Risk Factors for Predicting Mortality and Amputation of Patients with Necrotizing Soft-Tissue Infections: Retrospective Analysis of 111 Cases from a Single Medical Center

Objective

Necrotizing soft-tissue infections (NSTIs) are rare clinical infections with surgical emergencies having a high mortality rate. This study aimed to investigate risk factors for mortality and amputation of patients with NSTI.

Methods

We retrospectively analyzed critical factors for outcomes of 111 patients with NSTI hospitalized in our department from 1 January 1999 to 31 December 2018. NSTI diagnosis was based on the patient's clinical characteristics, laboratory risk indicator for necrotizing fasciitis (LRINEC) score, laboratory test data, and microbiological findings in blood and wound culture. The risk factors for mortality and amputation of NSTI were determined using univariate or multivariate logistic regression analysis, receiver operating characteristics (ROC), and the area under the ROC curve (AUC) at 90 days after admission.

Results

Diagnosis of 111 patients with NSTI was confirmed according to clinical features, LRINEC score, image data, laboratory findings, and microorganism culture in blood and wounds. The mortality rate was 9.91% (11/111) at day 90 follow-up. High white blood cell (WBC), low hematocrit (HCT), and multiple surgeries were identified to be critical risk factors for NSTI mortality in univariate and multivariate logistic analyses. AUCs, 95% confidence intervals (CI), and P values of risk factors were 0.699, 0.54-0.95, and P = 0.0117 for high WBC; 0.788, 0.63-0.97, and P = 0.0006 for low HCT; and 0.745, 0.59-0.90, and P = 0.0018 for multiple surgeries, respectively. These patients also had high LRINEC scores. Amputation occurred in 34.23% (38/111) of patients. Risk factors for amputation were higher age, low hemoglobin (Hb), and multiple wounds. AUCs, 95% confidence intervals (CI), and P values were 0.713, 0.11-0.32, and P < 0.0001 for higher age; 0.798, 0.08-0.29, and P=0.0007 for low Hb; and 0.757, 0.17-0.34, and P  < 0.0001 for multiple lesion sites, respectively.

Conclusions

High LRINEC scores, high WBC, low HCT, and multiple surgeries were relevant to increased mortality. Higher age, low Hb, and multiple wounds were associated with amputation risk. These clinical features must be paid attention to when patients are diagnosed with NSTI.

Necrotizing Soft-Tissue Infections After Hip Arthroplasty

Necrotizing soft-tissue infections are a rare complication following hip arthroplasty procedures. These rapidly spreading infections have a high mortality rate and must be diagnosed and treated in an expeditious manner. This article discusses the epidemiology, classification, diagnosis, and treatment of these conditions and describes 2 related case reports.

Evaluation of the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score for detecting necrotizing soft tissue infections in patients with diabetes and lower extremity infection

AIMS

The aim of this pilot study was to assess the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC), a scoring system for Necrotizing Soft Tissue Infections, to diagnose Necrotizing Soft Tissue Infections of the lower extremity in patients with diabetes.

METHODS

Sixty-nine patients with lower extremity infections were prospectively enrolled. The Laboratory Risk Indicator for Necrotizing Fasciitis was calculated and logistic regression was performed for each laboratory value.

RESULTS

The Laboratory Risk Indicator for Necrotizing Fasciitis was associated with Necrotizing Soft Tissue Infection diagnosis in patients with diabetes (p = 0.01). Sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 69%, 16.6%, and 100% respectively. Elevated C-reactive protein (OR 1.01, p = 0.02, 95% CI [1.002-1.23]) and white blood cell count (OR 1.34, p < 0.01, 95% CI [1.1-1.7]) were associated with Necrotizing Soft Tissue Infection.

CONCLUSIONS

The Laboratory Risk Indicator for Necrotizing Fasciitis was useful as a negative predictor of Necrotizing Soft Tissue Infection while C- reactive protein and white blood cell count may have value as individual predictors. We recommend high clinical suspicion of Necrotizing Soft Tissue Infections in diabetics as laboratory evaluation may be non-specific.

The role of point-of-care ultrasound in the diagnosis and management of necrotizing soft tissue infections

BACKGROUND

Necrotizing soft tissue infections are associated with high morbidity and mortality, even when the correct treatment is initiated. The diagnosis of these conditions is hard and the most sensitive methods are time-consuming, expensive and not readily available. Point-of-care ultrasound can complement clinical evaluation to increase the diagnostic accuracy.

CASE PRESENTATION

We bring a case of a woman, without comorbidities, who presented to the emergency department with signs of soft tissue infection. Bedside ultrasound showed subcutaneous tissue thickening, with fluid accumulation, and subcutaneous gas in the affected area. Based on the clinical suspicion and the ultrasound findings, the patient underwent prompt medical treatment and surgical debridement.

CONCLUSIONS

This case shows the utility of bedside ultrasound for the decision-making process in a disease where an early diagnosis is important. This information should always be used together with the clinical judgement, as it has a relative low sensitivity.

Necrotizing Soft Tissue Infection: Diagnostic Accuracy of Physical Examination, Imaging, and LRINEC Score: A Systematic Review and Meta-Analysis

OBJECTIVE

We sought to summarize accuracy of physical examination, imaging, and Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score in diagnosis of necrotizing soft tissue infection (NSTI) in adults with a soft tissue infection clinically concerning for NSTI.

SUMMARY OF BACKGROUND DATA

NSTI is a life-threatening diagnosis. Delay to diagnosis and surgical management is associated with increased mortality.

METHODS

We searched 6 databases from inception through November 2017. We included English-language studies reporting diagnostic accuracy of testing or LRINEC Score. Outcome was NSTI confirmed by surgery or histopathology. Two reviewers screened all citations and extracted data independently. Summary measures were obtained from the Hierarchical Summary Receiver Operating Characteristic model.

RESULTS

From 2,290 citations, we included 23 studies (n = 5982). Of physical examination signs, pooled sensitivity and specificity for fever was 46.0% and 77.0% respectively, for hemorrhagic bullae 25.2% and 95.8%, and for hypotension 21.0% and 97.7%. Computed tomography (CT) had sensitivity of 88.5% and specificity of 93.3%, while plain radiography had sensitivity of 48.9% and specificity of 94.0%. Finally, LRINEC ≥ 6 had sensitivity of 68.2% and specificity of 84.8%, while LRINEC ≥ 8 had sensitivity of 40.8% and specificity of 94.9%.

CONCLUSIONS

Absence of any 1 physical examination feature (eg, fever or hypotension) is not sufficient to rule-out NSTI. CT is superior to plain radiography. LRINEC had poor sensitivity, and should not be used to rule-out NSTI. Given the poor sensitivity of these tests, a high clinical suspicion warrants early surgical consultation for definitive diagnosis and management.

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.

Prognostic factors in necrotizing soft-tissue infections (NSTI): A cohort study

BACKGROUND

Necrotizing soft-tissue infection (NSTI) is uncommon but life-threatening. A recent meta-analysis estimated the overall mortality at 23.5%.

OBJECTIVE

We sought to identify risk factors associated with mortality in a cohort of patients with NSTI in a tertiary care center.

METHODS

We identified 512 patients with NSTI between 1996 and 2012 in the national hospital database Program for Medicalization of Information Systems and examined risk factors of mortality with NSTI by univariate and multivariate analysis.

RESULTS

We included 109 patients with a confirmed diagnosis of NSTI; 31 (28%) died at a median follow-up of 274 days (range 2-6135 days). On multivariate analysis, independent risk factors of mortality were age older than 75 years (hazard ratio [HR] 4.4, 95% confidence interval [CI] 1.8-10.3), multifocal NSTI (HR 5.9, 95% CI 1.9-18.5), severe peripheral vascular disease (HR 5.1, 95% CI 1.5-17.0), hospital-acquired infection (HR 3.9, 95% CI 1.4-10.7), severe sepsis (HR 7.4, 95% CI 1.7-33.1), and septic shock on hospital admission (HR 13.9, 95% CI 3.8-50.4).

LIMITATIONS

This was a retrospective cohort, which disallows a precise record of the delay between diagnosis and surgery.

CONCLUSION

Our findings for this robust cohort of patients with a definite diagnosis of NSTI could help clinicians stratify NSTI severity at clinical course onset.

The role of contrast enhanced computed tomography in the diagnosis of necrotizing fasciitis and comparison with the laboratory risk indicator for necrotizing fasciitis (LRINEC)

PURPOSE

To evaluate the diagnostic efficacy of contrast enhanced computed tomography (CECT) in emergency departments for diagnosis of necrotizing fasciitis (NF) and for differential diagnosis of other musculoskeletal infections; to correlate radiological findings with the laboratory risk indicator for necrotizing fasciitis (LRINEC).

MATERIALS AND METHODS

7 radiological parameters to be analysed on CECT scans were established, exams of 36 patients with proven diagnosis of NF (n 12) and other musculoskeletal infections (n 24) were retrospectively reviewed; LRINEC score was calculated. Fisher's test and Spearman's and Kendall's coefficients of rank correlations were performed.

RESULTS

Two parameters were found to be strongly associated with the diagnosis of NF: involvement of the fascia (Spearman's ρ of 0.888, p < 0.001) and lack of fascial enhancement (Spearman's ρ of 0.672, p < 0.001). LRINEC score did not show strong association with the presence of fasciitis NF (Spearman's ρ of 0.490, p = 0.0024).

CONCLUSION

Computed tomography (CT) parameters, which are significantly associated with the diagnosis of NF, are the involvement of the fascia and its lack of enhancement; LRINEC score could be high (>5) also in other musculoskeletal infections. Final diagnosis of necrosis among the fascia is surgical. Presence of gas is not a specific sign of necrotizing fasciitis being present in other musculoskeletal infections. CT could easily discriminate NF from other musculoskeletal infections, adds an important value to clinical and laboratory tests in diagnosis of NF in an emergency context when magnetic resonance imaging, which is superior to CT in this discernment, could not be performed.

Continuous renal replacement therapy as a supportive treatment for acute pediatric necrotizing fasciitis

Acute necrotizing fasciitis (NF) in children is a dangerous illness characterized by progressive necrosis of the skin and subcutaneous tissue. The present study summarizes our recent experience with the treatment of pediatric patients with severe NF. Between 2000 and 2009, eight children suffering from NF were admitted to our department. Four of the children received an active treatment strategy including continuous renal replacement therapy (CRRT), radical debridement, and broad-spectrum antibiotics. Another four children presented at a late stage of illness, and did not complete treatment. Clinical data for these two patient groups were retrospectively analyzed. The four patients that completed CRRT, radical debridement, and a course of broad-spectrum antibiotics were cured without any significant residual morbidity. The other four infants died shortly after admission. Early diagnosis, timely debridement, and aggressive use of broad-spectrum antibiotics are key factors for achieving a satisfactory outcome for cases of acute NF. Early intervention with CRRT to prevent septic shock may also improve patient outcome.

Similar superantigen gene profiles and superantigen activity in norwegian isolates of invasive and non-invasive group a streptococci

Group A streptococcus (GAS) harbours several virulence factors, including M protein (coded by the emm gene) and superantigens (SAgs). SAgs are extracellular toxins that directly activate the immune system by cross-binding to the HLA class II molecule and T cell receptor (TCR), thereby causing activation of up to 30% of the T cells and subsequent massive secretion of cytokines. Forty-eight GAS strains isolated from patients at Norwegian hospitals between 1988 and 2004 were included in this study. Of these, 24 were invasive streptococcal toxic shock syndrome (STSS) or necrotizing fasciitis (NF) isolates and 24 were non-invasive pharyngitis isolates, matched for having the same T-type and year of isolation as the invasive isolates. The isolates were characterized by emm sequence typing, multilocus sequence typing (MLST) and SAg gene profiles. A correlation between T-type, emm type, sequence type and SAg gene profile was revealed. No difference between invasive and non-invasive isolates regarding serotype or genotype was demonstrated. Selected invasive and non-invasive isolates with identical SAg gene profiles were analysed for SAg activity in bacterial growth culture media with and without human cell culture media added. A human T cell proliferation assay was used as measurement for SAg activity and simultaneously we also measured the cytokine content in normal human peripheral blood leucocyte cell culture media. The results revealed that invasive and non-invasive isolates did not differ significantly in SAg activity as it is present in semipurified bacterial culture medium.

Necrotizing fasciitis: review of 82 cases in South Auckland

BACKGROUND

Early recognition of necrotizing fasciitis (NF) can be difficult, but is important as infections progress rapidly and have significant mortality. The aim of this study of patients with NF was to determine the clinical characteristics at presentation, causative pathogens and subsequent clinical outcome.

METHODS

We retrospectively reviewed consecutive patients with NF presenting to Middlemore Hospital from January 2000 to June 2006.

RESULTS

Eighty-two patients were evaluated: 56% male, mean age 54.9 years (standard deviation 18.5), 40% Pacific Islanders. The site of infection was the lower limb in 46 (56%) patients, upper limb in 12 (15%) patients and perineum in 13 (16%) patients. Twenty-two (27%) patients were taking non-steroidal anti-inflammatory drugs, 29 (35%) had diabetes mellitus, 25 (30%) had gout and 17 (21%) had congestive heart failure. Forty-nine (60%) patients had a surgical procedure within 24 h of admission. Streptococcus pyogenes was isolated from tissue or blood cultures in 33 (40%) patients and 26 (32%) patients had polymicrobial infection. Twenty-five (30%) patients died, 17 (68%) within 72 h of admission. Independent predictors of mortality include congestive heart failure (P = 0.033) and a history of gout (P = 0.037).

CONCLUSION

NF remains an important disease in our community with significant morbidity and mortality. Pacific Islanders were disproportionately represented. Early diagnosis of NF can be difficult and requires a high index of suspicion in all patients presenting with cellulitis or unexplained sepsis. Congestive heart failure and gout are independent predictors of mortality and patients with these conditions and sepsis need early assessment with more aggressive hospital triaging.

Postirradiation Klebsiella pneumoniae-associated necrotizing fasciitis in the western hemisphere: a rare but life-threatening clinical entity

Necrotizing fasciitis (NF) caused by Klebsiella spp. is a unique entity, particularly, in Asia, where virulent strains of Klebsiella predominate. It is now clear that Klebsiella spp. are capable of causing NF either isolated or in the context of disseminated disease. We present a unique case of NF caused by Klebsiella pneumoniae in the Western hemisphere after radiotherapy in a hospitalized patient with significant comorbidities. Physicians should be aware of nosocomially acquired K. pneumoniae fasciitis after radiotherapy in the setting of chronic comorbidities, such as diabetes and malignancy. Early diagnosis, surgical intervention, and appropriate empirical antibiotics are essential for a favorable outcome in such rare but life-threatening cases of NF.

Skin and soft tissue infections

Skin and soft tissue infections are a common cause of hospitalization and use of antibiotic therapy, and may result in significant disability. Infections managed by surgeons may vary from simple, noncomplicated cellulitis to severe necrotizing soft tissue infections. The differentiation of necrotizing infections from nonnecrotizing infections is critical to achieving adequate surgical therapy. An understanding of the changing epidemiology of all complicated skin and soft tissue infections is required for selection of appropriate empiric antibiotic therapy.

Late diagnosed necrotizing fasciitis as a cause of multiorgan dysfunction syndrome: A case report

Necrotizing fasciitis is a rapidly progressive, life-threatening soft tissue bacterial infection. We present a serious case of a 43-year-old male who suffered from necrotizing fasciitis of the left leg in whom a delayed diagnosis caused multiorgan dysfunction.

Early recognition of important symptoms is essential in the management and surgical debridement of necrotizing fasciitis. Treatment should include comprehensive supportive measures (early goal-directed therapy, adequate ventilation strategy, activated protein C dosage, tight glucose control, steroids, renal replacement therapy) and early antibiotic therapy based on microbiologic monitoring. The pathophysiology and etiologic factors of necrotizing fasciitis are discussed.