Necrotizing Fasciitis: Pillaging the Acute Phase Response

Nutritional Support for Necrotizing Soft Tissue Infection Patients: From ICU to Outpatient Care

Although nutrition recommendations for patients with necrotizing soft tissue infections (NSTIs) often parallel those for patients with burn injuries, differences in the metabolic response to stress indicate that NSTIs require a unique approach. The sepsis and wound management associated with NSTIs trigger a metabolic response, driven by inflammatory and neuroendocrine changes, that leads to high circulating levels of cortisol, catecholamines, insulin, and pro-inflammatory cytokines. This metabolic response follows four phases of recovery (Early Acute; Late Acute; Persistent Inflammation, Immunosuppression, and Catabolism Syndrome; Recovery) that require a thoughtful approach to nutrition by risk screening, malnutrition assessment, and micronutrient deficiency assessment. Close monitoring of energy expenditure and protein needs is required for appropriate nutrition management. Nutrition intake after transfer from the intensive care unit and hospital discharge is often inadequate. Ongoing monitoring of nutrition intake at all outpatient follow-up appointments is necessary, regardless of the route of delivery, until the nutrition status stabilizes and any nutritional decline experienced during hospitalization has been corrected.

Imaging features of soft-tissue infections

Skin and soft tissues are among the most common sites of infections. Infections can involve the superficial epidermis to deep muscles and bones. Most infections spread through contiguous structures, although hematogenous spread can occur in the setting of an immunocompromised state and with atypical infections. While clinical diagnosis of infections is possible, it often lacks specificity, necessitating the use of imaging for confirmation. Cross-sectional imaging with US, CT, and MRI is frequently performed not just for diagnosis, but to delineate the extent of infection and to aid in management. Nonetheless, the imaging features have considerable overlap, and as such, it is essential to integrate imaging features with clinical features for managing soft tissue infections. Radiologists must be aware of the imaging features of different infections and their mimics, as well as the pros and cons of each imaging technique to properly use them for appropriate clinical situations. In this review, we summarize the most recent evidence-based features of key soft tissue infections.

Necrotizing Fasciitis Mimicking Interstitial Cystitis: An Atypical Clinical Presentation

Necrotizing fasciitis is a severe, life-threatening disease with a nonspecific clinical presentation, making it a challenging diagnosis. Early treatment with broad-spectrum antibiotics and surgical debridement is crucial to prevent rapid disease progression and poor outcomes. Given its high mortality rate and ambiguous presentation, maintaining a high index of suspicion for necrotizing fasciitis is essential. In this case, a 60-year-old woman presented to her gynecologist with urinary tract infection symptoms of frequency, hematuria, and suprapubic pain, with a year-long history of night sweats, hematuria, dysuria, and incomplete voiding. Although initially treated with outpatient antibiotics, she returned to the emergency department one day later with severe lower abdominal pain, overlying erythema, and a high fever. Abdominal imaging revealed extensive cellulitis. Upon the development of rapidly expanding erythema and crepitus, there was concern for necrotizing fasciitis. The patient received immediate treatment with broad-spectrum antibiotics and underwent urgent surgical debridement. While she showed clinical improvement in the following days, laboratory studies revealed profound hypercalcemia, anemia, and persistent leukocytosis. Additional testing ultimately led to the diagnosis of advanced bladder cancer. This case underscores the importance of prompt recognition and treatment of necrotizing fasciitis. It also highlights the influence of confirmation and availability biases, which can lead to overlooking symptoms that may indicate more serious underlying conditions. As medical professionals, it is crucial to remain vigilant and not disregard seemingly insignificant symptoms, as they could be indicative of life-threatening diagnoses.

[18F]FDG PET/CT in Necrotizing Fasciitis: A Case Series Investigating the Clinical Utility in a Challenging and Rare Condition

Necrotizing fasciitis is a deadly yet rare soft tissue and skin infection that is usually diagnosed clinically. At times, clinical signs may betray the underlying etiology and masquerade as cellulitis in the early course of the disease. We report four cases with clinical suspicion of necrotizing fasciitis, some after the failure of therapy for cellulitis who underwent 18-F fluorodeoxyglucose positron emission tomography-computed tomography (18-F FDG PET/CT) showing the extent of the disease, showing subclinical sites of involvement in patients with necrotizing fasciitis on baseline scan as well as its role in assessing response to treatment using 18-F FDG PET/CT.

Real-time identification of life-threatening necrotizing soft-tissue infections using indocyanine green fluorescence imaging

Significance

Necrotizing soft-tissue infections (NSTIs) are life-threatening infections with a cumulative case fatality rate of 21%. The initial presentation of an NSTI is non-specific, frequently leading to misdiagnosis and delays in care. No current strategies yield an accurate, real-time diagnosis of an NSTI.

Aim

A first-in-kind, observational, clinical pilot study tested the hypothesis that measurable fluorescence signal voids occur in NSTI-affected tissues following intravenous administration and imaging of perfusion-based indocyanine green (ICG) fluorescence. This hypothesis is based on the established knowledge that NSTI is associated with local microvascular thrombosis.

Approach

Adult patients presenting to the Emergency Department of a tertiary care medical center at high risk for NSTI were prospectively enrolled and imaged with a commercial fluorescence imager. Single-frame fluorescence snapshot and first-pass perfusion kinetic parameters-ingress slope (IS), time-to-peak (TTP) intensity, and maximum fluorescence intensity (IMAX)-were quantified using a dynamic contrast-enhanced fluorescence imaging technique. Clinical variables (comorbidities, blood laboratory values), fluorescence parameters, and fluorescence signal-to-background ratios (SBRs) were compared to final infection diagnosis.

Results

Fourteen patients were enrolled and imaged (six NSTI, six cellulitis, one diabetes mellitus-associated gangrene, and one osteomyelitis). Clinical variables demonstrated no statistically significant differences between NSTI and non-NSTI patient groups (p -value ≥ 0.22 ). All NSTI cases exhibited prominent fluorescence signal voids in affected tissues, including tissue features not visible to the naked eye. All cellulitis cases exhibited a hyperemic response with increased fluorescence and no distinct signal voids. Median lesion-to-background tissue SBRs based on snapshot, IS, TTP, and IMAX parameter maps ranged from 3.2 to 9.1, 2.2 to 33.8, 1.0 to 7.5, and 1.5 to 12.7, respectively, for the NSTI patient group. All fluorescence parameters except TTP demonstrated statistically significant differences between NSTI and cellulitis patient groups (p -value < 0.05 ).

Conclusions

Real-time, accurate discrimination of NSTIs compared with non-necrotizing infections may be possible with perfusion-based ICG fluorescence imaging.

Naja nigricincta nigricincta venom, a murine model. Evaluation of skeletal and cardio-myonecrosis, kidney injury and inflammatory response along with neutralisation efficacy by the SAIMR/SAVP - And EchiTAb-Plus-ICP polyvalent antivenoms

African spitting cobra, Naja nigricincta nigricincta (Zebra snake), envenomation is an important cause of snakebite morbidity and mortality in Namibia. The snake is endemic to central and northern Namibia as well as southern Angola. The venom is mainly cytotoxic, resulting in aggressive dermo-necrosis and often accompanied by severe systemic complications. No specific antivenom exists. Rhabdomyolysis, systemic inflammatory response, haemostatic abnormalities, infective necrotising fasciitis as well as acute kidney failure have been documented. Based on murine models, this study assessed SAVP/SAIMR - and EchiTAb-Plus-ICP polyvalent antivenom neutralisation as well as subdermal necrosis. Additional muscle, cardiac, kidney and lung histology, creatine kinase measurements and post-mortems were performed. An intravenous median lethal dose (LD50) of Naja nigricincta nigricincta venom was determined at 18.4 (CI: 16.3; 20.52) μg and a subdermal lethal dose at 15.3(CI: 12.96; 17.74)μg. The SAIMR/SAVP polyvalent antivenom median effective dose (ED50) was 1.2 ml antivenom/1 mg venom equating to a potency (WHO) of 1 ml antivenom neutralising 0.63 mg venom and approximately 240 ml (24 vials) needed for initial treatment. The ED50 of the EchiTAb-Plus-ICP was 1 ml antivenom/1 mg venom and a potency of 65 mg venom/ml antivenom (3.3 x LD50), estimating 230 ml (23 vials) for treatment. Histology and serology (creatine kinase) evidenced venom induced skeletal myotoxicity, which was not prevented by the antivenoms tested. Cardiac myonecrosis, an inflammatory response, direct venom kidney tubular necrosis and cardio-pulmonary failure were documented.

The microbiological profile of necrotising fasciitis at a secondary level hospital in Gauteng

Background

Necrotising fasciitis (NF) is a fulminant soft tissue infection that requires timely diagnosis, urgent surgical debridement, and appropriate antimicrobial therapy. The choice of empiric antimicrobial therapy depends on the microorganisms cultured and the antimicrobial resistance profile of the institution. Necrotising fasciitis has not been studied in our setting.

Objectives

The aim of the study was to audit the microbiological profile of NF and antimicrobial susceptibility profile.

Method

This was a retrospective study in a secondary level hospital from the period of 2014-2020. The patients' demographic data, clinical features, location of infection, comorbidities, laboratory and microbiological profiles were analysed.

Results

There were 53 patients during 2014-2020 with median age of 45.5 (38.5-56.0) years. The majority of the patients were males (35 [66.04%]), had no comorbidities (25 [47.17%]), and the lower limb was the most common anatomic site (17 [32.08%]). Type II (monomicrobial) NF was the predominant type (31 [58.49%]). Staphylococcus aureus was the most prevalent Gram-positive bacteria (18 [38%]) and Escherichia coli, the main species isolated in the Gram-negative bacteria (14 [36%]) with susceptibility to cloxacillin (94%) and amoxicillin and/or clavulanic acid (92%), respectively.

Conclusion

Staphylococcus aureus and Escherichia coli were the most common bacteria with low rate of antimicrobial resistance. Amoxicillin and/or clavulanic acid and an adjunctive clindamycin are appropriate antimicrobial therapy for empiric treatment for NF in our setting.

Contribution

Amoxicillin and/or clavulanic acid and an adjunctive clindamycin can be used as an empiric treatment for NF.

Necrotizing fasciitis: an update on epidemiology, diagnostic methods, and treatment

PURPOSE OF REVIEW

The aim of this review is to discuss the latest evidence of epidemiology, diagnostic methods, and treatment of necrotizing soft tissue infections (NSTIs) with a particular focus on necrotizing fasciitis (NF).

RECENT FINDINGS

NSTIs have been historically referred to as NF but encompass a broader range of infections, with variable rates ranging from 0.86 to 32.64 per 100 000 person-years, influenced by factors such as climate and seasonal variations. They have diverse microbiological profiles categorized into different types based on the involved pathogens, including polymicrobial or monomicrobial infections caused by organisms such as group A streptococcus (GAS), Staphylococcus aureus , some Gram-negative pathogens, and filamentous fungi following trauma and natural disasters. Diagnosis relies on clinical symptoms and signs, laboratory markers, and imaging. However, the gold standard for diagnosis remains intraoperative tissue culture. Treatment involves repeated surgical debridement of necrotic tissues in addition to intravenous antibiotics. Adjuvant therapies with intravenous immunoglobulin (IVIG) and hyperbaric oxygen therapy (HBOT) might have a role. Soft tissue reconstruction may be necessary following surgery.

SUMMARY

Prompt diagnosis and proper medical and surgical management of NSTI will improve outcomes.

Navigating the Enigma of Pediatric Musculoskeletal Infections: A Race Against Time

Musculoskeletal infection (MSKI) in children is a critical condition in pediatric orthopedics due to the potential for serious adverse outcomes, including multiorgan dysfunction syndrome, which can lead to death. The diagnosis and treatment of MSKI continue to evolve with advancements in infectious organisms, diagnostic technologies, and pharmacologic treatments. It is imperative for pediatric orthopedic surgeons and medical teams to remain up to date with the latest MSKI practices.

CRP Predicts the Need to Escalate Care After Initial Debridement for Musculoskeletal Infection

BACKGROUND

Musculoskeletal infections (MSKIs) are a major cause of morbidity in the pediatric population and account for nearly 1 in every 10 consultations with a pediatric orthopaedic provider at a tertiary care center. To prevent or deescalate the risk of adverse medical and musculoskeletal outcomes, timely medical intervention in the form of antibiotics and potential surgical debridement is required. While there have been numerous studies indicating the value of laboratory testing during the initial workup of a child with MSKI, few studies to date have examined the utility of longitudinal assessment of laboratory measures in the acute setting to monitor the efficacy of antibiotic therapy and/or surgical intervention. The purpose of this investigation was to retrospectively determine whether measuring changes in the inflammatory response could indicate the need for escalated care. Specifically, this study examined the hypothesis that serial measurements of C-reactive protein (CRP), immediately preoperatively and 2 days after surgical debridement, could predict the need for medical (change in antibiotics) or surgical (additional debridement) escalation.

METHODS

Retrospective review of pediatric patients undergoing operative debridement for the treatment of MSKI between September 2009 and December 2015 from whom laboratory data (CRP) was obtained preoperatively and at postoperative day (POD) 2. Patient demographics, the need for escalated care, and patient outcomes were evaluated.

RESULTS

Across 135 pediatric patients, preoperative CRP values >90 mg/L and a positive change in CRP at POD2 effectively predicted the need for escalation of care after initial surgical debridement (Area under the Receiver Operator Curve: 0.883). For each 10-unit increase in preoperative CRP or postoperative change in CRP, there was a 21% or 22% increased risk of needing escalated care, respectively. Stratification by preoperative CRP >90 mg/L and change in CRP postoperatively likewise correlated with increased rates of disseminated disease, percent tissue culture positivity, length of stay, and rate of adverse outcomes.

CONCLUSIONS

This study demonstrates the utility of serial CRP to assess the need for escalated care in patients being treated for MSKI. As serial CRP measurements become standard of practice in the acute setting, future prospective studies are needed to optimize the timing of CRP reassessment during inpatient hospitalization to prognosticate patient outcomes, weighing both improvements of patient care and clinical burden.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

Maintaining the balance: the critical role of plasmin activity in orthopedic surgery injury response

The musculoskeletal system plays vital roles in the body, facilitating movement, protecting vital structures, and regulating hematopoiesis and mineral metabolism. Injuries to this system are common and can cause chronic pain, loss of range of motion, and disability. The acute phase response (APR) is a complex process necessary for surviving and repairing injured musculoskeletal tissue. To conceptualize the APR, it is useful to divide it into 2 distinct phases, survival and repair. During the survival-APR, a "damage matrix" primarily composed of fibrin, via thrombin activity, is produced to contain the zone of injury. Once containment is achieved, the APR transitions to the repair phase, where reparative inflammatory cells use plasmin to systematically remove the damage matrix and replace it with new permanent matrices produced by differentiated mesenchymal stem cells. The timing of thrombin and plasmin activation during their respective APR phases is crucial for appropriate regulation of the damage matrix. This review focuses on evidence indicating that inappropriate exuberant activation of plasmin during the survival-APR can result in an overactive APR, leading to an "immunocoagulopathy" that may cause "immunothrombosis" and death. Conversely, preclinical data suggest that too little plasmin activity during the repair-APR may contribute to failed tissue repair, such as a fracture nonunion, and chronic inflammatory degenerative diseases like osteoporosis. Future clinical studies are required to affirm these findings. Therefore, the temporal-spatial functions of plasmin in response to musculoskeletal injury and its pharmacologic manipulation are intriguing new targets for improving orthopedic care.

The effect of hyperbaric oxygen therapy on the clinical outcomes of necrotizing soft tissue infections: a systematic review and meta-analysis

BACKGROUND

To determine the efficacy of hyperbaric oxygen therapy (HBO) in the treatment of necrotizing soft tissue infections (NSTI), we conducted a meta-analysis of the available evidence.

METHODS

Data sources were PubMed, Embase, Web of Science, Cochrane Library, and reference lists. The study included observational trials that compared HBO with non-HBO, or standard care. The primary outcome was the mortality rate. Secondary outcomes were the number of debridement, amputation rate and complication rate. Relative risks or standardized mean differences with 95% confidence intervals were calculated for dichotomous and continuous outcomes, respectively.

RESULTS

A total of retrospective cohort and case-control studies were included, including 49,152 patients, 1448 who received HBO and 47,704 in control. The mortality rate in the HBO group was significantly lower than that in the non-HBO group [RR = 0.522, 95% CI (0.403, 0.677), p < 0.05]. However, the number of debridements performed in the HBO group was higher than in the non-HBO group [SMD = 0.611, 95% CI (0.012, 1.211), p < 0.05]. There was no significant difference in amputation rates between the two groups [RR = 0.836, 95% CI (0.619, 1.129), p > 0.05]. In terms of complications, the incidence of MODS was lower in the HBO group than in the non-HBO group [RR = 0.205, 95% CI (0.164, 0.256), p < 0.05]. There was no significant difference in the incidence of other complications, such as sepsis, shock, myocardial infarction, pulmonary embolism, and pneumonia, between the two groups (p > 0.05).

CONCLUSION

The current evidence suggests that the use of HBO in the treatment of NSTI can significantly reduce the mortality rates and the incidence rates of complications. However, due to the retrospective nature of the studies, the evidence is weak, and further research is needed to establish its efficacy. It is also important to note that HBO is not available in all hospitals, and its use should be carefully considered based on the patient's individual circumstances. Additionally, it is still worthwhile to stress the significance of promptly evaluating surgical risks to prevent missing the optimal treatment time.

Fournier's Gangrene with Growth of Actinomyces europaeus: A Case Report

Fournier's gangrene (FG) is a rare infectious disease with rapid disease progression and a high mortality rate. We report a case of a 61-year-old female with type 2 diabetes who developed FG caused by Actinomyces europaeus. A. europaeus is associated with abscesses, decubitus ulcers, and purulent urethritis. Although A. europaeus rarely causes FG as the main causative pathogen, we should still be alert to this pathogenic microorganism. To our knowledge, this is the first case report of FG caused by A. europaeus mono-infection, and it adds to the evidence that A. europaeus has the potential to cause necrotizing fasciitis.

Measures of Admission Immunocoagulopathy as an Indicator for In-Hospital Mortality in Patients with Necrotizing Fasciitis: A Retrospective Study

Necrotizing fasciitis is a rapidly progressive infection with a high mortality rate. Pathogens evade the host containment and bactericidal mechanisms by hijacking the coagulation and inflammation signaling pathways, leading to their rapid dissemination, thrombosis, organ dysfunction, and death. This study examines the hypothesis that measures of immunocoagulopathy upon admission could aid in the identification of patients with necrotizing fasciitis at high risk for in-hospital mortality.

Methods

Demographic data, infection characteristics, and laboratory values from 389 confirmed necrotizing fasciitis cases from a single institution were analyzed. A multivariable logistic regression model was built on admission immunocoagulopathy measures (absolute neutrophil, absolute lymphocyte, and platelet counts) and patient age to predict in-hospital mortality.

Results

The overall in-hospital mortality rate was 19.8% for the 389 cases and 14.6% for the 261 cases with complete measures of immunocoagulopathy on admission. A multivariable logistic regression model indicated that platelet count was the most important predictor of mortality, followed by age and absolute neutrophil count. Greater age, higher neutrophil count, and lower platelet count led to significantly higher risk of mortality. The model discriminated well between survivors and non-survivors, with an overfitting-corrected C-index of 0.806.

Conclusions

This study determined that measures of immunocoagulopathy and patient age at admission effectively prognosticated the in-hospital mortality risk of patients with necrotizing fasciitis. Given the accessibility of neutrophil-to-lymphocyte ratio and platelet count measurements determined from a simple complete blood-cell count with differential, future prospective studies examining the utility of these measures are warranted.

Level of Evidence

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Early identification of life-threatening soft-tissue infection using dynamic fluorescence imaging: first-in-kind clinical study of first-pass kinetics

Necrotizing soft-tissue infections (NSTIs) are aggressive and deadly. Immediate surgical debridement is standard-of-care, but patients often present with non-specific symptoms, thereby delaying treatment. Because NSTIs cause microvascular thrombosis, we hypothesized that perfusion imaging using indocyanine green (ICG) would show diminished fluorescence signal in NSTI-affected tissues, particularly compared to non-necrotizing, superficial infections. Through a first-in-kind clinical study, we performed first-pass ICG fluorescence perfusion imaging of patients with suspected NSTIs. Early results support our hypothesis that ICG signal voids occur in NSTI-affected tissues and that dynamic contrast-enhanced fluorescence parameters reveal tissue kinetics that may be related to disease progression and extent.

Outcome of necrotizing fasciitis and Fournier's gangrene with and without hyperbaric oxygen therapy: a retrospective analysis over 10 years

BACKGROUND

Necrotizing soft tissue infections (NSTI) require immediate radical debridement, broad-spectrum antibiotics and intensive care. Hyperbaric oxygen therapy (HBOT) may be performed adjunctively, but unequivocal evidence for its benefits is still lacking.

METHODS

We performed a retrospective single-center study including 192 patients with necrotizing fasciitis or Fournier's gangrene to assess in-hospital mortality and outcome dependent on patient, disease and treatment characteristics with or without HBOT.

RESULTS

The in-hospital mortality rate was 27.6%. Factors associated with increased mortality according to multivariate analysis were higher age, affection of multiple or problem localizations (odds ratio (OR) = 2.88, P = 0.003), ineligibility for HBOT despite clinical indication (OR = 8.59, P = 0.005), pathogens in blood cultures (OR = 3.36, P = 0.002), complications (OR = 10.35, P < 0.001) and sepsis/organ dysfunction (OR = 19.58, P < 0.001). Factors associated with better survival included vacuum-assisted wound closure (OR = 0.17, P < 0.001), larger number of debridements (OR = 0.83, P < 0.001) and defect closure with mesh graft (OR = 0.06, P < 0.001) or flap (OR = 0.09, P = 0.024). When participants were stratified into subgroups without requirement of HBOT (n = 98), treated with HBOT (n = 83) and ineligible for HBOT due to contraindications (n = 11), the first two groups had similar survival rates (75.5% vs. 73.5%) and comparable outcome, although patients with HBOT suffered from more severe NSTI, reflected by more frequent affection of multiple localizations (P < 0.001), sepsis at admission (P < 0.001) and intensive care treatment (P < 0.001), more debridements (P < 0.001) and a larger number of antibiotics (P = 0.001). In the subgroup ineligible for HBOT, survival was significantly worse (36.4%, P = 0.022).

CONCLUSION

These results point to a benefit from HBOT for treatment of NSTI in critically ill patients.

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.

Case Report: Therapeutic Strategy With Delayed Debridement for Culture-Negative Invasive Group A Streptococcal Infections Diagnosed by Metagenomic Next-Generation Sequencing

Streptococcal toxic shock syndrome (STSS) caused by group A streptococcus is a rare condition that rapidly developed to multiple organ failure even death. Therefore, prompt diagnosis, initiate appropriate antibiotics and other supportive treatments are critical. Here we reported a case of STSS caused by group A streptococcus infection. A healthy 39-year-old man presented a sudden pain in the left lower extremity, followed by a high fever (40.0 °C) with dizziness, nausea, and shortness of breath. Twenty-four hours before the visit, the patient showed anuria. The patient was then admitted to the intensive care unit. Blood examination revealed elevated levels of inflammatory markers and creatinine. He suffered from septic shock, dysfunction of coagulation, acute kidney dysfunction, acute respiratory distress syndrome, and acute liver function injury. The diagnosis was obtained through clinical manifestation and metagenomic next-generation sequencing (mNGS) drawn from the pustule and deep soft tissue (lower limb) samples while all bacterial cultures came back negative. The pustule mNGS report detected a total of 132 unique group A streptococcus sequence reads, representing 96.3% of microbial reads while the soft tissue mNGS report identified a total of 142474 unique group A streptococcus sequence reads, representing 100% of microbial reads. The patient was treated with aggressive fluid resuscitation, antibiotics comprising piperacillin/tazobactam and clindamycin, respiratory support, following the delayed surgical debridement. Intravenous immunoglobulin was also used for 5 days. On the 14th day after admission, he was transferred to the general ward for follow-up treatment. Our case highlighted, for the first time, the key role of mNGS in the early diagnosis of culture-negative invasive group A streptococcal infection. The case also suggested that clindamycin combined with beta-lactam antibiotics and adjunction of intravenous immunoglobulin therapy with delayed debridement performed well in the management of unstable STSS patients.

Ultrasonography and X-ray micro-computed tomography characterization of the effects caused by carrageenin in the muscle of gilthead seabream (Sparus aurata)

The current work aimed to carry out an in vivo study of the λ-carrageenin-induced inflammation in the skin of gilthead seabream (Sparus aurata). The fish were injected intramuscularly with phosphate-buffered saline (PBS, as control) or λ-carrageenin (1% in PBS), and the injection zone was evaluated by real-time ultrasonography (Vevo Lab, VisualSonics) at 1.5, 3, 6, 12, and 24 h post-injection (p.i.). Results demonstrated that the skin thickness was increased in fish injected with λ-carrageenin and sampled at 1.5, 3, and 6 h p.i. However, the skin thickness of the injected area decreased to the normal values in those fish sampled at 12 and 24 h p.i. In addition, fish injected with λ-carrageenin and analysed at 1.5, 3, and 6 h p.i. showed, in the underlying muscle at the injection place, several hyperechoic small foci surrounded by an anechoic area which were not observed in control fish. Furthermore, the fish were analysed by X-ray micro-computed tomography (micro-CT). The analysis of the micro-CT acquisitions revealed also a dark area in the place of the injection with λ-carrageenin at 1.5, 3, and 6 h. These areas were smaller in fish analysed at longer times (12 h p.i.) and were almost disappeared in fish sampled at 24 h p.i. These areas had an average density of -850 to -115 HU, which did not correspond with any tissue density of the rest of the body. Furthermore, similar dark areas at the injection zones were never observed in control fish. Present results support the use of both non-invasive techniques to study the inflammatory process in fish of commercial interest such as gilthead seabream.