Case records of the Massachusetts General Hospital. Case 2-2009. A 25-year-old man with pain and swelling of the right hand and hypotension

"Emergency" definitive reconstruction of a necrotising fasciitis thigh debridement defect with a pedicled TRAM flap

INTRODUCTION

Necrotising fasciitis (NF) is a rare, severe, rapidly progressing and life-threatening synergistic infection primarily affecting the superficial fascia. A novel method of definitive and aesthetic reconstruction of NF thigh defects by using a pedicled transverse rectus abdominis myocutaneous (TRAM) flap without recourse to temporising skin grafts is presented.

PRESENTATION OF CASE

A 30-year-old parous woman presented in extremis with fulminant NF of her left anteromedial thigh. Following emergency radical debridement and intensive care stabilisation she was reconstructed 48h later in a single stage with a pedicled TRAM flap islanded on the ipsilateral deep inferior epigastric vessels. There was excellent contour restoration of her thigh and coverage of the exposed femoral vessels.

DISCUSSION

Pedicled flaps based on the rectus abdominis muscle provide a large, readily available reconstructive option for correction of substantial regional defects as herein illustrated. They are robust when based on dominant inferior vascular pedicle with a long reach and wide arc of rotation when designed transversely (as a TRAM flap).

CONCLUSION

This case also illustrates that definitive flap reconstruction of NF can be successfully undertaken in the emergent setting, thereby negating the need for large areas of skin grafting which can lead to contractures with consequent functional impairment and suboptimal aesthetic results.

An aggressive group a streptococcal cellulitis of the hand and forearm requiring surgical debridement

Group A streptococcus is responsible for a diverse range of soft tissue infections. Manifestations range from minor oropharyngeal and cellulitic skin infections to more severe conditions such as necrotizing fasciitis and septic shock. Troubling increases in the incidence and the severity of streptococcal infections have been reported over the past 25 years. Cases of streptococcal necrotizing fasciitis have received significant attention in the literature, with prompt surgical debridement being the mainstay of treatment. However, cases of rapidly progressing upper extremity streptococcal cellulitis leading to shock and a subsequent surgical intervention have not been well described. This article presents a case of an 85-year-old woman with a rapidly progressing, erythematous, painful, swollen hand associated with fever, hypotension, and mental status change. Due to a high clinical suspicion for necrotizing fasciitis, the patient was rapidly resuscitated and underwent immediate surgical irrigation and debridement. All intraoperative fascial pathology specimens were negative for necrotizing fasciitis, leading to a final diagnosis of Group A streptococcal cellulitis. Although surgical intervention is not commonly considered in patients with cellulitis, our patient benefited from irrigation and debridement with soft tissue decompression. In cases of necrotizing fasciitis as well as rapidly progressive cellulitis, prompt diagnosis and aggressive treatment may help patients avoid the catastrophic consequences of rapidly progressive group A streptococcal infections.

Molecular pathogenesis of necrotizing fasciitis

Necrotizing fasciitis, also known as the flesh-eating disease, is a severe invasive infection associated with very high rates of human morbidity and mortality. It is most commonly caused by group A Streptococcus(GAS), a versatile human pathogen that causes diseases ranging in severity from uncomplicated pharyngitis (or strep throat) to life-threatening infections such as necrotizing fasciitis. Herein, we review recent discoveries bearing on the molecular pathogenesis of GAS necrotizing fasciitis. Importantly, the integration of new technologies and the development of human-relevant animal models have markedly expanded our understanding of the key pathogen-host interactions underlying GAS necrotizing fasciitis. For example, we now know that GAS organisms secrete a variety of proteases that disrupt host tissue and that these proteolytic enzymes are regulated by multiple transcriptional and posttranslational processes. This pathogenesis knowledge will be crucial to supporting downstream efforts that seek to develop novel vaccines and therapeutic agents for this serious human infection.

Severe soft tissue infections

Severe skin and soft tissue infections (SSTIs) frequently require management in the ICU, in part related to associated septic shock or toxic shock syndrome or associated organ failure. Four fundamental management principles are key to a successful outcome in caring for patients who have severe SSTIs, including (1) early diagnosis and differentiation of necrotizing versus nonnecrotizing SSTI, (2) early initiation of appropriate empiric broad-spectrum antimicrobial therapy with consideration of risk factors for specific pathogens and mandatory coverage for methicillin-resistant Staphylococcus aureus (MRSA), (3) source control (ie, early aggressive surgical intervention for drainage of abscesses and debridement of necrotizing soft tissue infections), and (4) pathogen identification and appropriate de-escalation of antimicrobial therapy. MRSA has emerged as the most common identifiable cause of severe SSTIs; therefore, initiation of empiric anti-MRSA antimicrobials is warranted in all cases of severe SSTIs. In addition, appropriate critical care management-including fluid resuscitation, organ support and nutritional support-is a necessary component in treating severe SSTIs.

CD46 transgenic mouse model of necrotizing fasciitis caused by Streptococcus pyogenes infection

We developed a human CD46-expressing transgenic (Tg) mouse model of subcutaneous (s.c.) infection into both hind footpads with clinically isolated 11 group A streptococcus (GAS) serotype M1 strains. When the severity levels of foot lesions at 72 h and the mortality rates by 336 h were compared after s.c. infection with 1x10(7) CFU of each GAS strain, the GAS472 strain, isolated from the blood of a patient suffering from streptococcal toxic shock syndrome (STSS), induced the highest severity levels and mortality rates. GAS472 led to a 100% mortality rate in CD46 Tg mice after only 168 h postinfection through the supervention of severe necrotizing fasciitis (NF) of the feet. In contrast, GAS472 led to a 10% mortality rate in non-Tg mice through the supervention of partial necrotizing cutaneous lesions of the feet. The footpad skin sections of CD46 Tg mice showed hemorrhaging and necrotic striated muscle layers in the dermis, along with the exfoliation of epidermis with intracellular edema until 48 h after s.c. infection with GAS472. Thereafter, the bacteria proliferated, reaching a 90-fold or 7-fold increase in the livers of CD46 Tg mice or non-Tg mice, respectively, for 24 h between 48 and 72 h after s.c. infection with GAS472. As a result, the infected CD46 Tg mice appeared to suffer severe liver injuries. These findings suggest that human CD46 enhanced the progression of NF in the feet and the exponential growth of bacteria in deep tissues, leading to death.