Case Based Pediatrics For Medical Students and Residents

Chapter VI.33.  Necrotizing Fasciitis
Chad S.D. Sparks

This is an 11 year old, previously healthy male who presents to the office with a chief complaint of extreme pain from a 3 day old puncture wound on his right calf.  He also reports fever, redness, and swelling for one day.  The height of his fevers is not measured.  He was given acetaminophen for fever and pain.  The fever improved, but the pain has worsened.

Exam:  VS T 39 degrees C, HR 132, RR 26, BP 105/78.  He is alert and in obvious pain.  HEENT exam is negative.  Lungs are clear.  Breathing is tachypneic.  Heart is tachycardic, without murmurs or extra sounds.  Abdomen is soft and non-tender.  A round puncture wound measuring 0.3 cm in diameter is noted on his right lateral calf with erythema and edema extending distally for 3 cm.  Palpation of this area results in severe tenderness.  The capillary refill of the skin overlying this region is slightly delayed.

 A wound culture is obtained.  A CBC and blood culture are drawn.  IV ceftriaxone is administered and he is admitted to the hospital.  Over the next 36 hours, the skin near his wound progressively develops a bluish discoloration, blisters, and bullae.  Group A-beta hemolytic streptococci (GABHS) is isolated from the wound culture and blood culture.  Ceftriaxone is discontinued and he is started on IV penicillin G and clindamycin for necrotizing fasciitis (NF).  On the second day of hospitalization, an MRI finds fluid in a fascial plane of the lateral compartment of the lower leg.  Surgical debridement is performed and brown serous fluid is removed and cultured.  The surgeon confirms the diagnosis of NF.  GABHS grows from the serous fluid the next day.

He continues to require daily surgical debridement until the sixth day of hospitalization, but he slowly improves.  He is discharged on day ten.  Follow-up for the next month shows good recovery. 

Necrotizing fasciitis (NF) is a group of infections that present in any age group as an abrupt, rapidly advancing soft-tissue infection with systemic toxicity and high mortality (1).  It is characterized by microbial spread along the fascial planes into deep tissue, which results in necrosis of the superficial tissue. 

The classification of NF is ambiguous because of its similarity to other syndromes and its numerous etiologies.  Often, the diagnoses will overlap as infection spreads to adjacent tissue.  For example, necrotizing cellulitis may involve the fascial planes secondarily or vice versa.  Several studies have tried to classify NF based on anatomic location, bacterial flora, presence or absence of crepitance, and clinical progression.

NF falls under the general category of necrotizing soft tissue infection (NSTI).  There are three types of NSTI:  1) NF, 2) necrotizing cellulitis, and 3) myonecrosis.  However, NF is often used in clinical settings as a broadly inclusive term for overlapping types of NSTI.  Clinically, there are three syndromes of NF that are often described and easy to conceptualize:  Type I is polymicrobial and includes saltwater NF due mainly to marine Vibrio species.  Type II is group A streptococcal NF.  Type III is clostridial myonecrosis or gas gangrene (2).  The most common form of NF is the polymicrobial Type I.  In one pediatric study, 75% of children developed NF with polymicrobial etiology (Type I) (3).  The most common species of bacteria cultured from a study of 182 subjects in Maryland were Streptococcal species, Staphylococcal species, Enterococcal species, and Bacteroides species.  Anaerobes such as Clostridia were also common in type I NF and could be differentiated by gas production visible on imaging studies.  The most common bacteria in type I NF is Bacteroides, which is a gram-negative anaerobic bacillus.  Fournier's gangrene is a variant of polymicrobial NF usually found in the scrotum or penis of older, often immunocompromised individuals.  This variant is rare in children.

Type II infection with GABHS is probably the most extensively studied type of NF and is common in children (4,5).  However, Type II NF has received extra att