11/1/2020 Necrotizing Fasciitis ▪Is a surgical diagnosis characterized by friability of the superficial fascia, Necrotizing dishwater-gray exudate, and a notable Soft-Tissue absence of pus. Infections N ENGL J MED 2017;377:2253-65. 1 2 Necrotizing fasciitis type I: Necrotizing fasciitis type II ▪ Polymicrobial infection involving aerobic ▪ Often associated with gas in the tissue ▪ A monomicrobial infection. and anaerobic organisms. and thus is difficult to distinguish from gas gangrene ▪ Seen in the elderly or in those with ▪ Among gram-positive organisms, group A streptococcus is the underlying illnesses. ▪ Nonclostridial anaerobic cellulitis and most common pathogen, followed by MRSA. synergistic necrotizing cellulitis are type ▪ Predisposed I variants. Both occur in patients with ▪ May occur in any age group and in those without underlying illness ▪ Diabetic or decubitus ulcers diabetes and typically involve the feet, ▪ Hemorrhoids with rapid extension into the leg ▪ Aeromonas hydrophila (freshwater laceration) ▪ Rectal fissures ▪ Necrotizing fasciitis should be ▪ Vibrio vulnificus (saltwater laceration, ingestion of raw oysters, ▪ Episiotomies considered in patients with systemic cirrhosis) ▪ Colonic or urologic surgery or gynecologic manifestations of sepsis, such as procedures. tachycardia, leukocytosis, acidosis, or ▪ Necrotizing group A streptococcal and clostridial infections are marked hyperglycemia mediated by bacterial exotoxins and the host response ▪ Ludwigs- submandibular ▪ Lemierre’s –thrombophlebitis of jugular ▪ Fournier’s-urethral breach 3 4 Invasive Group A Streptococcal Soft-Tissue Infections Invasive Group A Streptococcal Soft-Tissue Infections (Streptococcus Continued pyogenes) ▪ Infection with a defined portal of bacterial entry: Infection that arises spontaneously in the deep tissue, without an overt wound or lesion: ▪ In 50% of patients with group A streptococcal necrotizing fasciitis or myonecrosis, are without a portal ▪ S. pyogenes gains entry to the deep tissues through superficial cutaneous lesions (chickenpox of entry, often at sites of nonpenetrating trauma (muscle strain or bruise). vesicles, insect bites), after breaches of skin or mucosal integrity (e.g. drug injections, surgical incisions, childbirth), or after penetrating trauma. ▪ Only fever and crescendo pain may be present. Malaise, myalgias, diarrhea, and anorexia may be present in the first 24 hours ▪ The initial lesion may appear to be only mildly erythematous, but over 24 - 72 hours, inflammation becomes extensive, the skin turns dusky and then purplish, and bullae appear. ▪ Since cutaneous manifestations are absent initially, the infection is often misdiagnosed or the correct diagnosis is delayed, and as a result, mortality is > 70%. ▪ By the time ecchymoses and bullae develop, tissue destruction is extensive, and systemic toxicity and organ ▪ Bacteremia is frequently present, and metastatic infections may occur. failure are evident. Very rapidly, the skin becomes gangrenous and undergoes extensive sloughing. At this stage, mortality is high, even with treatment ▪ Emergency surgery, including extensive debridement or multiple amputations, is often required to ensure survival 5 6 1 11/1/2020 Nonsteroidal Anti-inflammatory Drugs Necrotizing Clostridial Infections and Group A Streptococcal Infection ▪ Proponents note that NSAIDs can suppress neutrophil functions ▪ Gas gangrene (clostridial myonecrosis) is an acute invasion of and augment the production of tumor necrosis factor α, a key healthy living tissue that occurs spontaneously or as a result of mediator of septic shock. traumatic injury . It can recur. ▪ Others argue that NSAIDs merely mask the signs and symptoms of ▪ Deeply penetrating injuries that compromise the blood supply developing infection, delaying diagnosis and treatment. Studies create an anaerobic environment that is ideal for spore have not resolved the issue germination and bacterial proliferation. Such trauma accounts for 70% of cases of gas gangrene ▪ Other predisposing conditions: Bowel and biliary tract surgery, IM epinephrine injection, retained placenta, prolonged rupture of the membranes, and intrauterine fetal death. ▪ Clostridium perfringens causes approximately 80% 7 8 Diagnosis of Necrotizing Fasciitis and Other Spontaneous (nontraumatic) gas gangrene Necrotizing Infections ▪ C. septicum, which is more aerotolerant than other clostridial pathogens. ▪ Most infections occur in patients with GI portals of entry such as adenocarcinoma or in those with neutropenia. ▪ C. sordellii infections can affect women after natural childbirth, as well as after abortion or other GYN procedures. ▪ Such infections can also develop after traumatic injuries and surgical procedures or illicit-drug injection. ▪ Common sites include the skin, muscle, uterus, and perineum. ▪ Systemic signs include an absence of fever, profound hypotension, diffuse capillary leak, hemoconcentration (HCT 50 - 80%), and a marked leukemoid reaction (WBC 50,000 - 150,000/cubic mm). ▪ Mortality is 70 - 100%, and death occurs within 2 - 4 days after hospital admission NEJM377;23 December 7, 2017 9 10 Clinical Findings Imaging Tests ▪ Classic manifestations of necrotizing fasciitis: soft-tissue ▪ Imaging studies will show soft-tissue swelling with group A ▪ edema (in 75% of cases) ▪ erythema (72%) streptococcal infection and will show gas in the tissues of patients ▪ severe pain (72%), ▪ tenderness (68%) with gas gangrene or necrotizing fasciitis type I. ▪ fever (60%) ▪ skin bullae or necrosis (38%). ▪ Gas in the tissues, or the presence of crepitus, should prompt ▪ In a recent study, factors that differentiated necrotizing fasciitis from cellulitis: immediate surgical consultation. Recent surgery, pain out of proportion to clinical signs, hypotension, skin necrosis, and hemorrhagic bullae. ▪ MRI may show thickening and hyperintensity of intermuscular ▪ In patients with cryptogenic group A streptococcal infection (i.e., infection with fascia, findings that are sensitive but not entirely specific for no portal of entry), the process begins deep in the tissues. Crescendo pain is the most important clinical clue, and its onset typically occurs well before shock or necrotizing fasciitis. organ dysfunction is manifested ▪ The absence of fascial enhancement on enhanced CT has been ▪ all patients presenting with a sudden onset of severe pain in an extremity, with or without an obvious portal of bacterial entry or the presence of fever, should shown to be specific for necrotizing fasciitis as opposed to other be evaluated for severe soft-tissue infection musculoskeletal infections 11 12 2 11/1/2020 Tissue Biopsy, Histologic Tests, and Gram’s Surrogate Markers for Early Diagnosis Staining of Necrotizing Fasciitis ▪ Gram’s staining of surgically obtained material is crucial for ▪ Group A streptococcal infection determining the cause of infection and guiding treatment. ▪ C-reactive protein level of more than 200 mg ▪ White-cell count with a marked left shift ▪ Group A streptococcal necrotizing infection is characterized ▪ Elevated serum creatinine histologically by the destruction of muscle tissue, a paucity of ▪ C. sordellii infection infiltrating phagocytes, and large numbers of gram-positive cocci. ▪ Marked leukemoid reactions (50 to150,000 white cells per cubic millimeter) ▪ The findings are similar for gas gangrene, though with more ▪ profound hemoconcentration are characteristic evidence of edema, gas formation, or both. ▪ Necrotizing fasciitis I ▪ WBC > 15,400/mm3 plus ▪ serum sodium < 135 mmol/L ▪ Elevated CPK or AST suggest deep infection involving muscle or fascia (as opposed to cellulitis) 13 14 LRINEC Treatment Surgical Intervention Pharmacologic Treatment ▪ LRINEC scores of 5.8 or higher (on a scale of 0 to 13, with higher ▪ For patients with aggressive soft-tissue ▪ Polymicrobial Necrotizing Infections: IDSA scores indicating a greater likelihood of necrotizing soft-tissue infection or those with mild infection guidelines are Vancomycin or linezolid plus one plus evidence of systemic toxicity, of the following: piperacillin-tazobactam, a infection), prompt surgical exploration is very carbapenem, or ceftriaxone-metronidazole. ▪ the positive predictive value for necrotizing fasciitis ranged from 57 to important for 3 reasons: ▪ Group A Streptococcal Infections: Treatment 92% in three studies ,4,65,67 with negative predictive values of 86% ▪ to determine the extent of infection with penicillin plus clindamycin 10-14 days ▪ to assess the need for debridement or and 96% in two studies amputation ▪ A. hydrophila: Treated with doxycycline plus either ciprofloxacin or ceftriaxone. ▪ to obtain specimens for Gram’s staining and culture ▪ Use with caution, as the LRINEC Score has performed poorly in ▪ • V. vulnificus: Treated with doxycycline plus either ceftriaxone or cefotaxime. external validation, most recently in Neeki 2017 ▪ Survival is significantly increased among patients taken to surgery within ▪ • MRSA infections: Vancomycin, linezolid, 24 hours after admission. Survival is daptomycin, or ceftaroline. further increased with earlier surgical intervention (e.g., within 6 hours) 15 16 Care of Critically Ill Patients Adjunctive Measures ▪ Capillary Leak Syndrome ▪ Hyperbaric Oxygen: Controversial. Surgical debridement should not ▪ Circulating bacterial toxins and host mediators cause diffuse endothelial damage. ▪ IV fluid requirements may be extremely high (10 - 12 L of NS/day). be delayed for hyperbaric oxygen treatment ▪ Profound hypoalbuminemia