Empirical antibiotics use in soft tissue infections

PURPOSE:

Various antibiotics are available to treat soft-tissue infections. However, it is unclear if the empirical antibiotic is always appropriate or the most economical.

OBJECTIVE:

To determine the percentage of empirically treated wounds susceptible to the antibiotic therapy prescribed, and to determine the percentage of wounds treated with the most economical antibiotic therapy.

METHODS:

A retrospective chart review was performed on all charts with a diagnosis of ‘soft-tissue infection’ between January 1, 2005, and June 30, 2005, at St Joseph’s Hospital, Hamilton, Ontario. Eligible charts were identified using the medical diagnosis coding system. The following diagnoses (including subheadings) were included: cellulitis, lymphangitis, abscess, carbuncle or furuncle. The following was extracted: patient demographics; soft-tissue diagnosis; name, dose and duration of antibiotics used; culture results; and Gram-stain results. A comparison between the empirical antibiotic prescribed and the microbiology result was made. An assessment was performed on the cost of the initial empirical antibiotic treatment compared with less-expensive effective alternatives.

RESULTS:

For soft-tissue infections with positive culture growth, empirical antibiotic treatment was appropriate in all abscess cases, 50% of ulcer cases and 83% of cellulitis cases. For cellulitis patients receiving a single empirical antibiotic, it was appropriate in 89% of cases. Only 42% of culture-positive patients were treated with the most economical regimen, multiple antibiotics being the most common fault.

CONCLUSIONS:

To be most economical, a single empirical antibiotic should be used to treat cellulitis. Culture results should be used to guide any antibiotic changes.     

Necrotizing soft tissue infections

Necrotizing soft tissue infections (NSTI) represent a spectrum of diseases characterized by extensive rapidly progressive necrosis that may involve the skin, subcutaneous tissues, fascia or muscle. Their progress is extremely fast, leading often to sepsis and septic shock that ends up in multiple organ failure with abrupt and high mortality. A variety of classification systems have been developed based on parameters such as anatomic location of the disease or microbiology. There are a number of factors that predispose to the spread of these soft tissue infections, such as delays in recognition, immune suppression, diabetes mellitus and advanced age. The use of broad‐spectrum antibiotics tends to mask the severity of the underlying infection, modulates the clinical presentation, and even delays hospital admission. The most important factor affecting outcome in NSTI is early diagnosis and aggressive radical surgical treatment. The medical records of 13 patients who had been treated for NSTI from 1996 to 2005 were reviewed, retrospectively. There were eight men (61.5%) and five (38.5%) women. Mean age was 56 years (range 27–73). Seven cases of infection involved the perineal region (54%), two the lower limb, one the upper limb and three the abdominal wall/trunk. The most common associated comorbidity was diabetes mellitus in five patients (38.5%). A single organism was identified in two (15%) and multiple organisms in 11 (85%) patients. Necrotizing aponeurositis Type I was the most common of the polymicrobial necrotizing infections. Overall survival was 85%, and the mean hospital stay for survivors was 35 days (range 17–92).     

Perineal soft tissue infections

Fournier's gangrene (FG) is an aggressive necrotizing soft tissue infection of the perineum. FG takes hold as a mixture of pathogenic organisms enter the host via injured gastrointestinal or genitourinary mucosa. After soft tissue insult, a synergistic, polymicrobial infection destroys tissue through an obliterative endarteritis. FG particularly affects older, obese men with type 2 diabetes mellitus, but can affect everyone. Special populations at risk include patients who have undergone gender reassignment surgery. Early, aggressive debridement and fluid resuscitation are mandatory. Careful decisions must be made regarding the fecal stream, antibiosis, topical coverings and the use of adjunctive therapy. While untreated FG is certainly fatal, with effective diagnosis and treatment survival rates approach 95%.     

The use of drotrecogin alpha for necrotizing soft tissue infections

The use of Drotrecogin alfa (DAA) (Xigris) in select patients with sepsis has had demonstrable improvement in survival, though its benefit in necrotizing soft tissue infections (NSTI) is unclear. A retrospective review of NSTI patients receiving DAA at our institution from 2006 to 2009 was performed. Our previously derived mortality prediction model, based on classification and regression tree analysis, was applied to patients and the predicted mortality was compared with the actual mortality rate. Ten patients with severe NSTI received DAA. The median admission values were: white blood cell count of 27,000/mm3, serum lactate of 4.0 mmol/L, and serum sodium of 128 mEq/L. Four (40%) patients had systemic complications, five (50%) patients required amputation, and one died (10%). Median time to DAA administration was 12 hours after debridement. There were no bleeding complications attributed to DAA use. Mortality in this series of severe NSTI was only 10 per cent, which compares favorably with the predicted mortality of 18 per cent based on classification and regression tree analysis (P = 0.2). A prospective, randomized study is warranted to determine if the use of DAA should be part of the standard therapy for NSTI patients with a predicted high mortality.     

Skin and soft tissue infections

Infection can involve all layers of soft tissue. The severity of infection can range from a simple cutaneous infection to widespread necrosis of the skin, muscle, and fascia. While infections of soft tissue are common, and can usually be managed using conservative therapy or local surgery, clinicians should be aware of less commonly seen invasive infections that need immediate radical surgical débridement to treat the source adequately, contributing to improved survival.     

Mycobacterial soft tissue infections in North Queensland

BACKGROUND: Mycobacterial soft tissue infections are a heterogeneous group of infections that usually require a variety of therapeutic methods for cure. North Queensland has an environment, which predisposes to several such infections. The aim of this study was to assess the incidence and epidemiology of mycobacterial soft tissue infections in North Queensland and to review surgical and non-surgical interventions in these conditions. METHODS: This study was a retrospective review of all patients with a proven mycobacterial soft tissue infection, seen between 1997 and 2005 in a tertiary referral centre in North Queensland. RESULTS: In total, 34 patients were identified. The most common causative organisms were Mycobacterium fortuitum (44%), M. ulcerans (17.6%) and M. abscessus (11.8%). The risk factors identified were the male sex, lower-limb involvement and preceding trauma including surgery. Twenty-four (70.6%) patients had surgical excision or debridement with a variety of adjuvant antimicrobial therapies. There were eight (23.5%) local recurrences. CONCLUSION: The optimal management of soft tissue mycobacterial infections includes early microbiological identification based on tissue biopsy, appropriate combination antimicrobial therapy and early wide surgical excision where appropriate. North Queensland has a unique environment, which may predispose to these infections. An awareness of this is essential to surgical practice in the region.     

Complicated skin and soft tissue infections

Skin and soft tissue infections are common diseases. The spectrum ranges from slight furuncles to severe necrotizing soft tissue infections. Grampositive bacteria account for 70-80 % of cases as causative organisms. Diagnostics include rapid evaluation of locally limited or diffuse spreading extent of the disease. In complicated skin and soft tissue infections, surgical intervention with debridement and necronectomy is indicated. Necrotizing skin and soft tissue infections call for programmed redebridement. If systemic signs of inflammation are present (fever > 38 degrees C, leukocytosis, CRP elevation) or significant comorbidity exists, application of antibiotics is indicated. The prognosis in operatively treated patients is dependent on the time of surgical intervention.     

Hyperbaric oxygen therapy in necrotizing soft tissue infections

BackgroundSurgical debridement and antibiotics are the mainstays of therapy for patients with necrotizing soft tissue infections (NSTIs), but hyperbaric oxygen therapy (HBO) is often used as an adjunctive measure. Despite this, the efficacy of HBO remains unclear. We hypothesized that HBO would have no effect on mortality or amputation rates.MethodsWe performed a retrospective analysis of our institutional experience from 2005 to 2009. Inclusion criteria were age > 18 y and discharge diagnosis of NSTI. We abstracted baseline demographics, physiology, laboratory values, and operative course from the medical record. The primary endpoint was in-hospital mortality; the secondary endpoint was extremity amputation rate. We compared baseline variables using Mann-Whitney, chi-square, and Fisher's exact test, as appropriate. Significance was set at P < 0.05.ResultsWe identified 80 cases over the study period. The cohort was 54% male (n = 43) and 53% white (n = 43), and had a mean age of 55 ± 16 y. There were no significant differences in demographics, physiology, or comorbidities between groups. In-hospital mortality was not different between groups (16% in the HBO group versus 19% in the non-HBO group; P = 0.77). In patients with extremity NSTI, the amputation rate did not differ significantly between patients who did not receive HBO and those who did (17% versus 25%; P = 0.46).ConclusionsHyperbaric oxygen therapy does not appear to decrease in-hospital mortality or amputation rate after in patients with NSTI. There may be a role for HBO in treatment of NSTI; nevertheless, consideration of HBO should never delay operative therapy. Further evidence of efficacy is necessary before HBO can be considered the standard of care in NSTI.     

The microbiology of necrotizing soft tissue infections

OBJECTIVE: A large number of necrotizing soft tissue infections (NSTI) treated at a single institution over an 8-year period were analyzed with respect to microbial pathogens recovered, treatment administered, and outcome. Based on this analysis, optimal empiric antibiotic coverage is proposed. METHODS: A retrospective chart review of all patients with documented NSTI was conducted. Microbiologic variables were tested for impact on outcome using Fisher's exact test and multivariate analysis by logistic regression. RESULTS: Review of the charts of 198 patients with documented NSTI revealed 182 patients with sufficient microbiologic information for analysis. These 182 patients grew an average of 4.4 microbes from original wound cultures, although a single pathogen was responsible in 28 patients. Eighty-five patients had combined aerobic and anaerobic growth, the most common organisms being, in order, Bacteroides species, aerobic streptococci, staphylococci, enterococci, Escherichia coli, and other gram-negative rods. Clostridial growth was common but did not affect mortality unless associated with pure clostridial myonecrosis. Mortality was affected by the presence of bacteremia, delayed or inadequate surgery, and degree of organ system dysfunction on admission. CONCLUSIONS: NSTI are frequently polymicrobial and initial antibiotic coverage with a broad-spectrum regimen is warranted. The initial regimen should include agents effective against aerobic gram-positive cocci, gram-negative rods, and a variety of anaerobes. The most common organisms not covered by initial therapy were enterococci. All wounds should be cultured at initial debridement, as changes in antibiotic coverage are frequent once isolates are recovered.     

Lower-extremity soft tissue infections with intra-abdominal sources

This article describes a series of 3 patients who presented with lower-extremity soft tissue infections. Each patient was treated with prompt debridement by an orthopedic surgeon (J.F.G.) and required at least 1 additional procedure by another surgeon.These infections vary from superficial cellulitis to rapidly advancing necrotizing fasciitis. At times, the source of these infections is clear. Other times, no obvious source of infection exists, in which case the abdomen must be considered as a possible source of infection. A high level of suspicion, complete history and physical examination, and appropriate ancillary studies are required to make an accurate and prompt diagnosis. Options for the treatment of the intra-abdominal source of infection depend on the etiology of the infection and anatomic location of the process. Psoas abscesses can often be decompressed by an interventional radiologist using computed tomography guidance. In the case of bowel involvement, such as suspected carcinoma or diverticulitis, a general surgeon is necessary. When the appropriate diagnosis is made, soft tissue infections of the thigh often respond to appropriate surgical debridement and antibiotic therapy. It is important to remember the whole patient when evaluating soft tissue infections, especially in the thigh. A low threshold for imaging of the abdomen and pelvis is important, especially when the physical examination or medical history reveals the abdomen as a possible source of infection.     

The use of extracorporeal membrane oxygenation in severe necrotizing soft tissue infections complicated by septic shock

Necrotizing soft tissue infections remain a challenging clinical problem. Delays in diagnosis, incomplete débridement of necrotic tissues, and the hemodynamic instability and end-organ failure associated with overwhelming sepsis all contribute to significant mortality. Extracorporeal support is a well-established tool to support profound cardiopulmonary failure. To broaden the indications for use, we present two cases of young adults with necrotizing soft tissue infections who sustained sepsis-induced hemodynamic collapse and required extracorporeal support to facilitate adequate tissue débridement as a bridge to recovery.     

Outcome of necrotizing skin and soft tissue infections

ABSTRACT Background: Management of necrotizing skin and soft tissue infections (nSSTI) remains difficult, and the mortality rate has been high. We hypothesized that management of nSSTI by an emergency general surgery (EGS) service would improve outcomes. Methods: Retrospective review of EGS patients with idiopathic nSSTI and comparison with historical controls. Demographic, co-morbidity, laboratory, and surgical data were collected. Non-parametric statistical analysis was used to evaluate differences between survivors and non-survivors. Logistic regression analysis was performed to identify risk factors for the primary outcome measure of death. Results: Fifty-two patients met the inclusion criteria, with five deaths (9.6%). The median time to the operating room (OR) was 8.6 h. The Acute Physiology and Chronic Health Evaluation (APACHE) II score, serum lactic acid concentration, and intensive care unit length of stay were significantly different for non-survivors. The APACHE II score was an independent predictor of death when controlling for age and time to OR. Conclusions: An EGS service was associated with shorter time to OR, which may improve the outcome. Physiologic derangement, as estimated by the APACHE II score, is predictive of death from nSSTI.     

Strategies of management of necrotizing soft tissue infections

Necrotizing soft tissue infections represent a group of rapidly progressive diseases requiring early and repeated debridement, associated with broad spectrum antibiotics. Delay in surgery or inadequate therapy are the main risk factors for death. Most patients need aggressive critical care management and intensive nutritional support. The management of these patients by experimented senior surgeons is mandatory. A plastic surgeon can help debridement in order to preserve possibilities of later myocutaneous or rotational skin flaps. Intravenous immunoglobulins are an efficacious adjunctive therapy for severe group A streptococcal infection.     

Necrotizing soft tissue infections: a surgical disease

Despite advances in antibiotics and infection control practices necrotizing fasciitis is still a potentially lethal disease. We reviewed 37 patients with necrotizing fasciitis to identify prognostic factors indicating outcome. Overall mortality was 24 per cent. Mortality was significantly increased for elderly patients. Solid-organ transplant recipients also represented a subset of patients with increased mortality. Most infections were polymicrobial. There was no Clostridium perfringens cultured. Rapid diagnosis and treatment with surgical debridement remains the cornerstone of therapy.     

Comparison of serum and tissue antibiotic levels in diabetes-related foot infections

Parenteral antibiotics are used as an adjunct to amputation or operative debridement for patients with diabetes who require emergency surgery for a septic foot. In 26 patients with a diabetes-related foot infection, one dose of various intravenous antibiotic regimens (gentamicin and clindamycin, ticarcillin/clavulanate, ampicillin/sulbactam) was administered during the hour before the procedure, and assays were performed to measure the antibiotic serum and tissue levels at the time of surgical debridement. Aerobic and anaerobic cultures were performed on infected tissue. The 172 bacterial isolates, including 95 aerobes and 77 anaerobes, (6.6 isolates per patient) underwent antibiotic susceptibility testing. Antibiotic levels were calculated by biologic assay from serum and tissue biopsies from the viable margins of the surgical site, which subsequently healed primarily or supported a split-thickness skin graft. Sixteen of the patients achieved therapeutic serum levels, and therapeutic tissue levels were reached in six patients at the time of surgery. A significantly lower number of patients had therapeutic tissue levels compared to serum levels (p less than 0.01, chi square). Initial intravenous antibiotic administration provides inadequate tissue concentrations for treating foot infections in patients with diabetes. Adequate serum antibiotic levels do not reflect therapeutic tissue antibiotic levels at the surgical margins in this group of patients.