Independent predictors of mortality for necrotizing fasciitis: a retrospective analysis in a single institution

The laboratory risk indicator for necrotizing fasciitis (LRINEC) scoring: the diagnostic and potential prognostic role

BACKGROUND

Necrotizing fasciitis (NF) is a devastating soft tissue infection associated with potentially poor outcomes. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score has been introduced as a diagnostic tool for NF. We aimed to evaluate the prognostic value of LRINEC scoring in NF patients.

METHODS

A retrospective analysis was conducted for patients who were admitted with NF between 2000 and 2013. Based on LRINEC points, patients were classified into (Group 1: LRINEC < 6 and Group 2: LRINEC ≥ 6). The 2 groups were analyzed and compared. Primary outcomes were hospital length of stay, septic shock and hospital death.

RESULTS

A total of 294 NF cases were identified with a mean age 50.9 ± 15 years. When compared to Group1, patients in Group 2 were 5 years older (p = 0.009), more likely to have diabetes mellitus (61 vs 41%, p < 0.001), Pseudomonas aeruginosa infection (p = 0.004), greater Sequential Organ Failure Assessment (SOFA) score (11.5 ± 3 vs 8 ± 2, p = 0.001), and prolonged intensive care (median 7 vs 5 days) and hospital length of stay (22 vs 11 days, p = 0.001). Septic shock (37 vs. 15%, p = 0.001) and mortality (28.8 vs. 15.0%, p = 0.005) were also significantly higher in Group 2 patients. Using Receiver operating curve, cutoff LRINEC point for mortality was 8.5 with area under the curve of 0.64. Pearson correlation analysis showed a significant correlation between LRINEC and SOFA scorings (r = 0.51, p < 0.002).

DISCUSSION

Early diagnosis, simplified risk stratification and on-time management are vital to achieve better outcomes in patients with NF.

CONCLUSIONS

Beside its diagnostic role, LRINEC scoring could predict worse hospital outcomes in patients with NF and simply identify the high-risk patients. However, further prospective studies are needed to support this finding.

Necrotizing Fasciitis: How Reliable are the Cutaneous Signs?

Necrotizing fasciitis (NF) is a surgical emergency. It is often aggressive and characterized by the rapidly progressive inflammatory infection of the fascia that causes extensive necrosis of the subcutaneous tissue and fascia, relatively sparing the muscle and skin tissue. As the disease progresses, thrombosis of the affected cutaneous perforators subsequently devascularizes the overlying skin. The course indeed can be a fulminant one. The diagnosis of NF, especially in the early stages, is extremely challenging, and it can be very close in presentation to other skin and subcutaneous tissue infections. The primary site of the pathology is the deep fascia. Necrosis of the tissues and fascia may manifest as erythema without sharp margins, swelling, warmth, shiny, and exquisitely tender areas. Pain out of proportion to physical examination findings may be observed. The subcutaneous tissue may be firm and indurated such that the underlying muscle groups cannot be distinctly palpated. Eventually, as the overlying skin is stripped of its blood supply, skin necrosis ensues and hemorrhagic bullae form. Bacteremia and sepsis invariably develop when the infection is well established. This paper discusses some of issues related to the cutaneous signs found in NF and also provides a review the current, available literature on the subject matter.

A comparison of necrotising fasciitis in diabetics and non-diabetics

Aims

Diabetes mellitus is the most common co-morbidity associated with necrotising fasciitis. This study aims to compare the clinical presentation, investigations, Laboratory Risk Indicator for Necrotising Fasciitis (LRINEC) score, microbiology and outcome of management of this condition in diabetic and non-diabetic patients.

Patients and Methods

The medical records of all patients with surgically proven necrotising fasciitis treated at our institution between 2005 and 2014 were reviewed. Diagnosis of necrotising fasciitis was made on findings of ‘dishwater’ fluid, presence of greyish necrotic deep fascia and lack of bleeding on muscle dissection found intra-operatively. Information on patients’ demographics, presenting symptoms, clinical signs, investigations, treatment and outcome were recorded and analysed.

Results

A total of 127 patients with surgically proven necrotising fasciitis were included in this study. In all, 78 (61.4%) were diabetic and 49 (38.6%) were non-diabetic. Diabetics tended to have polymicrobial infections (p = 0.03), renal impairment (p < 0.001), end-stage renal disease (p = 0.001) and multiple co-morbidities (p < 0.001). They presented atypically, with less tenderness (p = 0.042) and less hypotension (p = 0.034). This resulted in higher rates of misdiagnosis (p = 0.038) and a longer time to surgery (p = 0.05) leading to longer hospital stays (p = 0.043) and higher rates of amputation (p = 0.045). However, the rate of mortality is comparable (p = 0.525). A LRINEC score of > 8 appears to be more sensitive in diabetic patients (p < 0.001). However, the increased sensitivity in diabetic patients may be related to hyperglycemia and electrolyte abnormalities associated with renal impairment in these patients.

Conclusion

The LRINEC score must be used with caution in diagnosing necrotising fasciitis in diabetic patients. A high index of suspicion is key to the early diagnosis and subsequent management of these patients. Cite this article: Bone Joint J 2016;98-B:1563–8.

Synchronous multifocal necrotizing fasciitis prognostic factors: a retrospective case series study in a single center

Purpose

No reports have been published on synchronous multifocal necrotizing fasciitis (SMNF), a multifocal presence of necrotizing fasciitis in different extremities. We evaluated the clinical characteristics and outcomes of SMNF.

Methods

Eighteen patients (14 men, 4 women; mean age: 59 years) diagnosed with SMNF of the extremities between January 2004 to December 2012 were enrolled and evaluated.

Results

Vibrio species were the most commonly (78%; n = 14) isolated; others were two cases (11%) of Aeromonas spp., one case (6%) of group A β-hemolytic streptococcus, and one case of coagulase-negative staphylococcus. SMNF was in the bilateral lower limbs (72%; n = 13), bilateral upper limbs (17%; n = 3), and one patient with one upper and one lower limb (11%). Non-surviving patients had more bilateral lower limb involvement and thrombocytopenia.

Conclusions

Most patients with SMNF were male and had bilateral lower limb and marine Gram-negative bacteria involvement. The mortality of SMNF remained extremely high in patients with involvement of bilateral lower limb and initial thrombocytopenia.

Thoracoabdominal necrotising soft tissue infection secondary to enterocutaneous fistulae: a case report

OBJECTIVE

Necrotising soft tissue infection is a rare surgical emergency, which requires immediate and aggressive surgical debridement. Following control of the infection, patients are often left with large defects, with wound reconstruction and closure creating significant challenges. Here we describe a case of extensive thoracoabdominal necrotising soft tissue infection and provide a discussion on the standard of care and treatment based on a current literature review.

METHOD

A 53-year-old female presented with bilious and feculent discharge from her surgical incision two weeks after a total abdominal hysterectomy. She was found to have two enterocutaneous fistulae and an extensive abdominal wall necrotising soft tissue infection extending to the lower thorax. Wide excision and debridement were performed, leaving a large triangular defect. Following serial washouts and debridements, a biologic mesh with openings for the enterocutaneous fistulae was used to cover the fascial defect Results: Postoperatively, the patient was discharged to a nursing facility where she remained on total parenteral nutrition due to high fistula output. She subsequently underwent fistulectomy nine months later followed by skin grafting. To date, she has not had any recurrent fistulae or infection.

CONCLUSION

Necrotising soft tissue infection resulting in a large abdominal wall defect secondary to enterocutaneous fistulae poses a significant challenge for source control and abdominal wall reconstruction. After serial debridements, use of biologic mesh for temporary closure followed by staged resection of the bowel with abdominal wall reconstruction can be performed.

DECLARATION OF INTEREST

The authors have no personal financial or institutional interest in any of the drugs, materials, or devices used.

Pattern and predictors of mortality in necrotizing fasciitis patients in a single tertiary hospital

Background

Necrotizing fasciitis (NF) is a fatal aggressive infectious disease. We aimed to assess the major contributing factors of mortality in NF patients.

Methods

A retrospective study was conducted at a single surgical intensive care unit between 2000 and 2013. Patients were categorized into 2 groups based on their in-hospital outcome (survivors versus non-survivors).

Results

During a14-year period, 331 NF patients were admitted with a mean age of 50.8 ± 15.4 years and 74 % of them were males Non-survivors (26 %) were 14.5 years older (p = 0.001) and had lower frequency of pain (p = 0.01) and fever (p = 0.001) than survivors (74 %) at hospital presentation. Diabetes mellitus, hypertension, and coronary artery disease were more prevalent among non-survivors (p = 0.001). The 2 groups were comparable for the site of infection; except for sacral region that was more involved in non-survivors (p = 0.005). On admission, non-survivors had lower hemoglobin levels (p = 0.001), platelet count (p = 0.02), blood glucose levels (p = 0.07) and had higher serum creatinine (p = 0.001). Non-survivors had greater median LRINEC (Laboratory Risk Indicator for NECrotizing fasciitis score) and Sequential Organ Failure Assessment (SOFA) scores (p = 0.001). Polybacterial and monobacterial gram negative infections were more evident in non-survivors group. Monobacterial pseudomonas (p = 0.01) and proteus infections (p = 0.005) were reported more among non-survivors. The overall mortality was 26 % and the major causes of death were bacteremia, septic shock and multiorgan failure. Multivariate analysis showed that age and SOFA score were independent predictors of mortality in the entire study population.

Conclusion

The mortality rate is quite high as one quarter of NF patients died during hospitalization. The present study highlights the clinical and laboratory characteristics and predictors of mortality in NF patients.

Cirrhosis-related musculoskeletal disease: radiological review

Musculoskeletal problems in patients with liver disease are common; however, they are not so well described in the literature. Therefore, there is a need to collate information on these disorders, as their incidence is on a constant rise and some of these pathologies can severely debilitate the patient's quality of life. These disorders are parietal wall varices with or without bleeding, spontaneous intramuscular haematoma (e.g. rectus sheath), abdominal wall hernia, anasarca, hepatic osteodystrophy, septic arthritis, osteomyelitis, necrotizing fasciitis, osseous metastases from hepatocellular carcinoma etc. While portal hypertension plays a key role in disorders, in others, dysregulation of the coagulation system or a compromised immune system are responsible. Imaging plays an essential role in the assessment of these complications and awareness of these musculoskeletal manifestations is vital for establishing a timely diagnosis and planning of appropriate therapy, as these disorders can significantly impact the morbidity and mortality and also influence candidacy for liver transplantation. We herein comprehensively appraise various musculoskeletal complications associated with chronic liver disease/liver cirrhosis especially from an imaging perspective which, to the best of our knowledge, have not been collectively described in English literature.

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.

Review of 58 patients with necrotizing fasciitis in the Netherlands

Background

Necrotizing fasciitis is a rare, life threatening soft tissue infection, primarily involving the fascia and subcutaneous tissue. In a large cohort of patients presenting with Necrotizing fasciitis in the Netherlands we analysed all available data to determine the causative pathogens and describe clinical management and outcome.

Methods

We conducted a retrospective, multicentre cohort study of patients with a necrotizing fasciitis between January 2003 and December 2013 in an university medical hospital and three teaching hospitals in the Netherlands. We only included patients who stayed at the Intensive Care Unit for at least one day.

Results

Fifty-eight patients were included. The mortality rate among those patients was 29.3 %. The central part of the body was affected in 28 patients (48.3 %) and in 21 patients (36.2 %) one of the extremities. Most common comorbidity was cardio vascular diseases in 39.7 %. Thirty-nine patients (67.2 %) were operated within 24 h after presentation. We found a type 1 necrotizing fasciitis in 35 patients (60.3 %) and a type 2 in 23 patients (39.7 %).

Conclusions

Our study, which is the largest study in Europe, reaffirmed that Necrotizing fasciitis is a life threatening disease with a high mortality. Early diagnosis and adequate treatment are necessary to improve the clinical outcome. Clinical awareness off necrotizing fasciitis remains pivotal.

Necrotizing fasciitis in patients with diabetes mellitus: clinical characteristics and risk factors for mortality

Background

Necrotizing fasciitis (NF) is a rapidly progressive and life-threatening infection. This study aimed to investigate the clinical characteristics and mortality- associated factors in diabetic patients.

Methods

Detailed clinical information of 165 NF cases was retrospectively collected and analyzed in National Taiwan University Hospital between January 1997 and February 2013. We documented and compared the clinical features according to the presence of underlying diabetes mellitus, and we identified risk factors associated with mortality.

Results

There were 84 patients (51 %) with diabetes. The overall case fatality rate was 29.7 %, and we found no significant difference between the patients with or without diabetes. Compared with the nondiabetic patients, diabetic patients were older and exhibited higher serum levels of glucose and potassium on admission. Polymicrobial infection and monomicrobial NF caused by Klebsiella pneumoniae were also more frequently associated with diabetic patients. Moreover, diabetic NF patients exhibit a significantly higher chance of limb loss during hospitalization. In the combined diabetic and nondiabetic cohort, a high serum level of potassium (odds ratio, 2.2; 95 % confidence interval, 1.2 to 4.02; P = 0.011) on admission was independently associated with mortality, whereas positive blood culture on admission was associated with mortality in the diabetic cohort (odds ratio, 7.36; 95 % confidence interval, 1.66 to 32.54; P = 0.009).

Conclusions

Diabetic patients are more susceptible to NF caused by polymicrobial infection or K. pneumoniae, and they are more likely to receive limb amputation for infection control. Bacteraemia on admission is a significant risk factor for mortality in diabetic NF patients.

Necrotizing Fasciitis and The Diabetic Foot

Necrotizing fasciitis (NF) represents a rapidly progressive, life-threatening infection involving skin, soft tissue, and deep fascia. An early diagnosis is crucial to treat NF effectively. The disease is generally due to an external trauma that occurs in predisposed patients: the most important risk factor is represented by diabetes mellitus. NF is classified into 3 different subtypes according to bacterial strains responsible: type 1 associated to polymicrobial infection, type 2 NF, generally associated to Streptococcus species, often associated to Staphylococcus aureus and, eventually, Type 3, due to Gram-negative strains, such as Clostridium difficile or Vibrio. NF is usually characterized by the presence of the classic triad of symptoms: local pain, swelling, and erythema. In daily clinical practice immune-compromised or neuropathic diabetic patients present with atypical symptomatology. This explains the high percentage of misdiagnosed cases in the emergency department and, consequently, the worse outcome presented by these patients. Prompt aggressive surgical debridement and antibiotic systemic therapy are the cornerstone of its treatment. These must be associated with an accurate systemic management, consisting in nutritional support, glycemic compensation, and hemodynamic stabilization. Innovative methods, such as negative pressure therapy, once the acute conditions have resolved, can help fasten the surgical wound closure. Prompt management can improve prognosis of patients affected from NF reducing limb loss and saving lives.

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.

Clinical presentations and outcomes of necrotizing fasciitis in males and females over a 13-year period

Background

Necrotizing fasciitis (NF) is a rapidly progressive infection of fascia and subcutaneous tissue resulting in serious outcomes. We aimed to evaluate the clinical presentations, hospital course and outcomes of NF based on patient gender.

Patients and methods

All patients admitted with NF were enrolled in the study over a 13-year period in the main tertiary hospital in Qatar. Clinical presentations, co-morbidities, severity and outcomes were analyzed and compared in male and female patients.

Results

A total of 331 NF patients were identified with a mean age of 51 ± 15 years and male to female ratio of 3:1. However, Arab Qatari females were more frequently affected by NF in comparison to their male counterparts and south Asian females (p < 0.001), respectively. Female patients were older and had significantly higher incidence of abdominal and groin NF (p < 0.004). There were 13 cases with recurrent NF; 85% of them were males. Male NF patients had significantly higher rate of organ failure (p = 0.02), but there was no significant difference in the hospital length of stay as well as mortality in both genders. Overall, there were 85 (25.7%) deaths (23 females and 62 males).

Conclusion

Necrotizing fasciitis remains a life threatening entity. Although, NF is more common in males, Qatari females are more likely to develop NF than males. NF of abdominal wall and groin is significantly higher in females. Development of organ failure is more common in males with NF. NF remains a challenging clinical problem in Qatar with a mortality rate ranging from 25 to 27% for both genders.

•

Majority of Necrotizing Fasciitis (NF) patients are males (74%).

•

NF of abdomen and groin is significantly higher in females.

•

Male patients are more severely ill with significantly more organ dysfunction.

•

Hospital stay and mortality of NF in both genders are comparable.

•

NF remains a challenging clinical problem in Qatar with a mortality rate ranging from 25 to 27% for both genders.

Clinical predictors for severe sepsis in patients with necrotizing fasciitis: an observational cohort study in northern Thailand

Background

Necrotizing fasciitis (NF) is a life-threatening infection of skin and fascia. Its progress is extremely fast, with extensive necrosis. Delay in treatment, with subsequent huge soft tissue loss and associated severe sepsis, remains a major cause of death in the management of NF.

Objective

The aim of this study was to explore clinical characteristics that may be used to predict severe sepsis in patients with NF, in the context of routine clinical practice in northern Thailand.

Methods

A retrospective observational cohort study was conducted. The patient cohort in this study consisted of all patients who were diagnosed with NF by surgical or pathological confirmation. The follow-up period started with the admission date and ended with the discharge date. The clinical variables were collected from patients registered at three provincial hospitals in northern Thailand from 2009 to 2012. The clinical predictors for severe sepsis were analyzed using multivariable risk regression.

Results

A total of 1,452 patients were diagnosed with NF, either with severe sepsis (n=237 [16.3%]) or without severe sepsis (n=1,215 [83.7%]). From the multivariable analysis, female sex (relative risk [RR] =1.51; 95% confidence interval [CI] =1.04–2.20), diabetes mellitus (RR =1.40; 95% CI =1.25–1.58), chronic heart disease (RR =1.31; 95% CI =1.15–1.49), hemorrhagic bleb (RR =1.47; 95% CI =1.32–1.63), skin necrosis (RR =1.45; 95% CI =1.34–1.57), and serum protein <6 g/dL (RR =2.67; 95% CI =1.60–4.47) were all predictive factors for severe sepsis.

Conclusion

The clinical predictors for severe sepsis in patients with suspicion of NF included female sex, diabetes mellitus, chronic heart disease, hemorrhagic bleb, skin necrosis, and serum protein <6 d/dL. The risk ratio was much higher in patients with total protein less than 6 g/dL, which is associated with malnutrition. Therefore, provision of sufficient nutritional support and close monitoring for these clinical predictors may be beneficial to reduce morbidity and mortality.

Development of cross-priming amplification assays for rapid and sensitive detection of Aeromonas hydrophila

Aeromonas hydrophila has been increasingly implicated as the aetiologic agent of various human diseases. Therefore, reliable laboratory detection and identification of this bacterium has become clinically and epidemiologically desirable. We developed a nearly instrument-free, simple molecular method for rapid detection of Aer. hydrophila using a cross-priming amplification (CPA) assay with the desA gene as the target. The desA gene is crucial for the survival and growth of Aer. hydrophila under iron starvation. The results can be visualized as colour changes without opening the reaction tubes. No false-positive results were observed for the 33 non-Aer. hydrophila strains tested to evaluate assay specificity. The limit of detection for Aer. hydrophila was approximately 200 copies of desA per reaction (on reference plasmids) and 5 × 10(3)  CFU g(-1) Aer. hydrophila in simulated human stool, which is the same sensitivity as a qPCR assay. The performance of the CPA assay was also evaluated with 100 stool specimens from diarrhoea patients and 40 environmental water samples. In conclusion, the simplicity, cost-effectiveness and nearly instrument-free platform of the CPA assay make it practical for use in primary care facilities and smaller clinical laboratories.

SIGNIFICANCE AND IMPACT OF THE STUDY

Aeromonas hydrophila is a human pathogen that infects via exposed wounds or ingestion of contaminated water and food. In this study, a CPA-based PCR method was developed for specific, rapid, cost-effective detection of Aer. hydrophila, and the test results could be visualized without opening the reaction tubes. This is the first report on the application of the CPA method for the detection of Aer. hydrophila. This novel method could be practical for use in primary care facilities and smaller clinical laboratories.

Cervical Necrotizing Fasciitis--The Value of the Laboratory Risk Indicator for Necrotizing Fasciitis Score as an Indicative Parameter

PURPOSE

Cervical necrotizing fasciitis (CNF) is uncommon, difficult to diagnose, and rapidly progressive. The objective of the present study was to determine the predictive value of the laboratory risk indicator for necrotizing fasciitis (LRINEC) score for CNF.

MATERIALS AND METHODS

The LRINEC score for 16 consecutive cases of CNF and 595 cases of severe non-necrotizing neck infections was determined over a 6.5-year period in a single-center retrospective cohort study and case report. CNF was confirmed by histologic examination and operative report documentation.

RESULTS

Using a cutoff score of 6, the LRINEC score had a sensitivity of 0.94 (95% confidence interval [CI] 0.92 to 0.96) and specificity of 0.94 (95% CI 0.70 to 1.00). The positive predictive value was 0.29 (95% CI 0.17 to 0.44), and the negative predictive value was 0.99 (95% CI 0.99 to 1.00).

CONCLUSIONS

The LRINEC score can detect early cases of CNF. Patients with a LRINEC score of ≥6 must be carefully evaluated for the presence of CNF.

Necrotizing fasciitis: risk factors of mortality

BACKGROUND

Necrotizing fasciitis (NF) is a serious infection of skin and soft tissues that rapidly progresses along the deep fascia. It becomes a fatal soft tissue infection with high mortality rate if treatment is delayed. Early diagnosis for emergency surgical debridement and broad-spectrum antibiotic therapy were the optimal treatments to reduce the mortality rate of NF.

OBJECTIVE

The aim of this study was to identify risk factors that increased the mortality rate in patients with NF under routine clinical practices.

METHODS

A retrospective cohort study was performed at three general hospitals located in northern Thailand. All medical records of patients with surgically confirmed NF treated between January 2009 and December 2012 were reviewed. Clinical predictors for mortality were analyzed using multivariable risk regression analysis.

RESULTS

Of a total of 1,504 patients with a diagnosis of NF, 19.3% (n=290) died in hospital and 80.7% (n=1,214) survived. From multivariable analysis, being female (risk ratio [RR] =1.37, 95% confidence interval [CI] =1.01-1.84); age >60 (RR=1.39, 95% CI =1.25-1.53); having chronic heart disease (RR=1.64, 95% CI=1.18-2.28), cirrhosis (RR =2.36, 95% CI=1.70-3.27), skin necrosis (RR =1.22, 95% CI=1.15-1.28), pulse rate >130/min (RR =2.26, 95% CI=1.79-2.85), systolic BP <90 mmHg (RR =2.05, 95% CI =1.44-2.91), and serum creatinine ≥1.6 mg/dL (RR=3.06, 95% CI=2.08-4.50) were risk factors for mortality.

CONCLUSION

Prognostic factors for mortality in NF patients included being female; age >60; or having chronic heart disease, cirrhosis, skin necrosis, pulse rate >130/min, systolic BP <90 mmHg, and serum creatinine ≥1.6 mg/dL. Thus, disease progression to mortality may occur in such patients presenting one of these risk factors. Further examination or close monitoring for systemic involvement may be advantageous to reduce morbidity and mortality.

Predictors of Mortality in Necrotizing Soft Tissue Infection

Necrotizing soft tissue infections (NSTIs) are a major source of morbidity and mortality, yet predictors of mortality for these critically ill patients remain poorly characterized. The aim of this study was to identify risk factors for mortality in patients with NSTI. We performed a retrospective review of all patients presenting with an NSTI to our county-funded, academic medical center between 2008 and 2013. Admission characteristics, comorbidities, laboratory values, time to operation, and perioperative cultures were assessed to identify predictors of mortality. During the 5-year study period, 138 patients were admitted with a NSTI; 20 (14.5%) of the patients died. Univariate predictors of mortality included bandemia, elevated creatinine, low bicarbonate, elevated lactate, a lower admission temperature, and shorter duration of presenting symptoms. Using Classification And Regression Tree analysis and subsequent logistic regression, bands greater than 25 per cent (odds ratio [OR], 8.0; 95% confidence interval [CI], 2.7 to 24.1; P = 0.0002), duration of symptoms less than 3.5 days (OR, 4.0; 95% CI, 1.2 to 13.9; P = 0.03), and temperature 37°C or less (OR, 3.6; 95% CI, 1.1 to 11.8; P = 0.03) were found to be independent predictors of mortality. Awareness of these predictors should prompt aggressive management of this at-risk population.

Current concepts in the management of necrotizing fasciitis

Necrotizing fasciitis (NF) is a severe, rare, potentially lethal soft tissue infection that develops in the scrotum and perineum, the abdominal wall, or the extremities. The infection progresses rapidly, and septic shock may ensue; hence, the mortality rate is high (median mortality 32.2%). Prognosis becomes poorer in the presence of co-morbidities, such as diabetes mellitus, immunosuppression, chronic alcohol disease, chronic renal failure, and liver cirrhosis. NF is classified into four types, depending on microbiological findings. Most cases are polymicrobial, classed as type I. The clinical status of the patient varies from erythema, swelling, and tenderness in the early stage to skin ischemia with blisters and bullae in the advanced stage of infection. In its fulminant form, the patient is critically ill with signs and symptoms of severe septic shock and multiple organ dysfunction. The clinical condition is the most important clue for diagnosis. However, in equivocal cases, the diagnosis and severity of the infection can be secured with laboratory-based scoring systems, such as the laboratory risk indicator for necrotizing fasciitis score or Fournier's gangrene severity index score, especially in regard to Fournier's gangrene. Computed tomography or ultrasonography can be helpful, but definitive diagnosis is attained by exploratory surgery at the infected sites. Management of the infection begins with broad-spectrum antibiotics, but early and aggressive drainage and meticulous debridement constitute the mainstay of treatment. Postoperative management of the surgical wound is also important for the patient's survival, along with proper nutrition. The vacuum-assisted closure system has proved to be helpful in wound management, with its combined benefits of continuous cleansing of the wound and the formation of granulation tissue.

Management of necrotizing skin and soft tissue infections

Although rare, necrotizing skin and soft tissue infections can be devastating infections that are difficult to diagnose and challenging to manage. Clinical presentation is often insidious, and a low index of suspicion is critical. Various diagnostic tools, such as scoring systems or imaging techniques, have been introduced, but none is convincingly superior to sound clinical judgment. Early diagnosis allows early adequate therapy that includes antibiotic therapy, critical care support, specific interventions such as intravenous immunoglobulin in selected patients and, most importantly, early source control. Empirical antibiotic therapy should cover a broad range of both Gram-negative and Gram-positive aerobic and anaerobic microorganisms, and clindamycin is recommended when group A Streptococcus is a suspected pathogen.

Red cell distribution width is an independent predictor of mortality in necrotizing fasciitis

INTRODUCTION

Necrotizing fasciitis (NF) is a rapidly progressing and potentially lethal infectious disease of the soft tissue. An elevated red blood cell distribution width (RDW) is associated with increased risk of death in patients with heart disease and infectious disease. We retrospectively assessed the association of elevated RDW with in-hospital mortality due to NF.

METHODS

All patients had diagnoses of NF and were admitted to the emergency department of a single institution in Taiwan over a 4-year period. Demographics, comorbidities, clinical presentations, and laboratory parameters were retrospectively reviewed. Red blood cell distribution width was categorized as elevated (>14.5%) or not elevated. Multivariate regression analysis was used to identify risk factors associated with mortality.

RESULTS

A total of 98 patients were enrolled, and the mortality rate was 23%. Univariate analysis indicated that advanced age, initial hypotension, low hemoglobin level, and elevated RDW (69.6% vs 20%, OR = 9.14, P < .001) were significantly associated with mortality. Multivariate analysis indicated that RDW was a significant and independent predictor of mortality in enrolled patients.

CONCLUSIONS

Elevated RDW is a significant and independent predictor of in-hospital mortality for patients with NF.

Liver cirrhosis as a real risk factor for necrotising fasciitis: a three-year population-based follow-up study

INTRODUCTION

Necrotising fasciitis (NF) is often found in patients with diabetes mellitus, chronic renal failure, alcoholism, malignancy or liver cirrhosis. However, it remains unknown whether liver cirrhosis is an independent risk factor for the occurrence of NF. This study aimed to determine whether liver cirrhosis is an independent risk factor for the occurrence of NF, and to identify the relationship between severity of liver cirrhosis and occurrence of NF.

METHODS

The National Health Insurance Research Database, maintained by Taiwan's National Health Insurance programme, was retrospectively analysed, and the hospitalisation data of 40,802 cirrhotic patients and 40,865 randomly selected, age‑ and gender‑matched non‑cirrhotic control patients was collected. The medical records of all patients were individually followed for a three‑year period from the patients' first hospitalisation in 2004.

RESULTS

During the three‑year follow‑up period, there were 299 (0.7%) cirrhotic patients with NF and 160 (0.4%) non‑cirrhotic patients with NF. Cox regression analysis showed that liver cirrhosis was a risk factor for the occurrence of NF during the study period (hazard ratio 1.982; p < 0.001). Among cirrhotic patients, those with complicated liver cirrhosis had a higher risk for the occurrence of NF than patients with non‑complicated liver cirrhosis (hazard ratio 1.320; p = 0.028).

CONCLUSION

Cirrhotic patients had a higher risk for the occurrence of NF than non‑cirrhotic patients, and the risk for NF was especially high among patients with complicated liver cirrhosis.

Modulation of host immune defenses by Aeromonas and Yersinia species: convergence on toxins secreted by various secretion systems

Like other pathogenic bacteria, Yersinia and Aeromonas species have been continuously co-evolving with their respective hosts. Although the former is a bonafide human pathogen, the latter has gained notararity as an emerging disease-causing agent. In response to immune cell challenges, bacterial pathogens have developed diverse mechanism(s) enabling their survival, and, at times, dominance over various host immune defense systems. The bacterial type three secretion system (T3SS) is evolutionarily derived from flagellar subunits and serves as a vehicle by which microbes can directly inject/translocate anti-host factors/effector proteins into targeted host immune cells. A large number of Gram-negative bacterial pathogens possess a T3SS empowering them to disrupt host cell signaling, actin cytoskeleton re-arrangements, and even to induce host-cell apoptotic and pyroptotic pathways. All pathogenic yersiniae and most Aeromonas species possess a T3SS, but they also possess T2- and T6-secreted toxins/effector proteins. This review will focus on the mechanisms by which the T3SS effectors Yersinia outer membrane protein J (YopJ) and an Aeromonas hydrophila AexU protein, isolated from the diarrheal isolate SSU, mollify host immune system defenses. Additionally, the mechanisms that are associated with host cell apoptosis/pyroptosis by Aeromonas T2SS secreted Act, a cytotoxic enterotoxin, and Hemolysin co-regulated protein (Hcp), an A. hydrophila T6SS effector, will also be discussed.

Characterization of Aeromonas hydrophila wound pathotypes by comparative genomic and functional analyses of virulence genes

Aeromonas hydrophila has increasingly been implicated as a virulent and antibiotic-resistant etiologic agent in various human diseases. In a previously published case report, we described a subject with a polymicrobial wound infection that included a persistent and aggressive strain of A. hydrophila (E1), as well as a more antibiotic-resistant strain of A. hydrophila (E2). To better understand the differences between pathogenic and environmental strains of A. hydrophila, we conducted comparative genomic and functional analyses of virulence-associated genes of these two wound isolates (E1 and E2), the environmental type strain A. hydrophila ATCC 7966^T, and four other isolates belonging to A. aquariorum, A. veronii, A. salmonicida, and A. caviae. Full-genome sequencing of strains E1 and E2 revealed extensive differences between the two and strain ATCC 7966^T. The more persistent wound infection strain, E1, harbored coding sequences for a cytotoxic enterotoxin (Act), a type 3 secretion system (T3SS), flagella, hemolysins, and a homolog of exotoxin A found in Pseudomonas aeruginosa. Corresponding phenotypic analyses with A. hydrophila ATCC 7966^T and SSU as reference strains demonstrated the functionality of these virulence genes, with strain E1 displaying enhanced swimming and swarming motility, lateral flagella on electron microscopy, the presence of T3SS effector AexU, and enhanced lethality in a mouse model of Aeromonas infection. By combining sequence-based analysis and functional assays, we characterized an A. hydrophila pathotype, exemplified by strain E1, that exhibited increased virulence in a mouse model of infection, likely because of encapsulation, enhanced motility, toxin secretion, and cellular toxicity.

Aeromonas hydrophila is a common aquatic bacterium that has increasingly been implicated in serious human infections. While many determinants of virulence have been identified in Aeromonas, rapid identification of pathogenic versus nonpathogenic strains remains a challenge for this genus, as it is for other opportunistic pathogens. This paper demonstrates, by using whole-genome sequencing of clinical Aeromonas strains, followed by corresponding virulence assays, that comparative genomics can be used to identify a virulent subtype of A. hydrophila that is aggressive during human infection and more lethal in a mouse model of infection. This aggressive pathotype contained genes for toxin production, toxin secretion, and bacterial motility that likely enabled its pathogenicity. Our results highlight the potential of whole-genome sequencing to transform microbial diagnostics; with further advances in rapid sequencing and annotation, genomic analysis will be able to provide timely information on the identities and virulence potential of clinically isolated microorganisms.

[Necrotizing soft tissue infection of the upper limb]

Necrotizing soft tissue infections and necrotizing fasciitis are life-threatening infections affecting the hypodermis, muscular fascia, and dermis secondarily. Mortality is high, with an average of 30%. The early diagnosis of necrotizing soft tissue infection is challenging, but is key to successful management of these patients. The mainstay of therapy includes early and wide surgical debridement, antibiotics and supportive care. Adjunctive therapies may have a role, but their effectiveness remains unproven. A review of the literature allows us to highlight this multidisciplinary management.

Recent trend of necrotizing fasciitis in Taiwan: focus on monomicrobial Klebsiella pneumoniae necrotizing fasciitis

BACKGROUND

Necrotizing fasciitis (NF) is a rapidly progressive, life-threatening soft-tissue infection that is traditionally caused by group A Streptococcus (GAS) or mixed aerobic/anaerobic bacteria. Monomicrobial Klebsiella pneumoniae NF (KP-NF) has been reported since 1996 but has not yet been systematically studied.

METHODS

We retrospectively studied consecutive NF cases treated at a university hospital in Taiwan during 1997-2010 and investigated the clinical characteristics and outcomes associated with monomicrobial KP-NF, using monomicrobial GAS-NF as a reference. We also analyzed the virulence gene profiles of the isolated K. pneumoniae strains.

RESULTS

Of 134 NF cases, 88 were monomicrobial, of which the most common pathogens were GAS (n = 16) and K. pneumoniae (n = 15). Monomicrobial KP-NF entailed a moderate risk of limb loss (20% vs 25%; P = 1.000) and high mortality (47% vs 19%; P = .135), and it was more likely to involve bacteremia (80% vs 31%; P = .011), concomitant distant abscesses (27% vs 0%; P = .043), and underlying immunocompromising conditions (100% vs 63%; P = .018), compared with GAS-NF. The isolated K. pneumoniae strains (n = 10) were of capsular polysaccharides genotype K1 (n = 4), K54/K20/K5 (n = 4), K2 (n = 1), and K16 (n = 1). All strains carried rmpA, iucABCDiutA, and iroA. Genotype K1 strains had a significantly higher risk of concomitant distant abscesses, compared with non-K1 strains (75% vs 0%; P = .033).

CONCLUSIONS

K. pneumoniae has become a common pathogen of monomicrobial NF in Taiwan. Physicians treating patients with monomicrobial KP-NF should be aware of the risk of concomitant distant abscesses, particularly in cases caused by genotype K1.