from 1st January 2000 to 31st May 2017. The search, performed in PubMed by the combined use of the terms ("emm") and ("invasive") retrieved 264 articles, of which 38 articles (31 from Europe and 7 from North America) met the inclusion criteria and were selected for this study. Additional five papers cited in the European articles but not retrieved by the search were included.

RESULTS

emm1 represented the dominant type in both Europe and North America, replaced by other emm types in only few occasions. The seven major emm types identified (emm1, emm28, emm89, emm3, emm12, emm4, and emm6) accounted for approximately 50-70% of the total isolates; less common emm types accounted for the remaining 30-50% of the cases. Most of the common emm types are included in either one or both the 26-valent and 30-valent vaccines, though some well-represented emm types found in Europe are not.

CONCLUSION

This study provided a picture of the prevalent emm types among invasive GAS (iGAS) in Europe and North America since the year 2000 onward. Continuous surveillance on the emm-type distribution among iGAS infections is strongly encouraged also to determine the potential coverage of the developing multivalent vaccines.

The Evaluation and Management of Toxic Shock Syndrome in the Emergency Department: A Review of the Literature

BACKGROUND

Toxic shock syndrome (TSS) is a severe, toxin-mediated illness that can mimic several other diseases and is lethal if not recognized and treated appropriately.

OBJECTIVE

This review provides an emergency medicine evidence-based summary of the current evaluation and treatment of TSS.

DISCUSSION

The most common etiologic agents are Staphylococcus aureus and Streptococcus pyogenes. Sources of TSS include postsurgical wounds, postpartum, postabortion, burns, soft tissue injuries, pharyngitis, and focal infections. Symptoms are due to toxin production and infection focus. Early symptoms include fever, chills, malaise, rash, vomiting, diarrhea, and hypotension. Diffuse erythema and desquamation may occur later in the disease course. Laboratory assessment may demonstrate anemia, thrombocytopenia, elevated liver enzymes, and abnormal coagulation studies. Diagnostic criteria are available to facilitate the diagnosis, but they should not be relied on for definitive diagnosis. Rather, specific situations should trigger consideration of this disease process. Treatment involves intravenous fluids, source control, and antibiotics. Antibiotics should include a penicillinase-resistant penicillin, cephalosporin, or vancomycin (in methicillin-resistant S. aureus prevalent areas) along with either clindamycin or linezolid.

CONCLUSION

TSS is a potentially deadly disease requiring prompt recognition and treatment. Focused history, physical examination, and laboratory testing are important for the diagnosis and management of this disease. Understanding the evaluation and treatment of TSS can assist providers with effectively managing these patients.

Impact of Intravenous Immunoglobulin on Survival in Necrotizing Fasciitis With Vasopressor-Dependent Shock: A Propensity Score-Matched Analysis From 130 US Hospitals

Background

Shock frequently complicates necrotizing fasciitis (NF) caused by group A Streptococcus (GAS) or Staphylococcus aureus. Intravenous immunoglobulin (IVIG) is sometimes administered for presumptive toxic shock syndrome (TSS), but its frequency of use and efficacy are unclear.

Methods

Adult patients with NF and vasopressor-dependent shock undergoing surgical debridement from 2010 to 2014 were identified at 130 US hospitals. IVIG cases were propensity-matched and risk-adjusted. The primary outcome was in-hospital mortality and the secondary outcome was median length of stay (LOS).

Results

Of 4127 cases of debrided NF with shock at 121 centers, only 164 patients (4%) at 61 centers received IVIG. IVIG subjects were younger with lower comorbidity indices, but higher illness severity. Clindamycin and vasopressor intensity were higher among IVIG cases, as was coding for TSS and GAS. In-hospital mortality did not differ between matched IVIG and non-IVIG groups (crude mortality, 27.3% vs 23.6%; adjusted odds ratio, 1.00 [95% confidence interval, .55-1.83]; P = .99). Early IVIG (≤2 days) did not alter this effect (P = .99). Among patients coded for TSS, GAS, and/or S. aureus, IVIG use was still unusual (59/868 [6.8%]) and lacked benefit (P = .63). Median LOS was similar between IVIG and non-IVIG groups (26 [13-49] vs 26 [11-43]; P = .84). Positive predictive values for identifying true NF and debridement among IVIG cases using our algorithms were 97% and 89%, respectively, based on records review at 4 hospitals.

Conclusions

Adjunctive IVIG was administered infrequently in NF with shock and had no apparent impact on mortality or hospital LOS beyond that achieved with debridement and antibiotics.

Genome sequence analysis of emm89 Streptococcus pyogenes strains causing infections in Scotland, 2010-2016

Purpose

Strains of type emm89 Streptococcus pyogenes have recently increased in frequency as a cause of human infections in several countries in Europe and North America. This increase has been molecular epidemiologically linked with the emergence of a new genetically distinct clone, designated clade 3. We sought to extend our understanding of this epidemic behavior by the genetic characterization of type emm89 strains responsible in recent years for an increased frequency of infections in Scotland.

Methodology

We sequenced the genomes of a retrospective cohort of 122 emm89 strains recovered from patients with invasive and noninvasive infections throughout Scotland during 2010 to 2016.

Results

All but one of the 122 emm89 infection isolates are of the recently emerged epidemic clade 3 clonal lineage. The Scotland isolates are closely related to and not genetically distinct from recent emm89 strains from England, they constitute a single genetic population.

Conclusions

The clade 3 clone causes virtually all-contemporary emm89 infections in Scotland. These findings add Scotland to a growing list of countries of Europe and North America where, by whole genome sequencing, emm89 clade 3 strains have been demonstrated to be the cause of an ongoing epidemic of invasive infections and to be genetically related due to descent from a recent common progenitor.

In vitro imaging of bacteria using 18F-fluorodeoxyglucose micro positron emission tomography

Positron emission tomography (PET) with fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) can be applied to detect infection and inflammation. However, it was so far not known to what extent bacterial pathogens may contribute to the PET signal. Therefore, we investigated whether clinical isolates of frequently encountered bacterial pathogens take up ¹⁸F-FDG in vitro, and whether FDG inhibits bacterial growth as previously shown for 2-deoxy-glucose. 22 isolates of Gram-positive and Gram-negative bacterial pathogens implicated in fever and inflammation were incubated with ¹⁸F-FDG and uptake of ¹⁸F-FDG was assessed by gamma-counting and µPET imaging. Possible growth inhibition by FDG was assayed with Staphylococcus aureus and the Gram-positive model bacterium Bacillus subtilis. The results show that all tested isolates accumulated ¹⁸F-FDG actively. Further, ¹⁸F-FDG uptake was hampered in B. subtilis pts mutants impaired in glucose uptake. FDG inhibited growth of S. aureus and B. subtilis only to minor extents, and this effect was abrogated by pts mutations in B. subtilis. These observations imply that bacteria may contribute to the signals observed in FDG-PET infection imaging in vivo. Active bacterial FDG uptake is corroborated by the fact that the B. subtilis phosphotransferase system is needed for ¹⁸F-FDG uptake, while pts mutations protect against growth inhibition by FDG.

Management and Novel Adjuncts of Necrotizing Soft Tissue Infections

Necrotizing soft tissue infections (NSTI) have been recognized for millennia and continue to impose considerable burden on both patient and society in terms of morbidity, death, and the allocation of resources. With improvements in the delivery of critical care, outcomes have improved, although disease-specific therapies are lacking. The basic principles of early diagnosis, of prompt and broad antimicrobial therapy, and of aggressive debridement have remained unchanged. Clearly novel and new therapeutics are needed to combat this persistently lethal disease. This review emphasizes the pillars of NSTI management and then summarizes the contemporary evidence supporting the incorporation of novel adjuncts to the pharmacologic and operative foundations of managing this disease.

Genomic Characteristics Behind the Spread of Bacteremic Group A Streptococcus Type emm89 in Finland, 2004-2014

Background. Many countries worldwide have reported increasing numbers of emm89 group A Streptococcus (GAS) infections during last decade. Pathogen genetic factors linked to this increase need assessment.

Methods. We investigated epidemiological characteristics of emm89 GAS bacteremic infections, including 7-day and 30-day case-fatality rates, in Finland during 2004–2014 and linked them to whole-genome sequencing data obtained from corresponding strains. The Fisher exact test and exact logistic regression were used to compare differences between bacteremic infections due to emm89 GAS belonging to different genetic clades and subclades.

Results. Out of 1928 cases of GAS bacteremic infection, 278 were caused by emm89 GAS. We identified 2 genetically distinct clades, arbitrarily designated clade 2 and clade 3. Both clades were present during 2004–2008, but clade 3 increased rapidly from 2009 onward. Six subclades (designated subclades A–F) were identified within clade 3, based on phylogenetic core genome analysis. The case-fatality rate differed significantly between subclades (P < .05), with subclade D having the highest 30-day estimated case-fatality rate (19% vs 3%–14%).

Conclusions. A new emm89 clone, clade 3, emerged in 2009 and spread rapidly in Finland. Patients infected with certain subclades of clade 3 were significantly more likely to die. A specific polymerase chain reaction assay was developed to follow the spread of subclade D in 2015.

When should clinicians suspect group A streptococcus empyema in children? A multicentre case-control study in French tertiary care centres

BACKGROUND

The incidence of invasive group A streptococcus (GAS) infections is increasing worldwide, whereas there has been a dramatic decrease in pneumococcal invasive diseases. Few data describing GAS pleural empyema in children are available.

OBJECTIVE

To describe the clinical and microbiological features, management and outcome of GAS pleural empyema in children and compare them with those of pneumococcal empyema.

DESIGN, SETTING AND PATIENTS

Fifty children admitted for GAS pleural empyema between January 2006 and May 2013 to 8 hospitals participating in a national pneumonia survey were included in a descriptive study and matched by age and centre with 50 children with pneumococcal empyema.

RESULTS

The median age of the children with GAS pleural empyema was 2 (range 0.1-7.6) years. Eighteen children (36%) had at least one risk factor for invasive GAS infection (corticosteroid use and/or current varicella). On admission, 37 patients (74%) had signs of circulatory failure, and 31 (62%) had a rash. GAS was isolated from 49/50 pleural fluid samples and from one blood culture. The commonest GAS genotype was emm1 (n=17/22). Two children died (4%). Children with GAS empyema presented more frequently with a rash (p<0.01), signs of circulatory failure (p=0.01) and respiratory disorders (p=0.02) and with low leucocyte levels (p=0.04) than children with pneumococcal empyema. Intensive care unit admissions (p<0.01), drainage procedures (p=0.04) and short-term complications (p=0.01) were also more frequent in patients with GAS empyema.

CONCLUSIONS

Pleural empyema following varicella or presenting with rash, signs of circulatory failure and leucopenia may be due to GAS. These features should prompt the addition to treatment of an antitoxin drug, such as clindamycin.

Skin and soft-tissue infections: a critical review and the role of telavancin in their treatment

Skin and soft-tissue infections (SSTIs) are an important cause of morbidity and mortality among hospitalized patients and a major therapeutic challenge for clinicians. Although uncomplicated SSTIs are managed successfully on an outpatient basis, more serious infections extending to the subcutaneous tissue, fascia, or muscle require complex management. Early diagnosis, selection of appropriate antimicrobials, and timely surgical intervention are key to successful treatment. Surgical-site infections, an important category of SSTI, occur in approximately half a million patients in North America annually. SSTIs are also a potential source for life-threatening bacteremia and metastatic abscesses. Gram-positive organisms, such as Staphylococcus aureus and Streptococcus pyogenes, are the dominant organisms isolated early in the infectious process, whereas gram-negative organisms are found in chronic wounds. Methicillin-resistant S. aureus (MRSA) is a potential bloodstream invader that requires aggressive antimicrobial treatment and surgery. Recent concerns regarding vancomycin activity include heteroresistance in MRSA and increase in the minimum inhibitory concentrations (>1 or 2 µg/mL); however, alternative agents, such as telavancin, daptomycin, linezolid, ceftaroline, dalbavancin, oritavancin, and tedizolid, are now available for the treatment of severe MRSA infections. Here, we present a review of the epidemiology, etiology, and available treatment options for the management of SSTIs.

Epidemiology of invasive group A Streptococcus infections in Sydney, Australia

There is concern of global resurgence of invasive group A Streptococcus (iGAS) infections. We compared the clinical and molecular epidemiology of patients admitted with iGAS over two time periods, 2008 and 2010, in Western Sydney, Australia. The annual incidence was 19 cases per 100,000 admissions in 2008, compared to 33 per 100,000 in 2010. An increasing proportion of patients died (0% versus 13%), had an APACHE II score ≥30 (0% versus 19%), and had no known risk-factors (12% versus 25%). A potential skin source was identified as a trigger in fewer cases in 2010 (36% versus 11%). In total, there were 27 different emm types and 11 different emm clusters. There were some new emm types/clusters in 2010 that were not present in 2008. However, the study was not adequately powered to detect statistically significant differences in the distribution of emm types (p = 0.06) and emm clusters (p = 0.16) between the two years. There were also no clear associations between emm types/clusters and severity and clinical manifestations of iGAS infections. Although the proposed 30-valent M protein vaccine encompasses only 47% of our isolates, it will likely provide coverage for at least 71% of iGAS infections due to cross-opsonisation.

Epidemiology of Invasive Group B Streptococcal Disease in Alberta, Canada, from 2003 to 2013

Group B streptococci (GBS) cause severe invasive disease in both neonates and adults. Understanding the epidemiology of GBS provides information that can include determining disease prevalence rates in defined populations and geographic regions, documenting the success of GBS screening programs, and understanding antimicrobial susceptibility patterns. In Alberta, only neonatal invasive GBS (iGBS) disease is notifiable to health authorities. We performed a surveillance study of iGBS in Alberta, Canada, from 2003 to 2013. Over the 11-year period, the disease incidence rate increased from a low of 3.92 cases/100,000 population to a high of 5.99 cases/100,000 population. The capsular polysaccharide serotypes (CPSs) found were CPS III (20.3%), CPS V (19.1%), CPS Ia (18.9%), CPS Ib (12.7%), CPS II (11.1%), CPS IV (6.3%), and nontypeable GBS (9.4%). Rates of early-onset disease (0 to 7 days) increased from 0.15 cases/1,000 live births (in 2003) to 0.34 cases/1,000 live births (in 2013). Rates of late-onset disease (>7 to 90 days) also rose, from 0.15 cases/1,000 live births (in 2003) to 0.39 cases/1,000 live births (in 2013). Alberta also experienced an increase in CPS IV isolates, from 2 cases (in 2003) to 24 cases (in 2013), of which the majority were hvgA negative (93.4%) [corrected]. The predominant sequence type (ST) in 2013 was ST459. Erythromycin resistance rose from 23.6% to 43.9% (in 2013). Clindamycin resistance also increased, from 12.2% to 32.5%. In summary, Alberta, Canada, has experienced an increase in GBS disease; the increase includes both neonatal and adult disease. CPS IV cases also notably increased during the surveillance period, as did resistance to erythromycin and clindamycin.

Sequential necrotizing fasciitis caused by the monomicrobial pathogens Streptococcus equisimilis and extended-spectrum beta-lactamase-producing Escherichia coli

Necrotizing fasciitis is a rapidly progressing bacterial infection of the superficial fascia and subcutaneous tissue that is associated with a high mortality rate and is caused by a single species of bacteria or polymicrobial organisms. Escherichia coli is rarely isolated from patients with monomicrobial disease. Further, there are few reports of extended-spectrum beta-lactamase (ESBL)-producing E. coli associated with necrotizing fasciitis. We report here our treatment of an 85-year-old man who was admitted because of necrotizing fasciitis of his right thigh. Streptococcus equisimilis was detected as a monomicrobial pathogen, and the infection was cured by amputation of the patient's right leg and the administration of antibiotics. However, 5 days after discontinuing antibiotic therapy, he developed necrotizing fasciitis on his right upper limb and died. ESBL-producing E. coli was the only bacterial species isolated from blood and skin cultures. This case demonstrates that ESBL-producing E. coli can cause monomicrobial necrotizing fasciitis, particularly during hospitalization and that a different bacterial species can cause disease shortly after a previous episode.