Necrotizing soft tissue infections

Necrotizing soft tissue infections (NSTIs) are aggressive severe soft tissue infection that cause rapid and widespread infection and necrosis of the skin and soft tissues and are highly lethal. NSTIs include necrotizing cellulitis, adipositis, fasciitis and myositis/myonecrosis and have significant potential for extensive soft tissue and limb loss. Early diagnosis and treatment of NSTIs remains the cornerstone of therapy. Timely aggressive surgical debridement and early appropriate antibiotic treatment are required for a successful outcome and clinical cure. Mortality rate has decreased from 25-50% in past years, to 10-16% in recent years with aggressive surgical and medical management. Additional innovative strategies for the treatment of NSTIs, including intravenous immuno-globulin G (IVIG), hyperbaric oxygen, and vacuum-assisted closure, do not yet have definitive evidence of efficacy, but may be considered in patients at high risk of death. A comprehensive knowledge of the pathophysiology, diagnostic features, causative microbial pathogens, and treatment strategies (including surgical debridement and antimicrobial therapy) is required for successful management of NSTIs.

Diabetic foot care: tips and tools to streamline your approach

Whether you're assessing risk, focusing on prevention, or treating an ulcer, this update--and handy treatment mnemonic--will help you optimize your care.

Necrotizing fasciitis

OBJECTIVE

To describe the defining characteristics and treatment of necrotizing fasciitis (NF), emphasizing early diagnostic indications.

QUALITY OF EVIDENCE

PubMed was searched using the terms necrotizing fasciitis and necrotizing soft tissue infections, paired with early diagnosis. Results were limited to human studies in English. Additional articles were obtained from references within articles. Evidence is levels II and III.

MAIN MESSAGE

Necrotizing fasciitis is classified according to its microbiology (polymicrobial or monomicrobial), anatomy, and depth of infection. Polymicrobial NF mostly occurs in immunocompromised individuals. Monomicrobial NF is less common and affects healthy individuals who often have a history of trauma (usually minor). Patients with NF can present with symptoms of sepsis, systemic toxicity, or evidence of skin inflammation, with pain that is disproportional to the degree of inflammation. However, these are also present in less serious conditions. Hyperacute cases present with sepsis and quickly progress to multiorgan failure, while subacute cases remain indolent, with festering soft-tissue infection. Because the condition is rare with minimal specific signs, it is often misdiagnosed. If NF is suspected, histology of tissue specimens is necessary. Laboratory and radiologic tests can be useful in deciding which patients require surgical consultation. Once NF is diagnosed, next steps include early wound debridement, excision of nonviable tissue, and wide spectrum cover with intravenous antibiotics.

CONCLUSION

Necrotizing fasciitis is an uncommon disease that results in gross morbidity and mortality if not treated in its early stages. At onset, however, it is difficult to differentiate from other superficial skin conditions such as cellulitis. Family physicians must have a high level of suspicion and low threshold for surgical referral when confronted with cases of pain, fever, and erythema.

[Pharmacodynamic and pharmacokinetic of antibiotics for treatment of skin and soft tissue infections]

The pharmacodynamic and pharmacokinetic characteristics of antimicrobial agents are the two fundamental pharmacological components which provide a rational for the choice of therapy for skin and skin structure infections, and especially serious infections. The most important PK-PD parameters are well known which can potentiate therapeutic efficacy. Antimicrobial agents ca be subdivided into categories based on whether their activity is dependent on concentration or exposure time. Therefore, a correct dosing regimen for the time-dependent molecules (i.e. beta-lactams, linezolid, tigecycline) should prolong the maximum exposure time to maintain serum levels over the minimum inhibitory concentration (MIC). The concentration-dependent molecules, on the other hand, which include aminoglycosides and fluoroquinolones, should be given in order to reach maximum concentrations, since they are bactericidal in direct proportion to their concentrations and possess a prolonged post-antibiotic effect.

[Etiology, resistance and diagnostic techniques in skin and skin structure infections]

Skin and soft tissue infections (SSTI) are common and, generally, uncomplicated at the time of initial presentation. However, these infections can worsen quickly when there are delays in diagnosis and treatment. The clinical presentation of most SSTI is the culmination of a microbial three-step process as follow: i) bacterial adherence to host cells; ii) invasion of tissue with evasion of host defences, and iii) elaboration of toxins. Even if the microbiology of wounds has been actively investigated in recent years, there is still much to be learned about the microbial mechanisms that induce infection and prevent wound healing. There are also several means by which bacteria penetrate the skin barrier. The most common route is through a break in the barrier (lacerations, bite wounds, scratches, instrumentations, pre-existing skin conditions, wounds or ulcers, burns and surgery); other routes of penetration include contiguous spread from adjacent infections (e.g. osteomyelitis), entry of water into the skin pores, and, rarely, haematogenous seeding (i.e septic emboli). From what it was said, many microorganisms, above all from the normal skin microbiota, can be involved in these often polymicrobial infections, with Gram-positives such as Staphylococcus aureus, Streptococcus pyogenes, Staphylococcus epidermidis, Corynebacterium spp being predominant. Many other aerobic and anaerobic species, including Gram-negative bacilli, can also be involved. Even if the diagnosis of most SSTI is based on clinical examination, laboratory investigations, guided by clinical information, can help to confirm the diagnosis and elucidate the characteristics of specific pathogens. These microbiological investigations may include blood cultures, tissue swabs with culture, and needle aspiration. In rapidly progressing infections, empirical therapy is essential, although microbiological data are important in confirming subsequently that the chosen regimen is appropriate. Furthermore, the number of microorganisms becoming resistant to many usual drugs and the changing microbial epidemiology of these infections, such as the emergence of CA-MRSA, required a constant cooperation between the microbiology lab and the clinician in order to address microbiological aspects that can be critical to the successful management of SSTI.

[Skin and skin tissue infections: main clinical patterns/pictures]

Skin and soft tissue infections represent a heterogeneous group of clinical entities that require to be accurately identified for an appropriate and immediate management. Clinicians are challenged by the need to rapidly select those patients requiring hospitalization and medical therapy only and those to be immediately submitted to surgery. Erysipelas and several forms of cellulitis, involving the superficial structures of epidermis and dermis, are medical conditions; some cutaneous abscess may require surgical drainage, and all the necrotizing infections, involving the subcutaneous tissue (necrotizing fasciitis) or muscles (myonecrosis) are surgical conditions. Among the clinical clues useful for the diagnosis are the presence of severe pain disproportionate to the clinical evidence of the lesion (necrotizing fasciitis), the presence of crepitus (gas gangrene) and signs of systemic toxicity (high fever, hypotension, tachycardia, shock and multiple organ failure).

[Antibiotic therapy in the outpatient setting: update 2009]

Rational outpatient therapy restricts antibiotics to infections where they are beneficial and selects substances based on local resistance patterns. Respiratory tract infections typically caused by viruses should not be treated with antibiotics (e.g., rhinitis, bronchitis, sinusitis). Many respiratory infections likely caused by bacteria can be treated with aminopenicillin, sometimes combined with a beta-lactamase inhibitor. Quinolones should be used only as exception for respiratory tract infections, since resistance is rising. For this reason uncomplicated urinary tract infections (cystitis) should be treated with trimethoprim-sulfa-methoxazole (TMP-SMX) instead of quinolones, even though approximately 20% of Escherichia coli are resistant to TMP-SMX. Skin and soft tissue infections are best treated with beta-lactam antibiotics, as long as the community acquired methicillin-resistant strains of S. aureus frequently seen in certain countries remain uncommon here.

Severe soft tissue infections of the head and neck: a primer for critical care physicians

Patients with severe infections of the potential spaces of the head and neck are commonly managed in the ICU. These infections may present with devastating complications such as airway obstruction, jugular septic thrombophlebitis, lung abscess, upper airway abscess rupture with asphyxiation, mediastinitis, pericarditis, and septic shock. A thorough understanding of the anatomy and microbiology of these infections is essential for proper management of these patients. Retropharyngeal, danger, prevertebral, lateral pharyngeal, and submandibular space infections and their site-specific clinical manifestations, complications, and therapeutic interventions are discussed.

Skin and soft tissue infections due to CA-MRSA

Infections caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) have become epidemic over the last decade. It causes a spectrum of diseases in humans but skin and soft tissue infections predominate. Molecular virulence factors in CA-MRSA are incompletely understood. In this article, the epidemiology, presentation, treatment, and surveillance of skin and soft tissue infections due to CA-MRSA are reviewed.

Extraintestinal manifestations of Edwardsiella tarda infection: a 10-year retrospective review

Edwardsiella tarda, a member of the family Enterobacteriaceae found in aquatic environments, is an unusual cause of human disease, presenting most frequently as gastroenteritis. Extraintestinal manifestations of E. tarda infection are rare but have included meningitis, cholecystitis, endocarditis, osteomyelitis, soft tissue infections, bacteremia, and septicemia. Over a 10-year period at our institution, 10 cases of extraintestinal infection related to E. tarda were identified. The infections ranged from soft tissue infections secondary to trauma to intra-abdominal infections with abscess formation. Several of the patients had documented factors predisposing them to infection including diabetes mellitus and C1 esterase deficiency. Interestingly, two of the patients had chronic idiopathic inflammatory bowel disease, and one patient developed a respiratory tract infection related to E. tarda, a previously unreported clinical manifestion. Although the mortality rate for extraintestinal E. tarda infections has been as high as 50% in some studies, antimicrobial treatment was eventually successful in each of the 10 cases at our institution.

[A new approach to clinical and laboratory diagnosis of systemic and local soft tissue infections]

Dynamic measurements of blood TNF-a, IL-IRA, CRP, oligopeptide, and lactoferrin levels in patients with systemic and local soft tissue infections revealed direct correlation between them which allowed to use these indicators for the diagnosis of systemic infections. Results of clinical and laboratory analyses provided a basis for distinguishing short-term systemic inflammatory response syndrome and sepsis and developing relevant diagnostic criteria. Sepsis combined with systemic inflammatory response syndrome persisting for more than 72 hours after the onset of adequate therapy was characterized by CRP levels > 30 mg/l, oligopeptides > 0.34 U, lactoferrin > 1900 ng/ml, TNF-a > 6 pg/ml, ILL-IRA < 1500 pg/ml Patients with systemic inflammatory response syndrome for less than 72 hours had lower TNF-a, CRP, oligopeptide, and lactoferrin levels with IL-IRA > 1500 pg/ml. This new approach to early diagnosis of systemic infections makes it possible to optimize their treatment and thereby enhance its efficiency.

[Necrotizing soft tissue infection of upper extremity complicated with toxic shock syndrome--clinical presentation and treatment options]

Necrotizing soft tissue infections (NSTI) are uncommon infections associated with considerable morbidity and mortality (20%-40%). They are characterized by rapidly progressive necrosis of soft tissue that primarily involves subcutaneous fat and fascia with variable involvement of the overlying skin and muscle. Extensive soft tissue necrosis is often accompanied by systemic toxicity. Establishing the diagnosis in the early stage of the infection can be difficult, which leads to a delay in surgical treatment and a poor outcome. The principles of treatment are early and aggressive surgical debridement, broad spectrum antimicrobial therapy administered empirically and reassessed pending culture and sensitivity results, and intensive care management. We report a case of NSTI of the arm in a 64-year-old female patient caused by group A Streptococcus and Staphylococcus aureus complicated with toxic shock-like syndrome with emphasis on the pathophysiology of toxic shock-like syndrome and treatment modalities. NSTI developed 10 days after a knife cut wound of the thumb. The patient had no significant comorbidity. Treatment included aggressive surgical debridement with removal of necrotic tissue and extensive fasciotomies 24 h of admission, cardiovascular stabilization and monitoring at intensive care unit, and repeat surgical debridement at 72 h of admission. Early triple drug antimicrobial therapy included high-dose clindamycin, which inhibits protein synthesis and bacterial exotoxin production that is responsible for inflammatory response and toxic shock-like syndrome. In addition, the patient received hyperbaric oxygen therapy (8 treatments in total). The above management led to control of the infective process. Prolonged surgical wound care followed by thin split-skin grafting and placement of secondary sutures on day 36 of admission preserved the extremity with good functional and cosmetic result.

Unresolved issues in the management of ulcers of the foot in diabetes

Management of diabetic foot ulcers presents a major clinical challenge. The response to treatment is often poor and the outcome disappointing, while the costs are high for both healthcare providers and the patient. In such circumstances, it is essential that management should be based on firm evidence and follow consensus. In the case of the diabetic foot, however, clinical practice can vary widely. It is for these reasons that the International Working Group on the Diabetic Foot has published guidelines for adoption worldwide. The Group has now also completed a series of non-systematic and systematic reviews on the subjects of soft tissue infection, osteomyelitis, offloading and other interventions designed to promote ulcer healing. The current article collates the results of this work in order to demonstrate the extent and quality of the evidence which is available in these areas. In general, the available scientific evidence is thin, leaving many issues unresolved. Although the complex nature of diabetic foot disease presents particular difficulties in the design of robust clinical trials, and the absence of published evidence to support the use of an intervention does not always mean that the intervention is ineffective, there is a clear need for more research in the area. Evidence from sound clinical studies is urgently needed to guide consensus and to underpin clinical practice. It is only in this way that patients suffering with these frequently neglected complications of diabetes can be offered the best hope for a favourable outcome, at the least cost.

[Fournier's gangrene caused by Candida albicans]

Fournier's gangrene characterized by fulminant necrotizing fasciitis of the perineal, genital or perianal regions, is generally caused by aerobic and anareobic bacteria. Although it is thought to be an idiopathic process, Fournier's gangrene has been shown to have a predilection for patients with diabetes, long term alcohol misuse and immunocompromised patients. The focus of infection is usually located in the urinary tract, lower gastrointestinal tract or skin. The development and progression of the gangrene is often fulminating and can rapidly lead to multiple organ failures and death. Here, we present a Fournier's gangrene case caused by Candida albicans. A 59-year-old woman was admitted to hospital with the complaint of swelling on the right thigh following a trauma occurred three weeks ago. Her history revealed that she had been hospitalized previously for four times due to diabetes mellitus, essential thrombocytopenia, chronic disease anemia and hypertension. Right trochanteric fracture was detected and the patient was taken under surgical debridement with the pre-diagnosis of secondary anaerobic soft tissue infection. Empirical treatment was started with cephalosporin and metronidazole. Since wo- und and blood cultures revealed C. albicans as the primary microorganism, fluconazole was added to the therapy. However, the patient died on the post-operative 25th day because of multi-organ disfunction secondary to fungal sepsis. This case has been reported to emphasize that yeasts should be considered as pathogenic agents in diabetic patients with gangrene.

Infection associated with hematoma formation after shoulder arthroplasty

Hematoma formation requiring operative treatment after shoulder arthroplasty may be associated with higher patient morbidity. We therefore determined whether there was an association of hematoma formation requiring operative treatment with deep infection after shoulder arthroplasty. Between 1978 and 2006, we performed 4147 shoulder arthroplasties in 3643 patients. Of these, 12 shoulders (0.3%) underwent reoperation for hematoma formation. The mean time interval from arthroplasty to surgery for the hematoma was 7 days (range, 0.5-31 days). Among nine cases in which cultures were taken, six had positive cultures; the organisms included Propionibacterium acnes in three, Staphylococcus epidermidis in one, Streptococcus species in one, and Staphylococcus epidermidis with Peptostreptococcus in one. The minimum followup was 12 months (mean, 68 months; range, 12 to 294 months). Two of the 12 patients eventually underwent resection arthroplasty for deep infection. The Neer score was excellent in one, satisfactory in six, and unsatisfactory in five patients. The data suggest hematoma formation after shoulder arthroplasty is often accompanied by positive intraoperative cultures. The surgeon should be aware of the high rate of unsatisfactory results associated with this complication as well as the possibility of developing a deep infection requiring additional surgery.

LEVEL OF EVIDENCE

Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

[Skin and soft tissue infections: current therapeutic options]

In the present review, the authors focus on skin and soft tissue infections (SSTIs), a set of commonly observed pathologies which can present different features in terms of site and localization, clinical characteristics, and the aetiological agent responsible; their severity is related to the depth of the affected sites. After a brief introduction to the diverse classification criteria which are currently adopted by various authors, the aetiology and role of the most frequently occurring pathogen, Staphylococcus aureus, often methicillin-resistant is discussed, as well as the possible therapeutic options. We first present the internationally recommended guidelines, and stress that SSTI management has to conform to different criteria, in accordance with the different clinical settings: mild infections require simple and cost-saving treatments while severe infections make timely and aggressive treatments mandatory. The review then reports the recent data concerning the efficacy of new antimicrobials for treating SSTIs. In particular, results observed with linezolid, tigecycline, and daptomycin are discussed.