Current hypotheses on synergistic microbial gangrene

Fournier's Gangrene with Edwardsiella tarda: A Gas Production Case by Bacterial Synergism with Streptococcus anginosus

Edwardsiella tarda is an anaerobe associated with freshwater and marine life. Necrotizing soft tissue infection caused by E. tarda is rare, but its mortality rate is extremely high (61.1%). We experienced a survival case of Fournier’s gangrene with E. tarda. A key clinical feature for the diagnosis was gas production; however, there have been no previous reports of such a phenomenon in relation to E. tarda. A 64-year-old man was admitted with a 3-day history of a high fever. His medical history, which included paraplegia from the Th6 level down, made the focus of inflammation at the perineum difficult to notice. Whole-body CT revealed subcutaneous gas from the posterior scrotum around the entire circumference of the anus. During emergency surgery, an incision at the posterior scrotum revealed extensive fascia necrosis, and E. tarda and Streptococcus anginosus were identified. We speculated the gas production in this case to be the product of a mixed infection of aerobes and anaerobes, which acted synergistically to induce bacterial growth. Timely surgical debridement and antibiotic therapy led to the patient’s survival.

Diagnostic value of laboratory parameters for the discrimination between erysipelas and limited cellulitis

BACKGROUND AND OBJECTIVES

Erysipelas, caused by beta-hemolytic streptococci, and limited cellulitis, frequently caused by Staphylococcus aureus or other bacteria, are skin and soft tissue infections characterized by typical clinical signs. However, despite the therapeutical relevance they are often not differentiated (e.g in clinical trials). Erysipelas are efficiently treated with penicillin, while limited cellulitis is treated with more wide-spectrum antibiotics. This study investigates whether parameters such as CRP, blood counts or novel parameters like immature granulocytes could serve as biomarkers to distinguish between these entities.

PATIENTS AND METHODS

For this retrospective analysis 163 patients were included. We compared laboratory markers in patients with erysipelas (n = 68) to those with limited cellulitis (n = 41) of the leg. Both erysipelas and limited cellulitis were defined clinically, with an additional aspect for erysipelas being a prompt response to penicillin.

RESULTS

Erysipelas were characterized by higher levels of inflammation. CRP and leukocyte counts are the best parameters to discriminate between both infections. A CRP value ≥ 3.27 mg/dl indicated the diagnosis of erysipelas with 75 % sensitivity and 73.2 % specificity.

CONCLUSIONS

Our results support the thesis that erysipelas and limited cellulitis are distinct infections as defined in the German guidelines and that an assessment of CRP and leukocytes is useful for differential diagnosis.

Calculated initial parenteral treatment of bacterial infections: Skin and soft tissue infections

This is the ninth chapter of the guideline "Calculated Parenteral Initial Therapy of Adult Bacterial Disorders - Update 2018" in the 2nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience. The chapter contains the first German S2k guidelines for bacterial skin and soft tissue infections. They encompass recommendations on diagnosis and treatment of the defined entities erysipelas (caused by beta-hämolytic streptococci), limited superficial cellulitis (S. aureus), severe cellulitis, abscess, complicated skin and soft tissue infections, infections of feet in diabetic patients ("diabetic foot"), necrotizing soft tissue infection and bite injuries.

S2k guidelines for skin and soft tissue infections Excerpts from the S2k guidelines for "calculated initial parenteral treatment of bacterial infections in adults - update 2018"

These first German S2k guidelines for bacterial skin and soft tissue infections were developed as one chapter of the recommendations for "calculated initial parenteral treatment of bacterial infections" issued under the auspices of the Paul-Ehrlich Society, of which the main part is presented here. Well-calculated antibiotic therapies require precise diagnostic criteria. Erysipelas is defined as non-purulent infection considered to be caused by beta-hemolytic strepto-cocci. It is diagnosed clinically by its bright-red erythema and early fever or chills at disease onset. Penicillin is the treatment of choice. Limited soft tissue infection (cellulitis) is usually caused by Staphylococcus (S.) aureus, frequently originates from chronic wounds and presents with a more violaceous-red hue and only rarely with initial fever or chills. Treatment consists of first- or second--generation cephalosporins or flucloxacillin (IV). Severe cellulitis is a purulent, partially necrotic infection which extends through tissue boundaries to fascias and requires surgical management in addition to antibiotics. Moreover, it frequently fulfills the criteria for "complicated soft tissue infections", as previously defined by the Food and Drug Administration for use in clinical trials (they include comorbidities such as uncontrolled diabetes, peripheral artery disease, neutropenia). It requires antibiotics which besides S. aureus target anaerobic and/or gramnegative bacteria. The rare so-called necrotizing skin and soft tissue infections represent a distinct entity. They are characterized by rapid, life-threatening progression due to special bacterial toxins that cause ischemic necrosis and shock and need rapid and thorough debridement in addition to appropriate antibiotics. For cutaneous abscesses the first-line treatment is adequate drainage. Additional antibiotic therapy is required only under certain circumstances (e.g., involvement of the face, hands, or anogenital region, or if drainage is somehow complicated). The present guidelines also contain consensus-based recommendations for higher doses of antibiotics than those approved or usually given in clinical trials. The goal is to deliver rational antibiotic treatment that is both effective and well-tolerated and that exerts no unnecessary selection pressure in terms of multidrug resistance.

Tigecycline in the Treatment of Patients with Necrotizing Skin and Soft Tissue Infections Due to Multiresistant Bacteria

BACKGROUND

Necrotizing skin and soft tissue infections (NSTI) form a group of aggressive diseases that require radical debridement for infection control. Simultaneously, a high-dose broad spectrum antibiotic regimen needs to be initiated with control of septic complications in the intensive care setting. The aim of this work is to analyze the efficacy and safety of tigecycline in a subpopulation of hospitalized, severely ill surgical NSTI patients who were documented in a large multicenter non-interventional study on tigecycline use in routine clinical practice.

METHODS

A total of 1,025 patients with severe infections including complicated skin and soft-tissue infections (cSSTI, n=163; 15,9%) were enrolled in a prospective multi-center non-interventional study. Patients were to receive an initial intravenous dose of 100 mg tigecycline, followed by 50 mg twice daily. Prospectively documented parameters included clinical findings, APACHE II score, microbiological and standard laboratory assessments, surgical measures, and clinical outcomes including adverse events.

RESULTS

Of 163 patients were treated for cSSTI, with the largest subgroup being NSTI patients (n=50, 30.7% of all cSSTI, mean age 61 y, median APACHE II score 20). Forty-eight NSTI patients (96%) had at least one comorbidity. In 80% of patients, the treatment was started after previous antibiotic treatment had failed and in 34% resistant pathogens were isolated (28% methicillin resistant Staphyloccocus aureus [MRSA], 4% extended-spectrum-beta-lactamase (ESBL)-producing bacteria, and 2% vancomycin-resistant Enterococci (VRE). Tigecycline was administered as a single agent in 32 patients; 17 received combination regimens. Data from one patient were not reported. Rates of clinical cure or improvement with tigecycline treatment were 90.2%. Two patients (4%) had drug related adverse events (one thrombocytopenia and one fever/chills); 10 patients (20%) died.

CONCLUSIONS

Tigecycline alone or in combination therapy was an effective and safe antibiotic treatment in critically ill and antimicrobially pre-treated patients with NSTI frequently caused by resistant pathogens.

Polymicrobial wound infections: pathophysiology and current therapeutic approaches

Acute and chronic wounds represent a very common health problem in the entire world. The dermal wounds are colonized by aerobic and anaerobic bacterial and fungal strains, most of them belonging to the resident microbiota of the surrounding skin, oral cavity and gut, or from the external environment, forming polymicrobial communities called biofilms, which are prevalent especially in chronic wounds. A better understanding of the precise mechanisms by which microbial biofilms delay repair processes together with optimizing methods for biofilm detection and prevention may enhance opportunities for chronic wounds healing. The purpose of this minireview is to assess the role of polymicrobial biofilms in the occurrence and evolution of wound infections, as well as the current and future preventive and therapeutic strategies used for the management of polymicrobial wound infections.

[Pathogenesis, classification and diagnosis of necrotizing soft tissue infections]

Necrotizing soft tissue infections are caused by a variety of pathogens and may affect different types of soft tissue. Even today mortality and lethality are very high. The primary symptoms of necrotizing soft tissue infections are local pain out of proportion, swelling, erythema and crepitation in cases of subcutaneous gas. A systemic inflammatory response syndrome (SIRS) is often associated. During the last decades early recognition and initiation of an adequate therapy were able to reduce lethality to an average of 20%. The physical examination remains the diagnostic gold standard and may be supported by typical findings of imaging technologies, e.g. subcutaneous gas on x-rays and laboratory tests. After diagnosis an adequate antibiotic and surgical therapy should be performed immediately.

[Management of soft tissue infections in the region of the extremities and the trunk]

Skin and soft tissue infections (SSTI) are amongst the most common bacterial infections in humans. SSTI have a broad range of aetiology, clinical manifestation and severity. The outcome may be spontaneous resolution or on the other end sepsis with lethal outcome. Useful classifications are those which differentiate SSTI according to urgency of surgical intervention. The definitive diagnosis should be made by the clinical picture of the lesion and the condition of the patient. The key to successful treatment of many severe necrotizing soft tissue infections is based on early detection and prompt surgical debridement. This procedure has to be followed by an optimal wound management. From the early beginning of treatment an adequately calculated antibiotic treatment is mandatory. At the end of the treatment the wound has to be closed by an aesthetic scar with high mechanical load capacity.

Complicated skin, skin structure and soft tissue infections - are we threatened by multi-resistant pathogens?

Tissue infections or skin, skin structure, and deep seated soft tissue infections are general terms for infections of the entire skin layer including the subcutaneous and muscle tissue layers and their respective fascia structures. Infections of the different mediastinal fascias (mediastinitis) and retroperitoneal fascia infections also belong to this category. Due to the variability of their clinical presentation, skin and soft tissue infections can be classified according to different features. The following aspects can be used for classification:

- anatomical structures

- pathogens

- necessity for urgent treatment

- extent of infection

The incidence of skin and soft tissue infections in which MRSA (methicillin-resistent Staphylococcus aureus) is involved has been steadily increasing over the past 15 years. These wounds should be treated according to the same open treatment principles as other infected wounds. Since these infections are often superficial contaminations, antibiotic therapy is not indicated. If systemic infection occurs in form of MRSA sepsis, antibiotic therapy is indicated.

Several recent reports identified MRSA as the leading pathogen in SSTIs. It also causes 20% to 50% of diabetes-associated foot infections in several countries and is associated with worse outcomes than other pathogens.

Treatment of complicated skin and soft-tissue infections caused by resistant bacteria: value of linezolid, tigecycline, daptomycin and vancomycin

Antibiotic-resistant organisms causing both hospital- and community-acquired complicated skin and soft-tissue infections (cSSTI) are increasingly reported. A substantial medical and economical burden associated with MRSA colonisation or infection has been documented. The number of currently available appropriate antimicrobial agents is limited. Good quality randomised, controlled clinical trial data on antibiotic efficacy and safety is available for cSSTI caused by MRSA. Linezolid, tigecycline, daptomycin and vancomycin showed efficacy and safety in MRSA-caused cSSTI. None of these drugs showed significant superiority in terms of clinical cure and eradication rates.To date, linezolid offers by far the greatest number of patients included in controlled trials with a strong tendency of superiority over vancomycin in terms of eradication and clinical success.. - Tigecycline is an alternative in polymicrobial infections except by diabetic foot infections. Daptomycin might be a treatment option for cases of cSSTI with MRSA bacteremia. cSSTI caused by resistant Gram-negative bacteria are a matter of great concern. The development of new antibiotics in this area is an urgent priority to avoid the risk of a postantibiotic era with no antimicrobial treatment options. An individual approach for every single patient is mandatory to evaluate the optimal antimicrobial treatment regimen.

The science of wound bed preparation

The concept of wound bed preparation (WBP) heralded a new era in terms of how we treat wounds. It emphasized the difference between acute and chronic wounds, and it cemented the idea that the processes involved in the healing of acute wounds do not apply completely to the healing of chronic wounds. The arbitrary division of the normal healing process into the phases of hemostasis, inflammation, proliferation, and maturation addresses the events in acute wound healing. We have realized that the impediments to healing in chronic wounds lead to a failure to progress through these phases and are independent factors that make the chronic wound a much more complex condition. A major advance in resolving or addressing the chronic wound has been the concept of WBP. WBP allows us to address the problems of wound healing individually the presence of necrotic tissue, hypoxia, high bacterial burden, corrupt matrix, and senescent cells within the wound bed. In WBP we can optimize our therapeutic agents to accelerate endogenous healing or to increase the effectiveness of advanced therapies.

It's Fournier's gangrene still dangerous?

BACKGROUND

Fournier's gangrene is known to have an impact in the morbidity and despite antibiotics and aggressive debridement, the mortality rate remains high.

OBJECTIVES

To assess the morbidity and mortality in the treatment of Fournier's gangrene in our experience.

METHODS

The medical records of 14 patients with Fournier's gangrene who presented at the University Hospital Center "Mother Teresa" from January 1997 to December 2006 were reviewed retrospectively to analyze the outcome and identify the risk factor and prognostic indicators of mortality.

RESULTS

Of the 14 patients, 5 died and 9 survived. Mean age was 54 years (range from 41-61): it was 53 years in the group of survivors and 62 years in deceased group. There was a significant difference in leukocyte count between patients who survived (range 4900-17000/mm) and those died (range 20.300-31000/mm3). Mean hospital stay was about 19 days (range 2-57 days).

CONCLUSION

The interval from the onset of clinical symptoms to the initial surgical intervention seems to be the most important prognostic factor with a significant impact on outcome. Despite extensive therapeutic efforts, Fournier's gangrene remains a surgical emergency and early recognition with prompt radical debridement is the mainstays of management.

Interleukin-6 concentrations in wound fluids rather than serological markers are useful in assessing bacterial triggers of ulcer inflammation

Bacterial pathogenicity, microbial load and diversity are decisive for outcome and therapy of non healing ulcers. However, until now, no routine laboratory parameter is available to assess the inflammatory level caused by chronic wound infections. We thus investigated the usefulness of levels of interleukin (IL)-6 and tumour necrosis factor alpha (TNFalpha) in wound fluids for assessing ulcer inflammation in the presence or absence of microbial triggers. In addition, the predictive values of local cytokine analyses were compared with those of C-reactive protein (CRP) and lipopolysaccharide-binding protein (LBP) because serological markers are normally used to underline the suspicion of wound infections. The present data from chronic arterial and venous ulcers (n = 45) clearly show that mixed bacterial infections increased IL-6 and TNFalpha concentrations in wound fluids when compared with ulcers with a monomicrobial infection (P < 0.01 and P < 0.05, respectively). IL-6 was also significantly elevated when a high bacterial load [versus <10(5) colony-forming units (cfu)/ml: P = 0.04] or an infection with Pseudomonas was observed (versus isolation of non Pseudomonas strains: P = 0.05). Although distinct proinflammatory triggers may interfere with regard to cytokine levels, sensitivity and specificity were significant in predicting bacterial risk factors, particularly for IL-6 at a designated cut-off of 125 pg/ml (sensitivity and specificity for predicting a mixed infection: 70% and 64%, for predicting a bacterial load of >10(5) cfu/ml: 62% and 57% and for predicting an infection with Pseudomonas: 90% and 57%). In contrast to local cytokine levels, the serological markers CRP and LBP were not associated with the presence of any of the investigated bacterial triggers. Focusing on the aim of the study, IL-6 analysed in wound washouts seems to be a useful diagnostic marker for a sensitive and specific assessment of ulcers inflammation with regard to bacterial triggers.

The science of wound bed preparation

The concept of wound bed preparation (WBP) heralded a new era in terms of how we treat wounds. It emphasized the difference between acute and chronic wounds, and it cemented the idea that the processes involved in the healing of acute wounds do not apply completely to the healing of chronic wounds. The arbitrary division of the normal healing process into the phases of hemostasis, inflammation, proliferation, and maturation addresses the events in acute wound healing. We have realized that the impediments to healing in chronic wounds lead to a failure to progress through these phases and are independent factors that make the chronic wound a much more complex condition. A major advance in resolving or addressing the chronic wound has been the concept of WBP. WBP allows us to address the problems of wound healing individually-the presence of necrotic tissue, hypoxia, high bacterial burden, corrupt matrix, and senescent cells within the wound bed. In WBP we can optimize our therapeutic agents to accelerate endogenous healing or to increase the effectiveness of advanced therapies.

Necrotizing fasciitis and gangrene associated with topical herbs in an infant

A 4-mo-old Chinese infant developed necrotizing fasciitis and gangrene from a small skin infection on his buttock that was treated with topical herbs. Sequential cultures revealed a number of organisms: Enterococcus species, sensitive to ampicillin, were isolated throughout the course, and coagulasenegative staphylococci replaced gram-negative rods during the later phase of the illness. The infant required prolonged intravenous antibiotic treatment and underwent multiple surgical procedures for debridement and reconstruction. This report serves to alert the public of the importance of avoiding application of unknown topical herbs in children with skin disease. A seemingly small wound, if inappropriately treated, may result in extensive tissue destruction and require extensive surgery.

[Necrotizing soft tissue infections: nomenclature and classification]

Terminology used to refer to necrotizing infections is extensive because of the absence of clear definitions and the use of classification systems based on a variety of criteria, including etiologic, microbiologic, anatomic, and clinical aspects. This situation has led to some confusion. In the attempt to unify terminology, it might be more appropriate to use only the terms necrotizing fasciitis and myonecrosis, in which differentiation is mainly anatomical. Another option would be to use only the expression necrotizing soft tissue infections, a non-specific term, since these constitute a group of clinical processes having similar pathophysiologic characteristics and therapeutic principles.

Wound pathophysiology, infection and therapeutic options

Wound healing is a complex and highly regulated process that can be compromised by both endogenous factors (pathophysiological) and exogenous factors (micro-organisms). Microbial colonisation of both acute and chronic wounds is inevitable, and in most situations endogenous bacteria predominate, many of which are potentially pathogenic in the wound environment. The risk of wound infection increases as local conditions favour bacterial growth rather than host defence. Consequently a primary objective in wound management is to redress the host-bacterial balance, and this is most effectively achieved by ensuring that the wound is cleared of devitalised tissue and foreign bodies, the bacterial load and inflammation are controlled, and that adequate tissue perfusion is maintained. Although surgical debridement is the most rapid and effective technique for removing devitalised tissue, topical enzymes, moisture-retentive dressings, biosurgical therapy and vacuum therapy have been used as alternative approaches to wound cleansing and preparation. Topical antimicrobial agents continue to be used widely for preventing wound infection and current interest is focused on alternatives to antibiotics, such as antimicrobial moisture-retentive dressings, honey, essential oils and cationic peptides. In addition to the need to control wound microflora, unregulated inflammation caused by both micro-organisms and underlying abnormal pathophysiological conditions is a major factor associated with poor healing in chronic wounds. Consequently, therapeutic strategies that target chronic inflammatory processes are critical to wound progression. The success of future therapies will be dependent on a growing understanding of the pathophysiological processes and the host-bacterial interactions that significantly influence wound healing.

Necrotising orbital cellulitis

PURPOSE

To report 2 cases of severe necrotising orbital cellulitis which illustrate the need for aggressive surgical management to prevent blindness.

METHODS

The case records of 2 patients with necrotising orbital cellulitis were reviewed.

RESULTS

Both patients had orbital cellulitis associated with sinusitis. Each case was characterised by the rapid development of severe systemic toxicity, extensive soft tissue necrosis and abscess formation. One patient developed panophthalmitis and the eye had to be eviscerated. The other patient underwent repeated surgical drainage of multiple orbital abscesses. This led to resolution of the infection and preservation of vision.

CONCLUSIONS

Atypical rapidly progressive necrotising orbital cellulitis may occasionally be encountered. In such cases, aggressive surgical drainage of orbital abscesses is crucial to prevent blindness and death.

Wound microbiology and associated approaches to wound management

The majority of dermal wounds are colonized with aerobic and anaerobic microorganisms that originate predominantly from mucosal surfaces such as those of the oral cavity and gut. The role and significance of microorganisms in wound healing has been debated for many years. While some experts consider the microbial density to be critical in predicting wound healing and infection, others consider the types of microorganisms to be of greater importance. However, these and other factors such as microbial synergy, the host immune response, and the quality of tissue must be considered collectively in assessing the probability of infection. Debate also exists regarding the value of wound sampling, the types of wounds that should be sampled, and the sampling technique required to generate the most meaningful data. In the laboratory, consideration must be given to the relevance of culturing polymicrobial specimens, the value in identifying one or more microorganisms, and the microorganisms that should be assayed for antibiotic susceptibility. Although appropriate systemic antibiotics are essential for the treatment of deteriorating, clinically infected wounds, debate exists regarding the relevance and use of antibiotics (systemic or topical) and antiseptics (topical) in the treatment of nonhealing wounds that have no clinical signs of infection. In providing a detailed analysis of wound microbiology, together with current opinion and controversies regarding wound assessment and treatment, this review has attempted to capture and address microbiological aspects that are critical to the successful management of microorganisms in wounds.

Hyperbaric oxygen therapy in the treatment of soft tissue necrosis resulting from a stingray puncture

Necrotizing soft tissue processes of the foot secondary to an acute stingray envenomation can be a challenge to manage. Very little is reported in the orthopaedic literature to aid the practicing surgeon faced with this problem. In this case report, we describe the wound management and team approach employed in this patient's care, including the indications for hyperbaric oxygen therapy, which, in this case, was ultimately successful.

The microbiology of infected and noninfected leg ulcers

BACKGROUND

A clinical study was undertaken to investigate and compare specifically the aerobic and anaerobic microbiology of infected and noninfected leg ulcers.

METHODS

Leg ulcers, defined as being infected on the basis of clinical signs, were swab sampled and investigated for aerobic and anaerobic microorganisms using stringent isolation and identification techniques.

RESULTS

Two hundred and twenty isolates were cultured from 44 infected leg ulcers, in comparison with 110 isolates from 30 noninfected leg ulcers. Statistical analysis indicated a significantly greater mean number of anaerobic bacteria per infected ulcer (particularly Peptostreptococcus spp. and Prevotella spp.) in comparison with the noninfected ulcer group (2.5 vs. 1.3, respectively) (P < 0.05). Also, anaerobes represented 49% of the total microbial composition in infected leg ulcers compared with 36% in noninfected leg ulcers. The mean numbers of aerobes per wound in the two ulcer groups were not statistically different (P > 0.05). The study failed to demonstrate a clear correlation between commonly implicated facultative pathogens and wound infection. The isolation rate of Pseudomonas aeruginosa was generally low and, although Staphylococcus aureus was a frequent isolate in both wound types, it was more prevalent in noninfected leg ulcers.

CONCLUSIONS

This study has demonstrated the complex aerobic-anaerobic microflora which exists in leg ulcers, the prevalence of anaerobes in infected wounds, and a poor correlation between the presence of specific aerobic pathogens and wound infection. In view of these findings, the role of microbial synergistic interactions in the pathogenesis of chronic wound infection may be of greater clinical importance than the isolated involvement of any specific potential pathogen.

[Four hours for a record, or a severe fuminating cellulitis: can Saccharomyces cerevisiae be the causal agent?]

A 31-year-old woman presented with a subcutaneous cellulitis which occurred within four hours following a minor wound of a knee. This very short delay could be explained neither by the health state, nor the mechanism of injury, nor the bacteria usually responsible for such a cellulitis. Considering the clinical characteristics (high gas production) and the professional context (wine cellar employee), Saccharomyces cerevisiae, a yeast used for wine or bread production, may explain this complication.

Aerobic and anaerobic microbiology of necrotizing fasciitis in children

Specimens obtained from eight children with necrotizing fasciitis (NF) were cultured for aerobic and anaerobic bacteria. A total of 21 isolates were recovered, 13 anaerobic and 8 aerobic or facultatives. The facultative organism Streptococcus pyogenes was present alone in two (25%) instances, and mixed aerobic and anaerobic bacteria were isolated in six (75%). The predominant isolates were Peptostreptococcus spp. (6 isolates, including 3 Peptostreptococcus magnus). S. pyogenes (4), Bacteroides fragilis group (3), Clostridium perfringens (2), Escherichia coli (2), and Prevotella spp. (2). Organisms similar to the ones isolated from the NF aspirates were recovered in the blood of all patients except one. These included S. pyogenes (3 isolates). B. fragilis group (2), E. coli (1), and P. magnus (1) and Clostridium perfringens (1). All patients underwent surgical fasciotomy, and four required skin grafting. Antimicrobials were administered to all children. Despite extensive resection and intense supportive therapy, three patients died from sepsis accompanied by shock acidosis and disseminated intravascular coagulation. These findings illustrate the polymicrobial aerobic-anaerobic flora of NF in children.

Streptococcal necrotising fasciitis

Three cases of streptococcal necrotising fasciitis are described. Its relative rarity and the lack of superficial inflammation leading to diagnostic difficulty is emphasised. The diagnosis is readily confirmed microbiologically but the clinician should bear in mind that antibiotics may not be curative and that surgery is often required.

Retroperitoneal necrotizing fasciitis

Necrotizing fasciitis is a mixed infection of the skin and subcutaneous tissues with a characteristic clinical and pathological appearance. Early radical surgical excision of all affected tissue is the treatment of choice. In a series of 19 patients with necrotizing fasciitis, bacteriological assessment in 15 confirmed the mixed nature of the infection, with Bacteroides sp. isolated from ten patients. All 12 patients who underwent radical surgical excision survived. A subgroup of patients was identified in whom the appearance of necrotizing fasciitis in the abdomen or perineum was indicative of more extensive disease in the retroperitoneal tissues. Surgical resection of all affected tissue was not feasible in these cases and the outcome was uniformly fatal, giving an overall mortality rate for the series of 37 per cent.