Original contribution
Community-Acquired Necrotizing Soft Tissue Infections: A Review of 122 Cases Presenting to a Single Emergency Department Over 12 Years

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Abstract

Purpose: To characterize the Emergency Department (ED) presentation of necrotizing soft tissue infections (NSTI) and identify severity markers. Procedures: Retrospective chart review of pathologically diagnosed NSTIs presenting to an urban ED from 1990–2001. Cases were identified from a surgical database, ICD-9 search and prospectively. Five Emergency Physicians (EPs) abstracted data using a standardized form. Severe NSTI was defined by any of the following: death, amputation, intensive care unit (ICU) stay >24 h, >300 cm2 debrided. Severe and non-severe cases were compared using chi-square, Fisher’s exact, and multivariate logistic regression testing. Findings: The 122 cases were characterized by: injection drug use, 80%; fever, 44%; systolic blood pressure (BP) <100 mm Hg, 21%; white blood cell count (WBC) >20 × 109/L, 43%; median time to operation, 8.4 h; mortality, 16%. The managing EP suspected NSTI in 59%. A systolic BP <100 mm Hg, BUN >18 mg/dL, radiographic soft tissue gas, admission to a non-surgical service and clostridial species were independently associated with severe NSTI. Conclusions: Pathologically defined NSTIs have a wide spectrum of ED presentations and early diagnosis remains difficult.

Introduction

Necrotizing soft tissue infections (NSTIs) include necrotizing cellulitis, necrotizing fasciitis, and myonecrosis. Although classifications vary, these infections are defined pathologically by necrosis and thrombosis that involves subcutaneous fat, fascia, or muscle (1, 2, 3). The bacteriology usually involves a synergistic combination of aerobic and anaerobic species, clostridial species, or group A streptococcus. Clinically, NSTIs tend to progress rapidly, leading to significant morbidity and mortality. Timely and aggressive surgical debridement is considered necessary for cure. Unfortunately, correct diagnosis of NSTI is notoriously difficult.

Injection drug use (IDU) is a leading risk factor for NSTI (3, 4, 5, 6). In this risk group, where simple abscesses and cellulitis are very common, accurate and rapid diagnosis of life-threatening NSTIs is particularly difficult.

Numerous large retrospective case series of NSTIs have been carried out by surgeons and published in the surgical literature (3, 6, 7, 8). Mortality in contemporary series has centered around 25%, although case findings and inclusion criteria have not been well described and selection bias favoring fulminate disease is likely (9).

Our experience with predominantly IDU-related infections suggests that NSTIs (defined pathologically) exhibit a wide spectrum of clinical severity that includes a relatively mild form of disease. Rapid diagnosis and proper management of these infections requires an understanding of their presenting features and recognition of the entire clinical spectrum.

The objectives of this primarily descriptive study were the following: 1) to include a wide clinical spectrum of NSTI cases as defined by surgical pathology findings; 2) to characterize in detail the Emergency Department (ED) presentation, ED diagnoses and course of community-acquired infections; and 3) to identify features that were associated with clinically severe disease.

Section snippets

Materials and Methods

This was a retrospective chart review study. The setting was a single academic, urban, county ED located in Oakland, California, with an annual census of approximately 75,000 visits. Inclusion criteria were cases of skin and soft tissue infection presenting to the ED between January 1, 1990 and December 31, 2001 that were taken to the operating room, in which surgical pathology findings (intra-operative or at autopsy) were consistent with NSTI. Terms in the pathology report taken to indicate

Results

A total of 240 cases were identified for data abstraction. One hundred eighteen were excluded after review concluded that they were not NSTI cases or had not presented through the ED. A total of 122 cases of community-acquired NSTI were included in the final data analysis. Demographics, co-morbidities, and presenting characteristics among all subjects are shown in Table 1.Table 2 summarizes important aspects of the clinical course, admitting diagnosis, and bacteriologic findings. Both Table 1,

Discussion

We report a 12-year retrospective series of 122 cases of community-acquired NSTI. All subjects presented through a single ED and 80% were associated with IDU. Overall case mortality was 16.4%. Table 6 summarizes several previous NSTI case series. This is the third largest series in the literature to date, and the largest involving strictly community-onset disease. Prior studies in which the mortality is as high as 29–50%, or a significant number of cases were transferred from outside

Limitations

Our study suffers from numerous limitations; some are inherent in retrospective chart reviews or in studies of NSTIs in general. Chart review is always hampered by a lack of consistent and objective terminology used by providers who document the findings, as well as by errors in abstraction and subjective interpretations by investigators reading the charts and recording data. Such difficulties were evident in our physical findings data where several features had kappa values of <0.6 (Table 1).

Future Directions

The study we would like to see in the future would attempt to carefully compare features of NSTIs to non-necrotizing skin and soft tissue infections. It might have the following characteristics: it would be a prospective, multicenter registry enrolling all significant skin and soft tissue infections presenting to the ED; it would use standardized criteria for history and physical examination findings, perhaps incorporating photography; there would be a protocol to establish liberal use of

Conclusions

We report a 12-year retrospective series of 122 cases of community-acquired NSTI in patients who presented through a single ED. Eighty percent were associated with IDU and overall case mortality was 16.4%. The frequency of selected presenting features was: fever, 44.3%; BP <100 mm Hg, 21.3%; WBC >20 × 109/L, 42.5%. NSTI was suspected by the managing EP in 59% of cases. Median time to operation was 8.4 h (range 1.9–304.9 h). Fifty-five cases met the definition of severe, among whom the mortality

Acknowledgments

We thank Dr. Helen Kuo for her assistance with data abstraction.

References (21)

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    Citation Excerpt :

    Necrotizing fasciitis of the extremities is the most frequent clinical presentation [23,27,29,31–34,36,37,39,41,42], followed by perineal NSTI, also known as Fournier's gangrene [26,31–36,41,42] (Table 1). Involvement of the trunk or head and neck region are less frequent [26,27,31,33,36,39,42]. From 4% to 12 % of patients with NSTI have a recurrent NSTI [26,27,31,33].

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